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NEET Biology Growth And Development Multiple Choice Questions

Question 1. Growth is defined as :

1. increase in size
2. increase in shape
3. increase in weight
4. permanent increase in dry weight accompanied by a permanent increase in weight, size, and volume.

Answer: 4. permanent increase in dry weight accompanied by a permanent increase in weight, size, and volume.

Question 2. The maximum growth rate occurs in:

1. exponential phase
2. lag phase
3. stationary phase
4. senescence phase.

Answer: 1. exponential phase

Question 3. Mobilization of stored food in germinating seeds is triggered by :

1. auxins
2. cytokinins
3. gibberellins
4. ethylene.

Answer: 3. gibberellins

Question 4. The highest concentrations of auxin exist:

1. at the base of various plant organs
2. in growing tips of plants
3. in leaves
4. in xylem and phloem cells only.

Answer: 2. in growing tips of plants

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Plant Growth and Development NEET Questions Question 5. Exogenous application of Gibberellins induces male flower formation on genetically female plants in:

1. Cucumis
2. Cucurbita
3. Ccirica
4. Coccinia.

Answer: 2. Cucurbita

Question 6. Presence of which of the following is associated with seed dormancy?

1. Starch
2. Ethylene
3. IAA
4. Abscisic acid.

Answer: 4. Abscisic acid

Question 7. Growth takes place when:

1. destructive processes are more than constructive ones
2. destructive and constructive processes are equal
3. constructive processes are more than destructive processes
4. only anabolic processes occur, and no catabolic processes.

Answer: 3. constructive processes are more than destructive processes

Question 8. Growing points possess :

1. meristematic cells
2. mature cells
3. dead cells
4. slowly enlarging cells.

Answer: 1. meristematic cells

Question 9. In higher plant growth takes place :

1. in the entire plant body
2. in aerial parts only
3. by growing points scattered all over the body
4. by growing points confined to certain regions of the plant.

Answer: 4. by growing points confined to certain regions of the plant.

Plant Growth and Development NEET Questions Question 10. The correct sequence of development stages in the plant is :

1. Flowering-fruiting-juvenility-germination
2. Germination-juvenility-flowering-fruiting
3. Juvenility-flowering-germination-fruiting
4. Fruiting-flowering-Juvenility-germination.

Answer: 2. Germination-juvenility-flowering-fruiting

Question 11. The correct sequence of cellular growth stage is :

1. Division-differentiation-elongation
2. Division-elongation-differentiation
3. Diffcrcntitation-division-elongation
4. Elongation-differentiation.

Answer: 2. Division-elongation-differentiation

Question 12. Some chemicals have profound effects on plant growth arc called:

1. catalytic agents
2. phytohormones
3. enzymes
4. simple hormones.

Answer: 2. phytohormones

Question 13. The short-day winter annual “Pansy” belongs to the genus:

1. Iberis
2. Viola
3. Papaver
4. Malva.

Answer: 2. Viola

Question 14. The rate of growth of a stem of the plant is measured using:

1. hydrometer
2. osmometer
3. auxanometer
4. photometer.

Answer: 3. auxanometer

Plant Growth and Development NEET Questions Question 15. Light of low intensity :

1. increases growth
2. develops weak stem
3. decreases growth
4. does not affect growth.

Answer: 2. develops weak stem

Question 16. The favorable temperature for plant growth is :

1. 10°-15°C
2. 15°-20°C
3. 35°-40°C
4. 20°-30°C.

Answer: 2. 15°-20°C

Question 17. Plant growth is regulated by :

1. environment
2. growth hormones
3. environment and growth hormones
4. None of the above.

Answer: 3. environment and growth hormones

Question 18. Classical experiments on plant growth were performed by:

1. Devers and Pall
2. Boysen-Jensen and Darwin
3. Lamarck-Boysen and Jensen
4. None of the above.

Answer:2. Boysen-Jensen and Darwin

Question 19. Phytohormones are :

1. hormones regulating growth from seed to adulthood
2. growth regulators synthesized by plants and influencing the physiological process
3. hormones regulating flowering
4. hormones regulating secondary growth.

Answer: 2. growth regulators synthesized by plants and influencing physiological process

NEET Questions Plant Growth and Development Question 20. Which type of light is favorable for plant growth?

1. White
2. Red
3. Green
4. Violet.

Answer: 2. Red

Question 21. Plants can be vernalized by :

1. heat treatment
2. hormonal treatment
3. cold temperature treatment
4. colchicine treatment.

Answer: 3. cold temperature treatment

Question 22. The combination of auxin and cytokinin which is likely to induce shoot differentiation in tobacco callus is :

1. only auxin and no cytokinin
2. only cytokinin and no auxin
3. higher concentration of auxin and lower concentration of cytokinin
4. lower concentration of cytokinin and higher concentration of auxin.

Answer: 3. higher concentration of auxin lower concentration of cytokinin

Question 23. The substance which enhances stem growth is :

1. enzyme
2. vitamin
3. auxin
4. abscisic acid.

Answer: 3. auxin

Question 24. The following plant growth substances are not growth promoters:

1. IAA
2. Gibberellins
3. Kinetin
4. Abscisic acid.

Answer: 4. Abscisic acid.

NEET Questions Plant Growth and Development Question 25. The habit of the cabbage plant can be changed drastically by the application of :

1. IAA
2. Gibberellins
3. Kinetin
4. Abscisic acid.

Answer: 2. Gibberellins

Question 26. The synthesis of amylase in certain cereals is stimulated by :

1. IAA
2. Gibberellins
3. Kinetin
4. Abscisic acid.

Answer: 2. Gibberellins

Question 27. The curvature in Avena coleoptile is associated with growth substance :

1. IAA
2. Gibberellins
3. Kinetin
4. Abscisic acid.

Answer: 1. IAA

Question 28. The short-day winter annual ‘Pansy’ belongs to the genus :

1. Iberis
2. Viola
3. Malva
4. Papaver.

Answer: 2. Viola

Question 29. 2,4-D stands for :

1. 2,4-Dichlorobutyric acid
2. 2,4-Dichlorophenoxy acetic acid
3. 2,4-Dichloronaphthalene acetic acid
4. 2,4-Dichloroacetic acid.

Answer: 2. 2,4-Dichlorophenoxy acetic acid

NEET Questions Plant Growth and Development Question 30. Intermodal elongation is promoted by :

1. gibberellic acid
2. ethylene
3. abscisic acid
4. coumarin.

Answer: 1. gibberellic acid

Question 31. To be very accurate, the long-day plants have :

1. Short night requirement for flowering
2. No night requirement for flowering
3. Long night requirement for flowering
4. Short-day requirement for flowering.

Answer: 1. Short night requirement for flowering

Question 32. In the R-FR responses of plants it is the :

1. the first treatment that counts
2. middle treatment that counts
3. last treatment that counts
4. total of all the treatments that count.

Answer: 3. The last treatment that counts

Question 33. Seedless varieties of tomatoes can be produced by :

1. spraying hormones on plants
2. spraying radioactive elements
3. by subjecting seeds to heat treatment
4. by vegetative propagation of stem.

Answer: 1. spraying hormones on plants

Question 34. Dormancy in potato buds and seeds can be broken by treating them with :

1. Auxins
2. Gibberellins
3. Auxins and cytokinins
4. Cytokinins and Gibberellins.

Answer: 4. Cytokinins and Gibberellins

Plant Growth And Development MCQ Important Concepts Question 35. Auxin hormones were first discovered by :

1. Skoog
2. Hales
3. Boysen and Jensen
4. Kogl.

Answer: 3. Boysen and Jensen

Question 36. The ethylene hormone is mainly responsible for:

1. formation of root hair
2. ripening of fruit
3. formation of nodes
4. formation of intemodes.

Answer: 2. ripening of fruit

Question 37. What will happen if Gibberellins are applied to intact plants?

1. Increase in root
2. Ripening of fruits
3. Leaf extension growth
4. Sudden elongation of the stem.

Answer: 4. Sudden elongation of the stem.

Question 38. One of the important roles of cytokinin is:

1. to check senescence
2. to check abscission
3. to mobilize solutes from one part to the other
4. to overcome dormancy.

Answer: 1. to check senescence

Plant Growth And Development MCQ Important Concepts Question 39. An excised leaf does not turn yellow if it is induced to root. This is attributed to synthesis in the root of:

1. ethylene
2. cytokinins
3. gibberellins
4. auxins.

Answer: 2. cytokinins

Question 40. Which one of the following hormones is chiefly concerned with cell division?

1. Auxin
2. Cytokinins
3. G.A.
4. 2-4

Answer: 2. Cytokinins

Question 41. In phototropism, auxins :

1. promote the growth of cells
2. stimulate differential growth of cells on different sides of the plant
3. inhibit the growth of cells
4. stimulate and signal the direction of light or gravity of the plant.

Answer: 2. stimulate differential growth of cells on different sides of the plant

Question 42. From which was kinetin isolated :

1. Coconut milk
2. Pineapple
3. Soyabean
4. Groundnut.

Answer: 1. Coconut milk

Question 43. In a short-day plant growing in a home garden, phytochrome is normally switched from one form to the other by:

1. red and far-red light
2. sunlight
3. activation by gibberellin or abscisic acid
4. measuring the length of the dark period between light periods.

Answer: 1. red and far-red light

Question 44. Which of the following are two growth inhibitors?

1. Florigen and ABA
2. Salicylic acid and ABA
3. Cinnamic acid and IAA
4. NAA and Coumarin.

Answer: 2. Salicylic acid and ABA

Question 45. In unisexual plants, sex can be changed by the application of:

1. Ethanol
2. GA
3. Cytokinins
4. ABA.

Answer: 2. GA

NEET Questions Plant Growth and Development Question 46. A long-day plant is one that :

1. requires more than 12 hours of light to flower
2. increases in height when it flowers
3. needs a certain minimum length of photoperiod to flower
4. is not affected by temperature in its flowering response.

Answer: 1. requires more than 12 hours of light to flower

Question 47. Short-day plants require :

1. Night
2. Light
3. Long dark period
4. Long light period.

Answer: 3. Long dark period

Question 48. During seed germination, its stored food is mobilized by:

1. ABA
2. Gibberellin
3. Ethylene
4. Cytoxinin

Answer: 4. Cytoxinin

Question 49. Name of the flowering hormone produced in some plants as a result of low-temperature treatment to :

1. Vemalin
2. Florigen
3. Abscisin
4. Dormin.

Answer: 1. Vemalin

Question 50. A substance that induces dormancy in the seed is :

1. GA
2. ABA
3. Thiourea
4. Cytokines

Answer: 2. ABA

NEET Questions Plant Growth and Development Question 51. The growth-controlling substances originating at the stem tips are :

1. Proteins
2. Vitamins
3. Enzymes
4. Auxins.

Answer: 4. Auxins

Question 52. An abnormally long-stemmed plant with pale yellow leaves is called:

1. Chlorotic
2. Etiolated
3. Necrotic
4. Abnormal.

Answer: 2. Etiolated

Question 53. The ripening of fruits can be accelerated by :

1. keeping fruits at high temperature
2. artificially adding ethylene
3. keeping fruits at low temperature
4. reducing H₂,O₂ supply by dehydration.

Answer: 2. artificially adding ethylene

Question 54. Cytokinin is used to :

1. cause dormancy
2. induce cell division
3. regulate cell movements
4. increase growth.

Answer: 2. induce cell division

NEET Questions Plant Growth and Development Question 55. Auxins are growth hormones related to :

1. cell elongation
2. cell differentiation
3. cell division
4. cell mutation.

Answer: 1. cell elongation

Question 56. Match the items of column 1 and Column 2.

1. A- q,   B – r,   C- p,    D- t
2. A- q,   B-s,    C-p,     D-t
3. A – q,  B -p,   C -1,    D – r
4. A – q,  B- t,   C- p,   D – r.

Answer: 3. A – q,  B -p,   C -1,    D – r

Question 57. Gibberellin was first extracted from :

1. fungi
2. algae
3. bacteria
4. roots of plants.

Answer: 1. fungi

Question 58. Hormones found in the liquid endosperm of coconut are:

1. Gibberellin
2. Auxin
3. Ethylene
4. Cytokinin.

Answer: 4. Cytokinin.

Question 59. Senescence in plants can be delayed by :

1. Auxins
2. Cytokinins
3. Gibberellins
4. Ascorbic acid.

Answer: 2. Cytokinins

NEET Important Questions Plant Growth and Development Question 60. The red-far red (R-FR) responses are not independent of:

1. IAA
2. 2, 4-D
3. GA
4. Abscisic acid.

Answer: 3. GA

Question 61. The growth hormone auxin occurs in :

1. root tip and shoot tip
2. branches
3. leaf apex
4. old leaves.

Answer: 1. root tip and shoot tip

Question 62. Gibberellin was discovered and named by :

1. Darwin
2. Yabuta and Sumiki
3. Boysen Jenson
4. Amon.

Answer: 2. Yabuta and Sumiki

Question 63. Seedless fruits can be had by treating unpollinated flowers with :

1. sucrose
2. enzymes
3. hormones
4. inhibitors.

Answer: 2. enzymes

Question 64. Photoperiodism is due to :

1. growth curvature in response to light
2. response to the relative length of day and night
3. light period
4. dark period.

Answer: 1. growth curvature in response to light

NEET Important Questions Plant Growth and Development Question 65. Photoperiodism is associated with the formation of :

1. auxin
2. florigen
3. cytokinin
4. enzymes.

Answer: 3. cytokinin

Question 66. When the terminal bud is removed, a plant grows more :

1. tall
2. bushy
3. slowly
4. rapidly.

Answer: 2. bushy

Question 67. Plant growth is :

1. Limited
2. Unlimited
3. Unlocalised
4. Diffused.

Answer: 2. Unlimited

Question 68. Genetically dwarf plants can elongate on the application of:

1. Kinetins
2. Indole acetic acid
3. GA3
4. All the above.

Answer: 3. GA3

Question 69. Maximum root growth occurs :

1. at the apex
2. in the presence of light
3. behind the apex
4. in the presence of soil.

Answer: 3. behind the apex

NEET Important Questions Plant Growth and Development Question 70. Apical dominance in higher plants is due to :

1. Excess of auxins
2. enzyme activity
3. C/N ratio
4. Light.

Answer: 1. Excess of auxins

Question 71. The Crcscofiraph was invented by :

1. Darwin
2. J.C, Bose
3. F.W, Went
4. C.V, Kaman,

Answer: 2. J.C, Bose

Question 72. Photoperiodic stimulus is perceived by :

1. Leaves
2. Flowers
3. Buds
4. Meristem.

Answer: 1. Leaves

Question 73. Which of the following plant growth substances can substitute for vernalization 7

1. Auxins
2. Cytokinins
3. Gibberellins
4. Ethylene.

Answer: 3. Ethylene.

Question 74. In a pineapple field, spraying NAA (an auxin) induces flowering because it:

1. stops vegetative growth
2. promotes flowering
3. gets converted to ethylene which induces flowering.
4. stimulates the production of ethylene,

Answer: 3. gets converted to ethylene which induces flowering

Question 75. Leaf aging is retarded by :

1. cytokinin
2. florigen
3. auxin
4. abscisic acid.

Answer: 1. cytokinin

Question 76. Which one of the following pigments is associated with flowering?

1. Photochromic
2. Cytochrome
3. Chlorophyll
4. Xanthophyll.

Answer: 1. Phytochromc

Question 77. The red-absorbing form of phytochrome gets converted to the far-red absorbing form after getting irradiated at

1. 530 nm
2. 660 nm
3. 730 nm
4. 660 nm to 730 nm.

Answer: 2. 660 nm

Plant Growth and Development NEET Questions Question 78. The stimulus of vernalization is received in annual and biennial plants by :

1. root
2. tips of young leaves
3. dry seeds
4. stem apex.

Answer: 4. stem apex

Question 79. The ‘S’ shaped (sigmoid) growth curve was postulated by:

1. Sachs
2. Blackman
3. Smith
4. Kogl.

Answer: 1. Sachs

Question 80. Lettuce seeds require a light treatment for germination. This treatment can be replaced by using one of the following phytohormones :

1. Auxins
2. Ethylene
3. Gibberellins
4. Cytokinins.

Answer: 3. Gibberellins

Question 81. The process of senescence in plants can be reversed by applying :

1. Ethylene
2. Auxins
3. Gibberellins
4. Cytokinins.

Answer: 4. Cytokinins.

Question 82. The natural form of active auxin, produced by plants, is:

1. indole acetic acid
2. colyledauxins
3. tryptophan
4. apical acid.

Answer: 1. indole acetic acid

Question 83. Parthenogenetic fruits are prepared by spraying :

1. auxins
2. cytokinins
3. Ethylene
4. Abscisic acid.

Answer: 1. auxins

Question 84. Elongation of genetically dwarf plants can be done with the help of:

1. Auxins
2. Gibberellins
3. IAA
4. Cytokinin.

Answer: 2. Gibberellins

Question 85. Which of the following pairs are correctly matched?

1. Auxin          –   Dwarf rice
2. Gibberellins   – Elongation
3. Cytokinin      – Coconut milk
4. Abscisic acid  – Early leaf fall,

Select the correct answer using the codes given below—

1. 2, 3, and 4
2. 1, 2, and 3
3. 1, Band 4
4. 1, 3, and 4

Answer: 1. 2, 3, and 4

Question 86. Hormones responsible for plant and seed dormancy during drought are:

1. IBA
2. NAA
3. ABA
4. Zealand.

Answer: 3. ABA

Question 87. Growth regulator ethylene is used for:

1. Retarding ripening of tomatoes
2. Speeding up the ripening of fruits
3. Slowing down the ripening of apples
4. Both B and C.

Answer: 2. Speeding up the ripening of fruits

Question 88. If total growth is plotted against time, the curve obtained is known as:

1. T-shaped curve
2. U-shaped curve
3. G-shaped curve
4. S-shaped curve.

Answer: 4. S-shaped curve

Question 89. The total period of growth is termed as :

1. Magnified period of growth
2. Total period of growth
3. Grand period of growth
4. Graceful period of growth.

Answer: 3. Grand period of growth

Plant Growth and Development NEET Questions Question 90. The bioassay for gibberellins is:

1. Avena curvature test
2. Soybean callus test
3. a-amylase induction test in barley aleurone cells
4. Barley leaf disc test for Chlorophylls.

Answer: 3. a-amylase induction test in barley aleurone cells

Question 91. Graph showing the growth of yeast; This is the type of growth curve noted for most organisms.

The log phase of growth is represented by :

1. Point A to B
2. Point B to C
3. Point C to D
4. Point A to C.

Answer: 2. Point B to C

Question 92. The segment C-D indicates a point where :

1. No new individuals are formed
2. The death rate is zero
3. The rate of formation and rate of death of individuals is the same
4. The experiment stopped.

Answer: 3. The rate of formation and rate of death of individuals is the same

Question 93. The segment D-E indicates a period of:

1. Decline
2. Maturation
3. Recommencement of growth
4. Active growth.

Answer: 1. Decline

Question 94. Which of the following is necessary for flower formation in higher plants?

1. Water and minerals
2. Florigen
3. Phyllocaline
4. None.

Answer: 2. Florigen

Question 95. If a brief flash of light is provided during a dark period to the plant that requires a short day then the plant is likely

1. to flower
2. not to flower
3. to have no effect
4. produces more flowers.

Answer: 2. not to flower

Question 96. In many plants, the change over from the vegetative phase to the reproductive phase takes place in response to :

1. the length of the day
2. the severity of the temperature
3. mainly the food material available in the soil
4. the oxygen present in the air.

Answer: 1. the length of the day

Question 97. In short-day plants, flowering is inhibited by :

1. Interruption of dark by white or red light
2. Dark interruption by far-red light
3. Dark interruption by red light followed by far-red light
4. Not possible.

Answer: 1. Interruption of the dark by white or red light

Question 98, Which of the following plant hormones substitutes for low-temperature treatment?

1. Auxins
2. Gibbcrcllins
3. Cytokinins
4. None of the above.

Answer: 2. Gibbcrcllins

NEET Questions Plant Growth and Development Question 99. What does the growth of a single cell, organism, and population have in common?

1. They are influenced by the environment
2. They require energy and acquire mass
3. They result in an S-shaped curve if the size is plotted against time.
4. All of the above.

Answer: 3. They result in an S-shaped curve if the size is plotted against time.

Question 100. A high concentration of auxin is present in :

1. Root apex
2. Shoot apex
3. Petiole
4. Node.

Answer: 2. Shoot apex

Question 101. Match List 1 with List 2 and select the correct answer using the codes given below the lists :

Codes :

1. 2,1,3,4
2. 2,1,4,3
3. 1,2,4,3
4. 1,2,3,4

Answer: 2. 2,1,4,3

NEET Biology Sense Organs

• Environmental information received by a sense organ is first changed into the language of the nervous system and the process is called transduction.
• Stimuli are perceived by receptors but interpretation of the stimuli is done by specific nervous centres in the brain. Receptors may be exteroreceptors, proprioreceptors or interoreceptors. Exteroreceptors are present in special sense organs like skin, nasal chamber, taste buds, eyes and ears.
• The five kinds of sensory receptors are mechanoreceptors which respond to physical deformations of tissues; chemoreceptors which respond to certain molecules dissolved in solution; thermoreceptors which respond to heat; and painreceptors which respond to excess heat, pressure, or certain chemicals; and electromagnetic which respond to energy of different wavelengths.
• Sensory receptors can also be categorized as exteroreceptors which receive information from the external environment; interoreceptors which receive information from the internal environment; and proprioreceptors which receive information about the body’s orientation in space.
• Skin receptors may be naked free nerve endings or covered bulbs or corpuscles. These may be tango receptors, thermoreceptors, algesia receptors etc.

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Principles Of Inheritance And Variation Neet Notes

NEET Biology Sense Of Smell

Olfactoreceptors are present in the olfactory epithelium and are chemoreceptors to specific odours. These show olfactory adaptation as are soon fatigued when exposed to specific odour for a long period.

Evolution Neet Notes

In the case of humans 7 groups of primary odours have been classified :

1. Camphoraceous (Scent of camphor)
2. Musky ( scent of musk )
3. Floral (flowers)
4. Pepperminty ( Scent of oil or peppermint)
5. Ethereal ( Scent of ether)
6. Pungent (Scent of spices)
7. Putrid ( Decaying meat)

NEET Biology Sense Taste Receptors

1. Gustatoreceptors are present in taste buds on the tongue. These are also chemoreceptors. Man can perceive four basic modalities of taste with the help of different taste buds located on different parts of the tongue.
2. Human beings recognise four basic modalities of taste, viz. sweet, sour, salty and bitter. Sweet, sour, salty and bitter tastes are principally perceived at the tip, along the lateral edges, on the upper side of the front half, and the back of the tongue respectively.
3. The taste of food is of vital importance in the process of digestion because taste stimulates reflexes causing secretions of saliva, gastric juice and pancreatic juice.

Rheo Receptors. They are responsible for perceiving water currents. They are of four types.

1. Lateral line sense organs
2. Scattered pit organs
3. Ampulla of Lorenzini
4. Vesicles of Sair
5. Watering of eyes due to gases or smoke is due to irritoreceptors.

Principles Of Inheritance And Variation Neet Notes

NEET Biology Sense The Eye

The eye captures light reflected from objects in the visual field and transforms it into electrical signals, which the brain interprets as visual perception.

• Light is emitted and absorbed in distinct quanta of photons. It propagates as waves of electromagnetic radiation, with wavelengths perceptible to the human eye ranging from 380 to 760 nm, and is most sensitive at 500 nm (i.e., green color).
• Free-living animals require photoreception to identify food, predators, and refuge. Photoreceptors have evolved for this purpose, undergoing progressive improvement over time.
• Planarians (flatworms) possess a “eye cup” that functions as a photosensory organ to perceive light intensity and direction.
• In annelids (polychaetes) and subsequent higher animals, the eye has evolved into a distinct organ.
• In insects and crustaceans, the compound eye consists of individual units known as ommatidia. They are adapted for apposition (mosaic) vision in bright illumination and superposition imagery in low light (darkness).
• It additionally produces colored visuals. Honeybees possess the ability to perceive ultraviolet energy.
• Among all invertebrates, only cephalopods (molluscs) possess eyes with real lenses like to those of vertebrates.

NEET Biology Sense Human (Mammalian) Eye

1. A fluid-filled ball with about 21 mm (17.5 mm just born) metro-posterior diameter (optical or visual avis) lodged in the bony orbit of sphenoid bone with a cushion of fat.
2. It weighs about 7 gin.
3. About 1/6 of the eyeball (l/3rd in frog and 1/5 in rabbit) projects outside while the rest parts remain within the socket. 1 Iris anterior part is covered with transparent cornea.
4. Each eye is protected by upper and lower eyelids with eyelashes.
5. The eyes are somewhat ball-like and are lodged in the deep skull cavities (orbits). The clevis can rapidly close to prevent dust or other things from entering the eyes. The eyelashes also help in this function. On any irritation, due to a fallen particle due to gas or smoke or under certain emotions, the eyes are flooded with a watery secretion or tears.
6. This secretion comes in front of the (car glands, located near the outer border of each eye and it is poured through minute ducts on the inner surface of the upper eyelid. Movements of the upper eyelid spread the secretion over the eye to wash off any dirt.

Structure. The wall of each eye is made of the three concentric layers sclerotic, choroid and retina. In the front, the sclerotic layer forms a transparent, somewhat bulging circular comea.

1. The cornea can be stored and grafted on the other person. The cornea and the rest of the exposed sclerotic layer are covered by another very thin transparent membrane, the conjunctiva, which is the continuation of the inner surface of the eyelids.
2. The pigmented iris, formed by the middle or choroid layer encloses the pupil, visible from outside as a dark window. The iris consists of delicate muscles which regulate the size of the pupil and consequently control the amount of light passing to the retina ciliary body.
3. Just behind the pupil lies a biconvex lens which is held in position by ligaments and muscles. A transparent watery fluid (aqueous humour) fills the narrow space between the lens and the comea. The large chamber behind the lens is filled with a clear, gelatinous substance (vitreous humour).
4. The sensory layer called the retina, consists of two types of cells, rods and cones. The rods are sensitive to dim light and do not distinguish colours, whereas the cone cells are sensitive to bright light and can distinguish colours.
5. The cone cells are most numerous near the back of the eye, opposite the pupil. This part is somewhat depressed and is known as the yellow spot or fovea. Vision is the sharpest here. The sensory fibres from the retina bundle together and emerge from the back of the eyeball as the optic nerve.
6. At the exit of the optic nerve, there are no rods or cones. The part of the image falling at this place is not perceived, and so this place is called the blind spot.

Principles Of Inheritance And Variation Neet Notes

NEET Biology Sense Associated Glands

1. Lacrimal gland (tear gland).Consists of a chain of three small glands located at the outer angle of each eye. Tear flows into the lacrimal duct through the small pore, and lacrimal punctum to pass into the nasal chamber of its side.

• Tear is a salty fluid, that contains amino acids, glucose and lysozyme.
• A continuous layer of tear is always present upon the comea to keep it moist, and away from dust and other foreign particles. It also nourishes comea and acts as a medium for refraction of light; lysozyme in it is antibacterial.
• In humans tear secretion begins at four months of birth.
• Tearing is stimulated by injury, irritation, emotions etc.

1. The meibomian gland (tarsal gland) is a modified sebaceous gland located on the mar¬gin of eyelids. Its oily secretion makes a film over the tear to prevent it1 fall from the surface of comea.
2. The Zeis gland is also a modified sebaceous gland in the hair follicle of eyelashes to keep them smooth and waterproof by its oily secretion.
3. Glands of Moll are modified sweat glands on the inner surface of eyelids found only in humans, of uncertain function.
4. Harderian Gland. It is a special type of mucous-secreting gland found in aquatic, fossorial and bush dwellers. Mucous keeps the eye moist and protected from abrasion. In frogs it remains beneath the lower eyelid towards the inner corner of the eye, also found in all reptiles and aquatic mammals, rabbits etc., but absent in man. Its secretion is known as crocodile tears.

Evolution Neet Notes

NEET Biology Sense Refraction Or Focusing

Tear → conjunctiva → cornea → aqueous humor → lens → vitreous humor refract light rays to converge on the retina.

• The cornea exhibits the highest degree of refraction, followed by the lens.
• The lens precisely directs the beam onto the retina to create a picture. Accommodation is achieved by altering the curvature (convexity) of the lens through the action of ciliary muscles, depending on the object’s distance.
• When the ciliary muscle is relaxed, the eye remains at rest and focuses on distant things. To focus on nearby objects, the ciliary muscle contracts to enhance the lens’s convexity.
• The frog possesses inadequate accommodation capabilities; it is hypermetropic in water and myopic on land. Nevertheless, a minor adjustment can be achieved by moving the lens anteriorly and posteriorly, akin to a camera.
• The inverted virtual image is produced on the retina, and normal vision is referred to as emmetropic.
• In humans, each eye possesses a vision field of around 170°. The significant overlap of visual fields aids in assessing the relative positions of objects, constituting depth awareness or stereoscopic vision.
• The typical range of vision in the human eye extends from 30 centimeters to 6 meters.

Evolution Neet Notes

NEET Biology Sense Common Defects Of Eye

1. Myopia (Near-sightedness). When the image of a distant object is focussed in front of the retina due to lengthening of the eyeball or due to increased convexity of the lens. It can be corrected by using appropriate concave lenses.
2. Hypermetropia or Far-sightedness. It is due to just the opposite condition as in myopia. It can be corrected by wearing suitable convex lenses.
3. Astigmatism. It is due to an error in the shape of the lens and cornea, as they are of different curvatures. Cylindrical glasses are used to correct this defect.
4. Presbyopia (old age sight). It is the diminished ability to focus the eye on near objects due to the gradual loss of elasticity of the crystalline lens with age. It can be corrected by use of the convex lens.
5. Cataract. The lens becomes opaque due to different reasons. It can be corrected by removing the lens and replacement by a convex lens by the specialist.
6. Glaucoma. It is an increase in intraocular tension when the pressure within the eye is raised above the normal level (15-20 mm Hg.) If prolonged it brings about blindness.
7. Trachoma. It is caused due to infection by virus conjunctivitis. The cornea may be ulcerated and vision is lost.
8. Squint/ Strabismus/Diplopia  – It is the formation of two images. Corrected surgically.

Evolution Neet Revision Notes

NEET Biology Sense The Ear

The ear consists of three parts :

1. External
2. Middle
3. Internal ear.

External Ear. The external or the outermost projecting part of the ear is a skin-covered cartilaginous organ called pinna. It collects sound waves and admits them into the tubular auditory passage.

• Some animals can move their external ears in the direction of sound, but such muscles are vestigial in man although some people do have the capacity to move their ears slightly. A waxy layer of cerumen glands in the auditory passage entangles the bacteria and any other minute organisms that may creep in.
• Similarly, the outer openings have fine hair for protection purposes. Somewhat obliquely placed at the inner end of the auditory passage is a delicate blue-grey membrane called the ear drum (tympanum).

Middle Ear. The middle ear consists of a set of three tiny bones, which are lodged in a chamber. The first bone is the hammer-shaped malleus, attached to the inner surface of the car drum (tympanum), by a muscle called tensor tympani.

• Next is the anvil-shaped incus and the third is the stirrup-shaped stapes, the inner end of which is attached to fenestra malls. An air passage of the castellan tube connects the floor of (the middle ear with the pharynx, to balance the air pressure on either side of the tympanum.
• The tympanic cavity opens into the internal ear’s cavity through two apertures – fenestra ovalis and fenestra rotundas.

The car ossicles help in the amplification of sound waves and their transmission to the internal car. These are three in mammals as a characteristic feature :

1. The malleus (hammer) comes first connected to the tympanum, derived from the articular bone of the low er jaw.
2. The incus (anvil) is the second bone upon which the malleus hammers. It is derived from the quadrate bone of the upper jaw.
3. Stapes (stirrup) the last, fork-shaped bone is connected to the membrane of fenestra ovalis. It is derived from oromandibular, a homologous bone, columella auris is the only ear ossicle found in frogs.
4. The middle car is connected with the pharynx through a cartilaginous eustachian tube which gets filled with air and helps maintain equal pressure on both sides of the tympanum.
5. The internal car is very delicate. It has two main regions – the upper utriculus and the lower sacculus. Both are connected by a small and narrow saccule-utricular duct. A small duct, the endolymphatic duct, opens into it; the other end of which opens into a closed endolymphatic sac which is present on the posterior side of the temporal bone.
6. The upper portion i.e. utriculus is connected with three semi-circular canals, which are concerned with the sense of position of the body and not with hearing.
7. From the sacculus arises a long tubular part or cochlea which is coiled like-conch shell and is embedded in a bone of the skull. It carries a system of canals and spaces which are filled with lymph-like fluid and there are fine sensitive membranes running across it.
8. Branches from the auditory nerve enter these membranes. This part is connected with the sense of hearing. The cochlea is attached to the sacculus through ductus reuniens. Cochlea has about 2 coils. The cochlea can be divided into three parts the upper one is scala vestibuli, the middle scala media and the lower one is scala tympani.
9. The upper and lower parts are filled with perilymph whereas the middle one with endolymph. Both the scala vestibule and scala tympani are continuous with each other through a passage called helicotrema.
10. The dorsal wall of scala media is called Reissner’s membrane and the ventral one is the Basilar membrane. Several sensitive structures are found on the basilar membrane like an organ of Corti, cell of deiter, the cells of Hensen and the tectorial membrane.

Evolution Neet Revision Notes

NEET Biology Sense Equilibrium

• Any alteration in body posture causes the otoliths within the endolymph of the cristae and maculae to contact sensory hairs, generating an impulse that is transmitted to the brain, which then adjusts to maintain balance.
• The cristae in the ampulla of semicircular canals sustain dynamic balance. It is activated when the body is in motion or rotation.
• The maculae in the utriculus and sacculus ensure static balance or orientation of the body or head during a static position (sitting or standing).

NEET Biology Sense Hearing

The process of hearing and its path of sound waves is as follows:

• Sound waves collected by pinna → external auditory meatus→ tympanum →tympanic cavity → ear ossicles (malleus→ incus → stapes) → membrane of fenestra ovalis → perilymph of scala vestibuli →helicotrema →scala tympani (vibrations cause movement of Reissner’s and basilar membranes result in the vibration of endolymph of scala media) → Tectorial membrane →Sensory hair cells of the organ of Corti → Impulse ’ generated → Auditory nerve→ Brain (perception and interpretation of sound vibrations) and sound Is perceived.

Evolution Neet Revision Notes

NEET Biology Sense Organs In Focus

1. Receptors are merely involved in receiving the stimuli and initiating the nerve impulses but cannot interpret the impulses.
2. Interpretation power of nerve impulses lies in the specific sensory areas of the brain,
3. Proprioceptors are maximally present in the sole of feet.
4. Exteroreceptois and proprioceptors are somatic receptors while interoceptors are visceral receptors,  Classification of receptors was given by Sherrington. Reading of a page is an example of exteroception i.e., sensing of the external environment, or Sensing of internal condition and position is inerorecspection.
5. Perception is the conscious awareness and interpretation of sensation.
6. Each eye weighs roughly 7 gins.
7. Photoreceptor cells are present on the innermost layer of the eye. the retina.
8.  The Iris of the eye contains radial bands and rings of circular smooth muscles.
9. The size of the pupil is larger in human females than in males. The Iris of the eye acts as a diaphragm of eye. Iris, being pigmented. gives colour to the eye which depends upon the amount of melanin present example, more melanin in brown eye, less melanin in blue eye but no melanin in albino eye.
10. Rods of the retina have rhodopsin (visual purple) while cones have iodopsin (visual violet), and Rods help in night vision. twilight and Black and white vision, while cones help in day vision and colour vision.
11. There are about 7 million cones in the human eye.
12. Zonula of Zinn is the other name for the suspensory ligament.
13. Monocular vision is found in animals like dogs, rabbits, pigeons, frogs, etc. In this, only one eye is focused on one object at a time.
14. Stereoscopic vision. Binocular vision is Found in most primates and owls among the birds. In this, both eyes can be focused on the same object at the same time.
15. In flatfishes, both eyes are on the right side of the body. Palpebrae. Eyelids. These act as shutters.
16. Meibomian glands are modified oil glands.
17. Glands lying at the edges of eyelids Gland of Zeis and Gland of Moll.
18. Sty Bacterial infection of the gland of Zeis. It is also called
19. hordeolum.
20. Eyelids are absent in cyclostomes, bony fishes and snakes.
21. Plica semilunaris. The third eyelid, also called the nictitating membrane, is vestigial in man.
22. The cornea is non-vascu, a part of the eye. So cornea is most easiest part to transplant as n does not stimulate the immune system.
23. Nutrition to the cornea is provided by alkaline lacrymal secretion. It is differentiated into Bulbar conjunctiva (outside cornea) and palpebral conjunctiva (inner to eyelids). It is a modified stratified epithelium.
24. Owls have a large number of rods and only a few cones in the retina of their eyes.
25. The retina of the fowl’s eye contains only cones.
26. Deer have the biggest eyes in proportion to body size.
27. The region of the environment from which each eye collects light is called the visual field.
28. The normal eye can accommodate light from objects from about 25 cm to infinity.
29. In the ear canal, there are about 4.000 specialized ceruminous glands.
30. The cochlea contains 16.000 and 24.000 hair cells and each hair cell has about 100 hair. They create waves in the lymph fluid of the cochlea and the wave causes the basilar membrane to ripple.
31. The ear acts as a statoacoustic organ that controls hearing and equilibrium.
32. The Pinna of the ear is called the auricle.
33. The pharyngeal opening of the eustachian tube opens during yawning, swallowing and during the ascent or descent of an aeroplane to equalise the pressure inside the tympanic cavity to that outside the eardrum for free vibrations of the eardrum.
34. Audiology. Study of hearing power.
35. Otology. Study of the structure, working and disorders of the ear.
36. Aquatic animals like seals, whales, etc. and monotremes like duck-billed platypi and spiny ant-eaters lack pinna.
37. Thermoreceptors are more in number on the face and hand of man.
38. The most sensitive chemical receptors are the taste and smell receptors.
39. Taste receptors in the tongue respond specifically to sweet, sour, salty and bitter molecules.
40. The nose contains mucus-coated olfactory receptors, over 2 million in number.
41. The mucus produced by Bowman’s gland absorbs odour-iferous substances that stimulate the reception of the cells.
42. The taste of chillies, black pepper and ‘hot’ sauces is not a true sensation. It is a sensation of burning pain produced by the stimulation of pain receptors of the tongue.
43. Many insects such as honey bees, flies, butterflies and moths possess chemoreceptors to taste sensation on their feet.
44. Some mammals such as rhesus monkeys, pigs, cats and dogs possess taste buds for tasting water. But man is deprived of them.

Evolution Neet Chapter Summary

NEET Biology Sense Organs Conclusion

• In fishes, accommodation for near objects is brought about by elongating the eyeball but in other animals, it is brought about by increasing the lens curvature.
• lives, capable of focussing the images of objects possessed by vertebrates and some higher invertebrates like prawns, crabs and insects.
• Prawns, crabs and cockroaches possess compound eyes, each made of many elongated tube-like units called ommatidia. They are crowded over a spherical surface and produce a composite blurred image of the object.
• All animals do not have their olfactory receptors located in the nose. For instance, moths and butterflies possess olfactory chemoreceptors on their antennae.
• The cornea has no vascular or immune systems. Therefore a complete transplant is not rejected by the body and is highly successful.
• Cornea from the eye of a dead person can be stored and transplanted to restore vision in another person. It is so because it is non-vascular and does not stimulate the immune system.
• Owls have the keenest eyesight at night because their eyes have a large number of rods and a few cones in the retina.
• Aquatic mammals like seals, whales, etc., and monotremes like duck-billed platypus and spiny ant eater lack pinna. Tympanum. It is the specialized hearing organ of insects.
• Sea sickness. Tendency of nausea and vomiting due to unusual stimulation of semicircular ducts by the movement
  ment of a ship in the sea.
• The area of the body most sensitive to the sensation of cold is the chest Merkel’s disc is slowly adapting receptors for touch.
• Organ of Ruffini arc the receptors for warmth.
• Cynnolabs. Cone cells are sensitive to blue light radiations.
• Erythrolabs. Cone cells are sensitive to red light radiations.
• Jacobson’s organs. Additional smelling organs of reptiles like Sphenodon, lizards and snakes (best developed). These are also called vomeronasal organs.
• Ampullae of Lorenzini. Thermoreceptors are found in the snout region of fishes.
• A sense of direction is given by the nose.
• Olfactory cells are modified bipolar neurons.
• Grandy’s corpuscles. A special type of Merkel’s corpuscles present in the skin and tongue of birds
• Otoliths/Otoconia. Calcium carbonate crystals
• Harberf s corpuscles. A simple type of Pacinian corpuscles in birds
• Pacinian corpuscles. Vater’s corpuscles and hence Vater Pacinian corpuscles
• Vibration to which the human ear is most sensitive. 1000 cycles /sec
• Harderian glands -Present at an angle of the eye, secrete lubricant for nictitating membrane.
• Eyelids are absent in snakes.

NEET Biology Nervous System

Systems of Coordination.

1. Nervous system. Fast, specific with the electrochemical transmission, along nerve fibers
2. Endocrine system. Slow, diffused with chemical transmission through body fluids.
3. Immune system (antigen-antibody reactions)
4. Neurology. Study of morphology, physiology, and pathology of the nervous system.
5. Neurophysiology. Physiology or working of the nervous system.

Read and Learn More NEET Biology Notes

Nervous System NEET Notes

NEET Biology Role Of The Nervous System

1. The nervous system illustrates the activities of different organs and the entire organism.
2. The nervous system links the various organ systems and coordinates all their activities.
3. It ensures the integrity of the organism.
4. The unity of an organism and its internal environment is affected and maintained through the nervous system.
5. Man’s brain is the material basis of thinking, memory, and good speech.
6. It stimulates or inhibits the activities of muscles and glands to evoke a response to the received information.
7. Special senses such as vision, hearing, smell, taste, and touch produced by information provided by sense organs are associated with the nervous system.

NEET Biology Nervous System Neuron

1. The fundamental components of nervous tissue are neurons, which originate from the ectoderm. Each neuron comprises a cell body, or cyton, containing a nucleus and many nerve fibers, classified into two categories.
2. An axon is an efferent process as it transmits impulses outward. The terminal branches of the axon, known as telocentric, possess end knobs that release neurotransmitters facilitating impulse conduction.
3. The branching processes of dendrites are afferent as they receive impulses for the neuron.
4. Nerve impulses are transmitted from the axon terminals of one neuron to the dendrites of another. The convergence of the two is referred to as a synapse.

NEET Biology Constituents Of the Nervous System

1. A central nervous system is composed of the brain and spinal cord. It contains nerve centers for all sensations. The brain and spinal cord are covered by protective membranes called meninges and their cavities are filled with cerebrospinal fluid.
2. The peripheral nervous system consists of various nerves which conduct impulses to all parts (Spinal and Cranial nerves).
3. The autonomic nervous system illustrates the working of viscera composed of sympathetic and parasympathetic nervous systems.
4. The central nervous system is made of nerve bodies forming the grey matter and of nerve fiber tracts which form the white matter.
5. The peripheral nervous system consists of nerves made of nerve fibers and nerve cell bodies located in the brain, spinal cord, and ganglia.
6. The autonomic nervous system consists of nerve cell bodies, their nerve fiber, and nerve plexies. However, all three divisions of the nervous system are connected intimately both structurally and functionally.

Structure And Function Of Neurons NEET

Brain. The brain reaches its highest development in mammals with better intFor exploration and mastery over the environment. The cerebral hemisphere reaches the status of a dominant inter-example rating part of the brain and acts as a coordinating center of the brain.

1. The cerebral hemispheres are immense projecting forwards above the olfactory lobes and backward above the diencephalon and mid-brain. The two hemispheres are separated by it deep median fissure.
2. Each hemisphere is further divided In an oblique Sylvimi (IsMire into an anterior frontal lobe and a posterior lateral temporal lobe
3. The cerebrum or cerebral hemispheres have a thick roof called a ‘neopallium’ in mammals, it is formed by upgrowth of the lateral portions of the pallium, but it differs histologically from the pallium in having a larger number of neurons which are arranged in layers of the cortex and medulla.
4. The cortex is further increased by many curved depressions or sulci and lobes or ‘gyri’ (absent in rabbits). Each hemisphere has a complex lateral ventricle, each ventricle has a middle body from which three prolongations come run forward, backward, and outward.
5. Above the lateral ventricles is a band of nerve fibers called corpus callosum which joins the neopallium or cortex of the two cerebral hemispheres, the anterior part of the corpus callosum is bent to form ‘menu while the posterior part is bent downwards and forwards forming splenium.
6. Below the corpus callosum is a band of longitudinal fibers forming the ‘fornix’. Its main body is formed by the union of two sets of fibers called fimbriae or taeniae hippocampi. Between the corpus callosum and fornix is a septum peculium having a small cavity called pseudocoel or 5th ventricle, which is not a true ventricle but a space between the two hemispheres.
7. The floor of the hemispheres forms anterior corpora striata and postero-lateral hippocampus which serves as an olfactory center, the median commissure of it is called psalterium or lyra, and that of corpora striata is the anterior commissure.

1. Running from the anterior commissure to the optic chiasma is a delicate membrane of the lamina terminals which marks the anterior boundary of the 3rd ventricle.
2. The cerebral hemispheres receive impulses from visual, auditory, olfactory, tactile, and peripheral receptors and they initiate voluntary motor impulses which are carried by bundles of nerve fibers to muscles. The cortex For exampleates the impulses and organizes and for example, rates them into coordinated activities.
3. The diencephalon is small and hidden dorsally by the hemispheres, it has a laterally compressed third ventricle or diaconal whose roof is formed by a delicate velum interpositum.
4. The side walls of the diencephalon or optic thalami are made of a thick mass of white and grey matter on the external surface of each thalamus near the anterior end is a rounded corpus geniculatum. The floor of the diencephalon is called the hypothalamus.
5. Recently a potent substance called hypothalamic D has been extracted from the hypothalamus which stimulates the production of adrenotrophic hormone of the pituitary gland.
6. The hypothalamus is composed of four parts optic chiasma, infundibulum and tuber cinereum, pituitary gland, and corpus albicans.
7. The diencephalon is a relay center of impulses from the posterior For example going to the cerebral cortex, the thalami are the centers of exploration and activity and for recognition of sensations of heat, cold, pain, and body movements.
8. Mid brain has two pairs of optic lobes called corpora quadri gemina. The floor of the mid brain is called crura cerebral which contains bundles of fibers. The canal which connects the 3rd ventricle with the 4th ventricle is called iter. Vision is controlled by the cerebrum and anterior parts of the anterior optic lobes.
9. The posterior optic lobes are auditory in function. The highly developed cerebellum is divided to form five lobes, central lobe vermis, two lateral lobes, and two outer floccular lobes.
10. In section, the cerebellum shows an outer thick layer of grey matter and a central mass of white matter, the two exhibit a tree-like pattern called arbor vitae.
11. The cerebellum is concerned with equilibrium and co-ordination of muscles and responses initiated by the cerebral hemispheres and carried out through the cerebellum Medulla oblongata lias a posterior choroid plexus below which is the fourth ventricle joined in front to the iter and behind to the central canal.
12. The medulla controls respiration, heartbeat, and blood vessels, it also has conduction pathways for impulses passing from cerebral hemispheres to the spinal cord and again in the opposite direction.

Central And Peripheral Nervous System NEET Study Material

NEET Biology Nervous System Spinal Cord

1. It is a cylindrical, cord-like, homogeneous extension of the medulla oblongata, measuring 42 to 45 cm in length and 2 cm in thickness in humans, extending from the neck to the lumbar region.
2. For instance, it traverses the neural canal of the spinal column and culminates in a slender extension known as the filum terminale. Growth ceases around 4 to 5 years of age.
3. In this structure, the white matter is located externally, while the H-shaped grey matter is situated internally, which is the inverse of the brain’s configuration.

NEET Biology Nervous System Peripheral

1. Cranial nerves. The peripheral nervous system consists of nerves connected to or arising from the central nervous system, it has cranial and spinal nerves. Twelve cranial nerve 1 – Olfactory (sensory). 11-Optic (sensory), lH-Oculomotor (motor), IV-Trochlear (motor), V-Trigeminal (mixed ), Vl-Abducens (motor), Vll-Facial (mixed), VIII-Auditory (sensory), IX- Glossopharyngeal (mixed), X-Vagus (mixed), Xl-Spinal accessory and XII-Hypoglossal (motor).
2. Sensory Cranial Nerves. Olfactory, Optic, and Auditory.
3. Motor Cranial Nerves. Oculomotor, Pathetic/Trochlear, Abducens, Accessory Spinal and Hypoglossal.
4. Mixed Cranial Nerves. Trigeminal, facial, Glossopharyngeal and Vagus,
5. Dentist’s nerves. Trigeminal (Vth nerve) [Has a swelling called gasserian ganglion from where it divides into 3 branches]
6. Number of Cranial Nerves. 10 pairs in amniotes (fishes and amphibians) and 12 pairs in amniotes (reptiles, birds, and mammals).
7. The facial nerve in frogs passes through the Gasserian ganglion but in mammals, it passes out through the Geniculate ganglion.
8. Glossopharyngeal and Vagus nerves in frogs pass out through the jugular ganglion but in mammals, they pass through the vagus ganglion. All are situated within the cranium.
9. The motor component of the vagus nerve controls sound production.

NEET Biology Nervous System Spinal Nerves

1. They originate from the spinal cord. Humans possess 31 pairs of spinal nerves.
2. Each spinal nerve comprises two roots: sensory (afferent) and motor (efferent) roots.
3. All spinal nerves possess a mixed composition. Each spinal neuron is partitioned into three rami.
4. The filum terminale and several posterior spinal nerves create a horse-tail-like structure known as the cauda equina within the neural canal.

NEET Biology Muscular System

• Movement is the displacement of body parts in relation to the body axis. It is a characteristic feature of living beings. Movements of, external and internal body parts occur.
• Locomotion is the displacement of the body from one place to another place. Locomotion is the basic character of animals. Locomotion enables the animals to protect their bodies to search and procure food and water, to find their mate, escape from predators, shift to a favourable environment and find a suitable breeding ground.
• Locomotion in acellular organisms takes place by three methods :
  1. Pseudopodial
  2. Ciliary
  3. Flagellar.
• Pseudopodial locomotion takes place in Amoeba.
• Ciliary locomotion takes place in Paramecium.
• Flagellar locomotion takes place in Euglena.
• Adult sponges are sedentary ties. fixed. Locomotion does not take place in them.
• Their larvae move by cilia.
• Locomotion in Hydra is muscular and also takes place by tentacles,
• Bending and swaying
• Looping
• Somersaulting

Read and Learn More NEET Biology Notes

• Gliding
• Walking
• Climbing
• Surfacing
• Floating
• Swimming.
• Locomotion in annelids takes place either by setae or parapodia. Locomotion by setae takes place in Pheretima and by parapodia in Nereis.
• Locomotion in leeches takes place by muscular contraction and suckers.
• Locomotion in arthropods takes place by jointed legs and wings.
• Locomotion in molluscs takes place by foot
• Locomotion in echinoderms takes place by tube feet
• Locomotion in vertebrates takes place by fins and limbs.

Muscular System NEET Notes

NEET Biology Kingdom Protista Movements of External Body Parts

1. Collection of information by the movement of pinnae, ocular orbits, neck, etc.
2. Facial expressions and gestures
3. Preservation of balance
4. Movement of extremities and limbs for locomotion.
5. Acquisition of sustenance, Consumption of nourishment.
6. Nourishing offspring, Offensive and Defensive
7. Respiration.

NEET Biology Kingdom Protista Movements of Internal Body Parts

1. The heartbeat facilitates blood circulation.
2. Contraction and relaxation of the diaphragm, ribs, and lungs facilitate gaseous exchange.
3. Peristalsis is the pendular or segmental motion facilitating the transit of food through the alimentary canal.
4. Peristalsis facilitates the movement of urine through the urinary system, while also generating sound.
5. Movements of the genital tract and uterine wall during oviposition and parturition.
6. Muscular activity in the movements of different body components.

NEET Biology Kingdom Protista Non Muscular Movements

1. Such movements occur in protists and individual cells in higher organisms in the following ways:
2. Pseudopodial/Amoeboid Movements. The movements occur using temporary protoplasmic outgrowths called pseudopodia.

• Pseudopodia can develop in any direction due to the flow of protoplasm. Fresh pseudopodia develop as older ones are withdrawn.
• Amoeba and iLs relatives creep using pseudopodia. The movements occur in macrophages and leucocytes. Because of them the cells can reach all body parts and engulf pathogens.

1. Cyclosis/Cytoplasmic or Protoplasmic Streaming. It occurs only inside eukaryotic cells. Cyclosis helps in the circulation of materials in the cells.
2. Flagellar Movements. Flagella perform locomotion In euglenoids and other flagellate pivots, Chlamydomonas and other unicellular/colonial motile green algae sperm, etc. Flagellate choanocytes bring about the circulation of water in the canal system of sponges.
3. Ciliary Movements. Paramecium and other ciliates swim using cilia.
4. Undulation movements due to plasma membrane as in fibroblasts.

Muscular System NEET Study Material

NEET Biology Kingdom Protista Types Of Muscles

1. Three types of muscles have been categorized based on the structure of their fibres.
2. Details discussed in a chapter on (Animal tissues)

• Skeletal muscles (Striated muscles). These generate external movement associated with the skeleton, remain attached to bone through the tendon, under conscious control and hence also termed as voluntary muscle. In lower magnification, these have transverse stripes hence also called striped or striated muscles.
• Smooth Muscles (Visceral muscles)
• Unstriped; hence structurally different from striated and cardiac muscles.
• Muscle cell spindle-shaped (not cylindrical) uninucleated each formed of single myoblast.
• Actin filaments remain attached, to dense bodies in the cytoplasm.
• There is no myofibril, no sarcomere and no Z-line.
• Actin and Myosin filaments are not arranged in any pattern hence no striations.
• Involuntary muscle, under ANS control, is found in visceral organs (visceral muscle).
• Cardiac muscle. This is also striated muscle but under involuntary control, hence has a rhythmic pattern of contraction with varying frequency.
• This is an untiring muscle (no fatigue) and keeps on acting lifelong.
• Being striated it is structurally similar to skeletal muscle except for the presence of (0 Cross fibres, besides parallel fibres

1. Intercalated discs – which represent the joints of two myoblasts.
2. The contraction pattern is rhythmic and the rate of contraction is controlled by the autonomic nervous system (ANS).
3. They do not get fatigued, and work ceaselessly throughout their lives.
4. Generates impulse-like nerve (i.e. the myogenic heart of vertebrates).

NEET Biology Kingdom Protista Chemical Composition Of Muscle Fibres

• Water 75%
• Proteins 20% (Myosin, actin, tropomyosin troponin complex and enzymes)
• Proteins of Muscles
• Actin, the filament'(F-actin) is formed by polymerization of G-actin monomer. It has the site, occupied by regulatory protein troponin and tropomyosin, for the attachment of myosin.
• Tropomyosin is a rod-shaped fibrous protein helically wrapped around the actin filament along its groove.
• Troponin is a small globulin protein with l components: troponin-e, troponin-l and troponin-T masking the site on F-mMin lor attachment of myosin.

1. Myosin is a versatile protein with both fibrous and globular parts. The fibrous part aggregates to find the filament while the globular part, projects out at both ends as cross bridges or heads. 1 lead is formed of HMM (heavy mcromysoin) consisting of Sub-fragment-1 and the neck (or hinge). The tail part is formed of LMM (light meromyosin). The head acts as ATPnse which after connecting with actin hydrolyse ATP.
2. Mineral and organic compounds 5% (K⁺ is the chief mineral constituent, Mg⁺⁺, P⁺⁺, Na⁺ and Ca⁺ 4  are present in minute quantities.
3. Organic compounds are present in the form of glycogen, lipids, steroids and non-poric nitrogenous compounds.

NEET Biology Kingdom Protista Some Major Muscles

1. Biceps. The front portion of the upper ami for bending of the arm at the elbow.
2. Triceps. Back of upper arm for straightening of ami at the elbow.
3. Biceps femoris. Back of thigh for bending leg at the knee.
4. Quadriceps. Front of thigh
5. Gluteus maximus. Buttocks.
6. Gastrocnemius. Calves, bending of the ankle joint.
7. Frontal. Fore-head.
8. Orbicularis oculi. Closure of eyes.
9. Orbicularis oris. Closure of mouth.
10. Masseter. Mastication.
11. Trapezius. Upper back and side of the neck
12. Deltoid. Shoulder raises an arm.
13. Pectoralis major. Lowers arm.

Muscular System NEET Question Bank

NEET Biology Kingdom Protista Features Of Muscle Fibers

• Excitability. The skeletal muscle fibres can be excited by the nerve impulses generated in the motor nerve fibre by the specific stimuli. This power is maximum in striated muscle fibres.
• Conductivity. The skeletal muscle fibres can conduct the excitation along the length of muscle fibres at the rate of 3-5 metres/second with the help of the T-tubule system and sarcoplasmic reticulum.
• All or None Rule (Bowditch’s Law). When the skeletal muscle fibre is stimulated, it responds either by shortening or lengthening. The response of a muscle fibre is independent of the strength of the stimulus. If there is any response, it is maximum.
• The minimum strength of stimulus (nerve impulse) required to bring about the response, is called threshold stimulus. It varies from fibre to fibre. If the stimulus is of a strength below the threshold stimulus, the muscle fibre is not excited, but if the stimulus has a strength equal to or higher than the threshold stimulus, the muscle fibre shows a maximum response.
• The force of contraction does not increase with the increase in the strength of the stimulus. But in the case of whole muscle, the extent of contraction depends upon the number of motor units which are contracting at any particular period.

NEET Biology Kingdom Protista Useful Terms

1. Latent phase or period. It is a brief time interval between the point of stimulation and the actual starting of response i.e. contraction phase. The duration of the latent period varies with the species, type of muscle, temperature and internal condition of the muscle.

• It is due to the time taken for the propagation of impulse from the point of stimulation to the” neuromuscular junction and then to sarcolemma  for initiation of contraction (In frogs it lasts about 10 milliseconds in skeletal muscles and up to 3 sec. in visceral muscles.)

1. Contraction phase. It is the time interval in which the muscle reaches the peak of contraction and performs work. (It lasts for 40 milliseconds in skeletal and 20 sec. in visceral muscles.)
2. Relaxation phase. It is the longest of three phases. It lasts about 50 milliseconds in skeletal muscles, and 2.3 sec in visceral muscles and is indicated by downward tracing in the kymograph (graph showing a twitch contraction). During the phase, the muscle returns to its original length.
3. Single Muscle Twitch. The response of a muscle to a single short stimulus, such as 1 electric shock is known as a twitch and can be recorded as a kymograph. A twitch can be divided into three successive phases.
4. Motor unit. All muscle fibres supplied by a single motor neuron are called a motor unit. On average, there are 100 muscle fibres in a motor unit.
5. Isotonic contractions. When a muscle contracts, with a constant load that it  can lift, it is said to be isotonic contraction In other words there is a change in the shape of the muscle and it maintains tension
6. Isometric contractions. When a muscle contracts against a weight dial it cannot lift, it is called an isometric contraction. In other words, llicic is no change in the shape of the muscle. AS u maintains umfoim length.
7. Tentas. It the muscle fibre is stimulated before it relaxes for a second time, it can contract again If we continue closely spaced stimuli, we gel a smooth sustained contraction, called a tetanus or tetanic contraction.
8. Summation. If a second stimulus is applied to a muscle that is still in the contraction phase, a second contraction is added to die first and results in greater shortening of muscle than caused by a single stimulation. It is termed summation.
9. Refractory period. (0.002 – 0.005 see in skeletal, 0.1-02 sec in cardiac muscle fibre.) If two stimuli are applied one immediately after the other, die muscle will respond to the first stimulus, but not to the second.
   1. The brief period during which the muscle does not respond to the second stimulus is called a refractory period or period of lost irritability. Its duration varies with the muscle involved. Skeletal muscle has a short refractory period w whereas cardiac muscle has a long refractory period.
   2. The absolute refractory period during which the recovering muscle fibre cannot be stimulated by a stimulus of any strength.
   3. The relative refractory period during which the muscle fibre can be excited only by a stimulus of strength higher than the previous strength of the stimulus.
10. Fatigue. If muscle fibres are repeatedly stimulated to contract, these fibres take a longer time to respond to the excitation during contraction and also to complete relaxation.
11. Their force of contraction also declines progressively. Finally, the fibres fail to contract at all for some time. It is known as muscle fatigue. It is caused by the accumulation of lactic acid and other changes in the muscle due to prolonged contraction.
12. Site of muscle fatigue. Stephens and Taylor suggested that the site of skeletal muscle fatigue is the neuro-muscular junction and occurs when there is increased K⁺ concentration and decreased Na+ concentration in the ECF of the muscle fibres.
13. Rigor mortis. Muscles become stiff after death. This state is called rigor mortis. It occurs due to the absence of ATP. It first appears in the muscles of the face and jaw. Rigour mortis disappears after three or four days because the proteins become soluble.
14. Red muscle fibres contain myoglobin, arc thin, dark red and contain mitochondria. These are capable of doing more work and do not easily get tired.
15. White muscle fibres are of light red or pink and do not contain myoglobin and mitochondria. Get easily tired and cannot work for long.

NEET Biology Kingdom Protista Muscle Contraction (Sliding Filament Theory)

1. The sequence of myosin-actin bonding, sliding and release is repeated rapidly over and over until the muscle has shortened sufficiently. This is the sliding fuming mechanism for muscle contraction, and it consumes a great deal of ATP.
2. When an individual muscle is stimulated, the actin filament in every sarcomere unit slides towards the middle of the sarcomere. As a result, the myofibrils shorten. A muscle cell shortens (contracts) then all its myofibrils shorten. An entire muscle contracts when many of its muscle cells contract simultaneously.
3. Contraction ends when the muscle cell ceases to be stimulated by the nerve cell. If an impulse no longer travels down the T – tubules to the cell’s interior, Ca2+ is actively transported back into the SR.
4. Without Ca2+, the troponin-tropomyosin protein complex shifts back into its original position, masking the sites on the actin filaments and preventing further bonding by the myosin heads. When this happens, the muscle relaxes and returns to its original shape.

NEET Biology Kingdom Protista Biochemical Aspects

1. During contraction actin and myosin combine to form actomyosin, this was shown in vitro by Szent Gyorgi (1946), who won the Nobel Prize for this work.
2. There are three basic pathways for providing energy to be utilised in muscle contraction.
3. The hydrolysis of ATP provides free energy to the converted to mechanical energy by the interaction of actin and myosin. Here myosin plays the role of ATPase.
4. ADP + CP + H⁺ → ADP + Pi + H⁺ ΔG
5. The ATP molecule present in muscle cells lasts for only a few seconds of muscle action. Hence muscle mainly depends upon other phosphate molecules creatine phosphate (CP) as a source of energy stored it. This acts as a recharger of ADP. ADP + CP + H⁺ →ATP + C (Lohmann’s Reaction)
6. This reaction was discovered by Lohmann (1932) which won him a Nobel Prize.
7. After the CP of reserve is exhausted muscle resorts to glycolysis of glycogen. Whose end product is the lactic acid that causes fatigue.
8. Oxygen debt. Till the entire amount of creatine phosphate is recovered through the regeneration of ATP by oxidative phosphorylation body remains in oxygen debt and to repay it the person keeps on panting after a strenuous exercise. Cori cycle. The accumulated lactic acid diffuses out of muscle through blood and reaches the liver where it is reconverted to glycogen.
9. Troponin and Tropomyosin are two regulatory proteins present on this filament and are essential for the actin-myosin interaction i.e., muscle contraction.

1. When during muscle contraction, muscle length remains c& the same but tension increases then it is called isometric contraction For Example Holding some weight.
2. When during muscle contraction, muscle length changes but tension remains constant then it is called isotonic contraction For Example during walking. c& Glycogen can be formed more readily from glucose in muscles.
3. Carl Ferdinand Cori shared the 1947 Nobel Prize for physiology and medicine with his wife Gerty Theresa Cori and B.A. Houssary for their work on the metabolism of glycogen.
4. Animals with“liquid skeleton”-Earthworms, Caterpillars (larvae of butterflies and silk moths), and Slugs. It gives shape and support to the body. c& In the case of non-chordates except echinoderms arginine is present in place of phosphocreatine.
5. Sarcomere functional unit of contraction of a muscle.
6. All or none law is also known as Bowditch’s law.  Biochemical and electrical events during muscle contraction were studied by Albert Szent Gyorgi Special conducting system of the heart consists of special cardiac muscle fibres.
7. Treppe (Staircase phenomenon) A stimulus of constant strength applied regularly at clock intervals to a muscle produces a series of contractions, the first of which are of increasing amplitude.
8. Glycogenolysis occurs in liver cells but not in muscle cells as these lack the Glucose-6 phosphatase enzyme. Troponin-Tropomyosin Complex prevents muscle contraction as it inhibits the activity of ATPase enzyme and prevents the formation of actomyosin complexes., Oxygen-Debt. Amount of extra oxygen consumed during the recovery after an exercise.
9. Shivering involves the involuntary contraction of voluntary muscle fibres.
10. 30-40 % of energy is used in contraction and the rest is converted into heat. This helps in warming the body.
11. Roles of Muscle and Bones in Movement The force generated by muscle contraction pulls or lifts bone through tendons. Movement occurs along the joint, hence the bone actually acts as a lever having 3 parts :
12. In the body joint acts as F, point of attachment of muscle to bone is E.
13. There are 3 classes of levers:
14. 1st class lever. F comes between E and R, very rare in the body, one such example is the head resting on the vertebral column.
15. 2nd class lever. R comes between F and E, only a few in the body, For Example, raising the body on the toes.
16. 3rd class lever. E remains in between the F and R, the most common type of lever in the body For Example, flexing the forearm at the elbow joint.

Muscular System NEET Mcqs

NEET Biology Kingdom Protista Questions From Competitive Examinations

Question 1. Immediate Source Of Energy For Muscle Contraction  Is:

1. Glucose
2. Gtp
3. Creatine Phosphate
4. ATP

Answer: 4. ATP

Question 2.  Which One Yields ATP Required For Muscle Contraction?

1. Myoglobin
2. Creatine Phosphate
3. Creatinine Phosphate
4. Myosin.

Answer: 2. Creatine Phosphate

Question 3. Edta Injected Into Muscles Combines With Ca₂⁺ And :

1. Stops Contraction
2. Causes Contraction
3. Slows Down Contraction
4. None Of The Above.

Answer: 1. Stops Contraction

Question 4. What Is Sarcomere?

1. Part Between Two H-Line
2. Part Between Two A-Line
3. Part Between Two I-Band
4. Part Between Two Z-Iine.

Answer: 4. Part Between Two Z-Iine.

Question 5. Which Statement Is Correct For Muscle Contraction?

1. Length Of H-Zone Becomes Decreased
2. Length Of A-Band Remains Constant
3. Length Of I-Band Becomes Increased
4. Length Of Two Z-Line Become Increase,

Answer: 1. Length Of H-Zone Becomes Decreased

Muscular System NEET Exam Preparation

Question 6. Which light band Contains The following fluid protein?

1. Myosin
2. Actin
3. Both 1 & 2
4. None Of These.

Answer: 2. Actin

Question 7. Largest Skeletal Muscle Is Present In :

1. Thigh
2. Neck
3. Arm
4. Belly.

Answer: 1. Thigh

Question 8. Hinge Joint Is Present In :

1. Elbow
2. Pivot
3. Interphalangeal
4. Atlas.

Answer: 1. Elbow

Question 9. Biceps & Triceps Are Found In :

1. Fore Arm
2. Upper Arm
3. Thigh
4. Shoulder.

Answer: 2. Upper Arm

Question 10. Actin Filaments Depolymerise And Repolymerise In Motile Cells With :

1. 0.2 – 0.3 Millisecond
2. 1.0 – 2.0 Minutes
3. 1 – 2 Hours
4. 2-3 Days.

Answer: 1. 0.2 – 0.3 Millisecond

Question 11. Sacromere Occurs Between :

1. Z – Line To Z – Line
2. Two I – Bands
3. Two Surfaces Of A Z – Line
4. Two A – Bands.

Answer: 1. Z – Line To Z – Line

Question 12. “All Or None Law” Is Not Associated With .

1. Muscle Fibre
2. Tiruiun
3. Cardiac Muscle
4. Uriniferous Tubules

Answer: 4. Uriniferous Tubules

Question 13. ATPase Enzyme  Needed For Muscle Contraction Is Located In :

1. Myosin
2. Actin
3. Actinin
4. Troponin.

Answer: 1. Myosin

Question 14. Which Of The Following Is Important For Muscle Contraction And Nerve Impulse Transmission ?

1. Ca_2⁺ Ions
2. Ca⁺⁺ And Mg⁺⁺ Ions
3. Mg⁺ ₄– Ions
4. Fe _2⁺ Ions.

Answer: 2. Ca⁺⁺ And Mg⁺⁺ Ions

Question 15. During Strenuous Exercise Glucose Is Converted Into :

1. Glycogen
2. Pyruvic Acid
3. Starch
4. Lactic Acid.

Answer: 4. Lactic Acid.

Muscular System NEET Previous Year Questions

Question 16. Which Of The Following Is Not Syncytial ?

1. Cardiac Muscle
2. Skeletal Muscle
3. Smooth Muscle
4. Interstitial Muscle.

Answer: 3. Smooth Muscle

Question 17. The Condition In Which A Number Of Nuclei Are Present In A Muscle Fibre Is Called :

1. Coenocytic
2. Syncytial
3. Polykaryon
4. Endoduplicaton.

Answer: 2. Syncytial

Question 18. Contractile Tissues Have The Following Features :

A. Mesodermal In Orign

B. They Contain Stretch Receptors.

C. Rhythmic Contractions Are Seen In Them

D. Hey Do Not Fatigue During The Life Of The Animal.

Which Of The Above Are Characteristics Of Sphincters ?

1. All The Four
2. Only A, B And C
3. Only A, B And D
4. Only A, C And D.

Answer: 2. Only A, B And C

Question 19. The Lactic Acid Generated During Muscle Contraction Is Converted To Glycogen In :

1. Muscle
2. Kidney
3. Pancreas
4. Liver.

Answer: 2. cAMP

Question 20. In Heart Cells, Which One Serves As A Second Messenger, Speeding Up Muscle Cell Contraction In Response To Adrenaline ?

1. cAMP
2. cGMP
3. GTP
4. ATP
5. AMP.

Answer: 1. cAMP

Question 21. The Contractile Protein Of Skeletal Muscle Involving Atpase Activity Is :

1. Troponin
2. A-Actin
3. Tropomyosin
4. Myosin.

Answer: 4. Myosin.

Question 22. The Globular Protein Molecule, Which Masks The Active Sites On The F-Actin Is :

1. Troponin
2. Myosin
3. Tropomyosin
4. Light Mbromyosin
5. Heavy Meromyosin.

Answer: 1. Troponin

Question 23. Statements :

1. A-Bands Of The Muscle Is Dark And Contain Myosin
2. I-Hamls Air The Light Hands Ami Contain Actin
3. During Muscle Contraction The A-band Contracts
4. The Part Between The Two Z-Lines Is Called As Sacromere
5. The Central Pan Of Thin Filament, Not Overlapped By Thick Filament Is Called H-Zone.

Of The Above Statements.

1. 1, 3, and 5 Are Correct While 2 And 4 Are Incorrect
2. 1, 2, 3 And 3 Are Correct While 4 Is Incorrect
3. 1, 2 And 3 Are Correct While 4 And 3 Are Incorrect
4. 1, 2 And 4 Are Correct While 3 And 3 Are Incorrect
5. 1 And 2 Are Correct While 3, 4 And 5 Are Incorrect.

Answer: 4. 1, 2 And 4 Are Correct While 3 And 3 Are Incorrect

Question 24. All Or None Law Is Not Applicable To :

1. Whole Skeletal Muscle
2. Single Skeletal Muscle Fibre
3. Whole Cardiac Muscle
4. Single Smooth Muscle Fibre.

Answer: 1. Whole Skeletal Muscle

Question 25. The H-Zonc In The Skeletal Muscle Fibre Is Due To :

1. The Central Gap Between Myosin Filaments In The A-Band.
2. The Central Gap Between Actin Filaments Extending  Through Myosin Filaments In The A Band.
3. Extension Of Myosin Filaments In The Central Portion Of The A-Band.
4. The Absence Of Myofibrils In The Central Portion Of A-Band.

Answer: 2. The Central Gap Between Actin Filaments Extending  Through Myosin Filaments In The A Band.

NEET Biology Endocrine System

Hormone (Gk: Hormoein = to excite) is the secretion of the endocrine (Gk. yendon = inside, Krinein = to separate) gland.

• Endocrine Glands. (The Greek word Rendon means inside, and kinesin means to separate) These are endogenously located glands that lack the ducts (so also called ductless glands) and generally secrete their secretions into the blood (so-called glands of internal secretion) for their transportation to target organs (sites of action). Exocrine glands. Secretions of these glands are transported by duct or ductules or directly.
• Heterocrine glands are composed of exocrine and endocrine tissues. The former sends its secretion or product through a duct and the latter discharges its secretion directly into the blood For example. pancreas, gonads.
• The blood contains all the hormones but target organs pick up the required hormones only and ignore all others because target cells have a specific protein called a receptor which has a specific affinity for a particular hormone.
• In man, there are the following endocrine glands: Thyroid, Parathyroid, Thymus, Pituitary, Adrenal, Pineal body, and (pancreas, stomach, intestine, skin, kidney, and gonads mixed glands).

Read and Learn More NEET Biology Notes

NEET Biology Endocrine System Types Of Hormones With Their Function Intracellular Receptors

• The steroid and thyroid hormones enter the cell directly and bind to the intracellular receptor proteins in the cytoplasm, this complex enters the nucleus and binds to the specific regulatory sites on the chromosome. This alters the pattern of gene expression initiating its transcription, formation of specific mRNA, and then protein (enzyme).
• Synergic hormone. A pair of hormones work together for a particular function. For example. LH and FSH work together for the maturation of Graafian follicles.
• Antagonistic hormone. A pair of hormones each with opposite function. For example. Insulin and glucagon. Insulin acts as a hypoglycemic factor but glucagon acts as a hyperglycemic factor,
• Tropic hormone. A hormone of one gland activates the secretion of the hormone of another gland. For example.TSH of the anterior lobe of the pituitary gland activates the thyroid gland to secrete thyroxine.
• Chalones. These substances inhibit the secretion of other glands. For example, enterogasterone from duodenal mucosa inhibits the secretion of HCI in the gastric juice of the stomach.

Endocrine System NEET Notes

NEET Biology Endocrine System Mechanism Of Hormone Action

Hormones are transported by the bloodstream to the entire body, but they influence only specific cells.

• Cells that respond to a certain hormone possess receptor sites for that hormone. This resembles a lock and key mechanism.
• Should the key be compatible with the lock, the door will unlock. If a hormone binds to the receptor location, an effect will ensue.
• All cells possessing receptor sites for a specific hormone constitute the target tissue for that hormone. In certain instances, the target tissue is confined to a specific gland or organ.
• In other instances, the target tissue is dispersed and disseminated throughout the body, resulting in many locations being impacted. Hormones exert their distinctive impacts on target cells by altering cellular functions.

Proteins, peptides, and modified amino acids

1. These hydrophilic (and mostly large) hormone molecules bind to receptors on the sur¬face of ‘ ‘target’ ’ cells: that is, cells able to the presence of the hormone. The receptors are transmembrane proteins. Binding of the hormone to its receptor initiates a sequence of intracellular signals that may :
2. alter the behavior of the cell (such as by opening or closing membrane channels) or stimulate (or repress) gene expression in the nucleus by turning on (or off) the promoters and enhancing the action of the genes.
3. The hormone binds to a site on the extracellular portion of the receptor.
4. The receptors are transmembrane proteins.
5. Many (but not all) pass through the plasma membrane 7 times, with their N-terminal exposed at the exterior of the cell and their C-terminal projecting into the cytoplasm.
6. Binding of the hormone to the receptor
7. Activates a G protein associated with the cytoplasmic C-terminal
8. This initiates the production of a “second messenger”. The most common of these are
9. cyclic AMP, (cAMP) which is produced by adenyl cyclase from ATP and
10. inositol 1,4, 5-triphosphate (IP₃)
11. The second messenger, in turn, initiates a series of intracellular events such as
12. phosphorylation and activation of enzymes
13. release of Ca_2⁺ stores within the cytoplasm
14. In the case of cAMP, these enzymatic changes activate the transcription factor CREB (cAMP response element binding protein)
15. Bound to its response element 5′ TGACGTCA 3′ in the promoter of genes that can respond to the hormone, activated CREB turns on gene transcription.
16. The cell begins to produce the appropriate gene products in response to the hormonal signal it has received at its surface.

NEET Biology Endocrine System Steroid Hormones

1. Steroid hormones, being hydrophobic molecules, diffuse freely into all cells. However, their “target” cells contain cytoplasmic and/or nuclear proteins that serve as receptors of the hormone.
2. The hormone binds to the receptor and the complex binds to hormone response elements – stretches of DNA within the promoters of genes responsive to the hormone. The hormone/receptor complex acts as a transcription factor turning the target gene “on” (or “off”). mRNA is formed and with translation, protein is synthesized. This protein formed is responsible for the biological action of that steroid.

NEET Biology Endocrine System Thyroid Gland

1. Discovered by Wharton (1908) it is the largest endocrine gland (3 – 7 cm in diameter and 15-20 gm in weight).
2. Situated below the thyroid cartilage of the larynx it is a bilobed structure, connected by an isthmus.
3. The only endodermal gland homologous to the endostyle of protochordate develops as a venial outgrowth from the pharyngeal wall.
4. Consists of many follicles formed by follicular cells as epithelial parts and interfollicular stroma of areolar connective tissue with parafollicular cells.

Hormones And Their Functions NEET Biology

NEET Biology Endocrine System Parathyroid Gland

Follicular cells are of two types.

1. Chief cells. The main secretory cells and Oxyntic cells with eosinophilic granules.
2. It secretes Parathormone (PTH or Collip’s hormone), a polypeptide with 84 amino acids which regulate the metabolism of calcium and phosphate;
3. Increase plasma Ca⁺⁺ level by increasing bone dissolution (osteoclastic activity) and enhancing reabsorption through renal tubules and by increasing Ca⁺⁺ absorption in the gut.
4. Thus, the maintenance of proper Ca⁺⁺ levels in the body is the synergistic effect of calcitonin, PTH, and Vit. D.
5. Increases phosphate elimination in urine and consequently lower phosphate concentration in plasma.

NEET Biology Endocrine System Adrenal Gland (OR Suprarenal body)

1. A small, yellowish-brown, paired gland situated at the anterior end of each kidney like a cap, is a semicircular structure weighing 3.5 – 4.5 gm (in adults).
2. Covered by a fibrous connective tissue capsule. The structure is internally differentiated as the outer mesodermal cortex and inner ectodermal medulla of nervous origin.
3. Cortex. The thick layer constitutes 70 – 75% part of the gland distinct into the following three zones of cells :
4. Zona glomerulosa. The outermost layer below the capsule, is made of five layers of small cuboidal basophilic cells densely set along an axis parallel to the surface.
5. Zona fasciculata. The thickest and middle parts have large polyhedral cells arranged in radiating columns perpendicular to the surface.
6. Zona reticularis. The innermost part has cells arranged in a layer to form a network.
7. Medulla. Consists of groups of round granulated cells which are modified postganglionic cells of the sympathetic nervous system having an exclusively secretory function. These are chromaffin cells, distinct in two layers :
8. Zona compactum. Densely packed rounded cells with thick plasma membrane, without any intercellular spaces, the average size of cells is 190 – 210 pm (diameter).
9. Zona spongiosum. The innermost layer of irregular cells in 5 – 12 layers with large intermolecular spaces with matrix and blood vessels, the average size of cells is 260 pm- 360 pm.

NEET Biology Endocrine System Cortical hormones

About 50 types of steroids have been isolated from the adrenal cortex hence called corticosteroids. But, only a few are biologically active, of the following 3 types.

NEET Biology Endocrine System Mineralocorticoid (Aldosterone)

• A 21-carbon steroid molecule is secreted by zona glomerulosa.
• Increases the reabsorption of Na⁺ and Cl^– by uriniferous tubules, also controls the level of other salts, and thus plays a role in osmoregulation.
• Increase the removal of K⁺ in urine.

NEET Biology Endocrine System Glucocorticoid (Cortisol or hydrocortisone and Corticosterone)

1. A steroid of 20 carbons it is secreted from zona fasciculata and zona reticularis.
2. It controls the metabolism of fat and amino acids into carbohydrates, protein, and fat, and stimulates gastric secretions.
3. Stimulates the conversion of fat and amino acids into carbohydrates (gluconeogenesis).
4. Reduces amino acid levels in tissues, and increases ketone formation in the blood.
5. Anti-inflammatory in nature suppresses the WBC movement but increases RBC count.
6. Immunosuppressive in nature, hence used for treatment of allergy and in transplantation surgery.
7. Dexotes synthesis of collagen, hence cortisole is used for treatment of arthritis or rheumatism.

NEET Biology Endocrine System Sex Corticoid

1. Secreted by zona fasciculata and zona reticularis is a 12 carbon steroid.
2. Influences sex-related changes in muscles on bone, maintains the normal growth of external sex organs, hair growth, etc., in the pre-puberty stage, and also influences sexual behavior.
3. Hypersecretion of this hormone causes gynecomastia in males with female-like characteristics like overgrowth of the mammary gland.
4. Hirsutism (Adrenal Virilism) in females: growth of facial hairs, temporal baldness, enlargement of the clitoris, atrophy of breast, hoarse voice, etc.
5. Control of Secretion. ACTH from the pituitary maintains its growth and secretion which in turn is controlled by corticotropin-releasing hormone (CRH) from the hypothalamus. Secretion of aldosterone is mainly controlled by the renin-angiotensin system.

NEET Biology Endocrine System Hormones Of Adrenal Medulla

1. Medullary hormones are formed from the amino acid tyrosine.
2. Chromaffin cells take up tyrosine which is first hydroxylated and then decarboxylated to form dopamine which is further hydroxylated to form noradrenaline, this is then methylated to form adrenaline.
3. All these, dopamine, noradrenaline, and adrenaline together are called catecholamines which means “catch-all” Adrenaline (or Epinephrine)
4. Its secretion (from zona compactum) is stimulated by emergency conditions like fear, anger, accident, injury, stress, etc. hence is also called an emergency hormone. Its effect is like a sympathetic nervous system.
5. Norepinephrine (or Noradrenaline).
6. Secreted from zona spongiosus it is a polypeptide.
7. It is a vasoconstrictor that increases blood pressure (both systolic and diastolic) and controls the normal circulation of blood.
8. Control of Adrenal Medulla.
9. Its secretion is controlled by the sympathetic (autonomic) nervous system and feedback system through the level of adrenaline and nor-adrenaline in the blood.

Pituitary Gland Hormones NEET Study Material

NEET Biology Endocrine System Thymus Gland

1. It is a single, bilobed, flattened, pyramidal gland, situated in the mediastinal space just in front of the heart.
2. Grows at an early age and becomes fully developed at 16 years but starts degenerating after 18 years and atrophies after the age of 25 years.
3. It is partly endocrine and partly lymphoid, covered by a connective tissue capsule, and consists of two zones: (i) Outer cortex with lymphocyte-like cells; and
4. Inner medulla comprising reticular cells. Thymosin is the only hormone secreted from this gland with the following functions :
5. Stimulates T-lymphocytes to counter the attack of pathogens and antigens.
6. Helps in the development of sex glands.
7. Controls the heartbeat through the S.A. node.

NEET Biology Endocrine System Pineal Body

1. Situated on the roof of 3rd ventricle (diencephalon), covered by a capsule from which many septa (or trabeculae extend inside dividing it into many lobules; contain 2 types of cells :
2. Parenchymal pinealocytes with minute processes; neuroglia with the darkly stained nucleus.
3. A few acervuli or brain sand are present within the capsule.

NEET Biology Endocrine System Hypothalamus

1. It is the floor of the diencephalon (forebrain) with many neurosecretory cells that secrete a variety of hormones to control the secretion of the pituitary gland.
2. It also contains several such nerve cells whose axons terminate into the posterior pituitary and secrete hormones.
3. The ability of endocrine secretion in the hypothalamus is to monitor metabolite and hormone levels in the body as per the information gathered by the brain. Hypothalamic hormones released in the blood come to the pituitary through hypothalamo-hypophyseal portal circulation.
4. These include various releasing and inhibiting hormones as follows :
5. Hypothalamic hormones Influence hormones of the pituitary

NEET Biology Endocrine System Pituitary Gland (Hypophysis)

• Located on the ventral aspect of the hypothalamus, this single pea-sized gland was historically regarded as the master gland (Vesalius) because to its regulatory influence over all endocrine glands. However, Webster (1967) rejected this notion.
• It is now referred to as the conductor of an endocrine orchestra.
• Situated in a cavity known as the sella turcica, at the base of the sphenoid bone, it is linked via a stalk termed the infundibulum to the hypothalamus.
• This stalk is lacking in mammals.

Pituitary Gland Hormones NEET Study Material

NEET Biology Endocrine System Hormones Of the Posterior Lobe Of the Pituitary Gland

Antidiuretic hormone (ADH or Vasopressin or Pitressin)

1. The osmoregulation hormone controls the volume of urine by increasing water reabsorption in nephric tubules.
2. Brings back the normalcy in the autonomic nervous system during periods of stress, pain, anger, and excitement.
3. Deficiency of its level causes ‘diabetes insipidus’ (drinking disease), an abnormal amount of water is lost in the urine and to compensate for it the patients keep taking equally high amounts of water.

Oxytocin (or Pitocin or labor hormone or birth hormone)

1. Secreted from median eminence of pars nervosa hence is the direct secretion of hypothalamus stored in the pituitary.
2. Facilitates childbirth by loosening pubic symphysis before the birth of the child causing contraction and relaxation of muscles of the uterus, relaxing vaginal muscles and vestibular sphincter of the vulva
3. The release of milk from the mammary gland is made by relaxing the muscles of the nipple.

NEET Biology Endocrine System Islets Of Langerhans (Pancreas)

1. The pancreas acts as both an exocrine and endocrine gland and hence is referred to as a heterochrony gland
2. The endocrine component of the pancreas Islets of Langerhans was discovered by Langerhans (1950).

NEET Biology Endocrine System Hormones Of Islets Of Langerhans

NEET Biology Endocrine System Insulin

• Isolated by Banting and Best and its primary structure was determined by Sanger(1950).
• Hypersecretion causes hypoglycemia(extreme case insulin shock)

NEET Biology Endocrine System Glucagon

1. Discovered by Kimbell and Murlin (1935) a polypeptide with a molecular weight of 2495; comprises 29 amino acids in a single chain.
2. Hyperglycemic, by enhancing glycogenolysis in the liver.
3. Promotes gluconeogenesis, uptake of amino acids, and its deamination in the liver.
4. Lowers blood calcium level by increasing its renal elimination.
5. It does not affect muscle glycogen.
6. Its hypersecretion causes diabetes mellitus.

NEET Biology Endocrine System Somatostatin

• Secreted from 8 cells, also called a GHH balances the level of glucagon and insulin as per requirement of the body.

NEET Biology Endocrine System GONADS

• Gonads also secrete a variety of hormones.

NEET Biology Endocrine System Testes

1. The interstitial cells (or cells of Leydig) in the stroma secrete androgen (steroid) from which the male sex hormone testosterone is synthesized.
2. Induces the production of male gametes (sperms) and their morphogenesis.
3. Promotes growth and virility of skeleton muscle, external genitalia (accessory sex organs) secondary sex characters in puberty.
4. Its hyposecretion causes eunuchoidism, with the following symptoms.
5. Less growth of secondary sex organs (prostate, seminal vesicle, penis)
6. Improper spermatogenesis (infertility) and loss of secondary sexual characters.
7. Extreme hyposecretion causes complete sterility.
8. Sertoli cells secrete inhibin hormone that inhibits sperm formation.

Pituitary Gland Hormones NEET Study Material

NEET Biology Endocrine System Ovaries

1. Follicular cells and theca of maturing follicles secrete estrogen (17 (J-estradiol), a steroid.
2. Stimulates production, growth, and maturation of ovum and functions of secondary sex organs (uterus, fallopian tube, and ducts of mammary glands).
3. Maintains external or secondary sexual characters.
4. FSH from the anterior pituitary controls the level and functions of estrogen.
5. The corpus luteum formed from a ruptured follicle after ovulation secretes another hormone progesterone (a steroid) the pregnancy hormone.
6. Helps in the thickening of the uterus wall (endometrium) increasing blood supply to restore normalcy after menstruation.
7. Implantation of zygote on uterus wall, and formation of placenta.
8. Maintains the level of dissolved 0₂ in the embryonic fluid.
9. It also secretes inhibin hormone that stops follicular maturation.

NEET Biology Endocrine System Memory Points

1. Thyroidectomy – removal of thyroid gland.
2. Hypophysectomy- removal of the entire pituitary gland.
3. Pheromones (Ectohormones). These are intraspecific chemical messengers released by an animal into the air to initiate specific responses in another animal of the same species. These may be signals of food, mate, etc. The term pheromone was coined by Karlson and Butenandt (1959). The first known pheromone is bombycol.
4. Synthetic oxytocin is administered to induce uterine contraction in a woman who is exhausted during delivery. It is also administered in female cattle to induce lactation.
5. Feedback inhibition. In this type of inhibition, when the end product is at the required level then it gives certain inhibitory signals (called negative feedback) which inhibit the formation of the end product.
6. G-proteins are related to the hormonal action of those hormones requiring a second messenger, C-AMP. They link hormone receptors on the outer surface of the cell and the interior of the cell.
7. Prostaglandins. These are lipid compounds secreted into the tissue fluid by cell membranes of the glandular cells. These control either contraction/relaxation of smooth muscles or dilation/ contraction of blood capillaries. These were first reported in the semen of men and are produced by the prostate gland.
8. Enzyme adenyl cyclase is secreted by the plasma membrane and changes ATP into C-AMP which helps in hormonal action.
9. Sutherland first described the role of C-AMP in hormone action and called it the “Second Messenger”
10. Origin of endocrine glands. Most endocrine glands are endodermal in origin  For example. Thyroid, Parathyroid, Islets of Langerhans, and Gastric glands.
11. Intestinal glands, Thymus, etc. while some are ectodermal in origin For example. Pituitary gland, Hypo-thalamus; Pineal body etc. Gonads are mesodermal in origin while the Adrenal gland is ecto-mesodermal in origin.
12. The sub-neural gland of Herdmania is homologous to the pituitary of vertebrates. Herring bodies. Structures present in the pituitary and store neurosecretory substances of the hypothalamus.
13. The H-shaped endocrine gland is the thyroid.
14. The endostyle of lower chordates like Herdmania, Amphioxus, etc. is homologous to the thyroid gland.
15. When under stress, adrenaline is secreted directly into the blood.
16. Many other organs such as the digestive tract secrete hormones, and erythropoietin from the kidney stimulates RBC production. An atrial natriuretic hormone secreted by the heart helps to regulate salt and water balance and blood pressure.
17. The iodine content of thyroxine is 65% and is called iodized hormone. Thyroxine contains 80% tetra do thyronine (T₄) and 20% triiodo thyroxines (T₃) is more active than T₄
18. Renin. A hormone secreted by the kidney. It helps in erythropoiesis in bone marrow and osmoregulation through the renin-angiotensinogen system. Adiposogenital syndrome of Hypothalamic eunuchoidism. Hypogonadism in males is caused by the genetic inability of the hypothalamus to secrete gonadotrophin-releasing hormones.
19. Contraceptive pills. These contain estrogens and progesterone.
20. Diseases Due To Deficiency/Excess Of Hormones
21. Grave’s disease. (Exophthalmic Goitre)
22. Cause: Hypersecretion of thyroxine due to enlargement of the thyroid gland.
23. Cretinism. Cause: Hyposecretion of thyroxine in children.
24. Myxoedema. Cause. Deficiency of thyroxine in adults

• Symptoms: a. puffy appearance due to accumulation of fats.
• Lack of alertness, and intelligence.
• Slow heartbeat, low BP, decreased body temperature.

1. Iodine Def. Goitre: Deficiency of iodine in diet.

• Symptoms: Enlargement of thyroid gland.

1. Parathyroid tetany : Cause: Deficiency of Parathormone.

• Symptoms: Sustained contraction of muscles of face, pharynx, hands and feet.

1. Addison’s Disease: Cause: Deficiency of mineralocorticoids and glucocorticoids.

• Symptoms: a. low blood sugar, low Na⁺ ion, high K⁺ ion concentration in blood.
• Bronze-like pigmentation of skin.
• Nausea, vomiting, diarrhea.
• Conn’s syndrome (Aldosteronism) Caused due to excessive secretion of aldosterone.

Cushing’s Syndrome. Cause. Excess of cortisol.

• Symptoms, a. High blood sugar, b. Sugar in urine, c. Obesity, d. Wasting of limb muscles
• Adrenal virilism. Excess of sex corticoids in (females) a tendency to develop male characteristics by the female due to imbalances in the secretion of adrenal hormones.
• Dwarfism. Deficiency of GH from early age. It may be Lorrain type, Frohlich type, or Progeria.
• Gigantism. Excess of GH from childhood.
• Acromegaly. Excess of GH after adolescence. The stage is called Acromicria.
• Diabetes Insipidus. Deficiency of ADH.
• Diabetes Mellitus. Deficiency of insulin.
• Eunuchoidism. Failure of testosterone.
• Infantilism. Characteristics of childhood continue beyond the years of puberty. Generally caused due to imbalances in the hormone of the anterior pituitary.
  1. Diabetes is a disease caused by a deficiency of insulin secreted by the pancreas.
  2. Hyperglycemia is an increased blood glucose level than the optimum level.
  3. Hypoglycemia is a lower blood glucose level than the optimum level.
  4. Osteoporosis is a disease caused by hypersecretion of parathormone.

1. Hashimoto’s Disease: Due to a fall in the secretion of thyroxine antibodies start forming against the gland, so the thyroid gets destroyed. It is also known as the suicide of the thyroid.
2. Ridding Henson disorder: It is caused by to deficiency of collip’s hormone as a result of which phosphate level in the blood decreases and Ca_2⁺ level increases.

Acidosis. Excessive loss of Na⁺ is known as acidosis. It may occur due to the hyposecretion of Aldosterone.

Thyroid Gland Disorders NEET Exam Preparation

1. Contributors related to Endocrinology
2. The first hormone was discovered by William M. Bayliss and Earnest H. Starling (1903).
3. The term hormone was introduced by Starling (1905).
4. Selye (1948) defined hormone as a functional chemically complex organic compound.
5. Berthold laid the foundation for the study of the functions of hormones.
6. Scharrer and Scharrer (1936) stated that hormones generally control or regulate reproductive activities, growth, maturation, regeneration, metabolism, and homeostasis. , Huxley called hormones as chemical messengers.
7. Thomas Addison is regarded as the father of endocrinology.
8. Claude Bernard (1955) established that the nervous system controls the function of endocrine glands.
9. The action of insulin hormone was demonstrated by Banting and later by Best. Shaefer (1912) gave the name insulin.
10. F. Sanger (1954) worked out the molecular structure of insulin. He established that it is polypeptide and was awarded the Nobel Prize (1958). i
11. Human insulin was synthesized by Tsan in 1965.
12. Kimball and Murlin discovered glucagon.
13. Karlson and Burtenandt coined the term pheromones.
14. Kochar (1916) isolated thyroxine (pure form).
15. Kendall (1919) obtained a crystallized form of thyroxine.
16. Harrington and Barges (1927) worked out the molecular structures of thyroxine.
17. Gudernatch (1912) discovered that metamorphosis in a frog’s tadpole begins only when an adequate amount of thyroxine is secreted by the thyroid of the tadpole.
18. Aldrich (1901) worked out the molecular structures of adrenaline and noradrenaline.
19. Stolz (1904) and Dakin (1905) synthesized adrenaline.
20. Enterocrinin. This hormone was isolated by Nasset from both small and large intestinal mucosa

• The nervous system and endocrine system together regulate the working of the body.
• Hormones affect all the cells of a target organ whereas a neuron will affect only a single muscle or fraction of it.
• A hormone is a chemical messenger secreted by the endocrine gland and carried to the target organ by blood.
• The pituitary gland is pea-shaped, 1.3 cm in diameter, and weighs only 0.5 gm.
• The pituitary is attached to the hypothalamus of the brain by a stalk-like structure called the infundibulum.
• Region of pituitary
• Anterior lobe (Adenohypophysis)
• Posterior lobe (Neurohypophysis)
• A third region is termed the intermediate lobe or pars intermedia.
• Neurons of the autonomic system stimulate hormone release from some glands. For instance, adrenaline and noradrenaline are released from the adrenal medulla on the arrival of nerve impulses during anxiety, stress, and danger. Thus endocrine system is considered a chemical extension of the nervous system.
• Corticotropes. about 20 % and secrete ACTH.
• Gonadotropes. secrete FSH and LH in female ; and FSH and ICSF1 in male.
• The gastrointestinal lining also secretes several hormones that regulate the secretion of digestive juices.
• Thymosin secreted by the thymus stimulates the maturation of immune system cells. Melatonin controls skin shade in some animals and appears to control annual reproductive cycles. Some hormones, such as steroid hormones, act by binding to DNA and altering gene expression.
• Other hormones bind to membrane receptors, where they either open ion channels (usually Ca₂⁺) or trigger the production of other chemical messengers inside the cell. Typically the receptor activates an enzyme via a G protein intermediate, which generates c AMP, which in turn activates the first step in an enzyme cascade.
• Cellular reactions are faster and more accurate when activity is determined by the ratio of two antagonistic hormones rather than the absolute level of a single hormone.

NEET Biology Endocrine System Quanta To Memory

1. Hormonology. Study of hormones.
2. Hormonotherapy. Treatment by hormones.
3. Largest Endocrine Gland. The thyroid (25 to 40 gms) is the largest endocrine gland in the human body.
4. Trophins (Tropins). The hormones which stimulate an endocrine gland to secrete its hormone (s,), For example.,  thyrotrophic hormone that stimulates the thyroid gland to secrete thyroxine.
5. All the pituitary hormones are molecules made chiefly of monomers of amino acids
6. The anterior pituitary has been called the master gland, because of the tropic hormones it releases. The real master “gland,” however, is the hypothalamus because its hormones regulate the secretory activity of the anterior pituitary.
7. Anterior and intermediate lobes of pituitary form adenohypophysis derived from Rathke’s pouch are ectodermal in origin.
8. The posterior lobe or neurohypophysis arises from the floor of the hypothalamus.
9. Rathke’s pouch: an embryonic outgrowth of the pharynx which forms adenohypophysis of the pituitary gland. Median eminence is a part of the posterior pituitary
10. Adenohypophysis gets its blood supply through the circle of Willis
11. In comparison with the nervous system, hormones are distributed by blood but slowly.
12. Hormonal action is generally less specific in comparison with nervous regulation.
13. Kyphosis. Hunched back in the person suffering from acromegaly.
14. Lag period. The period between secretion of hormone from the endocrine gland and biological response from the target organ.
15. Baldness. It is related to the sex hormones. Male sex hormone promotes baldness, female sex hormones inhibit it.
16. Melatonin is a hormone secreted by the pineal body and controls skin pigmentation.
17. Sella turcica is the pituitary fossa (a depression in the skull in which the pituitary gland lies).
18. Somatotropes are cells of the pituitary gland that secrete growth hormone (also called STH).
19. Thymosin is a hormone secreted by the thymus gland and increases the activity of T-lymphocytes.
20. Islets of Langerhans. These are approximately 1 to 2 million small clusters of endocrine cells which are named after the name of their discoverer (1869). Prostaglandins and leukotrienes are important eicosanoids.
21. These are local hormones and are derived from a 20-carbon fatty acid called arachidonic acid. Contraceptive pills contain the hormones estrogen and progesterone.
22. Melanocyte-stimulating hormone is secreted by the middle lobe of the pituitary. It darkens the skin of many animals including fishes and amphibians. It results from the stimulation of the synthesis of melanin in the skin.
23. Gravidex test is for detecting the presence of HCG hormone in the urine in case of pregnancy
24. Parathormone is a protein hormone consisting of 84 amino acids.
25. The British biologist V.B. Wigglesworth discovered, in the 1930s, two hormones that regulate development in insects. One is ecdysone, which promotes growth, molting, and the development of adult traits.
26. It is produced by the prothoracic glands in the head or thorax. The other hormone is juvenile hormone which promotes retention of larval characteristics. It is produced by the corpora allata glands in the head.
27. Of the two insect hormones discovered by Wiggles Worth, ecdysone has no role in the adult insect, whereas juvenile hormone promotes the development of eggs and sperm.
28. Prolactin and oxytocin are being used for increasing milk yield among dairy cattle. Recently genetically engineered Bovine growth hormone (BGH) was also used to boost milk yield in cows but was banned in March 1995.
29. The melanocyte-stimulating hormone was previously known as intermedin.
30. The adrenal gland is also known as the 3F gland (Fear, Flight, Fright)
31. Oral insulin is given as IZS [Insulin zinc suspension] or PZS (Protamine zinc suspension)
32. Hassels’ corpuscles are found in the thymus and are known as Thymic cells.
33. a-and (3-chains of insulin are connected through disulfide bonds.
34. The thymus is associated with our immune system. It acts as a lymphatic gland.
35. Humulin is a human insulin, produced by DNA recombinant technology.
36. Allaxonic diabetes is due to allaxon which destroys beta cells of the pancreas.
37. The adrenal gland is also known as the 3-F gland and the 4-S gland.
38. Oral contraceptive pills with a synthetic form of estrogen and progesterone hormones prevent ovulation in the female. Milk secreting hormone is prolactin and milk ejecting hormone is oxytocin.
39. The pregnancy hormone is progesterone and the birth hormone is oxytocin.

NEET Biology Endocrine System Multiple-Choice Questions

Question 1. Hormones Chemically Are :

1. Proteins
2. Fatty Acid Derivatives
3. Steroids
4. All The Above.

Answer: 4. All The Above

Question 2. Hormonal Diseases May Be Called :

1. Functional Diseases
2. Deficiency Diseases
3. Infectious Diseases
4. All The Above.

Answer: 1. Functional Diseases

Question 3. Which Of The Following Is A Hormonal Disease?

1. Measles
2. Rabies
3. Tuberculosis
4. Osteitis Fibrosa Cystica.

Answer: 4. Osteitis Fibrosa Cystica.

Question 4. A Hormone Is A Molecule That:

1. Moves Through The Blood Stream And Ducts
2. Influences Development
3. Has The Same Chemical Activity In A Variety Of Organisms
4. Alters The Activity Of Certain Non-Adjacent Cells.

Answer: 4. Alters The Activity Of Certain Non-Adjacent Cells

Adrenal Gland Hormones NEET Biology

Question 5. Adrenaline Is Secreted By :

1. Pituitary Gland
2. Pineal Gland
3. Adrenal Gland
4. Thymus Gland.

Answer: 3. Adrenal Gland

Question 6. Corticoids Are Secreted By :

1. Thymus
2. Adrenals
3. Pancreas
4. Kidney.

Answer: 2. Adrenals

Question 7. Islets Of Langerhans Secrete :

1. Adrenaline
2. Acth
3. Fsh
4. Insulin.

Answer: 4. Insulin.

Question 8. Based on the Chemical Nature Of Hormones, They Are Divided Into :

1. Two Categories
2. Three Categories
3. Five Categories
4. Six Categories.

Answer: 4. Six Categories.

Question 9. α-Cells Of Adenohypophysis Secrete Which Hormone?

1. ACTH And LH
2. GH And LTH
3. FSH And LH
4. TSH And FSH.

Answer: 2. GH And LTH

Question 10. The Trophic Factors Are Made Up Of Proteins Containing :

1. 1 To 4 Amino Acids
2. 4 To 10 Amino Acids
3. 3 To 15 Amino Acids
4. 3 To 20 Amino Acids.

Answer: 4. 3 To 20 Amino Acids.

Question 11. Which One Of The Following Is Not Synthesized In the Pituitary?

1. Lactotrophic
2. TSH
3. ICSH
4. ADH

Answer: 1. Lactotrophic

Question 12. Acth Is Secreted By :

1. Pineal Body
2. Anterior Lobe Of Pituitary Gland
3. Posterior Lobe Of Pituitary Gland
4. Thymus.

Answer: 2. Anterior Lobe Of Pituitary Gland

Question 13. Adh Is Produced By :

1. Pineal Body
2. Anterior Lobe Of Pituitary Body
3. Thymus
4. Posterior Lobe Of Pituitary Body.

Answer: 4. Posterior Lobe Of Pituitary Body.

Question 14. Which Of The Following Substances Is Released In Excess Quantity During Excitement?

1. Cortisone
2. Serotonin
3. Adrenaline
4. Nor-Epinephrine.

Answer: 3. Adrenaline

Adrenal Gland Hormones NEET Biology

Question 15. Which Of The Following Structures Act As Temporary Ductless Gland?

1. Pancreas
2. Pineal
3. Parathyroid
4. Placenta.

Answer: 4. Placenta

Question 16. Which Of The Following Secretory Glands Acts Both As Endocrine And Exocrine?

1. Adrenal
2. Parathyroid
3. Pancreas
4. Pineal.

Answer: 3. Pancreas

Question 17. Like Muscles, Hormones Are Antagonistic In Their Functioning. Mark The Wrong One :

1. Calcitonin And Parathormone
2. Insulin And Glucagon
3. Tsh And Thyroxine
4. Somatostatin And Growth Hormone.

Answer: 3. Tsh And Thyroxine

Question 18. The Hormone Released From the Intermediate Lobe Of the Pituitary Is:

1. FSH
2. LH
3. MSH
4. ACTH.

Answer: 3. ACTH

Question 19. Secretion Of The Following Hormones Results In Cretinism :

1. Thyroxine
2. Testosterone
3. Calcitonin
4. ADH.

Answer: 1. Thyroxine

Question 20. Vasopressin Is Related With :

1. Concentration Of Urine
2. Dilution Of Urine
3. Quick Digestion
4. Slow Heart Beat.

Answer: 1. Concentration Of Urine

Question 21. Which Of The Following Statements Is False?

1. Hormones Produced In Ovary Affects The Uterine Cycle
2. Hormones Produced In Small Intestine Stimulate Heart
3. Hormones Produced In Adrenal Medulla Stimulate HeartBeat
4. Hormones Produced In Thyroid Stimulate Metabolism.

Answer: 2. Hormones Produced In the Small Intestine Stimulate the Heart

Adrenal Gland Hormones NEET Biology

Question 22. The Target Cells Of A Hormone Always Have :

1. Special Receptors To Which The Hormones Bind
2. Special Channels Through Which The Hormones Move
3. Large Amounts Of Hormones Stored Within Vesicles.
4. Undifferentiated Cytoplasm.

Answer: 1. Special Receptors To Which The Hormones Bind

Question 23. The Cells That Produce Glucagon In Pancreas Are :

1. α Cells
2. β Cell
3. ϒ Cells
4. Acinar Cells.

Answer: 1. α Cells

Question 24. Calcium Ions Are Important In The Body Because They :

1. Are Involved As Co-Factors
2. Regulate Many Intercellular Metabolism
3. Influence Membrane Permeability
4. All The Above.

Answer: 4. All The Above.

Question 25. Fsh Is Produced By :

1. Posterior Lobe Of Pituitary Body
2. Middle Lobe Of Pituitary Body
3. Anterior Lobe Of Pituitary Body
4. Adrenal Cortex.

Answer: 3. Anterior Lobe Of Pituitary Body

Question 26. A Short Individual, Fairly Well Proportioned Body, Who Is Mentally And Physically Normal, Developed Due To The Undersecretion Of Growth Hormones, This Stage Is :

1. Lorrain’S Type
2. Frohlich’S Type
3. Acromegaly
4. Acromicria.

Answer: 1. Lorrain’s Type

Question 27. Adrenal Medullary Hormones Are Produced When :

1. Neurohypophysis Is Stimulated
2. Adenohypophysis Is Stimulated To Produce Oxytocin
3. Under Stress
4. Breeding Phase Starts.

Answer: 3. Under Stress

Question 28. Estrogen Is Necessary For :

1. Development And Maintenance Of Uterus
2. Proper Functioning Of Fallopian Tube
3. Normal Functioning Of The Cervix And Vagina
4. Development Of Secondary Sexual Characters In Females.

Answer: 4. Development Of Secondary Sexual Characters In Females.

Question 29. Vasopressin And Oxytocin Are Secreted By :

1. Hypothalamic Neurosecretory Cells
2. Neurohypophysis
3. Medulla
4. Pancreas.

Answer: 1. Hypothalamic Neurosecretory Cells

Question 30. Adrenal Cortical Cells Are Stimulated By :

1. Corticotropins From The Hypothalamus
2. Adreno Corticotropic Hormones
3. Corticoids
4. Changes In Blood Glucose Level.

Answer: 2. Adreno Corticotropic Hormones

Question 31. Many Hormones Are Initially Synthesised As Biologically Inactive Precursor Molecules Called :

1. Ectohormones
2. Pheromones
3. Endorphins
4. Prohormones.

Answer: 4. Prohormones.

Question 32. Rate Of Hormones Synthesis And Secretion Depend Upon :

1. Functional Efficiency Of The Feedback
2. Amount Of Excitation In Target Tissue
3. Degree Of Inhibition Causes
4. Functional State Of Tissue.

Answer: 1. Functional Efficiency Of The Feedback

Pancreatic Hormones And Blood Sugar Regulation NEET

Question 33. Thyrotrophic Releasing Hormone Is :

1. A Neurosecretion From The Hypothalamus Which Stimulates Anterior Lobe Of Pituitary
2. A Secretion Of Pars Distalis
3. Elaboration Of Neurohypophysis
4. From Thyroid Gland.

Answer: 1. A Neurosecretion From The Hypothalamus that stimulates the Anterior Lobe Of the Pituitary

Question 34. Involvement Of Any Hormone In The Control Of Cellular Function Depends On A Series Of Reactions Involving :

1. Synthesis Of Hormone In The Endocrine Cells
2. Feedback Control
3. Beginning With Hormone Synthesis And Finishing With Feedback Control
4. None Of The Above.

Answer: 3. Beginning With Hormone Synthesis And Finishing With Feedback Control

Question 35. Hormones Regulating The Morphogenetic Effects Are :

1. Growth Hormone
2. Testosterone
3. Androgens
4. All Of The Above.

Answer: 4. All Of Above.

Question 36. If the Ovaries Of A Lady Are Removed In The Fourth Month Of Pregnancy, The Result Will Be :

1. Embryo Will Develop Normally Till Birth
2. Abortion Will Occur After Some Time
3. Development Of Embryo Become Improper
4. None Of The Above.

Answer: 1. Embryo Will Develop Normally Till Birth

Question 37. A Substance Called ADH Is:

1. A Hormone That Promotes Glycogenesis In Liver Cell
2. An Enzyme Secreted By Cells Of Intestinal Wall; Hydrolyses Dipeptides Into Amino Acids
3. A High Energy Compound Involved In Muscle Contraction
4. A Pituitary Secretion Which Promotes Reabsorption Of Water From Glomerular Filtrate.

Answer: 4. A Pituitary Secretion that promotes Reabsorption Of Water From Glomerular Filtrate.

Question 38. The Pancreas Is A Mixed Gland In Which :

1. All Cells Secrete Enzymes And Hormones
2. Most Cells Secrete Hormones
3. A Few Cells Secrete Enzymes
4. Enzymes And Hormones Are Secreted By Separate Cells.

Answer: 4. Enzymes And Hormones Are Secreted By Separate Cells.

Question 39. Treatment With Alloxan Destroys :

1. STH Cells
2. β- cells of Islets Of Langerhans
3. Cells Of Sertoli
4. Cells Of Leydig.

Answer: 2. Islets Of Langerhans

Question 40. Select The Correct Answers To The Followings. Which Of The Following Techniques Should Be Least Likely To Help Elucidate The Function Of A Hormone Produced By An Endocrine Gland?

1. Removal Of The Gland And Subsequent Analysis Of What Functions Are Lost
2. Transplantation Of The Gland Into An Animal That Lacks The Gland
3. Transfusion Of Blood From An Animal Lacking The Gland Into An Animal That Has The Gland And Observation Of Its Effects
4. Observing Effects Of Gland Extract On Various Tissues Grown In Culture.

Answer: 3. Transfusion Of Blood From An Animal Lacking The Gland Into An Animal That Has The Gland And Observation Of Its Effects

Question 41. All The Following Commonly Serve As Signals Stimulating Hormone Secretion Except:

1. Conditions Outside The Body
2. Rising Levels Of Another Hormone
3. Rising Levels Of The Hormone In Question
4. Falling Levels Of The Hormone In Question.

Answer: 3. Rising Levels Of The Hormone In Question

Pancreatic Hormones And Blood Sugar Regulation NEET

Question 42. Hormones Are Known To Cause All The Following Changes In Target Cells Except:

1. Changes In Genetic Make-Up
2. Change In Permeability
3. Change In Metabolic Rate
4. Increase In Cyclic Amp Concentration.

Answer: 1. Changes In Genetic Make-Up

Question 43. An Advantage Of Having The Endocrine System As Well As The Nervous System Involved In The “Fight Or Flight” Response:

1. The Endocrine System Responds Faster
2. The Endocrine Response Usually Lasts Longer
3. The Endocrine System Is Turned More Precisely To The Degree Of Need
4. The Endocrine System Affects Only The Target Organ Whose Response Is Needed To Meet The Emergency.

Answer: 4. The Endocrine System Affects Only The Target Organ Whose Response Is Needed To Meet The Emergency.

Question 44. In Case Of Hypersecretion Of A Parathormone, Some Cells Of the Body Become Overactive. These Cells Are :

1. Ependymal Cells
2. Sarcoplasmic Reticulum
3. Osteoclasts
4. Osteocytes.

Answer: 3. Osteoclasts

Question 45. Hormones Controlling Expression Of Secondary Sexual Characters Are Secreted By Which Of These Cells In The Testis?

1. Sertoli Cells
2. Spermatogonia
3. Leydig’S Cells
4. Primary Spermatocytes.

Answer: 3. Leydig’s Cells

Question 46. Hormones Which Helps In The Implantation Of Embryo In Uterus Is :

1. Estrogen
2. Thyroxine
3. Relaxin
4. Progesterone.

Answer: 4. Progesterone

Question 47. In The Areas Of Destruction In The Bones, Fibrous Cysts Develop However The Parathyroid Becomes Overactive. This Is The :

1. Osteitis Fibrosa Cystica
2. Polydipsia
3. Osteomalacia
4. None.

Answer: 1. Osteitis Fibrosa Cystica

Question 48. Anti-Allergic Hormone Is :

1. Epinephrine
2. Non-Epinephrine
3. Gluco-Corticoid
4. Mineralo-Corticoid.

Answer: 3. Gluco-Corticoid

Question 49. Cretinism Is Due To :

1. Hypothyroidism In Children
2. Hypothyroidism In Adults
3. Hyperthyroidism In Children
4. Hyperthyroidism In Adults.

Answer: 1. Hypothyroidism In Children

Pancreatic Hormones And Blood Sugar Regulation NEET

Question 50. Which Of The Following Is Not Necessarily Property Of All Hormones?

1. Carrying Information
2. Secreted In Small Amounts
3. Short Half-Life
4. Proteinic Nature.

Answer: 4. Proteinic Nature.

Question 51. One Of The Following Hormones Is Not Produced By Alimentary Canal. Select?

1. Insulin
2. Cholecystokinin
3. Secretin
4. Gastrin.

Answer: 1. Insulin

Question 52. The True Proteinaceous Hormones Are Secreted By :

1. Pancreas
2. Anterior Lobe Of Pituitary
3. Posterior Lobe Of Pituitary
4. Thyroid.

Answer: 2. Anterior Lobe Of Pituitary

Question 53. What Does The Growth Hormone Do When the Growth Period Is Over:

1. Regulates Metabolism
2. Promotes Reproductive Activities
3. Stimulates Growth Of Secondary Sexual Characters
4. Stimulates Gametogenesis.

Answer: 1. Regulates Metabolism

Question 54. Strong Emotional Attachment To The Young Ones Is Due To:

1. Emotional Hormones Like Epinephrine And Gluco-Corticoids
2. Luteotropic Hormone (Lth)
3. Lh
4. All.

Answer: 2. Luteotropic Hormone (Lth)

Question 65. Secretion Of Vasopressin Is :

1. Acyclic And Not Affected By Seasonal Changes
2. Cyclic Phenomenon With Seasonal Changes
3. Effect Of Exercise
4. A Regular And Constant Feature.

Answer: 1. Acyclic And Not Affected By Seasonal Changes

Question 66. Precursor Chemical For Steroid Hormones Are:

1. Cholesterol
2. Nucleic Acid
3. Amino Acid
4. Mucoprotein.

Answer: 1. Cholesterol

Question 67. Function Of Progesterone Is :

1. Preparation Of Uterus For Pregnancy
2. To Maintain The Pregnancy
3. To Complete The Formation Of Milk In The Mammary Glands
4. Both  1 And 2.

Answer: 2. To Maintain The Pregnancy

Endocrine System NEET Notes

Question 68. A New Menstrual Cycle Starts When :

1. Pituitary Resumes Lh Production In The Absence Of Fsh And Progesterone
2. Ovary Resumes Progesterone Production In the Presence Of Lh
3. Ovary Resumes Estrogen Production In The Presence Of Fsh
4. Pituitary Resumes Lh Production In The Presence Of Fsh And Progesterone.

Answer: 3. Ovary Resumes Estrogen Production In The Presence Of Fsh

Question 69. Diabetes Mellitus Is Caused By Deficiency Of:

1. Secretin
2. Adrenaline
3. Insulin
4. Prolactin.

Answer: 3. Insulin

Question 70. The Growth Of Facial And Body Hair In Male Is Stimulated By :

1. Pituitary Hormones
2. Thyroxine
3. Parathyroid
4. Androgenic Hormones.

Answer: 4. Androgenic Hormones.

Question 71. The Phenomenon Of ‘Heat’ Or Oestrus In Females Is Due To The Hormones Secreted By :

1. Pituitary
2. Thyroid
3. Interstitial Cells Of Testes
4. Ovarian Follicles.

Answer: 4. Ovarian Follicles.

Question 72. Hyperadrenalism Is Called :

1. Cushing’S Disease
2. Addison’S Disease
3. Simmond’S Disease
4. None.

Answer: 1. Cushing’s Disease

Question 73. Which Of The Pituitary Hormones Is Responsible For The Secretion Of Milk By The Mammary Glands In Females?

1. ACTH-RH
2. LH And Prolactin
3. LTH-RH
4. TH.

Answer: 2. LH And Prolactin

Question 174. Which One Of The Endocrine Glands Shrinks After The Start Of Adolescence?

1. Pituitary Body
2. Pineal Glands
3. Hypothalamus
4. Thymus Glands.

Answer: 4. Thymus Glands.

Question 75. The Hormone That Regulates The Growth Of The Skeleton And The Body As A Whole Is :

1. Thyroxine
2. Parathormone
3. Thyroid Stimulating Hormone
4. Human Growth Hormone.

Answer: 4. Human Growth Hormone.

Question 76. Which One Of The Following Has an Anti-Insulin Effect?

1. Calcitonin
2. Cortisol
3. Oxytocin
4. Aldosterone.

Answer: 2. Cortisol

Question 77. Which Of The Following Hormones Is Proteinic In Nature But May Be Secreted By An Organ Which Normally Secretes Steroids Under Special Conditions Is :

1. Relaxin
2. LH
3. Estrogen
4. Oxytocin.

Answer: 1. Relaxin

Question 78. The Addison’s Disease Is Caused By The :

1. Hyposecretion Of Cortical Hormones
2. Hypersecretion Of Cortical Hormones
3. Hypersecretion Of Pituitary Hormones
4. Enlargement Of Thyroids.

Answer: 1. Hyposecretion Of Cortical Hormones

Question 79. The Determination And Masculinisation Of Female May Be Done By :

1. Ovary
2. Medulla Of Adrenals
3. Cortex Of Adrenals
4. Parathyroids.

Answer: 3. Cortex Of Adrenals

Question 80. Select The Odd One :

1. Insulin
2. Oxytocin
3. Thyroxine
4. Ecdysone.

Answer: 4. Ecdysone.

Question 81. Progesterone Is A / An :

1. Enzyme
2. Protein
3. Hormone That Relaxes Uterus During Birth
4. Hormone Responsible For Growth And Maintenance Of Foetus.

Answer: 4. Hormone Responsible For Growth And Maintenance Of Foetus.

Question 82. Which Hormone Of The Following Endocrine Glands Lacks Peptide, Amines And Sulphur?

1. Hormones Of the Anterior Lobe Of the Pituitary
2. Hormones Of the Posterior Lobe Of the Pituitary
3. Hormones Of Thyroids And Adrenal Gland
4. Hormones Of Gonads.

Answer: 4. Hormones Of Gonads.

Endocrine System NEET Notes

Question 83. Which Endocrine Gland Stores Its Secretion In The Extracellular Space Before Discharging It Into The Blood?

1. Adrenal
2. Pancreas
3. Testis
4. Thyroid.

Answer: 4. Thyroid.

Question 84. According To The Accepted Concept Of Hormone Action, If Receptor Molecules Are Removed From Target Organs :

1. The Target Organ Will Continue To Respond To The Hormone Without Any Difference
2. The Target Organ Will Continue To Respond To The Hormone But Will Require Higher Concentration
3. The Target Organ Will Not Respond To The Hormone
4. The Target Organ Will Continue To Respond To The Hormone But In The Opposite Way.

Answer: 3. The Target Organ Will Not Respond To The Hormone

Question 85. Oxytocin Is A :

1. Parathormone
2. Small Peptide
3. Fatty Acid Residue
4. Sugar Molecule.

Answer: 2. Small Peptide

Question 86. The Hormone that elevates Blood Calcium And Phosphorus levels is:

1. Parathormone
2. Calcitonin
3. Thyroxine
4. Triiodothyronine.

Answer: 1. Parathormone

Question 87. The Hormone Which Stimulates Milk Production In Mammals Is Known As:

1. Glucagon
2. Prolactin
3. Progesterone
4. Oestrogen.

Answer: 2. Prolactin

Question 88. Which Of The Following Is Not a Steroid?

1. Testosterone
2. Oestradiol-17b
3. Progesterone
4. Prolactin.

Answer: 4. Prolactin.

Question 89. Which Of The Following Hormones Stimulate the Conversion Of Proteins Into Amino Acids Particular During Fasting Or Hibernation?

1. Glucocorticoids
2. Secretin
3. Adrenaline
4. Enterogastrone.

Answer: 1. Glucocorticoids

Question 90. Growth Hormone Is Secreted By :

1. Hypothalamus
2. Thyroid Glands
3. Pituitary Gland
4. Pineal Body.

Answer: 3. Pituitary Gland

Question 91. The Hormone In the Pineal Gland Is Called :

1. Melatonin
2. Melatonin
3. Serotonin
4. Pincolin.

Answer: 1. Melatonin

Question 92. The Pineal Gland :

1. Is A Photoreceptor
2. Responds To Smell
3. Responds To Sound
4. Is Sensitive To Light Stimulus.

Answer: 4. Is Sensitive To Light Stimulus.

Endocrine System NEET Notes

Question 93. Endocrinology Term Was Proposed By :

1. Pande
2. Hardy
3. Sutherland
4. All Of These.

Answer: 1. Pande

Question 94. Hormones Are Needed In :

1. Gms.
2. Milligrams
3. Nanograms
4. Kilograms.

Answer: 3. Nanograms

Question 95. Pheromones Are :

1. Hormones Of Insects
2. Peripheral Hormones
3. Both 1 And 2
4. None.

Answer: 3. Both 1 And 2

Question 96. The Total No. Of Hormones Produced By Adrenal Cortex Is 20 But They Are Grouped Under :

1. One
2. Two
3. Three
4. Four.

Answer: 3. Three

Question 97. Calcitonin, Which Reduces The Excessive Amount Of Calcium Of The Blood, Is Secreted By The :

1. Hypothalamus
2. Parathyroid
3. Thyroid
4. Adrenal.

Answer: 3. Thyroid

Question 98. The Vesicles Of The Thyroid Gland Are Lined By :

1. Epithelium Which Is Single Layered
2. A Double Layer Of Epithelium
3. A Single Layer Of Endothelium
4. A Double Layer Of Endothelium.

Answer: 1. Epithelium Which Is Single Layered

Question 99. The Moulting In Insects Is Triggered Off By :

1. Thyroxine
2. Ecdysone
3. Juvenile Hormone
4. Pheromone.

Answer: 2. Ecdysone

Question 100. The Hormones Secreted By Hypothalamus Are Carried To The Pituitary Gland By :

1. Hypophyseal Stalk
2. Hypophyseal Portal System
3. Neural Complex
4. Neuro-Hypophyseal Portal System.

Answer: 2. Hypophyseal Portal System

Question 101. Cretinism In Children Is Caused By :

1. Hypothyroidism
2. Hypopituitarism
3. Hypoparathyroidism
4. Hypo-Insulin-Secretion.

Answer: 1. Hypothyroidism

Hormones And Their Functions NEET Biology

Question 102. Mammalian Thymus Is Mainly Concerned With :

1. Regulation Of Body Growth
2. Regulation Of Body Temperature
3. Immunological Functions
4. Secretion Of Thyrotropins.

Answer: 3. Immunological Functions

Question 103. Insulin Was Extracted First By :

1. Flemming
2. Khorana
3. Watson And Crick
4. Banting And Best.

Answer: 4. Banting And Best.

Question 104. The Effect Of Different Hormones On The Body Can Be Best Said To Bring About:

1. Stimulation Of Organs
2. Release Of Inherent Capacities
3. Proper Growth
4. Coordination Of Functions.

Answer: 4. Coordination Of Functions.

Question 105. Which Hormone Has The Anti-Insulin Effect?

1. Calcitonin
2. Cortisol
3. Oxytocin
4. Glucagon.

Answer: 2. Cortisol

Question 106. Hypoparathyroidism Results Due To :

1. Upset In Metabolism
2. Improper Gonadial Function
3. Convulsions And Tetany
4. Nervousness And Wasting.

Answer: 3. Convulsions And Tetany

Question 107. The Secretion From Which Of The Following Controls Wall Balance In The Body?

1. Cerebellum
2. Cerebrum
3. Pineal Body
4. Pituitary.

Answer: 4. Pituitary.

Question 108. Hypothyroidism In Adult Causes :

1. Cretinism
2. Exophthalmic Goitre
3. Myxoedema
4. Graves’s Disease

Answer: 3. Myxoedema

Question 109. Insulin Promotes :

1. Glycogenesis
2. Glycolysis
3. Glyconeogenesis
4. Glycogenolysis.

Answer: 1. Glycogenesis

Question 110. Mark The Gland In Whose Presence Sex Glands Fail To Develop :

1. Adrenal
2. Pituitary
3. Pineal
4. Thyroid.

Answer: 3. Pineal

Question 111. The Anterior Lobe Of Pituitary Affects :

1. Protein Metabolism
2. Fat Metabolism
3. Carbohydrate Metabolism
4. All Of The Above.

Answer: 4. All Of The Above.

Question 112. Survival Time Can Be Minimized If We Remove:

1. Adrenal
2. Pituitary
3. Thymus
4. Thyroid.

Answer: 1. Adrenal

Question 113. Testis Secretes Androgen, It Is :

1. Testosterone
2. Androsterone
3. Progesterone
4. Aldosterone.

Answer: 1. Testosterone

Question 114. Which Of The Following Causes Ageing?

1. Islets Of Langerhans
2. Parathyroid
3. Thyroid
4. Thymus.

Answer: 4. Thymus.

Hormones And Their Functions NEET Biology

Question 115. Breast Development During Pregnancy Is Induced By :

1. Estradiol
2. Progesterone
3. Relaxin
4. None Of These.

Answer: 2. Progesterone

Question 116. Which Of The Following Is Helpful For An Asthma Patient In Exhaling The Air?

1. Adrenaline
2. Insulin
3. Oxytocin
4. Thyroxine.

Answer: 1. Adrenaline

Question 117. Which Of The Following Controls Thirst?

1. Adrenal
2. Pituitary
3. Parathyroid
4. Thyroid.

Answer: 2. Pituitary

Question 118. Complete Failure Of Adenohypophysis Of Pituitary In Adult Women Causes :

1. Addison’S Disease
2. Cushing’S Disease
3. Dwarfism
4. Simmond’s Disease.

Answer: 3. Dwarfism

Question 119. Oxytocin Is Secreted By :

1. Adenohypophysis
2. Neurohypophysis
3. Hypophyseal Stalk
4. Only Pregnant Women.

Answer: 2. Neurohypophysis

Question 120. Fsh Is Produced By :

1. Adrenal
2. Thyroid
3. Anterior Lobe Of Pituitary
4. Posterior Lobe Of Pituitary.

Answer: 3. Anterior Lobe Of Pituitary

Question 121. Which Of The Following Hormones Is From the Parathyroid Gland?

1. Epinephrine
2. Gastrin
3. Noradrenaline
4. Parathormone.

Answer: 4. Parathormone.

Question 122. Thyroxine Is Produced Through :

1. Chlorination Of Serine
2. Iodination Of Isoleucine
3. Iodination Of Tyrosine
4. Phosphorylation Of Amino Acids.

Answer: 3. Iodination Of Tyrosine

Question 123. Which Of The Following Is Related To The Production Of Lymphocytes And Antibodies?

1. Thymus
2. Hypothalamus
3. Thyroid
4. Leydig Cells.

Answer: 1. Thymus

Question 124. Addison’s Disease Is Due To the Malfunctioning Of the:

1. Adrenal Cortex
2. Parathyroid
3. Pineal Gland
4. Pancreas.

Answer: 1. Adrenal Cortex

Question 125. The Recently Reported Hormone, Angiotensin Is Secreted By :

1. Liver
2. Kidney
3. Pancreas
4. Placenta.

Answer: 1. Liver

Question 126. Thyroxine Plays Significant Effect On :

1. Carbohydrate Metabolism
2. Protein Metabolism
3. Vitamin Metabolism And Central Nervous System
4. All Of The Above.

Answer: 3. Vitamin Metabolism And Central Nervous System

Question 127. Continued Secretion Of Milk Is Maintained By :

1. Prolactin
2. Progesterone
3. Oestrogen
4. Relaxin.

Answer: 1. Prolactin

Question 128. The Over-Secretion Of Which Of The Following Pituitary Hormones Causes Acromegaly (Irregularly Development Of Bones)?

1. ACTH
2. LH
3. GTH
4. STH Or GH.

Answer: 4. STH Or GH.

Question 129. Hormone Responsible For The Implantation Of Embryo In Uterus And Formation Of Placenta Is :

1. Adrenaline
2. Progesterone
3. Estradiol
4. FSH.

Answer: 2. Progesterone

Question 130. The Pituitary Gland’s Posterior Lobe Produces Two Hormones Called :

1. Cortisone And Corticosterone
2. Progesterone And Estradiol
3. Testosterone And Androsterone
4. Vasopressin And Oxytocin.

Answer: 4. Vasopressin And Oxytocin.

Question 131. According To Recent Knowledge, The Pineal Body Is Considered As :

1. An Organ Of Intelligence
2. An Endocrine Gland
3. A Vestigial Organ
4. An Organ Of Involuntary Action.

Answer: 2. An Endocrine Gland

Pituitary Gland Hormones NEET Study Material

Question 132. Which Hormone Is Responsible For The Relaxation Of The Ligaments Of The Pelvic Girdles In Females At The Time Of Birth?

1. Corpus Luteum
2. Gastrin
3. Estradiol
4. Relaxin.

Answer: 4. Relaxin.

Question 133. Who Studied The Effect Of Thyroxine On Metamorphosis :

1. Huxley
2. Starling
3. Kendall
4. Gudernatsch.

Answer: 4. Gudernatsch.

Question 134. Correct Hormonal Sequence In The Increase Of Menstruation Is:

1. Estrogen, Fsh And Progesterone
2. Estrogen, Progesterone And Fsh
3. Fsh, Progesterone And Estrogen
4. Fsh, Estrogen And Progesterone.

Answer: 4. Fsh, Estrogen And Progesterone.

Question 135. Hormone Secreted By Posterior Lobe Of Pituitary Is Concerned With :

1. Metabolism Of Carbohydrates
2. Stimulation Of Thyroid
3. Secondary Sexual Characters
4. Contraction Of Uterus.

Answer: 4. Contraction Of Uterus.

Question 136. Hormone-secreting cells, Called Neurosecretory Cells, Are Abundant In The following:

1. Hypothalamus
2. Amygdala
3. Cerebral Cortex
4. Medulla Oblongata.

Answer: 1. Hypothalamus

Question 137. Oxytocin And Antidiuretic Hormone Reach The Posterior Pituitary By Way Of :

1. The Anterior Pituitary Gland
2. Lymphatic Vessels
3. Blood Vessels
4. Axons.

Answer: 4. Axons.

Question 138. Oxytocin And Antidiuretic Hormone Reach Their Target Cells By Way Of :

1. The Anterior Pituitary Gland
2. Lymphatic Vessels
3. Blood Vessels
4. Axons

Answer: 3. Blood Vessels

Question 139. The Luteinising Hormone Is Secreted By :

1. Lactotrophs
2. Gonadotrophs
3. Thyrotrophs
4. Neurohypophysis.

Answer: 2. Gonadotrophs

Question 140. Hypothalamic Releasing Hormones Reach The Anterior Pituitary Gland By Way Of:

1. The Posterior Pituitary Gland
2. Lymphatic Vessels
3. Blood Vessels
4. Axons.

Answer: 3. Blood Vessels

Question 141. Excessive Production Of Growth Hormone During Adulthood Can Lead To :

1. A Pituitary Giant
2. A Pituitary Dwarf
3. Disproportionately Large Hands, Feet And Jaw
4. Deterioration Of The Bones.

Answer: 3. Disproportionately Large Hands, Feet And Jaw

Question 142. In Mammals, Prolactin Stimulates The Production Of :

1. Progesterone
2. Mucus In The Digestive Tract
3. Digestive Enzymes In The Small Intestine
4. Milk.

Answer: 4. Milk.

Question 143. Cushing’s Syndrome Is Associated With the:

1. Glucocorticosteroids
2. Mineralo Corticosteroids
3. Sex Corticosteroids
4. Gene Mutation.

Answer: 1. Glucocorticosteroids

Question 144. If A Person Is Subjected To Stress (Like Heat, Cold, Loud Noise, etc.) Continuously, Which Organ Will Undergo Hypertrophy :

1. Adrenal
2. Liver
3. Pancreas
4. Salivary Glands.

Answer: 1. Adrenal

Question 145. Addison’s Disease Is Caused By the:

1. Hyposecretion Of Corticosteroid
2. Oversecretion Of Corticosteroid
3. Hyposecretion Of Lh
4. Oversecretion Of Lh.

Answer: 1. Hyposecretion Of Corticosteroid

Pituitary Gland Hormones NEET Study Material

Question 146. The Adrenal Glands Are Located Adjacent To The :

1. Larynx
2. Urinary Bladder
3. Kidneys
4. Gonads.

Answer: 3. Kidneys

Question 147. The Fight-Or-Flight Response Is Developed By Hormones Of The :

1. Hypothalamus
2. Adrenal Medulla
3. Adrenal Cortex
4. Adreno-Pancreatic Complex.

Answer: 2. Adrenal Medulla

Question 148. The Main Function Of Norepinephrine Is To Increase :

1. Blood Pressure
2. Urine Production
3. Cellular Respiration
4. The Release Of Epinephrine.

Answer: 1. Blood Pressure

Question 149. Epinephrine And Norepinephrine Function As Both Hormones And :

1. Fuel For Cellular Respiration
2. Neurotransmitters
3. Ions To Promote Action Potentials
4. Solutes To Promote Osmotic Flow.

Answer: 2. Neurotransmitters

Question 150. All The Hormones Of The Adrenal Cortex Are Synthesized From:

1. Tyrosine
2. Glycoproteins
3. Cholesterol
4. Fats.

Answer: 3. Cholesterol

Question 151. Disease Osteitis Fibrosa Cystica Is Related With :

1. Hyposecretion Of Parathyroid Hormone
2. Hypersecretion Of Parathyroid Hormone
3. Hypersecretion Of Mineralocorticosteroids
4. Hyposecretion Of Glucocorticosteroids.

Answer: 2. Hypersecretion Of Parathyroid Hormone

Question 152. The Part Of The Brain With the Greatest Influence Over The Endocrine System Is The :

1. Hypothalamus
2. Amygdala
3. Cerebral Cortex
4. Medulla Oblongata.

Answer: 1. Hypothalamus

Question 153. Which Of The Following Groups Of Arthropoda Has a Well-Developed Endocrine System?

1. Arachnida
2. Crustacea
3. Insecta
4. All Classes Of Arthropoda.

Answer: 4. All Classes Of Arthropoda.

Question 154. If Adenohypophysectomy Is Done In Adults, Then Which Of The Following Is The Correct Statement:

1. Acromegaly
2. It Will Affect the Function Of the Testis And Ovary
3. Gigantism
4. B.M.R. Will Be Affected.

Answer: 2. It Will Affect the Function Of the Testis And Ovary

Question 155. The Moult Of An Insect Is Triggered By :

1. Thyroxine
2. Ecdysone
3. Juvenile Hormone
4. A Pheromone.

Answer: 2. Ecdysone

Question 156. The Development Of Adult Characteristics In A Moulting Insect Is Promoted By :

1. Thyroxine
2. Ecdysone
3. Juvenile Hormone
4. A Pheromone.

Answer: 2. Ecdysone

Question 157. The Retention Of Larval Characteristics In A Moulting Insect Is Promoted By :

1. Thyroxine
2. Ecdysone
3. Juvenile Hormone
4. A Pheromone.

Answer: 3. Juvenile Hormone

Question 158. A Male Moth Finds A Mate Using:

1. Thyroxine
2. Ecdysone
3. Brain Hormone
4. Pheromone.

Answer: 4. Pheromone.

Question 159. Diabetes Mellitus Develops Only When :

1. α Cells Of the Pancreas Are In Excess
2. α Cells Of the Pancreas Are Not Functioning
3. β Cells Of Pancreas Are In Excess
4. β Cells Of the Pancreas Are Not Functioning.

Answer: 4. 3 Cells Of Pancreas Are Not Functioning

Question 160. The Target Cells Of A Hormone Always Have :

1. Special Receptors To Which The Hormone Binds
2. Special Channels Through Which The Hormone Moves
3. Large Amounts Of The Hormone Stored Within Vesicles
4. Undifferentiated Cytoplasm.

Answer: 1. Special Receptors To Which The Hormone Binds

Question 161. The Hormone Which Is Related To The Urine Concentration In Mammals :

1. Antidiuretic Hormone Only
2. Antidiuretic Hormone And Oxytocin
3. Antidiuretic Hormone And Aldosterone
4. Testosterone Only.

Answer: 3. Antidiuretic Hormone And Aldosterone

Pituitary Gland Hormones NEET Study Material

Question 162. Which Of The Following Hormones Is A Steroid?

1. Prostaglandin
2. Estrogen
3. Epinephrine
4. Thyroxine.

Answer: 2. Estrogen

Question 163. In A Male Heavy Voice And Growth Of Beard And Moustaches Is Due To Oversecretion Of :

1. Androgen
2. Estrogen
3. Adrenaline
4. Estrogen And Progesterone.

Answer: 1. Androgen

Question 164. A Steroid Hormone Typically Alters The Activity Of Its Target Cells By :

1. Digesting Holes In The Cell’s Plasma Membrane
2. Entering The Cell And Altering Gene Expression
3. Passing Its Message To An Intracellular Messenger
4. Digesting Holes In The Cell’s Lysosomes.

Answer: 2. Entering The Cell And Altering Gene Expression

Question 165. Which Of The Following Hormones Is A Modified Amino Acid?

1. Prostaglandin
2. Estrogen
3. Epinephrine
4. Progesterone.

Answer: 3. Epinephrine

Question 166. A Peptide Hormone Typically Alters The Activity Of Its Target Cells By :

1. Digesting Holes In The Cell’s Plasma Membrane
2. Entering The Cell And Altering Gene Expression
3. Passing Its Message To An Intracellular Messenger
4. Digesting Holes In The Cell’s Lysosomes.

Answer:  3. Passing Its Message To An Intracellular Messenger

Question 167. Animal Tissues That Synthesize Hormones Are Closely Associated With, And Sometimes Resemble, Cells Of The :

1. Immune System
2. Embryonic Mesoderm
3. Circulatory System
4. Nervous System.

Answer: 4. Nervous System.

Question 168. Which One Of The following is Not Under Direct Control Of Pituitary Gland?

1. Adrenal Cortex
2. Adrenal Medulla
3. Thyroid
4. Testis.

Answer: 2. Adrenal Medulla

Question 169. If Thyroidectomy Of Tadpole Is Performed, Moulting Will Take Place :

1. Potassium Iodide Treatment
2. Fed On Adult Sheep Thyroid
3. Moulting Will Never Take Place
4. Normal Moulting Will Take Place.

Answer: 2. Fed On Adult Sheep Thyroid

Question 170. Spermatogenesis In the Mammalian Testis Is Controlled By :

1. FSH
2. LH
3. Progesterone
4. ICSH.

Answer: 1. FSH

Question 171. Vasopressin Is Related With :

1. Dilution Of Urine
2. Increased Heart Beat
3. Concentration Of Urine
4. Decreased Heart Beat.

Answer: 3. Concentration Of Urine

Question 172. The Part Of The Brain With The Greatest Influence Over The Endocrine System Is The :

1. Hypothalamus
2. Cerebellum
3. Cerebral Cortex
4. Medulla Oblongata.

Answer: 1. Hypothalamus

Question 173. Metabolic Rate In Mammals Is Controlled By :

1. Pancreas
2. Liver
3. Pituitary
4. Thyroid.

Answer: 4. Thyroid.

Question 174. Hypothalamo-Hypophyseal System Is Derived From :

1. Rathke’S Pouch
2. Neuroectoderm
3. Rathke’s Pouch And Neuroectoderm
4. None Of The Above.

Answer: 3. Rathke’s Pouch And Neuroectoderm

Question 175. The Cells Of the Pancreas That Produce Glucagon Are :

1. Alpha Cells
2. Gamma Cells
3. Acinar Cells
4. Beta Cells.

Answer: 1. Alpha Cells

Question 176. The First Hormone To Be Isolated (In 1902) Was :

1. Thyroxine
2. Testosterone
3. Epinephrine
4. Secretin.

Answer: 4. Secretin

Question 177. The Mammalian Thyroid Gland Is Located Adjacent To The

1. Adenoids
2. Trachea
3. Kidneys
4. Pancreas.

Answer: 2. Trachea

Question 178. Thyroxine And Triiodothyronine, Produced By The Thyroid Are Synthesized From Iodine And :

1. Phenylalanine
2. Cholesterol
3. Glycoproteins
4. Tyrosine.

Answer: 4. Tyrosine.

Pituitary Gland Hormones NEET Study Material

Question 179. The Parathyroid Glands Are Located Adjacent To The :

1. Adenoids
2. Thyroid Gland
3. Adrenal Glands
4. Pancreas.

Answer: 2. Thyroid Gland

Question 180. Progesterone Is Secreted By :

1. Corpora Allata
2. Corpus Albicans
3. Corpus Luteum
4. None Of These.

Answer: 3. Corpus Luteum

Question 181. Which Of The Following Statements is correct?

A. Endocrine Control Is Integrated With Neural Control At The Level Of The Hypothalamus.

B. Thyroid Hormones Are Required For Normal Prenatal Brain Development.

C. Glucocorticoids Are Anabolic Steroids.

D. Adrenal Medulla Releases Adrenaline And Noradrenaline In A Ratio Of Approximately 10:1:

Choose The Correct Answer

1. A And D
2. A And C
3. A And B
4. B And C

Answer: 3. A And B

Question 182. Which Of The Following Statement Is Correct?

1. Testosterone Is Not Water-Soluble And Acts Via Receptors On The Plasma Membrane Of The Target Cells.
2. Hypoglycemia Occurs Most Commonly In Diabetic Patients.
3. Oxytocin Is Released In Response To Mechanical Stimulation Of The Breast Nipple
4. Cellular Reactions Are Slow And More Accurate When Activity Is Determined By Two Antagonistic Hormones.

Answer: 2. Hypoglycemia Occurs Most Commonly In Diabetic Patients.

Question 183. The Posterior Pituitary :

1. Produces Oxytocin
2. Is Under The Control Of the Hypothalamic Releasing Neurohormone
3. Secretes Trophic Hormones
4. Secretes Neurohormones.

Answer: 1. Produces Oxytocin

Question 184. Parathyroid Hormone :

1. Is Produced By The Thyroid Gland
2. Is Released When Blood Calcium Levels Fall
3. Stimulates Osteoblasts To Lay Down New Bone
4. Stimulates Calcitonin Release.

Answer: 2. Is Released When Blood Calcium Levels Fall

Question 185. Steroid Hormones :

1. Have Only Cell Surface Receptors
2. Are Lipophobic
3. Act Through Altering The Activity Of Proteins In The Target Cell
4. Are Produced By The Adrenal Cortex.

Answer: 3. Act Through Altering The Activity Of Proteins In The Target Cell

Question 186. Match The Definitions Of Column 1 With the Appropriate Term Of Column 2

• A B C D E

1. 1 2 4 3 5
2. 5 1 2 3 4
3. 5 1 3 4 2
4. 5 1 2 4 3.

Answer: 2.  5 1 2 3 4

Question 187. Both Adrenaline And Cortisol Are Secreted In Response To Stress; Which Of The Following Statement Is Also True For Both Of These Hormones?

1. They Act To Increase Blood Glucose
2. They Are Secreted By The Adrenal Cortex
3. Their Secretion Is Stimulated By Adrenocorticotropin
4. They Are Secreted Into The Blood Within Seconds Of The Onset Of Stress.

Answer: 1. They Act To Increase Blood Glucose

Question 188. Which Of The Following Is Not Inhibitory Hormone?

1. PIH
2. GHIH
3. MIH
4. GI.

Answer: 4. GI.

Question 189. Melanocyte Stimulating Hormone Is Secreted By Which Cell Type Of Pituitary Gland?

1. Somatotroph
2. Thyrotroph
3. Corticotroph
4. Gonadotroph.

Answer: 3. Corticotroph

Question 190. Which Of The Following Can Cause the Release Of Oxytocin Hormone In A Lactating Mother?

1. Sight Of Baby
2. Sound Of Baby
3. Both 1 And 2
4. None Of Above.

Answer: 3. Both 1 And 2

Question 191. Which Of The Following Hormone Is Not Present In Both Sexes?

1. Oxytocin
2. ADH
3. FSH
4. ICSH.

Answer: 4. ICSH.

Question 192. About A Million Islets Of Langerhans Each With Approximately 3000 Cells Comprise What Percentage Of Pancreas?

1. 1
2. 1-5
3. 2
4. 2-5.

Answer: 2. 1-5

Question 193. Which Of The Following Statement Is Incorrect?

1. Somatostatin Inhibit The Secretion Of Insulin And Glucagon
2. Cortisol Hormone Has No Role During And After Danger
3. Hypoglycemic Results From Hypersecretion Of Insulin
4. Human Placental Lactogen Stimulate Mammary Growth.

Answer: 2. Cortisol Hormone Has No Role During And After Danger

Thyroid Gland Disorders NEET Exam Preparation

Question 194. Which Of The Following Is A Function Of Calcitonin?

1. Regulation Of Metabolic Rate
2. Maintenance Of Body Temperature
3. Regulate The Development Of Mental Faculties
4. All Of The Above.

Answer: 4. All Of Above.

Question 195. Hypophysectomy Results In Diminution Of All Except One Of The Following Hormones.

1. Acth (Adrenocorticotrophic Hormone)
2. Growth Hormone
3. Prolactin
4. Tsh (Thyroid Stimulating Hormone).

Answer: 3. Tsh (Thyroid Stimulating Hormone).

Question 196. The Glucocorticoids Are Mainly Responsible For :

1. Enhancement Of Glucose Formation
2. Diminution Of Glucose Formation
3. Excretion Of Sodium By Kidney
4. Retention Of Sodium By Kidney.

Answer: 1. Enhancement Of Glucose Formation

Question 197. Insulin Deficiency Produces :

1. Increased Entry Of Glucose Into Cells
2. Reduced Entry Of Glucose Into Cells
3. Decreased Release Of Glucose From Liver
4. No Effect On Carbohydrate Metabolism.

Answer: 2. Reduced Entry Of Glucose Into Cells

Question 198. Hormones Based On Fatty Acids Are :

1. Small In Size And Variable In Structure
2. Small In Size And Constant In Structure
3. Large In Size And Variable In Structure
4. Large In Size And Constant In Structure.

Answer: 2. Small In Size And Constant In Structure

Question 199. A Disease Which Is Caused By The Under-Secretion Of Adrenal Cortex Is :

1. Grave’s Disease
2. Addison’s Disease
3. Cushing’s Syndrome
4. Acromegaly.

Answer: 2. Addison’s Disease

Question 200. A Hormone Which Helps In The Implantation Of Embryo In Uterus Is :

1. Oestrogen
2. Relaxin
3. Progesterone
4. Thymosin.

Answer: 3. Progesterone

NEET Biology Endocrine System Questions From Competitive Examination

Question 1. Myxoedema Is Due To :

1. Decreased Production Of Thyroxine
2. Increased Production Of Thyroxine
3. Excess Gh
4. Decreased Insulin.

Answer: 1. Decreased Production Of Thyroxine

Question 2. Injection Of Glucagon Will :

1. Cause Hypoglycemia
2. Cause Galactosemia
3. Increase Blood Sugar
4. Cause Goitre.

Answer: 3. Increase Blood Sugar

Question 3. Goitre Influences :

1. Speech
2. Excretion
3. Metabolism
4. Vision.

Answer: 3. Metabolism

Question 4. Pheromones Are :

1. Produced By Endocrine Glands
2. Mrnas
3. Chemicals Used In Animal Communication
4. Proteins.

Answer: 3. Chemicals Used In Animal Communication

Question 5. Which Is Not Involved In Endocrine Secretion?

1. Ley Dig Cell
2. Lutein Cell
3. Para-Follicular Cells Of Thyroid
4. Kupffer Cells.

Answer: 4. Kupffer Cells

Thyroid Gland Disorders NEET Exam Preparation

Question 6. Gh Affects Growth By Controlling Production Of:

1. mRNA
2. tRNA
3. rRNA
4. None Of The Above.

Answer: 1. mRNA

Question 7. If the Receptor Molecule Is Removed From the Target Organ For Hormone Action, The Target Organ Will:

1. Continue To Respond But Requires Higher Concentration Of Hormone
2. Continue To Respond But In Opposite Way
3. Continue To Respond Without Any Difference
4. Not Respond To Hormone.

Answer: 4. Not Respond To Hormone.

Question 8. Melatonin Is Produced By :

1. Thymus
2. Skin
3. Pituitary
4. Pineal Gland.

Answer: 2. Skin

Question 9. On Seeing A Tiger, The Heart Beat And Blood Pressure Increase Due To Release Of Hormone :

1. Adrenaline
2. Thyroxine
3. Parathormone
4. Corticoids.

Answer: 2. Thyroxine

Question 10. A Person Has Protruding Eyes, Tachycardia, And Higher Body Temperature. He Is Suffering From :

1. Cretinism
2. Hyperthyroidism
3. Diabetes
4. Acromegaly.

Answer: 2. Hyperthyroidism

Question 11. Match The Endocrine Gland, Given Under Column 1 With Their Respective Position In The Body, Given Under Column 2. Choose The Answer Which Gives The Correct Combination Of Alphabets Of Two Columns :

1. A – S, B = T, C = P, D= Q
2. A = Q, B = S, C = T, D= P
3. A = T, B = R, C = P, D= Q
4. A = P, B = Q, C = R, D= T.

Answer: 3. A = T, B = R, C = P, D= Q

Question 12. Match The Hormone Listed Under Column 1 With The Roles  Given Under Column 2. Choose The Choice In Which The Alphabets Of The Two Columns Are Correctly Matched :

1. A = Q, B = S, C = P, D- R
2. A – T, B = P, C = S, D= Q
3. A = R, B = T, C = S, D= Q
4. A = T, B – S, C = P, D= Q.

Answer: 4. A = T, B – S, C = P, D= Q.

Question 13. Autoimmune Hypothyroidism Is :

1. Hashimoto Disease
2. Cushing Syndrome
3. Myxoedema
4. Addison’s Disease.

Answer: 1. Hashimoto Disease

Question 14. Steroids Are Precursors Of:

1. Progesterone
2. Oestrogen
3. Testosterone
4. All Of the Above.

Answer: 4. All Of Above

Thyroid Gland Disorders NEET Exam Preparation

Question 15. Thyrotropin – Releasing Factor (Trf) Is Produced By :

1. Cerebrum
2. Optic Lobe
3. Cerebellum
4. Hypothalamus.

Answer: 4. Hypothalamus.

Question 16. Tetany Is Caused By :

1. Hypothyroidism
2. Hyperthyroidism
3. Hypoparathyroidism
4. Hyperparathyroidism.

Answer: 3. Hypoparathyroidism

Question 17. Mainly Which Type Of Hormones Control The Menstrual Cycle In Human Beings :

1. FSH
2. Progesterone
3. FSH, LH, Estrogen
4. LH.

Answer: 3. FSH, LH, Estrogen

Question 18. When Both Ovaries Are Removed From the Rat Then Which Hormone Is Decreased In Blood?

1. Oxytocin
2. Gonadotrophic Releasing Factor
3. Estrogen
4. Prolactin.

Answer: 3. Estrogen

Question 19. Which One Of The Following Pairs Correctly Matches A Hormone With A Disease Resulting From Its Deficiency?

1. Insulin -Diabetes Insipidus
2. Relaxin -Gigantism
3. Prolactin -Cretinism
4. Parathyroid Hormone -Tetany.

Answer: 4. Parathyroid Hormone -Tetany

Question 20. Synthesis Of Testosterone By Leydig Cells Is Stimulated By :

1. FSH
2. ICSH
3. LTH
4. TSH

Answer: 2. ICSH

Question 21. Which One Of The Following Hormones Is A Modified Amino Acid?

1. Prostaglandin
2. Estrogens
3. Epinephrine
4. Progesterone.

Answer: 3. Epinephrine

Question 22. Which One Of The Following Pairs Correctly Matches A Hormone With A Disease Resulting From Its Deficiency?

1. Thyroxine-Tetany
2. Parathyroid Hormone-Diabetes Mellitus
3. Luteinizing Hormone-Failure Of Ovulation
4. Insuhn-Diabetes Insipidus.

Answer: 3. Luteinizing Hormone-Failure Of Ovulation

Question 23. Chemically The Hormones Are :

1. Proteins Only
2. Steroids Only
3. Biogenic Amines Only
4. Proteins, Steroids And Biogenic Amines.

Answer: 3. Biogenic Amines Only

Question 24. Which Of The Following Hormones Is Not A Secretion Product Of the Human Placenta?

1. Estrogens
2. Progesterone
3. Hcg
4. Prolactin.

Answer: 4. Prolactin.

Question 25. Damage To the Thymus In A Child May Lead To :

1. A Reduction In Haemoglobin Content Of Blood
2. A Reduction In Stem Cell Production
3. Loss Of Antibody-Mediated Immunity
4. Loss Of Cell-Mediated Immunity.

Answer: 4. Loss Of Cell-Mediated Immunity.

Question 26. Parkinson’s Disease (Characterized By Tremors And Progressive Rigidity Of Limbs) Is Caused By Degeneration Of Brain Neurons That Are Involved In Movement Control And Make Use Of Neurotransmitters:

1. Acetylcholine
2. Norepinephrine
3. Dopamine
4. Gaba.

Answer: 3. Dopamine

Question 27. Fsh Is Secreted By :

1. Anterior Lobe Of Pituitary
2. Hypothalamus
3. Gonads
4. Posterior Lobe Of Pituitary

Answer: 1. Anterior Lobe Of Pituitary

Question 28. Which One Of The Following Four Glands Is Correctly Matched With The Accompanying Description?

1. Thyroid – Hyperactivity In Young Children Causes Cretinism
2. Thymus – Starts Undergoing Atrophy After Puberty
3. Parathyroid – Secrete Parathormone Which Promotes the Movement Of Calcium Ions From Blood Into Bones During Calcification
4. Pancreas – Delta Cells Of The Islets Of Langerhans Secrete A Hormone That Stimulates Glycolysis In the Liver.

Answer: 2. Thymus – Starts Undergoing Atrophy After Puberty

Thyroid Gland Disorders NEET Exam Preparation

Question 29. The Hormone That Controls The Level Of Calcium And Phosphorus In The Blood Is Secreted By :

1. Thyroid
2. Parathyroid
3. Pituitary
4. Thymus.

Answer: 2. Parathyroid

Question 30. Which Of The Following diseases is Not Related To Thyroid Gland?

1. Myxoedema
2. Cretinism
3. Acromegaly
4. Goitre.

Answer: 3. Acromegaly

Question 31. Grave’s Disease Is Due To :

1. Hyperactivity Of the Thyroid Gland
2. Hypoactivity Of Adrenal Cortex
3. Hyperactivity Of the Adrenal Medulla
4. Hypoactivity Of Islets Of Langerhans.

Answer: 1. Hyperactivity Of Thyroid Gland

Question 32. Hassal’s Bodies/Corpuscles Are Found In :

1. Liver
2. Thymus
3. Thyroid
4. Adrenal.

Answer: 2. Thymus

Question 33. Choose The Correct Combination Of Labelling In The Hormonal Control Of the Female Reproductive System

1. A-GnRH, B-Tsh, C- Lth, D-Uterus
2. A-Gnrh, B-Fsh/Lh, C – Estrogen Of Progesterone, D- Utrerus
3. A-Gnrh, B-Sth, C-Lh, D-Uterus
4. A-Gnrh, B-Acth, C-Lh, D-Uterus.

Answer: 2. A-Gnrh, B-Fsh/Lh, C – Estrogen Of Progesterone, D- Utrerus

Question 34. Which Of The Following Is Not Paired Correctly?

1. Myxoedema – Swollen Facial Tissues
2. Cretinism – Mentally Retarded
3. Grave’s Disease – Exophthalmos
4. Insulin – Raise Blood Glucose.

Answer: 4. Insulin – Raise Blood Glucose.

Question 35. Match Item In Column 1 With Those Given In Column 2.

1. 1 – A, 2 – D, 3 – B,  4 – C, 5 – E
2. 1 – D, 2 – B, 3 – A,  4 – C,  5 – E
3. 1 – D, 2 – A, 3 – B,  4 – C,  5 – E
4. 1 – D, 2 – A, 3 – C,  4 – B,  5 – E.

Answer: 3. 1 – D, 2 – A, 3 – B,  4 – C,  5 – E

Question 36. If the Receptor Molecule Is Removed From the Target Organ For Hormone Action, The Target Organ Will:

1. Continue To Respond But Require Higher Concentration Of Hormone
2. Continue To Respond But In Opposite Away
3. Continue To Respond Without Any Difference
4. Not Respond To Hormone.

Answer: 4. Not Respond To Hormone.

Question 37. Match The List 1 Wish List 2

1. A : 3, B:1, C: 4, D: 2
2. A: 1, B: 2, C : 3, D: 4
3. A: 2, B: 1, C: 4, D : 3
4. A: 4, B : 3, C: 2, D: 1.

Answer: 3. A:2, B: 1, C: 4, D: 3

Question 38. A Patient Of Diabetes Mellitus excretes glucose In Urine Even When He Is Kept on a carbohydrate-free diet. It Is Because :

1. Fats Are Catabolised To Form Glucose
2. Amino Acids Are Catabolised In Liver
3. Amino Acids Are Discharged In Blood Stream From Liver
4. Glycogen From Muscles Are Released In The Blood  Stream.

Answer: 1. Fats Are Catabolised To Form Glucose

Question 39. Sertoli Cells Are Regulated By The Pituitary Known As:

1. Prolactin
2. LH
3. FSH
4. GH.

Answer: 3. FSH

Question 40. A Steroid Hormone Which Regulates Glucose Metabolism Is :

1. 11-Deoxycorticosterone
2. Cortisone
3. Cortisol
4. Corticosterone.

Answer: 3. Cortisol

Question 41. Which One Of The Following Is Not A Second Messenger In Hormone Action?

1. Sodium
2. Camp
3. Cgmp
4. Calcium.

Answer: 1. Sodium

Question 42. Which One Of The Following Statements Is Correct?

1. Neurons Regulate Endocrine Activity, But Not Vice Versa
2. Endocrine Glands Regulate Neural Activity, But Not Vice Versa
3. Neither Hormones Control Neural Activity Nor The Neurons Control Endocrine Activity
4. Endocrine Glands Regulate Neural Activity, And Nervous System Regulates Endocrine Glands.

Answer: 4. Endocrine Glands Regulate Neural Activity, And Nervous System Regulates Endocrine Glands.

Question 43. Which Hormone Causes Dilation Of Blood Vessels, Increased Oxygen Consumption And Glucogenesis?

1. Adrenalin
2. ACTH
3. Glucagon
4. Insulin.

Answer: 1. Adrenalin

Question 44. Withdrawal Of Which Of The Following Hormones Is The Immediate Cause Of Menstruation?

1. FSH
2. Progesterone
3. Estrogen
4. FSH-RH.

Answer: 2. Progesterone

Question 45. Which Is Not A Symptom Of Hypothyroidism?

1. Lethargy
2. Mental Retardation
3. Oedema
4. Rise In Blood Urea.

Answer: 4. Rise In Blood Urea

Question 46. Flyposecretion Of Which Of The Following Can Cause Diabetes Insipidus?

1. Insulin
2. Thyroxine
3. Glucagon
4. ADH.

Answer: 1. Insulin

Question 47. The Hormones That Initiate Ejection Of Milk, Stimulate Milk Production And Growth Of Ovarian Follicles Are Respectively Known As

1. PRL, OT, And LH
2. OT, PRL And FSH
3. LH, PRL, And FSH
4. PRH, OT, And LH
5. PRH, OT, And FSH

Answer: 2. OT, PRL And FSH

Question 48. Hypothyroidism In Adults And Hyperparathyroidism Will Respectively Lead To :

1. Myxoedema And Cretinism
2. Grave’s Disease And Hashimoto’s Disease
3. Myxoedema And Osteitis Fibrosa Cystica
4. Addison’s Disease And Cretinism
5. Cretinism And Osteitis Fibrosa Cystica.

Answer: 3. Myxoedema And Osteitis Fibrosa Cystica

Question 49. Which One Of The Following Endocrine glands functions As A Biological Clock And A Neurosecretory Transducer?

1. Adrenal Gland
2. Thyroid Gland
3. Pineal Gland
4. Thymus Gland
5. Pituitary Gland.

Answer: 3. Pineal Gland

Question 50. Match The Hormone In Column 1 With Their Function In Column 2.

1. A-5, B-4, C-L, D-2
2. A-4, B-5, C-2, D-1
3. A-4, B-3, C-2, D-5
4. A-5, B-1, C-2, D-4
5. A-4, B-2, C-3, D-5.

Answer: 1. A-5, B-4, C-1, D-2

Question 51. In The Homeostatic Control Of Blood Sugar Level, Which Organs Function Respectively As Modulator And Effector?

1. Liver And Islets Of Langerhans
2. Hypothalamus And Liver
3. Hypothalamus And Islets Of Langerhans
4. Islets Of Langerhans And Hypothalamus.

Answer: 3. Hypothalamus And Islets Of Langerhans

Question 52. Column 1 Lists The Endocrine Structure And Column 2 Lists The Corresponding Hormones. Match The Two Columns. Identify The Correct Option From Those Given.

1. P = t,  Q = r,  R = s,  S = q
2. P = t,  Q = r,  R = q,  S = s
3. P = p, Q = q, R = s,  S = r
4. P = r,  Q,= t,  R = s,  S = q.

Answer: 1. P = t, Q = r, R = s, S = q

Question 53. Which Of The Following Hormones Are Produced In The Hypothalamus And Stored In The Posterior Pituitary?

1. FSH And LH
2. ADH And Oxytocin
3. TSH And STH
4. ACTH and MSH.

Answer: 2. ADH And Oxytocin

Question 54. Parathyroid :

1. Increases Blood Ca Level
2. Decreases Blood Ca Level
3. Promotes Collagen Synthesis By Osteoblasts
4. All Of The Above.

Answer: 1. Increases Blood Ca Level

Question 55. Which Part Of the Ovary In Mammals Acts As An Endocrine Gland After Ovulation?

1. Stroma
2. Germinal Epithelium
3. Vitelline Membrane
4. Graffian Follicle.

Answer: 4. Graffian Follicle.

Question 56. A Person Is Having Problems With Calcium And Phosphorus Metabolism In His Body. Which One Of The Following Glands May Not Be Functioning Properly?

1. Parotid
2. Pancreas
3. Thyroid
4. Parathyroid.

Answer: 4. Parathyroid.

Question 57. Feeling The Tremors Of An Earthquake A Scared Resident Of the Seventh Floor Of A Multistoryed Building Starts Climbing Down The Stairs Rapidly. Which Hormone Initiated This Action?

1. Adrenaline
2. Glucagon
3. Gastrin
4. Thyroxine.

Answer: 1. Adrenaline

Question 58. Match List With List Ii And Select The Correct Option.

1. A – 2, B – 5, C – 4, D – 1, E – 3
2. A – 3, B – 4, C – 5, D -3,  E – 2 ‘
3. A – 5, B – 3, C – 2, D – 4, E – 1
4. A – 2, B -3,  C – 4, D – 5, E – 1
5. A – 5, B – 3, C – 4, D – 2, E – 1.

Answer: 1. A – 2, B – 5, C – 4, D – 1, E – 3

Question 59. Which One Of The Following Pairs Of Organs Includes Only The Endocrine Glands?

1. Thymus And Testes
2. Adrenal And Ovary
3. Parathyroid And Adrenal
4. Pancreas And Parathyroid.

Answer: 3. Parathyroid And Adrenal

Question 60. Which One Of The Following Is An Amine Hormone?

1. Insulin
2. Oxypurin
3. Thyroxine
4. Progesterone.

Answer: 3. Thyroxine

Question 61. The Blood Calcium Level Is Lowered By The Deficiency Of :

1. Thyroxine
2. Calcitonin
3. Parathormone
4. Both Calcitonin And Parathormone.

Answer: 3. Parathormone

Question 62. In Human Adult Females Oxytocin :

1. Is Secreted By the Anterior Pituitary
2. Stimulates Growth Of Mammary Glands
3. Stimulates Pituitary To Secrete Vasopressin
4. Causes Strong Uterine Contractions During Parturition.

Answer: 4. Causes Strong Uterine Contractions During Parturition.

Question 63. Match The Source Gland With Its Respective Hormone As Well As The Function.

Answer: 2. Posterior- Vasopressin- Stimulates resorption Of Water In the Distal tubules in the nephron

Question 64.  Given Below Is An Incomplete Table About Certain Hormones, Their Source Glands, And One Major Effect Of Each On The Body In Humans. Identify The Correct Option For The Three Blanks A, B, And C.

Answer: 1. A- Ovary, B- Glucagon, C- Growth Hormone

Question 65. Which One Of The Following Statements Is Incorrect?

1. Glucagon Is Secreted By Pancreas.
2. Androgen Is Produced By Ovary.
3. Thyroxine Is Secreted By Thyroid.
4. Oxytocin Is Secreted By the Pituitary.

Answer: 2. Androgen Is Produced By Ovary.

Question 66. Which Of The Following Statements Is Correct To The Endocrine System?

1. Organs In The Body Like the Gastrointestinal Tract, Heart, Kidney, And Liver Do Not Produce Any Hormones.
2. Non-Nutrient Chemicals Produced By The Body In Trace Amount That Act As Intercellular Messenger Are Known As Hormones.
3. Releasing And Inhibitory Hormones Are Produced By The Pituitary Gland.
4. Adenohypophysis Is Under Direct Neural Regulation Of The Hypothalamus.

Answer: 2. Non-Nutrient Chemicals Produced By The Body In Trace amounts that Act As Intercellular Messengers Are Known As Hormones.

Question 67. A Pregnant Female Delivers A Baby Who Suffers From Stunted Growth, Mental Retardation/Low Intelligence Quotient And Abnormal Skin. This Is The Result Of :

1. Low Secretion Of Growth Hormone
2. Cancer Of The Thyroid Gland
3. Oversecretion Of Pars Distalis
4. Deficiency Of Iodine In Diet.

Answer: 4. Deficiency Of Iodine In Diet.

68. Select The Answer Which Correctly Matches The Endocrine Gland With The Hormone It Secrets And Its Function/Deficiency Symptom :

Answer: 2.

NEET Biology Animal Nutrition And Digestive System

Nutrition: Nutrition is the procurement of substances termed nutrients necessary for growth, maintenance and providing energy to carry out synthetic activities of living bodies.

Nutrition is of two types :

1. Autotrophic mode of nutrition.
2. Heterotrophic mode of nutrition.

Autotrophic Nutrition. Mostly green plants can manufacture their organic food due to the presence of chlorophyll. They take up CO₂ and H₂O and manufacture carbohydrates in the presence of sunlight.

• Such organisms are called autotrophs and their mode of nutrition is called autotrophic. Organisms may be photoautotrophs Example, green plants. Euglena or chemoautotrophs, For Example, sulphur bacteria, nitrite bacteria etc.

Heterotrophic nutrition. In this type of mode of nutrition, the animals derive organic food materials by consuming bodies or products of other living or dead plants or animals. Heterotrophs may be holozoic, saprozoic or parasitic.

Myxotrophic nutrition. They carry out autotrophic as well as saprotrophic nutrition Example: Euglena.

Read and Learn More NEET Biology Notes

NEET Biology Animal Nutrition And Digestive System Notes

NEET Biology Animal Nutrition and Digestive System Modes of Animal Nutrition

Based on food, heterotrophic animals are classified into the following categories :

1. Herbivorous. These animals (herbivores) feed exclusively on plants Example, cows, horses, sheep, and rabbits.
2. Carnivorous. Carnivore animals kill and feed upon the flesh of other animals Example. lion, tiger, wolves.
3. Omnivorous. These animals feed on both plants and animals Example. man, cockroach, Pig-
4. Carrion eaters. They feed on dead animals, also termed scavengers Example., Hyaena, Neltura, Kites etc.
5. Fruitivorous animals feed on fruit and fruit juices, Example. Honey bees, and squirrels.
6. Insectivorous animals eat insects as food Example, Frog and wall lizard.
7. Sanguivorous animals are blood-sucking Examples, are leeches, body lice, and bed bugs.
8. Cannibolus organisms devour their species Example, cockroaches, some fishes, frogs and snakes.
9. Detritus. Animals feed chiefly upon organic matters present in the humus Example, earthworms.
10. Eggivorous. Eat eggs
11. Grainivorous Animals feed upon grains.
12. Soilivorous. Eat up the soil.

Animal Nutrition And Digestive System NEET Notes

NEET Biology Animal Nutrition and Digestive System Feeding Mechanism

Feeding mechanism in liquid feeders. (Fluid feeder)

1. Diffusion. Many parasitic organisms (protozoans, tapeworm) absorb the dissolved organic food through the body surface.
2. Bloodsucking. Their mouth parts are modified for sucking blood For Example. leeches, vampire bats and mosquitoes (piercing and sucking type of mouth parts).
3. Aphids suck plant sap.
4. Feeding mechanism in Microplmgous animals (Filter feeders). The food of such animals (paramecia, sponges, corals, bivalves, tadpoles, mosquito larvae) is suspended in water fluid and they possess filtering devices (clusters of pseudopodia, cilia, flagella, sheets of mucus).
5. The water current is drawn in and food is obtained.
6. Feeding mechanism in necrophagous animals. These animals feed on large plant or animal matter. Filters are absent. The methods of feeding are different in different animals.

• Amoeba has no mouth but ingests food with the help of pseudopodia. The process is called phagocytosis.
• Some animals like hydra have tentacles for capturing prey.
• Detritus feeders like earthworms suck solid organic food along with large quantities of soil.
• Frogs and toads have protrusible sticky tongues for capturing prey.
• Many animals apply their mouths directly to the food and use their teeth.

Primates including man carry the food with hands to mouth and teeth are special¬ized for biting, cutting, tearing, chewing and mastication. The tongue acts as a spoon for liquids. Their teeth jaw bones and muscles are well developed.

NEET Animal Nutrition And Digestive System Chapter Notes

NEET Biology Animal Nutrition and Digestive System Cockroach

Initially divided as foregut, midgut and hindgut.

1. Foregut (stomodaeum) ectodermal part, lined with cuticle divided into :
2. Buccal cavity and pharynx. The gut begins with a buccal cavity followed by a short pharynx.
3. Oesophagus. A narrow but longer tube-like part in the thorax.
4. Crop. The largest, thick-walled part, serves for storage of flood, digestion also occurs here but with the enzymes from the hepatic caeca.

• • Gizzard, (proventriculus) Thick walled, bulbous part with 6 cuticular teeth and a thick circular muscle layer, for grinding the food. From the lower part extends the secretory stomodaeal valve in the midgut to secrete the peritrophic membrane.
  • Midgut (or Mesenteron or ventriculus or stomach) A narrow tube of uniform diameter of endodermal origin. It is a true gut for digestion and absorption.
  • Food present in it is always covered by a peritrophic membrane, e 8-12 tube-like hepatic caeca demarcate the beginning of midgut as part of it.

Animal Nutrition And Digestive System NEET Notes

Hindgut (or Proctodaeum). Its junction with the mesenteron is marked by the presence of (60-150) Malpighian tubules the excretory organs.

• Relatively larger in diameter, it is divided into the ileum, colon and rectum.
• The cuticle lining of the ileum bears a minute spine which serves to break the peritrophic membrane.

The wall has six longitudinal fold, rectal papillae, for absorption of water.

NEET Biology Animal Nutrition And Digestive System Of Palaemon

The digestive system of Palaemon consists of an alimentary canal and a digestive gland, called hepatopancreas.

Alimentary Canal- The Alimentary canal is a straight tube and is distinguished into the following three parts :

1. Stomodaeum or foregut which comprises the mouth, buccal cavity, oesophagus and stomach.
2. Mesenteron or midgut which comprises the intestine.
3. Proclodacum or hindgut which comprises the rectum and the anus.

Animal Nutrition And Digestive System NEET Notes

The foregut and hindgut have an internal lining of the cuticle (intima) but the midgut is a soft lining of endoderm.

Foregut

1. Mouth. It is a longitudinal slit situated mid-ventrally in the third cephalic segment. The month is bounded by a shield-like Inbrum in front, bilobed labium behind and the incisor processes to mandible laterally. It leads into a short buccal cavity.
2. Huecal cavity. It is an anthem-posteriorly compressed small chamber. It has a thick chitmous lining which is turned into irregular folds. The molar processes or mandibles project into the buccal cavity and lie opposite to each other. These are used to crush the food between them.

1. Oesophagus. It is a short but broad tube which runs vertically upwards from the buccal cavity to the cardiac stomach. Internally the thick muscular walls of the oesophagus are thrown into four prominent longitudinal folds which project into its lumen.
2. Due to these folds, the lumen of the oesophagus assumes a star-shaped appearance.
3. Stomach. It is the largest part of the alimentary canal. It occupies most of the cephalorhoracic cavity. The stomach lies buried in the hepatopancreas, and it is covered over by the hepatopancreas laterally, posteriorly and ventrally.
4. The stomach is divided into two unequal chambers: the cardiac stomach and the pyloric stomach.

Cardiac stomach. It is a bag-like anterior chamber of the stomach. The internal chitinous lining (i.e., intima) of the cardiac stomach is thin and produced into numerous inconspicuous longitudinal folds covered by minute bristles. The wall of the stomach is supported by several calcified cuticular plates such as follows :

1. Circular plate
2. Lancevlate plate
3. Hastate plate
4. Combed plate
5. Lateral grooves and groove plates
6. Guiding ridges

Pyloric stomach. It is a very small narrow posterior chamber of the stomach. It lies below the posterior end of the cardiac stomach. Its lateral walls are thick and muscular.

• They divide the lumen of the pyloric stomach into a small dorsal chamber and a large ventral chamber. Both chambers are connected by a short narrow vertical slit-like apparture.
• Midgut It is a long, narrow, straight and slender tube which runs from the posterior part of the cephalothorax to the sixth abdominal segment. The midgut lies above the mass of the ventral abdominal muscles.

Hindgut. It extends from the posterior end of the midgut to the anus. It forms the shortest part of the alimentary canal. Anteriorly, the hindgut is swollen to a thick muscular sac, called the rectum while the posterior part is narrow and tubular which opens to the exterior through the. anus.

The rectum bears several thick longitudinal folds which project into the lumen of the hindgut. The rectum is lined internally by the chitinous cuticle.

Hepatopancreas. Die digestive gland, liver or hepatopancreas is a large bilobed, compact, orange-coloured gland which fills the cephalothoracic cavity. It surrounds the stomach and the anterior part of the midgut. Developmental!)’ it is formed from one pair of lateral tubular outgrowths, the hepatic caeca, of the midgut.

• The hepatopancreas of an adult consists of numerous glandular tubules which are branched in a resinous manner. These branches are held together by the connective tissue to form a compact mass. The wall of the tubules is formed of a single layer of columnar epithelium.
• This epithelium contains the following four types of cells. 1. granular cells; 2. ferment cells; 3, hepatic cells and -I. basal or replacing cells. All the epithelial cells rest on a basement membrane.
• Functions. The hepatopancreas functions like the liver, pancreas and small intestine of higher animals. It performs the following functions :
• Like the pancreas, it secretes digestive enzymes for the digestion of carbohydrates, fats and proteins. 2. Like the small intestine it absorbs digested food.

Like the liver. il serves as an important storage organ. It stores glycogen, fat and calcium. Some intracellular digestion also exists in its cells.

Food and Feeding: Polaemon is a nocturnal and omnivorous animal. It feeds on algae, mosses and other aquatic weeds. Occasionally, it feeds on small insects, snails, tadpoles, fishes, etc. and debris from the bottom.

The food is swallowed into the buccal cavity with the help of 1st pair of maxillipeds, maxillae and maxillulae. Inside the buccal cavity, food is masticated by the molar processes of mandibles.

Animal Nutrition And Digestive System NEET Notes

Digestion, Absorption and Egestion:

In Palaemon, the digestive process commences in the cardiac stomach.

• The hepatopancreas secretes enzymes into the pyloric stomach, from whence they travel to the cardiac stomach to combine with the food.
• The cardiac stomach alternately contracts and expands, facilitating the churning and enzymatic digestion of food.
• The undigested meal, containing unabsorbed material, ascends the dorsal chamber and proceeds into the midgut for absorption.
• The remaining digested food is absorbed in the midgut, while the residual faecal matter is sent to the hindgut and ultimately ejected through the anus.

Animal Nutrition And Digestive System Class 12 Notes For NEET

NEET Biology Animal Nutrition and Digestive System Of Vertebrates

The gut is divided only into functional parts not based on origin. The major parts are the mouth, pharynx, oesophagus, stomach, small intestine, large intestine and anus (or cloaca).

• It is longer in herbivores than carnivores.
• The major glands associated with it are the liver and pancreas.

Anatomy of Gut

Frog: Salivary glands are absent in frogs.

• The oesophagus is a short tube as a frog has no neck and thorax.
• The stomach is present in the middle of the body cavity and begins from the anterior part as a straight tube-like structure. Its posterior narrow pylorus makes ‘U with the duodenum, which lodges the pancreas.
• The small intestine is about 1-1.5 feet long.
• The large intestine is represented only by the rectum which opens into the cloaca.
  Rabbit (Mammals)
• The oesophagus is a long tube as that passes through the neck and thoracic cavity.
• The stomach is present in the left side of the abdominal cavity as a transverse bag-like structure and is roughly J-shaped.
• ‘U’ is formed by the duodenal loop only.
• The small intestine is about 4-5 feet long (giraffe = 250 ft).
• Sacculus rotundas act as a junction from which the caecum arises as a separate branch of the large intestine, as the site for cellulose digestion.
• Colon (50 cm) and rectum (75 cm) open into anus.

Ruminants. (for example cattle, sheep, goats, camel and deer) have a compound stomach with the following four chambers:

1. Rumen First and the largest part for the storage of food and digestion of cellulose by symbiotic bacteria living here (Kumcnococcus).
2. The reticulum (honeycomb) next chamber is also the site for cellulose digestion.
3. Omasum (psalterium)-concentrates the food by absorbing H₂O and H₃CO, (absent in camel and deer).
4. Abomasum or true stomach-last part is the secretion of gastric juice and digestion takes place here only. Camel’s rumen and reticulum have many diverticula (water pockets) but these do not store water.

Camel can live without water for two weeks. Its hump is a store of fats. For every 100 gms of fat metabolized, it produces 120 ml of H₂O.

NEET Biology Animal Nutrition And Digestive System Revision Notes

NEET Biology Animal Nutrition and Digestive System Parts Of the Digestive System

Parts of the alimentary canal of man.

1. Buccal Cavity
2. Pharynx
3. Oesophagus
4. Stomach
5. Small Intestine (Duodenum Jejunum, and Ileum)
6. Caecum and
7. Large Intestine (colon and rectum). It terminates at the anal opening.

Digestive Glands

1. Salivary glands
2. Gastric glands
3. Liver
4. Pancreas
5. Intestinal glands

Mouth Cavity: The mouth (oral or buccal cavity) is formed by cheeks, hard and soft palates and tongue.

1. The vestibule of die oral cavity is bounded externally by cheeks and lips and internally by gum and teeth.
2. The roof of the buccal cavity is the palate that separates it from the nasal chamber, consisting of hard and soft palate. The mucous epithelium has thick transverse folds called palatine rugae (thick in the case of carnivorous animals).
3. The terminal part of the soft palate hangs a fleshy ‘V’ shape in the throat called the uvula.

On either side of the uvula, tonsils are present that are made of lymphatic tissue.

Tongue: It is a thick, musculo-sensory organ.

1. Attached to the floor of the mouth by a soft ligamentous fold, the frenulum.
2. Covered by the mucous membrane of thick stratified squamous epithelium with papillae of 4 types.
3. The tongue is made up of striated muscles (voluntary).
4. The tongue possesses Nuhn’s glands (glandular lingual autistics).
5. Taste receptors (taste buds) are found mainly on the lingual papillae of the tongue.
6. Filiform: Most abundant short filamentous (absent in Rabbit),
7. Fungiform: Small mushroom-shaped on the upper part with taste buds.
8. Foliate: Small leaf-like folds on the lateral side.
9. Circumvallate: Largest cup-like, on the posterior part.

Animal Nutrition And Digestive System NEET Notes

NEET Biology Animal Nutrition and Digestive System Dentition and Structure of Tooth

Originated from ectoderm and mesoderm.

Dentition. The teeth are cone-shaped structures present in the mouth cavity. A full set of teeth in adult numbers 32 and child 20 represented by dental formula  2/2; c 1/1/; pm 2/ 2; m3/3 = 32 and  2/2: c 1/1: pm 0/0: m 2/2 = 20 respectively, as the teeth are heterodont initial represented by i-incisor. c-canine, pm-premolars and m-molar. The teeth of man are thecodont, and diphyodont. heterodont and bunodont.

Structure of tooth. The tooth is divisible into three parts-root, neck and crown. The root is lodged in the socket or alveolus of the jaw bone and is firmly fixed by a cement-like substance called cementum. The bulk of the tooth is composed of a hard ivory substance called dentine.

It encloses a pulp cavity containing soft pulp composed of adipose tissue, blood vessels and nerve fibres. The pulp cavity is lined by a layer of odontoblasts. The neck part of the tooth is firmly held by fleshy gum. The crown is covered by the hardest substance called enamel. The teeth help in cutting and mastication of food.

NEET Biology Animal Nutrition And Digestive System Revision Notes

NEET Biology Animal Nutrition and Digestive System Types of Teeth

1. Acrodont dentition. When the teeth are not embedded in sockets they are part of some bone as maxillary teeth and vomerine teeth of frogs.
2. Thecodont dentition. When teeth are separate entities and are embedded in the teeth sockets as in mammals and crocodiles.
3. Diphyodont dentition. When two sets of teeth are produced in the lifetime i.e. milk teeth and permanent teeth, as in Mammals.

1. Polyphyodnnt dentition. When teeth can be replaced many times in life as a frog.
2. Homodont Dentition (Isodont). When teeth are alike as in frog.
3. Heterodont Dentition . When there are different types of teeth present, like incisors canines, premolars and molars as in Mammals.
4. pleurodont  Dentition. When the sides of teeth are fixed over the lateral surface of jaws as in reptiles.
5. Bunodont Dentition. When there are low cusps present made by ridges of the teeth as in man,
6. Solenodont. When the cusps are present as in sheep, etc,
7. lophodont. When cusps fuse into transverse ridges as in elephants.
8. Secodont. In carnivores such as cats. dog. lion. etc. cusps are pointed and are used in cutting.
9. Crocodilian Teeth. Among the reptiles, crocodilians are exceptional in having theodont teeth. This suggests an evolutionary relationship between the reptiles and mammals.
10. Carnnssial Teeth. In many carnivores (dogs, cats), the last upper premolar and the first lower molar are modified for shearing flesh. They are large and bite on each other like a pair of scissors. They are also called sectorial or shearing teeth.
11. Eye Teeth. The upper canine is called eye teeth.

NEET Biology Animal Nutrition And Digestive System Important Points

NEET Biology Animal Nutrition and Digestive System Pharynx

The pharynx is about a 12 cm long vertical canal beyond the soft palate. The food and air passages cross here. The pharynx may be divided into 3 parts: nasopharynx, oropharynx and laryngopharynx.

Function. The function of the pharynx as a part of the digestive tract is merely to serve as a passageway for food from the oral cavity to the oesophagus. It has in its walls the voluntary muscles which start swallowing movements.

NEET Biology Animal Nutrition and Digestive System Oesophagus

Esophagus:

The esophagus is a 25 cm long, narrow, muscular, straight tube lined with stratified squamous epithelium containing mucous glands.

• It descends down the neck posterior to the trachea, traverses the thorax behind the heart, and passes through the diaphragm into the abdomen.
• Here, it sharply curves to enter the stomach. This bend is a mechanism to prevent the reflux of stomach contents into the oesophagus.
• Longitudinal folds maintain the cavity in a nearly closed state, except during the act of swallowing food.
• This monitors the air intake during respiration; the upper section of the oesophagus has striated muscle, the middle section contains a combination of striated and smooth muscle, while the lower section consists solely of smooth muscle.

Functionality:

The esophagus transmits food via peristalsis from the pharynx to the stomach.

Human Digestive System NEET Biology

NEET Biology Animal Nutrition and Digestive System Stomach

This stomach is wide, and J-shaped. distensible, muscular sac plated obliquely on the left side in the upper part of the abdomen just below the diaphragm. It is about 30. cm long and 15 cm wide. It has a greater curvature and a lesser curvature along its lower and upper sides.

The stomach is the most dilated part of the alimentary canal. In mammals, it is divided into three regions :

1. Cardiac stomach- Anterior
2. pyloric stomach-Posterior
3. Fundic stomach-Middle

The narrow central end of the stomach is called the pylorus.

• The fundic part of the stomach is absent.
• An empty stomach is lined with folds called rugae.
• Ruminant animals such as cattle, buffalo, sheep, goats and camel have a compound stomach.
• compound stomach consists of four chambers, rumen, reticulum, omasum and abomasum.
• Some ruminants like camel and deer do not have omasum.
• Rumen is the largest and first of (ho four chambers.
• The rumen and reticulum are the sites of cellulose digestion these harbour numerous bacteria and protozoa w which carry out extensive fermentation of cellulose.
• Cyclostomes and lobed fishes do not have stomachs.
• Omasum concentrates the food by absorbing water and bicarbonates.
• The fourth chamber, abomasum is the (rue stomach as it secretes gastric juice and HCL.
• From the abomasum, the food passes to the small intestine.

Functions of stomach

1. Temporary storage of food
2. Mechanical breakdown of food
3. Secretion of digestive juices.
4. Partial digestion of food.

NEET Biology Animal Nutrition And Digestive System Important Points

NEET Biology Animal Nutrition and Digestive System Intestine

The intestine is quite longer in mammals, about 13 feet in rabbits, and 22 feet long in men because such a length increases the scope of food absorption.

1. The intestine is usually longer in herbivores.
2. The wall of the intestine is provided with only involuntary muscles.
3. Small Intestine. The small intestine is a narrow tube, about 6 metres long in a living adult. It is the longest part of the alimentary canal. It comprises three parts: duodenum, jejunum and ileum.
4. duodenum. It follows the stomach. It is somewhat C-shaped and about 25 cm. long.
5. It receives the hepatopancreatic ampulla of the hepatopancreatic duct formed by the union of the bile duct and pancreatic duct.
6. Jejunum. The jejunum is the middle part of the small intestine. It follows the duodenum and is about 2-4 metres long. Its wall is thicker and more vascular than that of the ileum.
7. Ileum. The ileum forms the lower part of the small intestine. It is about 3-6 metres long and opens into the large intestine. Its wall is thinner and less vascular than that of the

Functions. The small intestine serves 2 main functions: completion of digestion and absorption of digested food. It also secretes some hormones such as cholecystokinin, secretin, duocrinin, and villikinin. entcrocrinin and enterogastrone.

NEET Biology Animal Nutrition and Digestive System Small Intestine

• In men, there is a common opening of the bile duct and pancreatic duct.
• Behind the duodenum is the jejunum, followed by the ileum.
• The lining of the small intestine bears a series of transverse folds called plicae circular or valves of Kerkering.
• Their internal lining is raised into innumerable minute finger-like processes called villi.
• In the wall of the small intestine, lymphatic tissues arc present collated Pcycr’s patches.
• Peyer’s patches are groups of lymph nodules that are most numerous in the ileum. They produce lymphocytes.
• The distal end of the ileum is expanded to form a small dilated spherical sac called sacculus rotundas in rabbits.
• The ileum opens into the caecum through an ileo-caccnl valve. large Intestine
• The large intestine is shorter than the small intestine. It is called the large intestine as it is wider than the small intestine. It is arranged around the mass of the small intestine.
• It is about 1-5 metres long. It lacks villi and microvilli. It shows three regions: caecum, colon and rectum.
• The caecum is very large and spacious in herbivores such as rabbit, horse and ass.
• The caecum of a rabbit is a thin-walled tube with peculiar external spiral constriction, which marks the presence of an internal spiral valve.
• Digestion of cellulose in rabbits takes place in caecum (Stomach in ruminants).
• Distally caecum terminates in a small, narrow, thick-walled tube vermiform appendix.
• But in man, the caecum is a reduced small pouch-like part below the opening of the ileum into the large intestine.
• In man, attached to the caecum is a twisted, coiled tube, measuring about 3 inches in length, called the vermiform appendix.
• The colon is thicker than the small intestine and thinner than the caecum. Constrictions of its wall form a series of small pockets called haustra.
• The haustra are arranged on either side of three median longitudinal muscle cords of the wall called taeniae.
• The colon of man is divided into ascending, transverse, descending and pelvic (sigmoid) portions.
• Mass peristalsis is initiated in the colon about half an hour after taking food.
• The pelvic colon continues into the rectum.
• The rectum is the last part of the alimentary canal, in man it is about 7-8 inches long.
• The terminal one inch of the rectum is called the anal canal and its exterior opening is called the anus.
• The Rectum of a rabbit is the narrow terminal part with faecal pellets present inside giving it a beaded appearance.

Human Digestive System NEET Biology

Functions. The large intestine mainly aids in the absorption of water; formation, temporary storage and elimination of faeces; and production of mucus for lubrication of mucosa.

• It also plays some role in digestion, absorption and excretion. The colon bacteria produce vitamins B and K which are absorbed.

NEET Biology Animal Nutrition And Digestive System Important Points

NEET Biology Animal Nutrition and Digestive System Digestive Glands

Salivary glands in humans 3 pairs in man, four pairs in rabbit, 5 pairs in rat and absent in frog. These are compound tubular-alveolar types.

Parotid gland

1. It is present near the ear (pinna).
2. It is the largest salivary gland but produces only  29% of saliva.
3. It contains the enzyme- Ptyalin (a-amylase). Ptyalin is lacking in predators, Example: Lion and Tiger.
4. The viral infection of these glands causes Mumps.
5. The secretion of these glands is poured into the buccal cavity through Slenson’s duct.

Submaxillary (submandibular) gland

1. It is present in the lower side of the upper jaw.
2. It produces- 70% of saliva secretion.
3. Its secretion reaches the buccal cavity through Wharton’s duct.

Sublingual gland

• It is present below the tongue.
• It is the smallest salivary gland and produces only 5% of the secretion
• Its secretion passes through the Duct of Rivins.

The salivary glands are absent in fishes, amphibians and aquatic  mammals,

Saliva -1.5 lit/day

1. pH – 6 to 7 (slightly acidic), on standing/heating it releases CO₂ and becomes alkaline.
2. The mucus of saliva helps in lubrication
3. Saliva also causes the denaturation of raw proteins without hydrolyzing them.
4. Thiocyanate ions, present in saliva, act as an antimicrobial agent to prevent infection by the microbes that often enter along with the food.
5. Saliva also has lysozymes.
6. Ptylain of saliva acts on boiled starch and converts it into maltose (a disaccharide).

NEET Biology Animal Nutrition And Digestive System Important Points

NEET Biology Animal Nutrition and Digestive System Liver

It is the largest sized, reddish-brown gland of the body. It is present in the posterior concavity of the diaphragm in the right upper part of the abdomen.

• The liver is a multilobulated gland. It is formed of two main and two small lobes. Two main lobes are the larger right and smaller left lobes, while two small lobes are the quadrate and caudate lobes.
• Each liver lobe is formed of hexagonal lobules surrounded by a connective tissue sheath called a Glisson capsule.
• Present on the lower surface of the right liver lobe, there is a thin-walled, pear-shaped sac, called the gall bladder. It stores the bile (about 60 ml) secreted by the liver.
• Bile is drained from the liver by a bile duct which is formed by the joining of a cystic duct from the gall bladder and a common hepatic duct from different liver lobes.
• Just near the duodenum, the bile and pancreatic ducts join to form the hepatopancreatic duct. The opening of the hepatopancreatic duct in the duodenum is guarded by a sphincter of Oddi. Daily secretion of bile is about 600-1200 ml.
• Bilirubin is formed by the daily destruction of haemoglobin due to the death of 1% RBC every day.

1. The human liver weighs about 1.5 to 2 kg. and is divided into 3 lobes
2. Glisson’s capsule, connective tissue sheath around each lobule, is a characteristic feature of mammals.
3. Kupffer’s cells are large phagocytic cells to remove unwanted substances or foreign material from the liver hence, also known as hepatic macrophages.
4. Hepatic capillaries arise from the cell level and unite to form the main hepatic duct emerging from each lobe to join the bile duct (ductus choledocus) which is also joined by the Cystic duct emerging from the gall bladder.
5. The cystic duct conducts bile to the gall bladder.
6. Opening of the bile duct in the duodenum is guarded by the sphincter of Oddi.
7. The gall bladder is a separate part associated with the liver for the storage and concentration of bile.
8. The gall bladder is a sac located along the underside of the liver.
9. The gall bladder is absent in birds, rats, whales and horses.
10. Gall bladder stores bile.

• Functions of Liver. The liver performs a variety of functions like synthesis, interconversions, storage, and secretion of various substances as follows:
• Glycogenesis. Extra glucose is converted to glycogen with the help of insulin and stored in this form either in the liver or in muscles.
• Glycogenolysis. Glycogen is converted into glucose when its level falls (below 80 mg/ 100 ml) in the blood. This is influenced by the glucagon hormone.
• Glucogenesis. Synthesis of glucose from other carbohydrates.
• Gluconeogenesis. Synthesis of glucose/carbohydrates from protein and lipids (non-carbohydrate sources)
• Lipogenesis. Extra protein and carbohydrates are converted into lipids for storage in adipose connective tissue.
• Deamination of protein. If protein is used for energy production, the NH₂ group is removed from amino acid as NH₂, the end product of keto acid, enters the Krebs cycle.
• Ornithine Cycle. The chemical part of excretion, NH₃ is converted into urea in a cyclic chain of reactions in which ornithine plays a pivotal role.
• Cori Cycle. Lactic acid formed in muscle is convened buck In glycogen. Synthesis of substances like.
• VitA from carotene.
• Vit-D front cholesterol or ergocalciferol.
• Plasma protein (Albumin, globulin. clotting proteins). heparin.
• Angiotensinogen is an osmoregulatory substance in the blood.
• Haemoglobin, formation of UHC in frog and embryonic mammals.

Human Digestive System NEET Biology

Somatomedin, a growth-promoting factor also called IGF (insulin-like growth I actor) Detoxification of the following substances take place in the liver

• Indole, skulls. cresol. phenol, alcohol, prussic acid and other toxic substances formed during digestion or obtained in blood.
• Excess alcoholism affects the liver by overburdening work and fat deposition.
• It converts alcohol to aldehyde which promotes lat deposition and causes puffiness and liver cirrhosis.
• Storage of the following substances takes place in the liver
• Glycogen, Vitamins like VitA, VitD, Vitk, VitB₁₂  folic acid etc. Fe and Cu.
• Water, lymph and blood, (about 1/5th of total blood).
• By storing blood and water, the liver controls the volume and viscosity (concentration) of blood.
• By generating and consuming heat in a different chemical reaction it acts as a thermoregulatory organ.

Secretion of Bile

• Bile is a yellowish watery fluid, concentrated in the gall bladder, contains 85% water; 6% organic salt of bile acids (sodium glycocholate and sodium taurocholate); 1% inorganic salt (bicarbonate, carbonates and chlorides of Na and K); 1.5 to 2% lipid (cholesterol, lecithin); 3% mucin and bile pigment (bilirubin and biliverdin).
• Extra cholesterol and bilirubin are eliminated from the body through the gut.
• An increase in bilirubin level beyond normal (0.1 to 0.9 mg/100 ml.) in the blood is called jaundice. This happens if hepatic cells become sick due to viral or bacterial infection obstruction or lesion,

Gastric glands

• Gastric glands are microscopic and present in the walls of the stomach. These glands secrete gastric juice,
• A gastric, gland. has three types of cells.
• Mucous cells,- Secreting mucus
• Chief or peptic cell – Secreting pepsinogen zymogen cells and prorenin

Oxyntic. cells or parietal cells – Secreting HCL

Pancreas

The pancreas is the second largest gland in the human body. It is yellow-coloured, 12-15 cm long and a compound racemose gland. It is present in the loop of the duodenum. It is formed of head, body and tail.

• Pancreas is a heterocrine gland. Its exocrine part is formed of a large number of lobules or acini. Each acinus consists of several glandular cells which secrete the pancreatic juices (pH 8.8). Pancreatic juices are drained by a pancreatic duct which joins the bile duct as described in the liver. About 1500 ml of pancreatic juice is secreted per day.
• The rest part remains filled with areolar connective tissue known as stroma.

1. Pancreatic secretion water-99%
2. Inorganic – 0.5% (High amount of NaHCO₃)
3. Organic – 0.5% Mostly enzymes

Intestinal glands

1. They are present in the wall of the intestine. These glands secrete intestinal juice (succus entericus)
2. The wall of the duodenum contains intestinal glands (crypts of Lieberkuhn) and characteristic duodenal glands or Brunner’s glands produce alkaline mucus.
3. In between the villi, the mucous membrane of the small intestine is folded forming intestinal glands or crypts of Lieberkuhn.
4. The intestinal juice or succus entericus is secreted by the crypts of Lieberkuhn.
5. Intestinal villi are more numerous and larger in the posterior part of the small intestine than in the anterior part because there is more digested food in the posterior part.

NEET Biology Animal Nutrition And Digestive System Important Points

NEET Biology Animal Nutrition and Digestive System Histology Of Wall Of Gut

• Histology of wall of gut from outer to inner side.
• Serosa – Peritoneum and Connective tissue Muscular Layer – Outer Longitudinal and inner Circular (Stomach – oblique muscles additional layers)
• Sulunueosa – Connective tissue Mucosa

1. Muscularis mucosa
2. Lamina propria (reticular connective tissue)
3. Surface epithelium.
4. Mouth and Pharynx

• Lined with the stratified squamous epithelium of ectodermal origin, hence representing the stomodaeal part. Possesses a striated muscle layer, hence the movement of food here is voluntary.

Oesophagus

1. All four layers are typical as it serves only as the passage.
2. Its thoracic part is without a serosa layer which shifts to form the mediastinal wall

Stomach

1. Thick and highly distensible wall, when empty it forms inner longitudinal folds, rugae.
2. The muscular layer is the thickest of all parts with the third and innermost oblique muscle layer.
3. Submucosa has no speciality.
4. Mucosa forms glands by invaginating into the submucosa and has three types of cells :
5. Mucous (Goblet) cells secrete mucin
6. Oxyntic (Parietal) cells secrete HCL
7. Chief cells (Peptic or zymogenic) cells secrete enzymes.
8. Cells of mucosa are secretory but not absorptive.

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Small Intestine

The muscle layer is typical (no speciality).

1. Submucosa is the most developed and specialised of all parts with the following structures :
2. A highly organised system of blood capillaries up to villi for the transportation of absorbed food.
3. Fine lymphatic channels (lacteals) are extended up to villi for absorption and transportation of lipids.
4. The muscle layer (muscular mucosa) is present just behind the mucosa for the movement of villi.
5. Two nerve plexuses of the autonomic nervous system (ANS) are present.
6. The lymph nodes and Peyer’s patches are present which act as biological filters.
7. Submucosa and mucosa together form inner transverse finger-like folds to increase the surface area of absorption. In mammals, the primary folds are called folds of Kerkering (or valvulae connivance or plica circular), which bear true villi as secondary folds.
8. Folds of Kerkering increase surface area of absorption by 3 times, villi increase by 10 times and microvilli of mucosal cells increase by 20 times, thus total increase is by 600 times which comes to about 250 mtr2 in man.

• Mucosa is the main functional layer for digestion and absorption with brush border cells both secretory and absorptive. Mucosa forms glands embedded in submucosa are:
• Brunner’s gland (duodenal gland). Present mainly in the duodenum; secretes mucus; absent in the frog.

1. Crypts of Lieberkuhn. Small flask-shaped gland in the crypts between two villi.
2. Cells of Paneth in it secrete digestive enzymes, called succus entericus

Large Intestine: Thin-walled and transparent, divided as caecum, colon, and rectum.

Colon

1. No secretion, no glands at all.
2. There are three inner longitudinal folds called taeniae – specialized structures for the absorption of water.
3. The transverse membranous foils between two taeniae form a series of pockets, dentistry, highly developed in desert or dryland animals like rabbit, pont. camel etc. but, less developed in man

NEET Biology Animal Nutrition And Digestive System Important Points

NEET Biology Animal Nutrition and Digestive System Rectum

1. Has six or more folds called rectal papillae for the absorption of water,
2. Goblet cells secrete mucus to facilitate defecation.
3. Physiology of Digestion
4. Digestion is the process of conversion of complex food into simple (absorbable) form, lists involve two parts :
5. Mechanical part. Cutting and chewing of food to increase its surface area for enzymatic action,
6. Chemical part. Enzymatic hydrolysis of food i.e. breaking tit molecular level i.e. actual digestion.
7. It could be both extracellular and intracellular, but secures, optimal efficiency of extracellular digestion.
8. Discovered by Beaumont (1833).
9. It begins from the mouth and continues up to the small intestine, in herbivores digestion also takes place in the caecum but with the help of bacterial enzymes.

NEET Biology Animal Nutrition and Digestive System Absorption Of Food

Talcs place, mainly jejunum and ileum through villi and microvilli by both active and passive preveses. It first enters mucosal cells and then passes into the submucosa.

1. No absorption occurs in the stomach except that of ethanol (alcohol) and aspirin.
2. Water is absorbed in the small intestine and large intestine.

Absorbed food is transported through two pathways: the hepatic portal system, directly to the liver and through the lymphatic channel it is drained into subclavian veins via the thoracic duct.

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Absorption of Glucose and Amino acids

1. Both are absorbed mainly by active transport as this process is many thousand times faster than passive transport.
2. Entry of glucose in the cell is coupled with Na⁺  where it immediately gets phosphorylated.
3. Galactose is absorbed like glucose, and some disaccharides are absorbed directly.
4. Fructose and mannose are absorbed by facilitated diffusion.
5. From submucosa, these pass out through blood capillaries.

Absorption of Lipid: Glycerol and fatty acids in the cell generally combine to form lipids again. Thus lipid is absorbed in both forms :

Directly as lipid

• Lipid enters mucosal cells as chylomicrons and micelles by pinocytosis in the crypts between villi.
• Chylomicrons are lipid droplets of < I pm diameter formed by emulsification. With non-lipid substances like salts, amino acids etc. it forms micelles.
• In submucosa, it enters lacteals and moves with lymph.
• As glycerol and fatty acid
• Glycerol is soluble in both the aqueous and lipid phases and hence easily passes through the cell membrane.
• Small soluble fatty acids enter the cell as the membrane component, while large insoluble fatty acid after combining with (bile) forms a soluble micelle.

Animal Nutrition And Digestive System NEET Chapter Summary

NEET Biology Animal Nutrition and Digestive System Egestion (Efaecation or Defecation)

• It is a tile process of elimination of faeces.
• Slercobilin causes the brown/yellowish colour of faeces.
• The foul odour of faeces is due to indole and skatole funned by decarboxylation of amino acids by bacteria in the colon.

NEET Biology Animal Nutrition and Digestive System Components Of Foods

The food of animals is chiefly formed of six kinds of components

1. Carbohydrates
2. Proteins
3. lipids
4. vitamins
5. Water
6. Minerals.

Out of these food components, carbohydrates, proteins, and fats are called macronutrients or proximate principles of food, while vitamins and minerals are called micronutrients or protective principles of food.

Proteins

• Proteins are major building blocks as 75% of our body consists of proteins. All enzymes, O. earning pigments, antibodies, most hormones, arc proteins.
• The chief source of proteins is milk. egg. fish. meat, pulse and cereals. Its requirement is more for growing children and pregnant and lactating mothers.
• Proteins are more important for anabolism than catabolism Calorific value of proteins is 5.65 K cal and 20 amino acids, linked together by peptide bonds, make all different proteins.

Eight are considered essential (which cannot be synthesized in the body and lias to be taken in diet), and 12 are non-essential (which can be synthesized in the body) which 2 are considered semi-indispensable because they may be synthesized in tissues but not at adequate rates to support growth in younger human individuals.

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NEET Biology Animal Nutrition and Digestive System Carbohydrates

1. Chemical composition. Carbohydrates are polyhydroxyaldehydic or ketonic organic compounds. These are usually formed of C, H and O in the ratio of 1:2:1 with only a few exceptions.
2. These are called carbohydrates because there is generally one water molecule for every carbon atom. The general formula is :
3. Cn(H₂:0)_n where n is several carbon atoms, so arc called “hydrates of carbon” The Name of carbohydrates ends with the suffix – ose.
4. Sources. Main sources of carbohydrates are potatoes (20%), fruits (banana – 20%, mango), cereals (rice – 23%. wheat – 57.3%), sugar, honey, sugarcane, sugarbeet, jam,’ bread, milk 4%) etc.

Daily requirements. On average, the need for carbohydrates for an adult person is 100 g per day. About 55-75% of total good calories should be in the form of carbohydrates.

1. Of these. 80-85% should consist of easily digestible starch and dextrins. Requirements are more for mountaineers, athletes, labourers etc.
2. Carbohydrates form about 1% of our body weight.

Functions. As Respiratory fuels. Carbohydrates, especially glucose, are the main respiratory fuels. About 60% of our total energy needs are provided by the breakdown of carbohydrates is 4.1 kcal of energy while the physiological fuel value of one gram of carbohydrates is 4.0 kcal (17 kJ) of energy.

• To provide energy, the glucose undergoes biological oxidation in the mitochondria (powerhouse) of the cell to produce about 36 or 38 molecules of ATP.
• So die theoretical recovery- of energy from one glucose molecule of 40%. The main reasons for the glucose being chief respiratory fuel are its presence in abundance and its easy oxidisability.
• C₆H₁₂O₆+6O₂ > 6CO₂ + 6H₂O + Energy
• So carbohydrates form the cheapest sources of energy.
• Monosaccharides as structural components

Ribose (Pentose sugar) is a component of RNA; conenzymes like NAD, FAD etc. and energy carriers like ATP, GTP etc.

• 2′-Deoxyribose (Pentose) is a component of DNA.
• Galactose is a structural component of the medullary sheath.
• As building blocks. Monosugars act as monomers for the formation of disaccha¬rides and polysaccharides.
• Reserve foods. There are two main polysaccharides which act as reserve foods e.g. starch is a storage polysaccharide of plants and is stored as granules in amyloplasts.
• Glycogen is the reserve food stored in the liver and muscles in animals.
• The energy requirement of the body Organisms requires energy continuously. When work is done, energy is being spent. This energy is required to keep all systems in the body functioning.

• A normal healthy man requires about 3000-kilo calories per day. Perhaps a sedentary worker needs a little less, say 2500 kilo calories hardworking labourer may need about 3500-kilo calories per day.
• (Note: The term Calorie (capital C) as used by nutritionists is equivalent to 1 kilo calorie (kcal)) The energy requirement is calculated as so many calories for an hour for a particular type of work.

1. Basil metabolism. The amount of energy required by the body to maintain vital functions when no muscular work is being done and no food is being digested.
2. Rasul metabolic rate (BMR). The amount of energy required daily by a person to maintain their basal metabolism is about 1,600 keal/day.
3. Active metabolic rate (AMR). The amount of energy required daily by a person to maintain their high metabolic rate during heavy physical work is about 6,000 kcal/ day.
4. Roughage. The indigestible fibrous material of food is called roughage For Example. cellulose of cell walls of plant material promotes peristalsis and checks constipation.
5. Balanced diet. A diet which can provide materials for all the metabolic requirements of the body. Carbohydrates, proteins and fats should be nearly in the proportion of 4: 1: 1.

Lipids. Lipids comprise heterogenous organic compounds which are insoluble in water but are readily soluble in non-polar organic solvents like ether, chloroform, benzene etc. On hydrolysis.

• lipids yield fatty acids which are utilized by living organisms. In addition to fats, lipids include waxes, phospholipids, glycolipids and fat-soluble vitamins A, D, E and K).

Daily Requirement. About 50 gms. of fat are needed by man daily. Fats are digested slowly and delay the hunger sensation between meals. Our diet should contain less saturated fats, such as butter, ghee and hydrogenated vegetable oils, than unsaturated fats, such as simple vegetable oils.

• Excess of saturated fats increases the cholesterol and causes arteriosclerosis.

Sources. The sources of fats in our diet are vegetable cooking oil, vanaspati ghee, desi ghee, butter, cream, oil seeds and nuts, milk, cheese, mutton and eggs.

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Uses. The fats also serve a variety of functions:

1. fuel,
2. reserve food
3. insulator
4. formation of cell organelles
5. shock absorption.

Animal Nutrition And Digestive System NEET Chapter Summary

NEET Biology Animal Nutrition And Digestive System Vitamins

N.I. Lunin was the first to identify vitamins, and Funk was the first to use the term “vitamins.” The “vitamin theory” was introduced by Hopkin and Funk in 1912, which posits that deficiencies in vitamins are the cause of deficiency diseases.

• As growth and metabolic regulatory substances, vitamins are intricate organic compounds that are required daily in minute quantities.
• Green plants are the sole source of vitamin synthesis; consequently, animals are reliant on plants to meet their vitamin needs.
• The human body can store A, D, and ll,2 and produces vitamin D through the use of ultraviolet radiation of sunlight. Vitamins are named after the alphabets they represent, their chemical composition, and the deficiency diseases they prevent.
• Vitamins are compromised by excessive heating, frying, and low temperatures. It is feasible to synthesize vitamins, as their chemical composition is recognized. Vitamins are classified as either fat-soluble (A, D, E, and K) or water-soluble (B and C).

Animal Nutrition And Digestive System NEET Chapter Summary

NEET Biology Animal Nutrition and Digestive System Memory Points

• PFA Polyunsaturated fatty acids are found in abundance in corn oil and sunflower oil
• NiN National Institute of Nutrition
• Vit C was the first vitamin to be produced during the fermentation process using wild bacteria.
• Vit B₁₂ was first to be isolated in 1948 from liver extract and during the production of antibiotics in fermentation.
• Within the body, vitamin B₁₂ is produced by the microflora of the digestive system.

Excessive intake of vitamin A causes bone reabsorption and hypercalcaemia.

1. An alcoholic is always deficient in Vit. C
2. Vitamin B₁₇ is a recently discovered vitamin with anti-cancer properties.
3. Vitamin theory was proposed by Hopkins and Funk.
4. Earlier known vitamin -Vitamin C
5. Vitamin B₆ is used in the treatment of tuberculosis

• Vit P Hesperdin is insoluble in water and is present in citrus fruits and green vegetables. It maintains blood capillary resistance. Its deficiency causes subcutaneous bleeding. ,
• Vitamins which are synthesized by the intestinal flora are vitamin K, Thiamine, Riboflavin, Pantothenic Acid, Niacin, Pyridoxine, Biotin and Folic acid.
• Vitamin B₁₂ and alcohol. Alcohol interferes with the metabolism of B₁ in the liver. Alcohol intake along with a deficiency of vitamin B₁ can also cause brain cell damage. Therefore, regular alcohol drinkers should take vitamin B complex every day.
• Cod Liver oil is considered to be a rich source of vitamins A and D.
• Presently Vit B₁₂ is produced directly during the courses of fermentation by propioni bacteria and certain strains of Pseudomonas.
• Vit B₁₂ is found essentially in cereals, vegetables and brewer’s yeast. It was produced in 1938 by using microbes.
• Most of the B complex vitamins are coenzymes.
• Wheat grain contains – Vitamins such as thiamine, riboflavin, niacin, pantothenic acid, folic acid, and tocopherol (The richest source)
• Proteins & Minerals P, K, Mg, Mn, Ca, Na, Sn, Zn. & Fat.
• Destruction of vitamins. Overcooking, excessive alcohol, tobacco and coffee; certain medicines destroy vitamins
• Dietary deficiency of proteins leads to a fall in plasma proteins which are important for the retention of water in blood plasma by their osmotic effect.
• A fall in plasma proteins leads to filtering out excessive volumes of water from the blood to the tissues. Excessive accumulation of fluids in the body tissues causes oedema.
• Zinc is necessary to maintain normal plasma concentration of vitamin A.

Animal Nutrition And Digestive System NEET Chapter Summary

NEET Biology Animal Nutrition And Digestive System Physiological Role And Source Of The Important Minerals

NEET Biology Animal Nutrition and Digestive System Disorders Of the Digestive System

• Nausea- discomfort preceding vomiting.
• Anorexia – loss of appetite.
• In India, Orissa tops the list of states of people suffering from malnutrition.
• Enlargement of rectal vein which causes piles.

Dyspepsia. Indigestion due to defective diet.

• Pavlov pouch was fabricated by Pavlov to study the effect of feeding on gastric secretion.
• Peristaltic movements are low in the rectum.
• A hiatal hernia or diaphragm is the opening in the diaphragm. The part of the stomach is pushed into the thoracic cavity.
• Gastritis is inflammation of the gastric mucosa.
• A peptic ulcer is an erosion of the stomach or duodenal mucosa.

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Cirrhosis of the liver – The liver appears orange. It is due to the accumulation of bilirubin in the liver. Other substances are mixed with the yellow pigment (bilirubin), hence the liver appears orange.

• Hepatitis is inflammation of the liver.
• Pancreatitis is inflammation of the pancreas.
• Constipation is the infrequent passage of dry, hardened faeces.
• In ulcerative colitis the mucosal lining of the colon becomes ulcerated.
• Some people cannot digest milk and milk consumption in them causes diarrhoea and gas generation because they do not produce lactase. The lactose of the milk is fermented by intestinal microflora-producing gas.
• Removal of the stomach produces dumping syndrome.
• Treatment with all axons destroys 3 cells of pancreatic islets
• Treatment with CaC₁₂ destroys cells of islets of Langerhans
• Abnormal metabolism of fats causes Gaucher’s disease (also called cerebroside lipidosis)
• PEM Protein Energy Malnutrition
• Kwashiorkor Marasmus
• FFA Free fatty acid,
• Avg. Indians Iwvo to obtain about 50% of their requirements of energy from early dratos, 33% from fats and 15% from protein.
• The vermiform appendix (1.. vermiformis, worm-like; appendix, attachment) is a short, thin outpouching of the caecum. It does not function in digestion, but like the tonsils, it contains numerous lymphatic nodules and is subjected to inflammation a condition called appendicitis.
• It is commonly detected in its later stages be pain. Rupture of the appendix can cause inflammation of the surrounding body cavity peritonitis.

1. The substances which provide materials for growth, energy and maintenance are called nutrients.
2. The process of procurement of nutrients is called nutrition.
3. The mode of nutrition may be autotrophic or heterotrophic.
4. Nutrients may be organic or inorganic.
5. Proximate principles of food
6. They are macronutrients
7. These include carbohydrates, lipids and proteins.
8. They are energy sources and help in carrying out organic functions.
9. Protective principles of food
10. They are micronutrients.
11. These include water and minerals.

• They do not provide energy but help in carrying out various vital processes.
• About 20 vitamins are required in small amounts.
• The mode of nutrition in animals is heterotrophic which may be holozoic or saprozoic.
• Based on food habits holozoic animals are classified into herbivores, carnivores, omnivores, insectivores, sanguivores, detritivores, insectivores or fluid feeders.
• Ingestion is the intake of food.
• Microphagous animals. These animals feed on those solid particles which are too small to be captured singly. These animals possess different types of filtering devices. Therefore, the method of intake is also known as filter feeding.

1. The water passes through the filters and food is retained (e,g., pseudopodia, cilia, flagella and setae in some crustaceans etc.)
2. Filter feeders. They are aquatic animals and feed on tiny particles suspended in water.
3. Examples. Lepas (Crustacean), Molluscs, Amphioxus. Herdmania.
4. Macrophagous animals. These animals feed on those solid particles which are large enough to be captured singly. Filters are absent in these animals. The method of capturing food is different in different animals.
5. Pseudopodia capture and ingest the food in amoeba. This process is called phagocytosis. Earthworms spreads its mouth cavity to capture the food. Coelenterates capture the food with the help of tentacles.
6. Fish, amphibians, creeping animals and birds capture their food with the help of jaws, tongues and beaks and ingest it without chewing them. The food captured by most of the mammals is masticated before being swallowed.
7. Their teeth as well as jaw bones and muscles are specially developed for mastica¬tion. In herbivores, the premolars and molars have predominant ridges on the crowns for effective grinding. The carnivores, however, have large and sharp canines for tearing the flesh of prey.

Mutualism. Two organisms living in association with each other derive nutrition from each other, in such case nutrition is called mutualism.

Examples of mutualism

• E.coli living in the intestine of man synthesises vita-min B₁₂, which is utilised by man and E.coli receives, in return simpler food from the intestine of man.
• Rhizobium bacteria live in the nodules of leguminous plants.
• The cloacal thymus is the purely endocrine gland on the roof of the cloaca of the birds discovered by Fabricius.
• Mass peristalsis is initiated in the colon about half an hour after taking food.
• Riboflavin was called ‘yellow enzyme’ by Warburg and Christian.

Animal Nutrition And Digestive System NEET Chapter Summary

NEET Biology Animal Nutrition And Digestive System Quanta To Memory

Oesophagus. In Birds, the oesophagus is very long and often dilated in front of the sternum into a large, thin-walled crop to store food before digestion. Crop glands in both sexes secrete a nutritive fluid the pigeon’s milk, which is regurgitated and fed to the hatchlings.

1. In the upper one-third of the oesophagus, only skeletal muscles are found.
2. After the voluntary phase, swallowing of ‘bolus’ becomes an involuntary reflex triggered by tactile stimulation of the palate and pharyngeal wall controlled by the swallowing centre in the medulla and lower parts of the brain stem.
3. In humans, more than one litre of saliva is secreted into the oral cavity.
4. spite of the fact the mucus protects the stomach lining from being digested, it is completely replaced every 3 days.
5. Each day, the stomach wall secretes about 3 litres of gastric juice.
6. About every 20 seconds, the stomach contents are mixed by the churning action of smooth muscles. When an empty stomach churns, hunger pangs are felt.
7. It takes about 2-6 hours after a meal for the stomach to empty.
8. Amylases found in animals are called a-amylose, and those in plants are called /Lamylose.
   • Stomach. Cyclostomes and the carp, Labeo, lack stomach.
   • Water Cells. These are sac-like diverticula arising from the rumen and reticulum of the camel stomach. They contain food undergoing digestion and do not store water as commonly supposed.
   • Camel can go without taking water for a long time as it can use metabolic water formed by chemical breakdown of stored glycogen and fat.
   • Intrinsic Castle’s Factor. It is secreted by parietal cells of the gastric glands and aids in vitamin B]2 absorption. Lack of this vitamin makes the bone marrow unable to form sufficient red corpuscles, causing pernicious anaemia.
   • Small Intestine. Final digestion of double sugars right on the surface of microvilli and of dipeptides on the microvilli and within the microvilli-bearing cells. Products of digestion, viz., glucose and amino acids, are released into the intestinal lumen.
   • Paneth Cells. These occur at the base of the crypts of Lieberkuhn and secrete antibacterial lysozyme.
   • Argentaffin Cells. These also occur at the base of the crypts of Lieberkuhn. They secrete some gastrointestinal hormones and neurotransmitters.
   • Peyer’s Patches. These are white patches on the intestinal mucosa. They consist of lymphoid tissue packets with white corpuscles. They fight infection and are often called abdominal tonsils.

Nutrient Absorption In Small Intestine NEET Exam Preparation

Large intestine. The vermiform appendix contains lymphoid tissue that neutralizes bacterial toxins.

1. Some of the bacteria including Escherichia coli present in the large intestine or colon produce vitamin K, which is absorbed by the host and this is probably the main source of this vitamin for humans.
2. Millions of cells lining the human stomach and intestine are abraded away and destroyed every time the food is digested, but cell division constantly regenerates the lining of the digestive tract.

• Every five days, the lining of the human small intestine is entirely replaced as a result of ongoing cell division.
• Parietal cells of the stomach give MCI and chief cells give pepsinogen.
• The surface of the upper gastrointestinal tract, oesophagus, and mouth have a much thinner, mucous cell layer than the stomach, which is why vomiting can cause, a burning sensation in the oesophagus or mouth.
• The vermiform appendix (L. vermiform’s, worn-like; appendix, attachment) is a short, thin outpouching of the caecum. It does not function in digestion, but like the tonsils, it contains numerous lymphatic nodules and is subject to inflammation a condition called appendicitis.
• It is commonly detected in its, later stages by pain. Rupture of the appendix can cause inflammation of the surrounding body cavity peritonitis.
• About 40-50 lakh villi are present in the human intestine.
  1. On the surface of each epithelial cell of villi about 650 microvilli are present, ‘
  2. The functional and structural unit of the liver is the liver lobule Part of the alimentary canal where NH₃ (Ammonia) is produced during digestion is the caecum
  3. Bursa Fabrici. It is a blind sac on the cloaca in birds. It has lymphoid tissue involved in antibody production and in fighting invading bacteria. It is, therefore called cloacal thymus.
  4. Like the thymus, it is prominent in early life and tends to atrophy in the adult.
  5. The centre in the brain which controls hunger is known as the satiety centre. It is located in the hypothalamus of the brain.
  6. The chief function of the ileum is absorption.
  7. The most important functions of saliva are mechanical.
• Piscivorous animals feed on fish. ,
• Saliva and tears contain an antibacterial enzyme called lysozymes.
• Poison glands of snakes are modified labial glands homologous to parotid salivary glands.
• The liver of a rabbit is encapsulated by two sheaths – an outer membranous serous capsule consisting of a visceral peritoneum and an inner Glisson’s capsule of a thin layer of dense connective tissue. Glisson’s capsule is found in the liver of some mammals.
• The rumen, Reticulum, Omasum and Abomasum are the correct sequence through which food passes through a ruminant.
• Diastema is a toothless space in rabbits between the incisors and premolars.
• Fibres running between the periodontal membrane to the root of the tooth across the cement are known as Sharpey’s fibres.
• C-shaped duodenum is a characteristic of man. Reverse peristalsis or anti-peristalsis in the stomach and duodenum causes vomiting.
• The vomiting centre is the medulla oblongata of the brain.
• Some people suffer from “travelling sickness” on their way to a hill station in a bus, the sickness comprises nausea and vomiting, which are due to rapidly changing directions of motion of the body stimulating the receptors of the membranous labyrinth, from where the stimuli reach the vomiting centres in the medulla oblongata through the cerebellum.
• Peristaltic movements are the least in the rectum of the alimentary canal.
• In herbivorous animals, the small intestine is much longer (tadpole) than that of carnivorous animals (For Example. frog in proportion to body size)
• In rabbits, there are 4 pairs of salivary glands: Parotid, sub-axillary, sub-lingual and infraorbital (below the orbits and absent in man).
• Liver. It is relatively much larger in the foetus. It has a double blood supply: about 70% coming from the hepatic portal system and 30% from the arterial system.
• The liver of a rabbit is formed of five lobes: Right central (largest), left central, left lateral, caudate and Spigelian (smallest and absent in the liver of man).
• Faecal matter is solid in the descending colon.
• The lining cells of the small intestine have microvilli for absorbing digested food. The microvilli are not present in the embryo but develop after birth as the young one starts suckling.
• Once glycogen reserve is exhausted the adipose tissue (fat cells) comes to the rescue of the fasting person.
• Bp is absent in plants, but present in almost all animal tissues of which rich sources are liver, kidney, milk, etc.
• Tapeworms are said to be “Wallowers” because they absorb nourishment through their body surface.
• Rennin is secreted by young mammals. It is not secreted by adult mammals.
• The first pancreatic transplant took place in l%6 in the U.S.
• Bad breath is usually due to cavities in the teeth, and infection of the throat and nose.
• Many people are overfed but undernourished.

1. Tea/coffee inhibits the absorption of iron from the diet. Prolonged consumption of tea or coffee after meals can lead to iron deficiency anaemia.
2. The cells of the epithelial lining in a vertebrate stomach are not damaged by HC₁ because of mucus secretion covering the epithelium.
3. Under extreme demand of glucose (starving) even reserve proteins and fats are converted into glucose through a process of gluconeogenesis.
4. Wound healing is enhanced by Vit-C.
5. Lips (Labia Ora). Chelonians and birds lack lips. The upper lip of rabbits, hares, rats and squirrels has a median vertical cleft, the harelip, exposing the upper teeth. Some humans also have harelip as a congenital abnormality.
6. It can be set right by a surgical operation. The upper lip and snout are prolonged into a long, thick, prehensile proboscis or trunk in elephants. Platypus and whales lack movable lips.
7. Cheek Pouches. In some rodents (squirrel, rat) and certain old-world monkeys, the vestibule (space between cheeks and jaws) extends to form cheek pouches for temporary storage of masticated food.

Animal Nutrition And Digestive System NEET Chapter Summary

NEET Biology Questions For Competitive Examinations

Question 1. Protein/enzyme is absent in :

1. Saliva
2. Bile
3. Pancreatic juice
4. Intestinal juice.

Answer: 2. Bile

Question 2. Match the degestive juices listed under Column-1 with the enzymes given under Column-2; Choose the choice which gives the correct combination of the alphabets of the two columns.

1. A — r, B — s, C — p, D — t
2. A — r, B — t, C — p, D — q
3. A — s, B — r, C — p, D — t
4. A — r, B — S, C — q, D — p.

Answer: 4. A — r, B — S, C — q, D — p.

Question 3. What should be taken to offset the deficiency of rhodopsin?

1. Papaya and Mango
2. Orange and Amla
3. Watermelon and Strawberry
4. All the above.

Answer: 1. Papaya and Mango

Question 4. Vitamins required for the development of erythrocytes are:

1. D
2. B₁₂
3. E
4. K.

Answer: 2. B₁₂

Disorders Of Digestive System NEET Biology

Question 5. In the case of taking food rich in lime juice, the action of ptyalin on starch is :

1. Enhanced
2. Reduced
3. Unaffected
4. Stopped.

Answer: 2. Reduced

Question 6. Digestive juice contains catalytic agents called :

1. Vitamins
2. Hormones
3. Enzymes
4. Nitrates.

Answer: 3. Enzymes

Question 7. Bile acids are :

1. Steroids
2. Carbohydrates
3. Modified proteins
4. Vitamins.

Answer: 1. Steroids

Question 8.Which one correctly matched :

1. Vit. E-Tocoferol
2. Vit. D-Riboflavin
3. Vit. B-Calciferol
4. Vit. A-Thiamine

Answer: 1. Vit. E-Tocoferol

Question 9. Where does the conversion of harmful prussic acid into potassium sulphocyanide take place?

1. spleen
2. liver
3. bone marrow
4. lymph glands.

Answer: 2. liver

Question 10. Water is absorbed mainly by :

1. Large intestine
2. small intestine
3. stomach
4. pancreas.

Answer: 1. Large intestine

Question 11. The number of different teeth (incisors, canines, pre¬molars and molars) in each jaw are :

1. 4, 4, 6. 4
2. 4,2,4,6
3. 4, 2, 5, 6
4. 6, 2, 4, 4.

Answer: 2. 4,2,4,6

Question 12. “Your food shall be your medicine”. This quotation was given by :

1. Newton
2. Hippocrates
3. Einstein
4. Lenz.

Answer: 2. Hippocrates

Question 13. Term proteins were first used by :

1. Berzelius
2. Funk
3. Kuhne
4. Marconi.

Answer: 1. Marconi

Question 14. Gall baldder is absent in :

1. cow
2. pig
3. horse
4. cat.

Answer: 3. horse

Disorders Of Digestive System NEET Biology

Question 15. Vitamin K is necessary for:

1. R.B.C.
2. W.B.C.
3. plasma
4. production of prothrombin.

Answer: 4. production of prothrombin

Question 16. A person suffering from profuse bleeding after an injury. Such a person is deficient in which vitamin?

1. Vit A
2. Vit K
3. Vit D
4. Vit E.

Answer: 2. Vit K

Question 17. Which of the following is the largest part of a cow’s alimentary canal?

1. Reticulum
2. Rumen
3. Omasum
4. Abomasum.

Answer: 2. Rumen

Question 18. Absorption of glucose and amino acids occurs by:

1. Passive absorption
2. Active absorption
3. Simple diffusion
4. Facilitated diffusion.

Answer: 2. active absorption

Question 19. Magnesium is most abundant in :

1. milk
2. meat
3. soybean
4. fish.

Answer: 2. meat

Question 20. Deficiency of which of these causes anaemia?

1. Fe
2. Zn
3. A1
4. Mg.

Answer: 1. Fe

Question 21. Which one pair is not correctly matched?

1. Vit Bp-Pernicious anaemia
2. Vit B6-Beri-Beri
3. Vit C-Scurvy
4. Vit B₂ -Pellagra.

Answer: 4. Vit B₂ -Pellagra

Question 22. Lysozymes are found in :

1. Mitochondria
2. Tears
3. Saliva and tears both
4. Saliva.

Answer: 3. Saliva and tears both

Question 23. Just as hydrochloric acid is to pepsinogen so is :

1. Enterokinase to trypsinogen
2. Haemoglobin to oxygen
3. Bile juice to fat
4. Glucagon to glycogen.

Answer: 1. Enterokinase to trypsinogen

Disorders Of Digestive System NEET Biology

Question 24. Plasma protein also performs :

1. Nutritive function
2. Physioehemienl function
3. Transportive function
4. All the above three.

Answer: 4. All the above three

Question 25. Which is non-reducing sugar?

1. glucose
2. galactose
3. mannose
4. sucrose.

Answer: 4. sucrose

Question 26. Which is false for nutrition in Amoeba?

1. pseudopodia feeder
2. holozoic nutrition
3. photonivorous
4. Photoautotroph.

Answer: 4. photoautotroph

Question 27. Match the types of cells listed under column 1 with the secretions under column II. Choose the answer which gives the correct combination of the alphabet of two columns :

1. A = s b = r ; C = p D = t
2. A = q b = r; C = p D = t
3. A – s b = q; C = p D = t
4. A = t b = q; C = r, D = S.

Answer: 1. A = s b = r ; C = p D = t

Question 28. The lacteals are found in :

1. Spleen
2. Mammary gland
3. Salivary gland
4. Villi.

Answer: 4. Villi

Question 29. Number of teeth which grow twice are :

1. 8
2. 14
3. 12
4. 20.

Answer: 4. 20

Animal Nutrition And Digestive System NEET Notes

Question 30. Which of the following is not an insectivorous plant?

1. Drosera
2. Nepenthes
3. Monotropa
4. Utricularia.

Answer: 3. Monotropa

Question 31. Seaweeds are important sources of :

1. Chlorine
2. Fluorine
3. Iodine
4. Bromine.

Answer: 3. Iodine

Question 32. During digestion, lymphatics of the intestine become filled with fat globules giving a white colour to the lymph. This lymph is called :

1. Cistron
2. Chyle
3. Chyme
4. Bilirubin.

Answer: 2. Chyle

Question 33. Cattle fed with spoilt hay of sweet clover which contains dicumarol :

1. Are healthier due to a good diet
2. Catch infections easily
3. May suffer from vitamin K deficiency and prolonged bleeding
4. May suffer from Beri Beri due to a deficiency of B vitamins.

Answer: 3. May suffer from vitamin K deficiency and prolonged bleeding

Question 34. Duodenum has characteristic Brunner’s glands which secrete two hormones called :

1. Prolactin, Parathormone
2. Estradiol, Progesterone
3. Kinase, Estrogens
4. Secretin, cholecystokinin.

Answer: 4. Secretin, cholecystokinin

Question 35. The richest sources of vitamin B,2 are :

1. Chocolate and green grain
2. Rice and Men’s egg
3. Carrol and chicken’s breast
4. Goat’s liver and Spirulliiui

Answer: 4. Goat’s liver and Spirulliiui

Question 36. Which one of the following pairs is not correctly matched?

1. Vitamin B₁ = Beri-Beri
2. Vitamin B₂ = Pellagra
3. Vitamin B₁₂ = Pernicious anaemia
4. Vitamin B₆ = Loss of appetite.

Answer: 2. Vitamin B₂ = Pellagra

Question 37. Which one of the following is the correct matching of a vitamin, its nature and its deficiency disease?

1. Vitamin A – Fat-soluble – Beri-Beri
2. Vitamin K – water-soluble – Pellagra
3. Vitamin A – Fat soluble-Night blindness
4. Vitamin K – fat soluble – Beri-Beri.

Answer: 3. Vitamin A – Fat soluble-Night blindness

Animal Nutrition And Digestive System NEET Notes

Question 38. Which of the following is a mismatch? :

1. Thiamine – Damage to nerves and heart
2. Ascorbic acid – Scurvy
3. Riboflavin – Slow rate of clotting of blood
4. Niacin – Damage to skin and intestinal lining.

Answer: 3. Riboflavin – Slow rate of clotting of blood

Question 39. Carboxypeptidase is secreted by :

1. Pancreas
2. Lining of intestine
3. Salivary glands
4. Stomach.

Answer: 1. Pancreas

Question 40. Which group of three of the following five statements (a-e) contains all three correct statements regarding bribery?

1. A crippling disease prevalent among the native population of sub-Saharan Africa;
2. A deficiency disease caused by lack of thiamine (vitamin B1);
3. A nutritional disorder in infants and young children when the diet is persistently deficient in essential protein;
4. Occurs in those countries where the staple diet is polished rice;
5. The symptoms are pain from neuritis, paralysis, muscle wasting, progressive oedema, mental deterioration and finally heart failure;

1. 1, 2 and 4
2. 2, 3 and 5
3. 1, 3 and 5
4. 2, 4 and 5

Answer: 4. 2, 4 and 5

Question 41. A patient is generally advised to consume especially more meat, lentils, milk and eggs in the diet only when he suffers from :

1. Kwashiorkor
2. Scurvy
3. Anaemia
4. Rickets.

Answer: 1. Kwashiorkor

Question 42. Secretin and cholecystokinin are digestive hormones. They are secreted in :

1. Oesophagus
2. Ileum
3. Duodenum
4. Pyloric stomach.

Answer: 3. Duodenum

Question 43. Epithelial cells of the intestine involved in food absorption have on their surface :

1. Pinocytic vesicles
2. Microvilli
3. Zymogen granules
4. Phagocytic vesicles.

Answer: 2. Microvilli

Question 44. enzymes, vitamins and hormones can be classified into a single category of biological chemicals because all of these :

1. help in regulating metabolism
2. are exclusively synthesized in the body of a living organism
3. are conjugated proteins
4. enhance oxidative metabolism.

Answer: 1. help in regulating metabolism

Question 45. HCL is secreted by :

1. zymogen cells
2. peptic cell
3. oxyntic cells
4. None of these.

Answer: 3. oxyntic cells

Animal Nutrition And Digestive System NEET Notes

Question 46. Which of the following vitamins is water soluble as well as anti-oxidant?

1. Vit B₁
2. Vit A
3. Vit D
4. Vit C.

Answer: 4. vit C

Question 47. The given graph shows the effect of substrate concentration on the rate of reaction of the enzyme green-gram-phosphatase. What does the graph indicate?

1. The rate of enzyme reaction is directly proportional to the substrate concentration
2. Presence of an enzyme inhibitor in the reaction mixture
3. Formation of an enzyme-substrate complex
4. At higher substrate concentration the pH increases.

Answer: 2. Presence of an enzyme inhibitor in the reaction mixture

Question 48. Which one of the following four secretions is correctly matched with its source, target and nature of action?

Answer: 1.

Question 49. Maltase converts,

1. maltose to glucose at pH greater than 7
2. maltose to glucose at a pH lesser than 7.0
3. maltose to alcohol
4. starch to maltose at pi 1 higher than 7.0,

Answer: 1. Maltose to glucose at pi I greater than 7

Question 50. Which pair is essential for the growth of first in water?

1. calcium and phosphorus
2. phosphates and carbonates
3. sulphate and carbonates
4. nitrates and sulphates.

Answer: 1. calcium and phosphorus

Question 51. Match the following nutritional vitamin deficiencies in column 1 with the causes/deficiencies in column 2 and choose the correct option from the answer key.

1. A = p, B = t, C = q, D = r, E = s
2. A = t, B = q, C = r, D = s, E = p
3. A = t, B = r, C = s, D = p, E = q
4. A = r, B = s, C = p, D = t, E = q.

Answer: 4. A = r, B = s, C = p, D = t, E = q

Question 52. The main function of lacteals in the villi of human small intestine is the absorption of:

1. amino acids and glucose
2. glucose and vitamins
3. water and mineral salts
4. fatty acids and glycerol.

Answer: 4. fatty acids and glycerol

Question 53. Which of the following is called a detritivore?

1. an animal feeding on decaying organic matter
2. an animal feeding on a plant
3. a plant feeding on an animal
4. an animal feeding on another animal.

Answer: 1. an animal feeding on decaying organic matter

Question 54. Which one of the following enzymes carries out the initial step in the digestion of milk in humans?

1. Pepsin
2. Rennin
3. Lipase
4. Trypsin.

Answer: 2. Rennin

Human Digestive System NEET Biology

Question 55. Examination of the blood of a person suspected of having anaemia shows large, immature, nucleated erythrocytes without haemoglobin. Supplementary his diet with which of the following, is likely to alleviate his symptoms?

1. Riboflavin
2. Iron compounds
3. Thiamine
4. Folic acid and cobalamine.

Answer: 4. Folic acid and cobalamine

Question 56. Which of the following pairs of the kind of cells and their secretion is correctly matched?

1. oxyntic cells – a secretion with pH between 2.0 and 3.0
2. alpha cells of islets of Langerhans – secretion that decreases blood sugar level
3. Kupffer cells – a digestive enzyme that hydrolyses nucleic acids
4. sebaceous glands a socialism trial evaporates on cooling,

Answer: 1. oxyntic cells – a secretion with pH between 2.0 and 3.0

Question 57. The following is a scheme showing the rate of carbohydrate timing digestion in the human alimentary canal. Identify the enzymes acting at stages indicated as a, b, c and d. Choose the convict option from those given

1. a = amalyse, b = maltase, c = lactase, d = invertase
2. a = amylase, b = maltase, c = invertase, d = lactase
3. a = amylase, b = invertase, c = maltase, d = lactase
4. a = amylase, b = lactase, c = maltase, d = invertase.

Answer: 4. a = amylase, b = lactase, c = maltase, d = invertase.

Question 58. Which one is correctly matched?

1. vitamin E-thiamine
2. vitamin D-riboflavin
3. vitamin B₁ -tocopherol
4. vitamin A-calciferol
5. vitamin B₁₂-cyanocobalamine.

Answer: 5. vitamin B₁₂-cyanocobalamine

Question 59. Which of the following is the correct chronological order for enzyme activity of some enzymes taking part in protein digestion?

1. pepsin→ trypsin -4 peptidase
2. pepsin →peptidase →trypsin
3. trypsin → pepsin → peptidase
4. peptidase → trypsin → pepsin

Answer: 1. pepsin →trypsin -4 peptidase

Question 60. Which of the following can be absorbed by hepatic caeca?

1. glucose and amino acid
2. glucose and lipid
3. lipid
4. glucose.

Answer: 4. glucose

Question 61. Which of the following hormones helps in the secretion of HCL from the stomach?

1. renin
2. gastrin
3. secretin
4. somatomedin,

Answer: 2. gastrin

Human Digestive System NEET Biology

Question 62. Statements

1. The element which is very important for the production of thyroxine is iodine
2. Vitamin B₆ is otherwise known as niacin or nicotinic acid
3. Fructose is a monosaccharide and is a hexose sugar
4. Globulin is an example of a conjugated protein of the above statements.

1. 1, 2 and 3 are correct but 4 is wrong
2. 1 and 3 are correct but 2 and 4 are wrong
3. 1 and 2 are correct but 3 and 4 are wrong
4. 1 is correct while 2, 3 and 4 are wrong
5. 1, 3 and 4 are correct but b is wrong.

Answer: 2. 1 and 3 are correct but 2 and 4 are wrong

Question 63. ‘Crypts of Liebcrkuhn’ are found in :

1. gall bladder
2. liver
3. pancreas
4. intestinal tracts
5. salivary glands.

Answer: 4. salivary glands

Question 64. Glisson’s capsule is associated with

1. liver
2. pancreas
3. lung
4. Kidney.

Answer: 1. liver

Question 65. The main digestive function of enterokinase is :

1. conversion of casein into paracasein
2. conversion of pepsinogen into pepsin
3. conversion of trypsinogen into trypsin
4. Stimulation of the gastric glands to secrete gastric juice
5. conversion of trypsin into trypsinogen.

Answer: 3. conversion of trypsinogen into trypsin

Question 66. Which of the following is the correct matching of the site of action on the given substrate, the enzyme acting upon it and the end product?

Answer: 3

Question 67. What will happen if the secretion of parietal cells of the gastric glands is blocked with an inhibitor?

1. Gastric juice will be deficient in chymosin
2. Gastric juice will be deficient in pepsinogen
3. In the absence of HCL secretion, inactive pepsinogen is not converted into the active enzyme pepsin
4. Enterokinase will not be released from the duodenal mucosa so trypsinogen is not converted to trypsin.

Answer: 3. In the absence of HCL secretion, inactive pepsinogen is not converted into the active enzyme pepsin

Question 68. Anxiety and eating spicy food together in an otherwise normal human may lead to:

1. Jaundice
2. Diarrhoea
3. Vomiting
4. indigestion.

Answer: 4. indigestion

Question 69. Select the correct match of the digested products in humans given in column 1 with their absorption site and mechanism in column 2. ‘

Answer: 4.  Glycine, Glucose – Small Intestine, Active absorption

NEET Biology Respiration In Plants

NEET Biology Respiration In Plants Respiration

• Living organisms require energy in order to maintain their chemical composition, and movement, repair of damaged parts, grow, and reproduce.
• Photosynthesis and respiration are the central energy-processing pathways of life.
• The ultimate task of both processes is to produce energy intermediates to drive endergonic reactions.
• These energy intermediates in living cells have phosphate groups attached by so-called high-energy phosphate bonds.
• ATP (Adenosine triphosphate) is the energy intermediate or energy currency in every living organism.
• UTP and GTP are other common energy intermediates.
• Energy is usually released from ATP by hydrolyzing the terminal phosphate group, yielding ADP and inorganic phosphate group iP and about 8.9 kilo calories of energy per mole of ATP hydrolyzed.
• ADP may be further hydrolyzed to form AMP and iP and 6.5 Kcal. of energy per mol.
• ATP is resynthesized during phosphorylation. It is of three types: Photophosphorylation, oxidative phosphorylation, and substrate-level phosphorylation.
• By weight each gram mol of glucose and fat yields 4.1 and 9.3 Kcal of biological energy respectively.
• Complete combustion of glucose molecules in a calorimeter, into CO₂ and H₂O yields about 686,000 calories (686 Kcal.) of heat energy.
• In biological oxidation, a glucose molecule yields 38 molecules of ATP ( 36 molecules of ATP in eukaryotes).
• Biological systems are capable of utilizing only about 40% of chemical energy stored in glucose, the remaining is lost as heat

Read and Learn More NEET Biology Notes

NEET Biology Respiration In Plants Broad Outline Scheme Of Respiration

• Respiration is the process in which there is a breakdown of complex substances into simple substances with the evolution of energy. If the breakdown occurs in the presence of oxygen then it is aerobic respiration.

In this kind, the breakdown is complete and a lot of energy is released. On the other hand, in anaerobic respiration, as O₂ is not needed, the breakdown is incomplete and less energy is released.

Respiration In Plants NEET Notes

• During aerobic respiration, pyruvic acid is formed from glucose in the first step. The various reactions take place in the cytoplasm. This step is called glycolysis.

Pyruvic acid enters mitochondria and changes into Acetyl COA which then enters Krebs’ cycle in mitochondria to produce H-,0 and CO^–, NADH-, and FADH, produced in Krebs’ cycle enter ETS to release ATP molecules (energy source). There”is terminal oxidation and oxidative phosphorylation.

NEET Biology Respiration In Plants Glycolysis

NEET Biology Respiration In Plants Other Methods Of Formation Of Pyruvic Acid

In addition to the EMP pathway, pyruvic acid

Can also be formed by following metabolic pathways of carbohydrates :

• Hexose monophosphate pathway or shunt (HMP) Pentose phosphate pathway or 6-Phosphogluconate pathway
• Phosphoketolase pathways.
• Entner-Duodoroff (ED) pathway.
• Hexose monophosphate pathway (HMP):

 Pathway Definition:

This is a multifunctional process primarily designed to produce reducing power in the form of NADPH, which acts as a donor of hydrogen and electrons in several reductive biosynthetic pathways, including in the synthesis of fatty acids and steroids.

• The HMP details were provided by Warberg and Dickens, so it is referred to as the YVarberg-Dickens pathway. Event.
• It is present in various animal tissues, including the liver (phospholipid synthesis), mammary glands (milk fat synthesis), adipose tissue (fatty acid synthesis), erythrocytes, adrenal cortex, and other endocrine glands associated with steroid hormone synthesis. It is lacking in the muscle cells. It also transpires in the

 Pathway Properties:

1. In HMP, ATP is neither consumed nor produced.
2. It occurs in the extramitochondrial cytoplasm which has all the enzymes of HMP.
3. In this, hexoses arc is converted into pentoses, especially ribose-5-P.
4. It is also called the direct oxidative pathway because in this C-l of glucose is oxidized first (In glycolysis, C₃ and C₄ are first oxidized),
5. The co-enzyme used in oxidative reactions of HMP is NADP+ which is reduced to NADPII + H+ (In glycolysis, the H-acceptor used is NAD+).
6. CO₂ is produced.

Significance Of Ppp

1. It provides an alternative route other than glycolysis for carbohydrate breakdown.
2. It provides the erythrose-4-phosphate required for the synthesis of shikimic acid. It is the precursor of an aromatic ring compound.
3. It generates NADPII molecules which are used as reductants in biosynthetic processes under conditions when NADPH molecules are not generated by photosynthesis.
4. It is, therefore, important in non-photosynthetic tissues such as in differentiating tissues, germinating seeds, and during periods of darkness. Production of NADPH is not linked to ATP generation in the pentose phosphate pathway.
5. It provides ribose sugar for the synthesis of nucleic acids.
6. It plays an important role in the fixation of CO₂.

Glycolysis And Krebs Cycle NEET Study Material

NEET Biology Respiration In Plants Oxidation Of Pyruvic Acid Formation of Acetyl Co-A

The Acetyl Co A is the connecting link between glycolysis and Krebs’ cycle.

NEET Biology Respiration In Plants Electron Transport System Ets Or Cytochrome System Cs

Cytochromes identified by Mac Cunn are intrinsic proteins abundant in iron (Fe+2). Cyt a3 contains both Cu²⁺ and Fe²⁺ and functions as cytochrome oxidase.

• It is the primary energy source within a cell. It additionally regenerates coenzymes and creates water. The hydrogen atom pairs that dissociate from the prior processes do not directly combine with oxygen to produce water; instead, they first traverse a sequence of seven intermediate carriers situated on the inner mitochondrial membrane, including the cristae.
• The transfer of electrons releases energy at three stages during the enzymatic binding of ADP and inorganic phosphate to produce ATP. The mechanism of energy storage via electron transport in the phosphate bond of ATP is termed oxidative phosphorylation.

The sequence of electron carriers is :

1. NADH₂ → FMN -V FeS

→ CoQ → Cyt b →Cyt c

1. → Cyt a-a₃ oxygen.

ATP Synthesis according to Chemisoniatic hypothesis (Peter Mitchell 1979).

• It involves the passage of 2e from NADH₂ pushing out three pairs of protons from the inner to the outer chamber of mitochondria resulting in proton gradient and electric potential.
• These two jointly create a proton motive force. It causes the proton to move back through proton channels of F₀ particles. Energy is made available to F₀ particles for the synthesis of ATP as these particles have ATP activity

NEET Biology Respiration In Plants Factors Affecting Respiration In Plants

External Factors :

1. Light. Light has no direct effect, however, the respiration rate is higher in sunlight than in darkness.
2. Temperature. Respiration is maximum at 30°C. Above this temperature respiration rate decreases due to denaturation of enzymes. At low temperatures (zero or below zero) the enzymes become inactive and thus respiration decreases.
3. Low temperatures in cold storage are useful in storing food grains, and vegetables. In hilly areas, the temperature is low at night and moderate during the day causing reduced respiration and high photosynthesis.
4. According to Vant Hoffs law, the rate of respiration increases 2-2.5 times with every 10°C increase in temperature between 0-25°C, i.e. Q10 = 2-2.5 (cascade effect).
5. Oxygen. It is essential for aerobic respiration. A high concentration of O₂ inactivates the respiratory enzyme and reduces respiration. Oxygen also inhibits the fermentation of sugar by yeast cells or anaerobic respiration (Pasteur effect).
6. Carbon dioxide. Respiration decreases with increases in CO₂ concentration. High CO₂ concentration causes stomatal closure and checks the intake of O₂. Thus reduces respiration.
7. Water. Water is essential for enzyme activity. Respiration will not occur in the absence of oxygen. This is the reason that dry seeds with 8-12% moisture do not germinate unless watered.
8. Wound and injuries. For healing the injured areas, respiration is increased.
9. Chemicals. Cyanide and carbon monoxide inhibit respiration.

Electron Transport Chain In Plants NEET Important Points

Internal Factors: Protoplasm. (Meristematic) cells with dense protoplasm have a high rate of respiration.

1. Substrate. The rate of respiration is directly proportional to the amount of substrate. Respiration decreases if end products accumulate.

Outline of ATP production during aerobic oxidation of glucose to CO₂ and H₂O

GLYCOLYSIS

• ATP produced directly    ….4 molecules
• ATP consumed             …. 2 molecules
• Net gain of ATP          … 2 molecules
• From hydrogen produced and sent down the electron transport system Route II and Route I (2 x 2) / (2 x 3) respectively       4/6 molecules

Pyruvic Acid Oxidation

• From hydrogen produced and sent down the electron transport system (2×3)      6 molecules

Krebs’ Cycle (Tricarboxylic Acid Cycle)

• ATP produced directly (From GTP)      …. 2 molecules
• From hydrogen accepted by NAD (3 x 3)  ….9 molecules
• Therefore for the two molecules of citric acid metabolized (9×2)….18 molecules
• From hydrogens accepted by FAD (1×2)                           …. 2 molecules
• Thus for the two molecules of citric acid metabolized (2 x 2) …..4 molecules
• Total                                                         ..36/38 molecules

2 molecules of ATP consumed in transferring NADH into mitochondria in eukaryotes _2 molecules

Net gain of ATP in eukaryotes = 36 molecules

NEET Biology Respiration In Plants Anaerobic Respiration

The path for anaerobic respiration from glucose to pyruvic acid is the same as in aerobic respiration i.e. glycolysis.

• Pyruvic acid then forms ethyl alcohol and CO₂ or lactic acid. All these reactions occur in the cytoplasm and mitochondria are not involved.
• Fate of Pyruvic acid in anaerobic respiration. When there is no oxygen available to
  accept hydrogen atom, pyruvic acid (the end product of glycolysis) itself becomes the acceptor
  of hydrogen ions and protons.
• In animals, when cells are temporarily deprived of oxygen (as in skeletal muscles during exercise), pyruvic acid is converted into Inctic acid.
• In this reaction, NADH produced in glycolysis is oxidized into NAD⁺, and the two protons and two electrons So released are used in the conversion of pyruvic acid into lactic acid.
• The accumulation of lactic acid in the muscle causes fatigue. However, during rest, the lactic acid is again converted into pyruvic acid and undergoes aerobic respiration. Many bacteria obtain energy from glycolysis and convert pyruvic acid to lactic acid.

The net yield of ATP in anaerobic respiration.

There is a gain of only 2 molecules of ATP, that too, during glycolysis in anaerobic respiration. Production of much lesser ATP moleculeÿ, during anaerobic respiration is due to the following reasons-

1. Reactions do not proceed beyond glycolysis.
2. Even NADH produced in glycolysis is not channeled through the respiratory chain to produce ATP. Instead, it is used in the reduction of pyruvic acid.

Respiration In Plants NEET Mcqs With Answers

Fermentation differs from anaerobic respiration by the following features-

1. Fermentation is an extracellular process.
2. It usually occurs in microbes.
3. Enzymes extracted from cells perform fermentation.
4. A small quantity of oxygen rather stimulates fermentation while anaerobic respiration occurs in the absence of oxygen.

The energy stored during photosynthesis in carbohydrates In plants glucose is derived from sucrose. The latter such as glucose and starch, is released by breaking the C-C bonds of such molecules through oxidation for cellular use.

• This process of release of energy is called respiration.
• One molecule of glucose releases about 2870 KJ of energy during aerobic respiration and 247 KJ during anaerobic respiration.
• In plants, glucose is derived from sucrose. The latter is converted into glucose and fructose by an enzyme invertase and these two molecules readily enter the glycolysis pathway.
• The total energy yield from 38 molecules comes to 12c KJ (one ATP molecule yields 34 KJ of energy). Enter released in one molecule of glucose on complete oxidation corresponds to 2870 KJ. Tim the efficiency is 45 percent and the rest of the energy is lost as heat.
• In the bacterium Pseudomonas, glucose gives rise to pyru¬vic acid through the ED pathway. In this bacterium a molecule of glucose yields only one molecule of pyruvic acid. One ATP molecule is used and two are generated with a net gain of I ATP. Pyruvic acid is decarboxylated to acetaldehyde, which is then reduced to ethanol as in yeast.
• Plants show cyanide-resistant respiration because of an additional enzyme catalase which converts O₂ into water and oxygen. This respiration induces climacteric effect and atherogenicity

NEET Biology Respiration In Plants Quanta To Memory

1. Respiration is independent of light.
2. Photosynthesis is 10 times faster than respiration.
3. Efficiency of energy is 40-45%.
4. The term respiration was coined by Dutrocliet.
5. 264 gms of CO₂ is liberated during the complete oxidation of 180 gms. of glucose.
6. 88 gms of ethyl alcohol is formed by partial oxidation of 180 gms. of glucose.
7. 92 gms. of CO₂ is formed by anaerobic respiration of 180 gms of glucose.
8. All the respiratory substrates join a common scheme of oxidation, Krebs’ cycle.
9. All enzymes, substrates, intermediates, and end products of glycolysis are present in the cytosol.
10. Krebs cycle is the central pathway of cell respiration where the catabolic pathways converge upon it and anabolic pathways diverge from it.
11. The only high-energy phosphate produced in the Krebs cycle is GTP.
12. Glucose is the most common respiratory substrate.
13. During starvation, first glycogen, then, fats, and finally proteins are oxidized to liberate energy.
14. Ripening fruits show an increase in the rate of respiration (climacteric respiration)
15. F0 carries proton channels while F0 has ATP ase activity according to Mitchell’s chemiosmotic coupling theory.
16. Each pyruvic acid produces 15 ATP molecules in aerobic respiration while each Acetyl Co-A produces
17. 12 ATP molecules.
18. Krebs cycle is also called the Amphibolic process in which a number of intermediates of the Krebs cycle are used in anabolic pathways.
19. The ratio of ATP in aerobic and anaerobic respiration is 18.1 (36:2)
20. The ratio of C09 formation in aerobic and anaerobic respiration is 3:2.
21. Respiratory poisons are 2, 4 dinitrophenol, Antimycin-A, and cyanides.
22. Fats constitute the reserve energy and are used only after the consumption of carbohydrates. Proteins are used only after the consumption of both carbohydrates and fats.
23. Cytochromes are Fc-containing electron carriers except cytochrome which contains both Fe and Cu.
24. The pentose phosphate pathway: Also called hexose Monophosphate shunt, was explained by Warburg and Dickens. As a result of PPP, overall 35 ATP molecules are produced. It occurs in the cytosol. In the liver, this pathway is responsible for nearly 60% of the total carbohydrate oxidation,
25. Pasteur effect: Reduction in the amount of breakdown of the respiratory substrate and evolution of CO, when an anaerobically respiring material is brought into an O2-containing environment.
26. Dormant seeds represent a state of autooxidation.
27. Acetyl CoA is the common intermediate of carbohydrate and fat metabolism.
28. Fermentation was discovered by Gay Lussac.
29. The enzyme extracted from yeasts that brought about the fermentation is zymase.
30. RBCs and muscles get energy by glycolysis.
31. Fruits and seeds are stored at low temperatures to reduce the rate of respiration.
32. Viruses are infective agents that do not show the rate of respiration.
33. If a leaf is kept in a sugar solution, its rate of respiration increases.
34. The minimum concentration of O₂ for aerobic respiration extinction point is 3 – 10 %.
35. Dinitrophenol inhibits ATP synthesis (uncoupler of oxidative phosphorylation) but does not stop the transfer of electrons.
36. Oligomycin inhibits oxidative phosphorylation (energy transfer inhibitor).
37. Antimycin A stops the transfer of electrons from Cyt B to Cyt C and Cyanide prevents the transfer of electrons from cyt a3 to oxygen.

Respiration In Plants NEET Previous Year Questions

NEET Biology Respiration In Plants Questions For Competitive Examinations

Question 1. The three boxes in this diagram represent the three major biosynthetic pathways in aerobic respiration. Arrows represent net reactants or products.

Arrows numbered 4, 8, and 12 can all be :

1. ATP
2. H20
3. FAD+orFADH₂
4. NADH.

Answer: 4. NADH.

Question 2. Consider the following statements with respect to respiration.

1. Glycolysis occurs in the cytoplasm of the cell.
2. Aerobic respiration takes place within the mitochondria.
3. The electron transport system is present in the outer mitochondrial membrane.
4. C₅₁H₉₈C₆ is the chemical formula of Tripalmi- tin, a fatty acid.
5. Volume of O₂ evolved

Respiratory quotient = Volume of O₂ evolved \ Volume of CO₂ consumed

Of the above statements

1. 1, 2, and 4 alone are correct.
2. 2, 3, and 4 alone are correct.
3. 3, 4, and 5 alone are correct.
4. 2, 4, and 5 alone are correct.
5. 1, 3, and 5 alone are correct.

Answer: 1. 1, 2, and 4 alone are correct

Question 3. Anaerobic respiration of yeast produces :

1. Oxygen
2. Nitrogen
3. CO₂
4. H₂O.

Answer: 3. CO₂

Question 4. Metabolism of one palmitic acid yields ATP :

1. 36 ATP
2. 56 ATP
3. 136 ATP
4. 48 ATP.

Answer: 3. 136 ATP

Question 5. Alcoholic fermentation is carried out by :

1. Saccharomyces
2. Lactobacillus
3. Clostridium
4. Aspergillus.

Answer: 1. Saccharomyces

Respiration In Plants NEET Exam Preparation

Question 6. Cytochrome is :

1. Metallo flavoprotein
2. Fe containing porphyrin pigment
3. Glycoprotein
4. Lipid.

Answer: 2. Fe containing porphyrin pigment

Question 7. In the case of the Kerbs cycle, the pyruvic acid before being combined with oxaloacetic acid is converted to :

1. citric acid
2. isocitrate
3. succinyl CoA
4. acetyl CoA.

Answer: 4. acetyl CoA.

Question 8. Which of the following receives electrons at the end of ETC?

1. H₂O
2. H₂
3. CO₂
4. Cytochrome a3.

Answer: 4. Cytochrome a3.

Question 9. What is the total production of ATP at the end of a complete breakdown of one molecule of glucose during aerobic respiration?

1. 4
2. 8
3. 38
4. 34.

Answer: 3. 38

Question  10. Respiration in germinating seeds is usually high but with a decline in water and maturation the rate of respiration :

1. increases steadily
2. decreases steadily
3. remains constant
4. increases and decreases alternatively.

Answer: 2. decreases steadily

Question 11. PPP shunt is more advantageous than the Krebs cycle as :

1. it utilizes less oxygen
2. it reduces more of oxygen
3. it yields more ATP
4. ribose sugar is released which is used in the formation of nucleic acid.

Answer: 4. ribose sugar is released which is used in the formation of nucleic acid.

Question 12. The mechanism of aerobic respiration was discovered by :

1. Calvin
2. H. Krebs
3. Hatch and
4. Slack Pasteur.

Answer: 2. H. Krebs

Question 13. The dough kept overnight in a warm place becomes soft and spongy due to :

1. osmosis
2. absorption of CO₂
3. cohesion
4. fermentation.

Answer: 4. fermentation.

Respiration In Plants NEET Syllabus Topics

Question 14. In glycolysis, electrons are removed by :

1. ATP
2. NAD
3. Glyceraldehyde 3-phosphate
4. Molecular oxygen.

Answer: 2. NAD

Question 15. During which stage in the complete oxidation of glucose are the greatest number of ATP molecules formed from ADP?

1. Conversion of pyruvic acid to acetyl CoA
2. Electron transport chain
3. Glycolysis
4. Krebs cycle.

Answer: 4. Krebs cycle.

Question 16. The chemiosmotic theory of ATP synthesis in the chloroplasts and mitochondria is based on :

1. Proton gradient
2. Membrane potential
3. Accumulation of Na ions
4. Accumulation of K ions.

Answer: 1. Proton gradient

Question 17. How many ATP molecules could maximally be generated from one molecule of glucose, if the complete oxidation of one mole of glucose to CO^–, and H₂O yields 686 kcal and the useful chemical energy available in the high energy phosphate bond of one mole of ATP is 12 kcal?

1. Fifty-seven
2. One
3. Two
4. Thirty.

Answer: 1. Fifty-seven

Question 18. Which of the following statements is/are not true?

A. one ATP molecule yields 32 kJ of energy

B. pentose phosphate pathway was discovered by Dickens

C. when tripalmitin is used as a substrate, the R.Q. is 0.7

D. energy released by one molecule of glucose on complete oxidation corresponds to 1292 kJ.

1. A, B, and D
2. only C and D only
3. A and D only
4. A, C, and D only.
5. C only.

Answer: 3. A, C, and D only.

Question 19. All enzymes of the TCA cycle are located in the mitochondrial matrix except one which is located in inner mitochondrial membranes in eukaryotes and the cytosol in prokaryotes. This enzyme is :

1. isocitrate dehydrogenase
2. malate dehydrogenase
3. succinate dehydrogenase
4. lactate dehydrogenase.

Answer: 3. succinate dehydrogenase

Question 20. The overall goal of glycolysis. Krebs cycle and the electron transport system is the formation of:

1. ATP in one large oxidation reaction
2. Sugars
3. Nucleic acids
4. ATP in small stepwise units.

Answer: 4. ATP in small stepwise units.

Respiration In Plants NEET Syllabus Topics

Question 21. Which one of the following mammalian cells is not capable of metabolizing glucose to carbon dioxide aerobically?

1. Unstriated muscle cells
2. Liver cells
3. Red blood cells
4. White blood cells.

Answer: 3. Red blood cells

Question 22. Which of the metabolites is common to the respiration-mediated breakdown of fats, carbohydrates, and proteins?

1. Frutosc 1,6- bisphosphate
2. Pyruvic acid
3. Acetyl CoA
4. Glucose – 6 – phosphate

Answer: 3. Acetyl CoA

NEET Biology Mineral Nutrition In Plants

The mineral elements that are essential for the plant body are mostly absorbed by roots. Only Carbon, Oxygen and Hydrogen are obtained from air and water. The utilization of various elements absorbed by plants in growth and development is called mineral nutrition.

NEET Biology Mineral Nutrition In Plants Essentiality Of An Element

The essentiality of an element can be judged by ash analysis, solution culture or solid medium culture. The earliest culture solution was prepared by Sachs.

NEET Biology Mineral Nutrition In Plants Functions Of Minerals

The minerals perform several functions such as the construction of the plant body, maintenance of osmotic pressure, permeability, pH, performing catalytic function, imparting toxicity and balancing function.

NEET Biology Mineral Nutrition In Plants Physiological Role of Essential Elements

• Each important element executes a unique array of functions that are not entirely replicated by other essential elements.
• An element is crucial for the survival of a higher green plant for one or more of the following four reasons.
• It may provide a nutritive function as a constituent of one or more primary classes of plant compounds.
• It may also play a catalytic role, either as an enzyme activator or as an essential component of an enzyme.
• It may operate as three non-catalytic ‘metallo-biomolecules’ or as a free ion.

Macro-elements. A scientific approach to the role of mineral elements started with Sachs and Knop in 1850. It has been proved that carbon, hydrogen, oxygen, sulfur, phosphorus, calcium, magnesium, and iron are essential for the growth and development of plants.

Read and Learn More NEET Biology Notes

These elements are required in large amounts and without them normal metabolism is retarded. These elements are referred to as Macro-elements or Major elements because of the relatively large quantities in which they are needed for plant life.

Essential Mineral Elements In Plants NEET Notes

Micro-elements. Plants also require other elements in small quantities. These elements are not involved in the composition of plants but are present in traces. They help as catalysts in various metabolic processes.

These elements which are required in small quantities or traces are called micro-elements or trace elements. Some important micro-nutrients are Manganese, Zinc, Boron, Copper Molybdenum and Chlorine.

NEET Biology Mineral Nutrition In Plants Minerals Critical Concentration

1. The need of individual plants for any particular element is normally defined in terms of -critical concentration. This is the concentration of that nutrient, measured in the tissue, 1st below the level which gives maximum growth (Epstein, 1972).
2. In the absence of any essential element, the plant will be expected to exhibit certain morphological and biochemical symptoms of that deficiency. In some cases, the deficiency symptoms will clearly reflect the functional role of that element (Hopkins, 1995)

NEET Biology Mineral Nutrition In Plants Minerals Other Elements

1. Sodium. The importance of sodium for the growth of marine algae was first realised by Osterhout in 1906. It is also needed by blue-green algae for growth. In higher plants, it maintains the differential permeability of cytomembranes.
2. It also participates in nitrogen metabolism. The C₄  plants also require sodium. It may partially substitute for potassium in lower as well as higher plants.
3. Silicon. It is present in grasses, sedges, rushes, equisetum, and several algal forms. Somnar, 1926 observed that it is essential for the growth of rice and millet whereas Lipman, 1938 discovered that it is necessary for the growth of sunflower and barley.
4. Aluminium. It is found to improve the growth of several plants. On the other hand, many plants are known to possess sensitivity to aluminium toxicity.
5. Cobalt. It is a component of vitamin B₁₂  (Cyanocobalamin). A few blue-green algae and the bacterium Rbizobium, a symbiotic nitrogen-fixing bacteria of leguminous nodules also require cobalt
6. Gallium. Steinberg, 1945-46 found that the fungus Aspergillus niger and Lenina minor need gallium for their growth.
7. Selenium. Plants like Astragalus and Stanleya act as selenium indicators. They contain a high concentration of selenium.
8. Iodine. Some marine algae like Laminaria accumulate iodine in huge amounts.
9. Besides, gold is known to occur in Equisetum and vanadium is necessary for the growth of certain plants.

NEET Biology Mineral Nutrition In Plants Mineral Uptake By Plants

A plant obtains C₂ H₂ and O₂ as CO₇ are obtained from the atmosphere and water and the rest of the minerals are taken from the soil (solution mining). The absorption may occur through root hair Mycorrhizae or the mature part of the root.

• The soils may be acidic having principal cation H⁺, or alkaline where Ca₄-1″ predominates. Acidic soils are made alkaline by liming (cation exchange) and alkaline soil by adding sulphur becomes acidic.
• This sulphur is oxidised to sulphuric acid by microbes.
• The cell-to-cell movement of ions occurs through symplast and plasmodesmata. There may be pores of 7 A diameter in the plasma membrane. Besides, there are carrier proteins (permeases) in this membrane.
• Dead membranes are more permeable than living. The membranes are more permeable to O_7, N₂ COT and other smaller molecules. The lipophilic molecules are more permeable than hydrophilic.
• The ionic absorption has been regarded as an active process or passive. In the latter process, there is no expenditure of metabolic energy,
• According to Hylmo, there is a mass flow of mineral ions into the root along with transpiration current. Many other workers believe that the mineral ions diffuse into the root along a concentration gradient.
• The part of the plant cell or tissue that permits free diffusion is called outer space and the apparent volume accommodating these ions is apparent free space.
• The facilitated diffusion occurs through protein channels. It is stereospecific and occurs up to the saturation limit. The ions are transported through carrier proteins,
• The ion exchange hypothesis states that a particular ion is exchanged by a similar type of ion i.e., a cation by a cation and anion by an anion. It may occur by contact exchange or by the formation of carbonic acid.
• The Donnan equilibrium is believed to be reached due to the presence of some diffusible or fixed zones. It explains the entry of ions against a concentration gradient,
• There is ample evidence to believe in the active uptake of salts such as a faster rate of absorption, absorption against a concentration gradient, the correlation between rates of respiration and salt absorption, salt-induced respiration etc.
• According to Van den Honert, the cation and anions are transported through separate carriers. They make a complex and release them into the cell enzymatically,
• Lundegardh believes that the anions are transported across the membrane through a cytochrome pump whereas the cations are transported passively,
• Many people think that in the transport of ions, ATP is used up. The hydrolysis of ATP causes the release of energy. The transport is mediated by ATP ase.
• The movement of ions and carriers may occur in the same direction (symport carrier) or the opposite direction ( antiport carrier).
• While Goldacre believes that contractile proteins act as carriers. IJennett-CJark considers that lecithin is the main carrier of ions across the membrane.
• The process of salt absorption is influenced by many factors such as temperature, light, oxygen, and growth. pH and mineral interaction.

Role Of Macronutrients In Plant Growth NEET

NEET Biology Mineral Nutrition In Plants Deficiency Symptoms Due To Mineral Deficiencies

1. Chlorosis: Chlorophyll formation in leaf tissue is impaired due to mineral shortage or illness. It is sometimes referred to as a physiological disease, arising from deficiencies in certain minerals such as iron, magnesium, and nitrogen.
2. Etiolation: Etiolation refers to the yellowing or whitening of green plant tissues. Etiolation is a physiological occurrence observed in green plants cultivated in the absence of light.
3. Necrosis: Cellular and tissue necrosis.
4. Impeded development: Plants do not achieve normal height and stay stunted.
5. Abscission: Leaves, flowers, and fruit exhibit premature abscission in the fall.
6. Mottling: Presence of verdant and non-verdant regions.
7. Leaf Deformations: Abnormal leaf curling resulting from uneven growth is termed helotism. Heart rot in plants refers to the internal weakening or decomposition of tissues due to their breakdown.

NEET Biology Mineral Nutrition In Plants Special Modes Of Nutrition

1. The plants which are dependent on sonic other sources for their nutritional requirements are called heterotrophic plants which can be placed into four groups depending upon the sources of food: Parasites, saprophytes, symbionts and insectivorous or carnivorous plants.
2. Parasites are common among fungi and bacteria but less common among flowering plants. The angiospermic parasites are of two types: Partial parasites and total parasites or holopurnsites.
3. The partial parasites are green and thus photosynthesize but they obtain water and minerals from their host through their haustoria which remain in contact only with the xylem of the host. 1 he partial parasites are of two types i.e.
4. Partial stem parasites For example. Viscum (mistletoe), Loranthus and Arceuthobium. Arccuthobium minutissimum is the smallest green leafless parasite growing on Pinus excelsa. This plant is the minutest one among the dicots;
5. Partial root parasites For example. Sanlalum album (sandalwood tree) and Tliesitim.
6. The total parasites are non-green as they do not possess chlorophyll and hence derive their entire food from their host. Their haustoria communicates with both the xylem and phloem of the host.
7. Saprophytes obtain their food from dead and decaying organic matter and are common among fungi and bacteria but less common among higher plants. The saprophytic flowering plants are Neottia (bird’s nest orchid), Monotropa (Indian pipe), Corallorhiza, Epipogon, etc.
8. Almost all the saprophytic angiosperms possess mycorrhiza (an association of the fungus with the roots) and lack root hairs. Mycorrhiza may be ectotrophic as in Pinus, Belula, Monotropa (the Indian pipe), and Sarcodes; or endotrophic as in Neottia, Epipogon and Corallorhiza.
9. Symbionts form symbiotic associations in which both the organisms of the association are benefited Example. lichens, and the association of legumes with Rhizobium (N₂-fixing bacteria).
10. Insectivorous plants are autotrophic so far as their carbohydrate nutrition is concerned but they are dependent on captured insects for their nitrogen requirement as they grow in N₂-deficient soils (generally swamps and bogs). Thus, they are partly autotrophic and partly heterotrophic.
11. About 200 species of angiosperms are insectivorous and some of them are :
12. Drosera or Sundew – Its leaves possess glandular hairs called tentacles which secrete a sticky fluid containing digestive enzymes.
13. Utricularia or bladderwort is an aquatic, free-floating, rootless plant with dissected leaves and some of the leaf lobes are modified into sac-like structures called bladders.
14. Nitrogen And Nitrogen Metabolism.

• Nitrogen is a highly inert gas. Most of the nitrogen exists in proteins and amino acids. However, it is also found in large quantities in nucleic acids, cytochromes, chlorophyll, vitamins, alkaloids etc.
• It is not used directly and is found in fixed forms in combination with C₂ H₂O₂ to constitute other compounds. Nitrogen plays an important role in metabolism, heredity, reproduction and growth. Nitrogen combines with oxygen and hydrogen to form nitrate (NO₂), nitrite (NO₂) and ammonium salts (NH₂). Bacteria and blue-green algae can also fix atmospheric nitrogen.

• Soil contains nitrogen in the form of nitrate, ammonium salts and organic nitrogenous compounds. Ammonia is absorbed by the plants directly. Urea and amino acids can be absorbed directly by the plants. Urea is first converted into ammonia by the action of the enzyme urease.

Important Contributors

• Sachs, using a culture solution showed the essentiality of nitrogen for plant growth.
• Jenny and Overstreet (1938) proposed ion-exchange theory.
• Bulk flow or mass flow theory was given by Hylmo (1953) and later sup¬ported by Kramer (1956).
• The study of mineral nutrition was carried out by Knop (1865).
• Winogradsky (1891) discovered biological nitrogen
• P.R. Stout and D.R. Hoagland proved that minerals transport are translocated in the plants through the xylem.
• Aristotle (300 B.C.) thought that plants get their nutrients in organic form from the soil.
• Theodore de Saussure (1804) proposed that nutrients are made available to the plants from soil.
• T.H. Vanden-Honert (1936) proposed carrier-mediated uptake of ions.
• Jenny and Overstreet (1938) proposed ion-exchange theory.
• Goerick (1940) developed Hydroponics.
• Lundegardh (1950) proposed the cytochrome pump theory of salt absorption.
• Hylmo (1953) proposed mass flow theory.
• Bennet Clark (1956) proposed protein-lecithin as a carrier.
• The enzyme nitrogenase successively reduces N2 into diimide and hydrazine and finally to 2NH with the utilisation of ATP.

1. NHN NH = NH→NHT – NHT→2NH₄ 
2. Nitrogen Diimide Hydrazine Ammonium
3. Hydrogen ions and electrons for the reduction process are provided by reduced ferredoxin.
4. Nitrogenase acts only in anaerobic conditions and under aerobic conditions it undergoes irreversible damage.
5. The enzyme nitrogenase requires ATP, Mg⁺⁺, an electron source and anaerobic conditions for converting nitrogen to ammonia.
6. Anaerobic condition in symbiotic nitrogen fixation is provided by leghaemoglobin present in root nodules.
7. Haemoglobin is made up of four peptide chains while leghaemoglobin in root nodules is a single peptide chain.
8. Leghaemoglobins are red colour haemoglobin-like pigments which absorb oxygen and protect enzymes from oxygen.
9. Though nitrogen is present in abundance in the atmosphere but cannot be directly used. It is converted into nitrates and nitrites by certain nitrogen-fixing bacteria and cyanobacteria.
10. Species of Rhizobium are associated symbiotically with nodules of nodulated tap roots of leguminous plants.

• The di-nitrogen (N,) of the atmosphere is reduced to ammonia by the action of the enzyme nitrogenase in the presence of a reducing agent and energy currency ATP.
• Nitrogen Fixation Requires Three Components.
• Strong reducing agent
• ATP to transfer hydrogen atoms to dinitrogen ami the (f/x) enzyme sj-stem.
• The reducing agents (FAD) and ATP are provided by photosynthesis and respiration.
• Ammonia is utilized by plants as nitrate which is absorbed with the help of enzymes nitrate reductase and nitrite reductase.
• Ammonium ions are used for the synthesis of amino acids, proteins and other nitrog¬enous molecules of plants.
• Reductive animation. It is the primary pathway of amino acid formation. It involves the incorporation of ammonia or ammonium ions into ketoglutaric acid to yield glutamic acid.
  n-ketoglutaric acid + NH, -MX-Iminoglutaric acid a-Iminoglutaric acid + NADH + H⁺ Glutamic acid + NAD
• Transamination. It involves tyre transfer of the amino group (-NH,) of one amino acid to the carboxylic group of a keto acid. As far as 17 different amino acids can be synthesized from glutamic acid by transamination.
• Eight protons and six electrons are required to reduce a molecule of nitrogen into two molecules of ammonium.

Micronutrient Deficiencies In Plants NEET Study Material

Hydrogen is used in the conversion of molecular nitrogen to ammonia.

NEET Biology Mineral Nutrition In Plants Minerals

• The chemical substances that provide nourishment to living organisms are termed nutrients,
• Mostly all plants obtain their inorganic nutrients from soil, water and atmosphere.
• Some green plants supplement their nutritional requirements with parasitic and insectivorous habits, Out of 105 elements, plants require about 20 elements. <=S> Inorganic elements are essential for their normal growth and reproduction.
• Some elements form structural components whereas others participate in metabolic reactions or act as cofactors for several enzymes.
• Elements become essential constituents of proteins, carbohydrates, fats, nucleic acids etc. co Some of them serve as activators/cofactors for various enzymes.
• Heterotrophic plants could be parasitic, saprophytic, symbionts and insectivorous.
• Lichens, mycorrhizae etc. are examples of symbionts. CO Droserci, Utricularia and Nepenthes are examples of insectivorous plants.
• The carbon of plants is derived from that of atmospheric carbon dioxide.
• Deficiency of minerals results in disorders such as reduction in growth, chlorosis and necrosis, co The elements are absorbed through the root by active or pas¬sive absorption and transported through the xylem to other parts of the plant.
• Plants absorb minerals in the form of ions from the soil, Absorption of minerals occurs mainly from the region of elongation in the root.
• Outer space or apoplast includes cell walls and intercellular spaces.
• Inner space or symplast is formed by protoplast and plasmodesmata.
• Mineral ions enter into the apoplast by a passive process named diffusion.

The movement of ions from apoplast to symplast is by

1. Passive absorption
2. Active absorption

These are 

1. Passive ion absorption:

• Passive ion absorption transpires along the concentration gradient without the expenditure of energy (ATP).
• Theories explaining the passive absorption of minerals include
  1. Donnan equilibrium
  2. Ion exchange
  3. Mass flow hypothesis.
• According to the Don equilibrium concept (proposed by Donnan 1911) fixed ions present on the inner surface of the plasma membrane disturb the ionic equilibrium (electrochemical) of the cell. Initially, the cell accumulates cations when fixed ions are present, followed by the diffusion of anions into the cell.
• The ion exchange theory posited by Jenny and Overstreet involves the exchange of ions from root I P₂ OH with soil ions, facilitated by carbonic acid generated from the dissolution of CO₂ in water, which dissociates to produce fP and HCO₂ions for the ion exchange process.
• The movement of ions accompanying the movement of water owing to transpiration is termed mass low.

Active absorption:

The process of actively absorbing ions against their concentration gradient by utilizing energy is termed active absorption. Vandcn presented a carrier notion to elucidate active absorption.

NEET Biology Mineral Nutrition In Plants Quanta To Memory

• The roots of plants absorb a large number of elements from the soil. But only a few of these are essential for plant life.
• Sodium and Iodine which are essential for animals, are not required by most plants.
• Micronutrients are as important as macronutrients in plant nutrition.
• Among the micronutrients. Iron is required in much larger quantities.
• Recent research has shown that in addition to the already established microelements, Cobalt, Vanadium, Silicon, and Nickel may be essential for certain plants.
• Examples of electrophilic mycorrhiza are beech and oak.
• An example of endotrophic mycorrhiza which shows fungus within the roots is Epigonon.
• Loranthus and Viscum album are partial parasites.
• Cusciita reflex is a total stem parasite
• A few members of the family Orobanchaceae such as Orobanchc are total root parasites flourishing on the roots of tomato, potato, and brinjal.
• Epigonon (orchids), Monotropa, and sarcodes are a few examples of saprophyte plants.
• Excess of salts in soils leads to the development of plant indicators.
• The most common free ion in the cells is K⁺.
• Potassium is required for the activity of about 40 enzymes.
• Interveinal chlorosis of young leaves is due to deficiency of Iron, while that in old leaves is due to deficiency of Mg.
• Deficiency of Zn causes little leaf disease in cereals.
• The plants growing in water or by solution culture technique are termed hydroponics or soilless culture.
• Manganese is essential for the photolysis of water.
• Prokaryotes absorb the element nitrogen in gaseous form.
• Gold has been reported to occur in the stems of Equisetum
• Na-EDTA is the disodium salt of ethylene diamine tetra acetic acid.
• In plants growing in nitrogen-deficient soils, the older leaves become chlorotic first, because nitrogen from older leaves moves into younger leaves. Younger leaves show normal nitrogen as they receive it from older leaves.
• The pungent smell of onion and garlic is due to sulphur compounds.
• NPK are the critical elements.
• NPK fertilizers contain nitrophosphate with potassium.
• Nitrogen is translocated from roots as amides, amines and amino acids through the xylem. Phloem sap contains P-proteins as well as citrates and malates. The concentration of Ca⁺⁺ in phloem sap is lower than in xylem.
• The young leaves collect phosphorus and older leaves have calcium deposition. Iron is deposited along the veins and cobalt is in the hydathodes.
  Aeroponics is a system for growing plants with their roots bathed in the nutrient mist (a cloud of moisture in the air).

Symptoms Of Mineral Deficiency In Plants NEET Biology

NEET Biology Mineral Nutrition In Plants Questions From Competitive Examinations

Question 1. Inorganic nutrients are present in the soil as :

1. Biomolecules
2. Atoms
3. Electrically charged ions
4. Colloids.

Answer: 3. Electrically charged ions

Question 2. Clay and organic matter in the soil have negative charges. They attract positively charged ions like :

1. Ca²⁺
2. Mg²⁺
3. K⁺
4. All the above.

Answer: 4.  All the above.

Question 3. Which of the following is required by plants for the formation of ATP’?

1. N, Ca
2. N, Cu
3. N, K
4. N. Ca.

Answer: 1.  N, Ca

Question 4. Magnesium is an important component of:

1. Chlorophyll
2. Florigen
3. Hacmoerythrin
4. Enzyme.

Answer: 1.  Chlorophyll

Question 5. Plants use Zinc as :

1. Zn
2. Zn_2⁺
3. ZnSO₄
4. Zn(NO₃)₂.

Answer: 2. Zn_2⁺

Question 6.’ Plants growing in urea sprayed but Mg deficient soil
will show:

1. Deep green foliage
2. Early flowering
3. Yellowing of leaves
4. Loss of pigmentation in petals.

Answer: 3. Yellowing of leaves

Question 7. ATP molecules combine with carrier molecules and allow passage of substances :

1. No ATP is required
2. Along concentration gradient
3. Against concentration gradient
4. Both (2) & (3).

Answer: 3. Against concentration gradient

Question 8. Enzyme first used for nitrogen fixation :

1. Nitrogenase
2. Nitroreductase
3. Transferase
4. Transaminase.

Answer: 1. Nitrogenase

Question 9. This is an insectivorous plant:

1. Eichhornia
2. Opuntia
3. Crotolariadarsa
4. Utricularia.

Answer: 4. Utricularia.

Symptoms Of Mineral Deficiency In Plants NEET Biology

Question 10. Which of the following is non-symbiotic?

1. Azotobacter
2. Nostoc
3. Rliizobiwn
4. None of the above.

Answer: 1. Azotobacter

Question 11. Trace elements in plants are:

1. K
2. P
3. Zn
4. S.

Answer: 3. Zn

Question 12. Which of the following elements is essential for nitrogen metabolism in plants?

1. Iron
2. Potassium
3. Magnesium
4. Molybdenum.

Answer: 4. Molybdenum

Question 13. Plants absorb nitrogen in the form of:

1. Nitrate
2. Nitrites
3. Urea and NH₃
4. NH₄.

Answer: 1. Nitrate

Question 14. Which element is located at the centre of the porphyrin ring in chlorophyll?

1. Manganese
2. Calcium
3. Magnesium
4. Potassium.

Answer: 3. Magnesium

Question 15. The major role of minor elements inside living organisms is to act as:

1. Binder of cell structure
2. Co-factors of enzymes
3. Building blocks of important amino acids
4. Constituent of hormones.

Answer: 2. Co-factors of enzymes

Question 16. Plants deficient in the element zinc, show its effect on the biosynthesis of plant growth hormones:

1. Abscisic acid
2. Auxin
3. Cytokinin
4. Ethylene.

Answer: 2. Auxin

Question 17. The most abundant element found in plants is :

1. Carbon
2. Nitrogen
3. Iron
4. Manganese.

Answer: 1. Carbon

Question 18. The movement of ions is usually called llux. The inward movement into cells is called :

1. Efflux as an active process
2. Influx as a passive process
3. Influx as an active process
4. Efflux as a passive process

Answer: 3. Influx as an active process

Symptoms Of Mineral Deficiency In Plants NEET Biology

Question 19. Molybdenum is obtained by plants and is a part of enzymes

1. P – MO            Q – Nitrogenase
2. P – MqO⁺²₂    Q – All enzymes
3. P – M_q              Q – Nitrate reductase
4. P – MqO⁺²₂    Q – Nitrogenase

Answer: 4. P – MqO⁺²₂    Q – Nitrogenase

Question 20. Which of the following is incorrect :

1. Potassium plays an important role in the opening and closing of stomata.
2. Some essential elements cannot alter the osmotic potential of a cell
3. C, H, 0 and N are structural elements of the cell.
4. In addition to 17 elements, there are some beneficial elements such as sodium, silicon, cobalt and sodium

Answer: 2.  Some essential elements cannot alter the osmotic potential of a cell

Question 21. Copper is the activator in enzymes:

1. Carbonic anhydrase
2. Tyrosinase
3. Lactic dehydrogenase
4. Tryptophanase.

Answer: 2. Tyrosinase

Question 22. If by radiation all the nitrogenase enzymes are inactivated, then there will be no :

1. Conversion of nitrate to nitrite
2. Fixation of atmospheric nitrogen
3. Fixation of nitrogen in legumes
4. Conversion of ammonium to nitrate.

Answer: 3. Fixation of nitrogen in legumes

Question 23. The ability of the Venus Flytrap to capture insects is due to :

1. A passive process requiring no special ability on the part of the plant
2. Chemical stimulation by the prey
3. specialized “muscle-like” cells
4. Rapid turgor pressure changes.

Answer: 4. Rapid turgor pressure changes.

Question 24. All of the following statements concerning the actinomycetous filamentous soil bacterium Frankia are correct EXCEPT that Frankia :

1. Can induce root nodules on many plant species
2. Cannot fix nitrogen in the free-living state
3. Forms specialized vesicles in which the nitrogenase is protected from oxygen by a chemical barrier involving triterpene hopanoids
4. Like Rhizobium, it usually Infects its host plant through root hair deformation and stimulates cell proliferation in the host’s cortex.

Answer: 2. Cannot fix nitrogen in the free-living state

Question 25. If there is a deficiency of micronutrients that not only affects the growth of plants but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list given below, which group of three elements shall affect most, both photosynthetic and mitochondrial electron transport :

1. Cu, Mn, Fe
2. Ca, K, Na
3. Mn, Co.
4. Co, Ni, Mo

Answer: 1. Cu, Mn, Fe

Question 26. Prolonged liberal irrigation of agricultural fields is likely to create the problem of:

1. Acidity
2. Aridity
3. Salinity
4. Metal toxicity.

Answer: 3. Salinity

Question 27. The first stable product of fixation of atmospheric nitrogen in leguminous plants is:

1. Ammonia
2. NO₃
3. Glutamate
4. NO₂

Answer: 1. Ammonia

Question 28. Which is essential for root hair growth?

1. Ca
2. Zn
3. MO
4. S.

Answer: 1. Ca

Mechanisms Of Mineral Uptake In Plants NEET Exam

Question 29. Sulphur is an important nutrient for optimum growth and productivity in :

1. Fibre crops
2. Oilseed crops
3. Pulse crops
4. Cereals.

Answer: 3. Pulse crops

Question 30. Nitrogen fixation in root nodules of legumes is to :

1. Convert atmospheric N₂ to NH₃
2. Convert ammonia to nitrite
3. Transport oxygen for the activity of nitrogenase
4. Protect nitrogenase from oxygen.

Answer: 4. Protect nitrogenase from oxygen.

Question 31. Match the following and choose the correct combination from the options given.

1. A-2 ,   B-l,   C-4,   D-3
2. A -4,  B- 2,  C-3,  D-4
3. A-4,   B-3,   C-2,   D- 1
4. A-1,   B-3,  C-4,    D-2
5. A-3,   B -4,  C-1,  D-2.

Answer: 1. A-2 ,B-l ,C-4 ,D-3

Question 32. A plant requires magnesium for :

1. Protein synthesis
2. Chlorophyll synthesis
3. Cell wall development
4. Holding cells together.

Answer: 2. Chlorophyll synthesis

Question 33. Which one of the following elements is not an essential micronutrient for plant growth?

1. Zn
2. Cl
3. Ca
4. Mn.

Answer: 3. Ca

Question 34. Match the following mineral elements with their deficiency symptom and choose the correct option.

1. A-3,  B-1,  C-5,  D-2,  E-4
2. A-1,  B-4,  C-5,  D-3,  E-2
3. A-3,  B-4,  C-5,  D-1,  E-2
4. A-2,  B-3,  C-4,  D-1,  E-5
5. A-4,  B-2,  C-1,  D-3,  E-5

Answer: 3.

Question 35. Which one of the following elements in plants is not remobilised?

1. Phosphorus
2. Calcium
3. Potassium
4. Sulphur.

Answer: 2. Calcium

Question 36. Nitrifying bacteria :

1. Oxidize ammonia to nitrates
2. Convert free nitrogen to nitrogen compounds
3. Convert proteins into ammonia
4. Reduce nitrates to free nitrogen.

Answer: 1.  Oxidize ammonia to nitrates

Question 37. The function of leghaemoglobin in the root nodules of legumes is:

1. Inhibition of nitrogenase activity
2. Oxygen removal
3. Nodule differentiation
4. Expression of if gene.

Answer: 2. Oxygen removal

Question 38. Which one of the following is the wrong statement?

1. Root nodule-forming nitrogen fixers live as aerobes under free-living conditions.
2. Phosphorus is a constituent of cell membranes, certain nucleic acids and all proteins.
3. Nitrosomonas and Nitrobacter are chemoautotrophs
4. Anabaena and Nostoc are capable of fixing nitrogen in a free-living state also.

Answer: 2.  Phosphorus is a constituent of cell membranes, certain nucleic acids and all proteins.

Question 39. Consider the following statements concerning facilitated transport.

1. Requires ATP energy,
2. Transport saturates
3. Highly selective.
4. Requires special membrane properties.
5. Uphill transport.

Of The Above Statements

1. 1, 2 and 3 are relevant but 4 and 5 are irrelevant
2. 2, 3 and 5 are relevant but 1 and 4 are irrelevant
3. 3, 4 and 5 are relevant but 1 and 2 are irrelevant
4. 1, 4 and 5 are relevant but 2 and 3 are irrelevant
5. 2, 3 and 4 are relevant but 1 and 5 are irrelevant.

Answer:  3. 3, 4 and 5 are relevant but 1 and 2 are irrelevant

Question 40. Find out the Correctly matched pair.

Answer. 4. Manganese – Needed in the splitting of water to liberate oxygen during photosynthesis.

NEET Biology Photosynthesis And Translocation Of Organic Solutes

The food is manufactured by green parts of the plants by the process of photosynthesis. In the presence of sunlight. CO₂ and water, green parts synthesize carbohydrates and liberate O₂.

• The pigments needed are chlorophyll, carotenes, xanthophylls and phycobilins. The cells have chloroplasts which are semi-autonomous cell organelles, double membranous structures with matrix, and stroma. DNA. RNA, grana etc.
• The mechanism involves light and dark reactions. The light reaction needs light in which there is photolysis of water, photophosphorylation, formation of assimilatory power (NADPH, and ATP) and O₂ is released. Phosphorylation may be cyclic or non-cyclic.
• The dark reaction, as the name indicates, does not require light but continues even in the presence of light. Various reactions are in the form of a cycle called the Calvin cycle.
• Ribulose 1,5 diphosphate is the initial acceptor of CO^–, to produce phosphoglyceric acid (3-carbon compound). It utilises assimilatory power (NADPH₂, ATP) to produce 3 phosphoglyceraldehyde.
• A part of it is converted into carbohydrates while the remaining part is converted in a series of reactions into Ribulose 1,5 diphosphate. So there is cyclic production and utilization of this compound. On one side CO₂, ATP and NADPH₂ are used while on the other side, carbohydrates are produced.
• Plants showing the above mechanism are called C₃ plants as the first stable product is 3- phospho-glyceraldehyde. In C₄ plants, the first stable product is oxaloacetic acid. Important Events in the Discovery of Photosynthesis

Read and Learn More NEET Biology Notes

NEET Biology Photosynthesis And Translocation Of Organic Solutes Important Events In The Discovery Of Photosynthesis

• Aristotle and Theophrastus (370 B.C.) believed that plants get their food supply from organic matter in the soil by absorption.
• Ancient Indians believed that plants feed from their feet.
• Van Helmont (1648). He experimented with a small willow twig and concluded that “All vegetation is only water.”
• Woodward (1699) concluded by his experiments that when water is absorbed from the soil, certain material for growth is also made available to the plant.
• Stephen Hales (1727) often known as the ‘Father of Plant Physiology’ was the first to say that leaves to manufacture the food and light may play some role in manufacturing the food.
• Priestley (1722) gave the elementary idea of gaseous exchange, due to which the atmosphere remains pure. He concluded that vegetation purifies the air.
• Ingenhousz (1779) propounded the view that light and chlorophyll play a definite role in photosynthesis. He gave the following reaction for photosynthesis.
  Plants
• Lavoisier (1783) identified the purifying principle produced by green plants in sunlight as oxygen and the noxious air produced by the burning of candles as CO₂ (phlogiston).
• Senebier (1782) gave the idea that as the concentration of CO₂ is increased, the rate of evolution of O₂ also increases.
• Jean Senebier (1800) said that O₂ is released from CO₂ from green plants. He further said that red light of the visible spectrum is the best light for the process of photosynthesis.
• Dutrochet (1837) confirmed by his experiments that chlorophyll is necessary for the process of photosynthesis.
• De Saussure (I804) gave the following additions:
• Importance of water in the process.
• CO₂ is absorbed by plants instead of carbonic acid.
• Another significant breakthrough was the discovery of the fact that CO7 absorbed is equal to oxygen released.
• Von Mayer (1845) gave the following equation :
• CO₂ + H₂O + light energy Green Plants ^ Organic matter + chemical energy + O₂
• Lcibig 0845) pointed out that organic matter was derived from CO, and water was used in the photosynthesis.
• Sachs et al 0 887) concluded that chloroplasts use CO₂ to release O₂ He found starch as the first visible food.
• Engelmann 0888) plotted the action spectrum of photosynthesis.
• Blackman 0905) introduced Blackman’s law of limiting factor.
• Warburg 0 920) introduced the unicellular green alga chlorella as a suitable material to study photosynthesis.
• Van Neil 0930) established the foundation of a new era for solving the mystery of photosynthesis by concluding that 02 is released from H,0 and not from CO₂
• Robin Hill 0939) demonstrated that separate light reactions were present in a chloroplast.
• Ruben and Kamen 0941) used radioactive O18 to confirm that O₂ released is produced from H,O₂

1. Amon (1954) found that light and dark reactions are separable.
2. Emerson (1957) showed a red drop and the Emerson effect.
3. Amon (1967) proposed a scheme for the existence of two photosystems in the light phase.
4. Hatch and Slack (1965) formulated the Hatch and Slack cycle of C₄ plants for fixation of CO₂.
5. Rouhani et al, (1973) introduced the CAM pathways in the Sedum plants.
6. Huber, Michael and Dissenhofer (1985) crystallized the photosynthetic centre of the bacterium Rhodobacter and analysed its structure by X-ray Diffraction technique. They were awarded the Nobel Prize in Chemistry (1988).
7. Peftilier and Caventon (1818) coined the term chlorophyll.
8. G.G. Stokes was the first to separate pure fractions of chlorophyll-u and chlorophyll-b
9. Willstatter and Stoll (1913) were the pioneers in the studies of chlorophyll synthesis.
10. Menke (1961) stated that thylakoids are the structural and functional units of chloroplasts.
11. Park and Biggins coined the term quantosomes.
12. Photosynthetic Pigments

Ingenhousz (1779) recognised the participation of chlorophyll and light in the photosynthetic process. However, it is well-known now that besides chlorophyll, other pigments such as carotenoids and phycobilins are also involved in light absorption during photosynthesis.

• Chlorophylls The chlorophylls are the most important pigments active in photosynthesis. Today at least 9 types of Chlorophylls may be distinguished.
• Chlorophyll a (C₅₅H₇₂O₅N₄Mg Universal (ii) Chlorophyll b (C₅₅H₇₀O₆N₄Mg) Almost universal (Hi) Chlorophyll c (C35H7205N4Mg) Brown algae and diatoms etc O’v) Chlorophyll d (C₅₅H₇₀O₆N₄Mg) Red Algae
• Chlorophyll e (empirical formula not known) Xanthophyta
• Bacteriochlorophyll! a (C₅₅H₇₀O₆N₄Mg) Most of bacteria
• Bacteriochlorophylls b (formula not known) Rhodopseudomonas
• Chlorobium chlorophyll a (Bactcrioviridin) 650 (formula not known) Chloropium.
• Chlorobium chlorophyll (Bacterioviridin) 660 (formula not known)
• Chlorophyll a is bluish-green while chlorophyll b is olive green. Chlorophyll has a nyrrole porphyrin head (15 x 15 A) and a long-chain alcohol called phytol (20 A).
• Chlorophyll a has a methyl group at carbon 3 while chlorophyll b has a formyl (= aldehyde) group attached to this atom. Phytol is attached to carbon 7 through a propionic acid residue. The porphyrin head contains Mg (non-ionic) in its centre.
• Carotenoids. Carotenoids tire lipid compounds which are thought to be the derivatives of lycopene, a pigment present in tomatoes. They are present in nearly all higher plants, algae and many microorganisms, and are of two types:
• Carotenes. They are orange-yellow and are composed of carbon and hydrogen. They are insoluble in water but soluble in chloroform, ether and carbon disulphide. Four isomeric fonts of carotenes are now recognised: a, (3, y and 5 of which P- carotene is most common in all green plants and is readily converted into vitamin A in animal bodies.
• Xanthophylls or Carotenoids. They are yellow with the empirical formula C₄0H₅₆O₂. In normal green leaves, proportionately there is more xanthophyll than carotene and the most common xanthophyll in green leaves is luteol or lutein.
• Carotenoids, like chlorophylls, are located in the chloroplast and the chromatophore. Goodwin (1960) suggested that the chlorophylls and carotenoids may be attached to the same protein, forming a complex known as photosynthesis.
• Phycobilins or Biliproteins. They are protein-linked pigments which are easily destroyed by heat. They are soluble in hot water and are of three types:
• Phycocyanin. It is mostly found in blue-green algae and a few red algae.
• Phycoerythrin. It is mostly found in red algae and a few brown algae. Red algae growing in deep sea water show the highest efficiency of photosynthesis in green light which penetrates farthest in clear water and is absorbed by phycoerythrin, a red pigment present in them.
• Allophycocyanins. It is found in both blue-green and red algae.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Quantosome

• Park and Biggins (1964) coined the term for a group of pigment molecules required for carrying out a photochemical reaction. Quantosomes are present as small units on the membranes of thylakoids.
• Each quant some consists of about 250-300 chlorophyll molecules, carotenoids, quinone compounds, sulpholipids, phospholipids, proteins etc. including special types of chlorophyll molecules :
• P6g0 and P700 (P = Pigment; 680 and 700 denote the wavelength of light these molecules absorb).
• P680 and P700 constitute the reaction centre (or photocentres). Other accessory pigments and chlorophyll molecules are light-gatherers or antenna molecules (capture solar energy and transfer it onto the reaction centres by resonance transfer or inductive resonance).

NEET Biology Photosynthesis And Translocation Of Organic Solutes Absorption And Action Spectra

An action spectrum is a graph showing the rate of a process (e.g. photosynthesis) at different wavelengths of light. An absorption spectrum is a graph showing the amount of light of different wavelengths absorbed by a pigment.

The close similarity between the action spectrum of photosynthesis and the absorption spectrum of chlorophyll shows that chlorophylls are responsible for the absorption of light in photosynthesis.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Photosystem 1 And Photosystem 2

• Emerson’s enhancement effect. Emerson and Lewis (1943) observed a sudden drop in photosynthetic yield (evolution of O₂) by Clilorella above 680 mn (far red) – redtdrop. But if red light of shorter wavelength was also supplied simultaneously, photosynthetic yield increased (enhancement effect).
• Hence, Emerson (1957) proposed that two pigment systems or photochemical reaction systems are involved in the light phase (which act synergistically).
• A photon absorbed anywhere in the trapping (or harvesting) zone of a P6g0 centre can pass its energy to the P680 molecule. The cluster of pigment molecules which transfer their energy to P680 absorb light at or below the wavelength of 680 runs.
• Along with these molecules make tip the Photosystem II or PS II In the same way.P700 along with accessory pigments which absorb at or below 700 constitute the Photosystem I or PS I. PS I is located both in Stroma and Grana Lamellae. PS II is located in Grana. It possesses chlorophyll a. chlorophyll b and carotenoids.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Photophosphorylation Light phase

• Arnon et al (1954) discovered that isolated chloroplasts could synthesise ATP in the presence of light. Such a light-driven formation of ATP was called photophosphorylation.
• This is accompanied by photolysis of water, as a result of which O₂ is released and H combines with N’.ADP to form NADPH. Photophosphorylation can be defined as the coupling of phosphate with ADP to produce ATP using light energy during photosynthesis.
• Cyclic photophosphorylation. When the photons activate Photosvstem I. a pair of electrons are raised to a higher energy level. They are captured by the primary acceptor which passes them on to ferredoxin (Fd), and plastoquinone (PQ). cytochrome complex, plasticity and (PC) and finally back to chlorophyll P₇OQ.

• The process is cyclic. At each step of electron transfer, the electrons lose potential energy. Their trip downhill is used by the transport chain to pump H⁺ across the thylakoid membrane. The proton gradient triggers ATP synthesis.
• Non-cyclic photophosphorylation. When both photosystems are illuminated, there is a continuous current of electrons flowing from water to NADP⁺. Electrons from P6g0 are replaced by electrons removed from water by splitting of water that evolves oxygen.

The excited electron from P680 flows down an electron transport chain to P700 (Pc- plastoquinone, cytochrome complex, PC-plastocyanin) generating ATP. Illumination of PSI boosts electrons to a high energy state which are passed to NADP reducing it to NADPH (protons from H₂O. The net products of non-cyclic electron flow are ATP and NADPH.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Calvin Cycle

Melvin Calvin (1954), an American scientist, worked out the path of carbon by using the paper chromatography technique. In recognition of his work, Calvin was awarded with Nobel Prize in 1961. Analysis of plant extracts was made within seconds after the beginning of photosynthesis with the injection of 14CO₂.

Photosynthesis And Translocation Of Organic Solutes NEET Notes

Various steps of the dark phase can be studied as under:

• Carboxylation. The first step is the carboxylation of Ribulose, 1,5 biphosphate (RuBP) by atmospheric CO₂ in the presence of the enzyme RuBP carboxylase or rubisco.
• Six molecules of RuBP (5-carbon compound) come in contact with six molecules of CO₂ to form six molecules of six carbon unstable compounds which are converted into 12 molecules of PGA (3-carbon compound) with the help of an enzyme called carboxydisniutase.
• Rubisco is a large protein molecule and constitutes 16 per cent of chloroplast protein and is one of the most abundant proteins on the earth.
• Glycolytic reversal. The 6 molecules of PGA utilise 6 ATP molecules to form 6 molecules of 1,3- diphosphoglyceric acid. These, in turn, utilize 6 NADPH supplied by the light reactions and get converted to a 3-C glyceraldehyde phosphate- a triose phosphate (TP).
• It seems to be a reversal of glycolysis, the only difference being that the reducing power is obtained from NADPH, and not NADP.
• PGA + ATP + NADPH -» Glyceraldehyde.
  phosphate + NADP+ + ADP + IP
• Regeneration of RuBP- F-6-P next undergoes a transketola.se relation that removes, the two top carbons as the thiamine pyrophosphate (TPP) derivative,, of glycoaldehyde, leaving the tetrose erythrose 4-phosphate (E-4-P).
• The (E-4-P) condenses,s by aldolase reaction, with DHAP to form sedoheptulose diphosphate (SDP), and this is converted by a second^ energy-liberating step to sedoheptulose-7-phosphate (S-7-P) and Pi by a phosphatase reaction.
• As far as can be determined, the same phosphatase works on FDP and SDP. The S-7-P undergoes a transketolase reaction in which. the two top carbons are removed as TPP- glycolaldehyde leaving the pentose ribose-5 phosphate (Ru-5-P).
• This is converted to ribulose-5-phosphate (Ru-5-P) by phosphopento.se isomerase. The TPP-glycoaldehyde derived from F-6-P and F-7-P in the transketolase reaction is transferred to PGA forming xylulose-5-phosphate (Xu-5-P) which is converted to Ru-5-R hy n phosphopentose epimerase. The R-5-P is converted to Ru-5-P by an isomer.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Factors Affecting Photosynthesis

se and is phosphorylated by phosphoribulokinase. ATP being the donor produces ribulose biphosphate (RuDP) and ADP ( a second “priming” reaction that prepares the pentose for carboxylation).

1. Light Intensity. The compensation point is 25-100 ft candles in shade plants and 100- 400 ft candles in sun plants. The optimum light intensity is 10% of full sunlight for shade plants and 50-70% of full summer sunlight for C₃ sun plants.
2. In C4 plants saturation point is not reached even in full sunlight. At higher light intensity, there is a decrease in photosynthesis called solarisation. It can be due to photoinhibition (reduction in hydration)and photoxidation.
3. Light Quality. Red light favours carbohydrate synthesis while blue light stimulates protein synthesis. Maximum photosynthesis occurs in the blue and red parts while minimum photosynthesis takes place in the green part of the spectrum.
4. Red light is more efficient in photosynthesis as compared to blue light. However, maximum photosynthesis occurs in full sunlight.
5. Oxygen. In C₃ plants, the optimum oxygen for photosynthesis is 2-5%. It is reduced at normal atmospheric concentration of oxygen. No such effect is found in C₄ plants. Above 21% there is a reduction in photosynthesis (Warburg Effect).
6. Chlorophyll. It is essential for photosynthesis. Photosynthesis does not occur in chlorotic regions. Willstatter and Stoll coined the term assimilation number or photosynthetic number as the number of CO₂ molecules reduced per unit of chlorophyll. However, chlorophyll is always supra-optimal.
7. Age. The rate of photosynthesis is maximum in just matured leaves but declines with age.
8. If the rate of translocation becomes slower than the rate of synthesis, the latter also declines due to the accumulation of end products. Chemicals like cyanides, NH^–, OH, CO, H₂S, iodoacetates, chloroform, ethers, DCMU, CMU etc. inhibit photosynthesis.
9. Accumulation of End Products. Accumulation of food in the chloroplasts reduces the rate of photosynthesis.
10. Duration. Photosynthesis can continue indefinitely in the presence of light though the rate begins to fall slightly after 3-4 days of continuous exposure.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Photorespiration

Respiration that is initiated in chloroplast and occurs in light is called photorespiration.
With an increase in temperature as on a hot summer day the affinity of RuBP carboxylase for CO₂ decreases and O₂ increases.

• As a result, RuBP is changed to 2 Phosphoglycolate and PGA. Thus photosynthetically fixed carbon is lost by photorespiration.
• Photorespiration takes place through the Involvement of three cell organelles, the chloroplast, peroxisomes and mitochondria.
• Photorespiration is the process of the uptake of O₂ and the production of CO₂ in light by photosynthesising tissues. It is quite common in C₃ plants.
• Photorespiration causes a high loss of fixed carbon without producing energy-rich compounds is produced during this process.
• Photorespiration is also called a cycle because of 2-carbon intermediates.
• Linking Of Photorespiration To Calvin Cycle

1. The first oxidative slop is the conversion of Rnl)P into 3-carbo PGA and 2-Carlion phosphor glycolic acid which moves lo peroxisomes to form glyoxylic acid, and the glyoxylic acid is converted to serine. Serine passes out to the mitochondria is converted into IHIA and finally enters the Calvin cycle.

NEET Biology Photosynthesis And Translocation Of Organic Solutes C4 Pathway

In plants like maize, sorghum, sugarcane etc. the CO₂ molecule combines with IMiP to form a four-carbon compound, oxaloacetic acid (OAA). It is known as the C₂ cycle because the initial product of CO₂ fixation is a 4-carbon compound.

Overall C4 equation is
6PEP+ 6RuBP + 6CO₂  + 30ATP + 12NAPH-> 6PEP + 6RuBP + C₆ H₂ O6 + 30ADP +30 H₃ PQ₄  + 12NADP

Difference Between C3 And C4 Plants

NEET Biology Photosynthesis And Translocation Of Organic Solutes Important Terms

• Calvin Cycle. The reductive pentose pathway of photosynthesis is named after its discoverer. It is also called a pathway”.
• Hill Reaction. It is the name of a part of the light reaction of photosynthesis, after R. Hill, who first observed it in 1937, Under Hill’s reaction, NADP is reduced to NADPH₂
• Blackman’s law of limiting factors. It suggested that when a process is conditioned to its rapidity by it number of factors, keeping other factors constant, the rate of process is determined by the slowest or limiting factor.
• Reductive I’cntose Pathway. It is a set of reactions in the process of photosynthesis in which CO₂ is fixed by ribulose-diphosphate ( a pentose sugar) to give PGA, which is used to produce a hexose sugar and more ribulose-diphosphate, which is used for further CO₂ fixation.
• Sedohcpliilo.se. A seven-carbon compound formed in the Calvin cycle.
• C3 Pathway. It is another name for the Colvin cycle which is also called the reductive pentose pathway.
• C4 Pathway. It is a kind of CO₂ fixation, found in some tropical plants-both monocotyledons and dicotyledons. It is also called the Hatch and Slack cycle.
• In this pathway, CO₂ is fixed by a three-carbon compound (phosphoenol pyruvate) and ultimately a molecule with 4 carbon atoms (male) is produced.
• Plants, in which the C₄ pathway is found, are called C₄ plants, For Example. Saccharum, Sorghum, Maize, Cyperus etc.
• Photorespiration is absent in C4 plants. These plants use CO₂ more efficiently than C₃ plants.
• Crassulacean Acid Metabolism (CAM). It is a kind of CO₂ fixation found in many succulent plants, For Example. Crassulaceae.
• Phosphoglyceric Acid (PGA). It is a compound with three atoms of carbon. It is the first product of the reaction between CO₂ and ribulose diphosphate in the reductive pentose pathway of the process of photosynthesis.
• Ribulose diphosphate. A compound made up of a molecule of the pentose sugar ribulose and two phosphate groups. It is also called ribulose 1,5-diphosphate or RuDP. It is the main compound involved in CO₂ fixation.
• Red drop. Sharp fall in the rate of photosynthesis as found by Emerson near the far end of the spectrum, This decline in photosynthesis is called the red drop.
• Spectrophotometer. An instrument used to measure the rate of absorption of different wavelengths of light by different pigments. The absorption of different wavelengths of light by a particular pigment is plotted and called the absorption spectrum.

NEET Biology Photosynthesis And Translocation Of Organic Solutes

1. The food is translocated from the supply end or source (leaves) to the consumption end or sink (storage regions).
2. The translocation of organic solutes takes place in plants in all directions.

• • Downward translocation (from leaf to stem and roots)
  • Upward translocation (from leaves to developing buds)
  • Radial translocation (from the pith to the cortex).

1. There is ample evidence to believe that food is translocated through phloem such as
   its component structure, the effect of blocking phloem and ringing experiments conducted by Malpighin Stephan Hales and Curtis.
2. The experimental evidence collected by Rabadieu and Burr by using C₁₄ and experiments-with aphids performed by Kennedy and Mittler also confirms phloem translocation of food. Some days may be translocated in an upward direction through the xylem.
3. Radioactive isotopes such as P₃₂, S₃₅, Sr₉₀, N₁₅, C₁₄, C₁₁ and H₃ have been used in recent years along with techniques like a reverse flap, autoradiography and freeze-drying.
4. Food is translocated mainly as sucrose but also in the form of raffinose, stachyose, verbascose, mannitol, myoinositol and sorbitol.
5. The rate of metabolite movement is calculated in terms of mass transfer rate. The translocation velocity may be 55 cm/hr (sucrose). It is 270 cm/hr in sugarcane and 290 cm/ hr in squash.
6. Mechanism of Translocation. Several hypotheses have been proposed to explain the mechanism of translocation.

• It was earlier believed that good is translocated from source to sink by simple diffusion. Since the rate of diffusion is extremely slow hence Mason and Phillips proposed an activated diflusion hypothesis which lacked experimental evidence.
• De Vries proposed that food is translocated by streaming currents of protoplasm.
• It explains the bidirectional movement of metabolites and the faster rate of translocation. observe the streaming of protoplasm in mature sieve elements.
• Thaine and Canny observed streaming in vertically running transcellular strands in sieve elements. The presence of these strands has been confirmed by the use of C₂ But the die rate of translocation as last as 290 cm/hr cannot be achieved by protoplasmic streaming.
• The activated diffusion theory of Mason and Maskell (1936) takes into account the utilization of ATP.

1. Electro-osmotic theory was proposed by Fensom (1957) and Spanner (1958). According to this, an electropotential across the sieve plate is responsible for a faster rate of liquid flow.
2. Munch’s Mass Flow or Pressure Flow Hypothesis (1930) Munch’s hypothesis postulated the movement of protoplasm mass along a turgor pressure gradient induced by the maintained gradient of water potential.
3. This is based on the principle that an increase in turgor pressure causes mass flow’ of solution from production chamber A (comparable to leaf) to consumption chamber (comparable to root).
4. The movement of solute will continue till the solutions in both chambers attain the same concentration.
5. In living plants, the carbohydrates are continuously synthesized in mesophyll cells and are translocated to roots or storage organs through phloem.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Factors Affecting Translocation

The process of food translocation is influenced by several factors as follows :

• Temperature: The effect of temperature may be direct or indirect. It has been experimentally confirmed that the optimum temperature for translocation ranges between 20 -30 C. It increases with the increase of temperature up to a maximum limit and then decreases.
• By using C14 it has been observed that the translocation rate increases in sugarcane when temperature is raised from 20 to 33 C. It has been also observed that when the root temperature is higher than the shoot, translocation to the root increases but to the shoot tip, decreases.
• If the condition is reversed i.e. when the shoot temperature is higher than the roots, translocation to the shoot tip increases and to the roots decreases.
• Light: The rate of translocation is influenced by light intensity. With the increase in light intensity the translocation to root as compared to shoot increases. However, by using C*  it has been observed that in the dark, more food is translocated in the root of Glycine than in light.
• Minerals: It has been demonstrated that boron enhances the translocation of labelled sucrose in tomatoes. It is thought that boron makes a complex with sucrose. This borate sugar moves more rapidly than non-borate sugar. Phosphorus deficiency also reduces the translocation rate.
• Hormones: It is well known that cytokinins influence the translocation of soluble nitrogen
• compounds. When they have sprayed the leaves externally, translocation of N^–, t compounds from lamina to petiole is retarded,’ hence it remains green for a longer period.
• Inhibitors: The metabolic inhibitors like azides, CP, 2-4 dinitrophenol (DNP), fluorides, HCN, iodoacetates etc. retard metabolism and thus indirectly influence the translocation process.

Photosynthesis is the single most important biological process required for human existence.

• Jan Baptism Van Uelmont (Belgian physician) with his simple experiments concluded that all the substance of plant was produced from water and none from soil Contribution of Jan Ingcnhonsz. He confirmed Priestley’s work and also discovered that the release of O, by plants was possible only in sunlight by green plants.
• Contribution of C.B. Van Nicl. He gave a simplified equation of photosynthesis.
• Contribution of Joseph Priestley (1703-1804). He showed that plants can take up CO₂ from the atmosphere and release O₂
• Within the leaf, photosynthesis occurs in specialised cells called mesophyll cells.
• PAR is photosynthetically active radiation of visible speed
• ATP, NADPH + H⁺ are produced in light reaction and are used for the reduction of CO₂ Isolated chloroplast cannot carry out CO₂ reduction because enzymes necessary for CO₂ reduction are leached out during the isolation of chloroplasts.
• Chlorophyll acts as a reaction centre and accessory pigments called carotenoids act as antenna complexes and harvest light from different regions of the spectrum.

Photosynthesis And Translocation Of Organic Solutes NEET Notes

Crassulaccan Acid Metabolism (Cam Plants)

CAM plants fix CO₂ at night, from malice which is stored in large vacuoles in mesophyll cells until the next day. CAM plants use the enzyme Pepco (PEP carboxylase). The malate formed at night releases CO₂ during the day to the Calvin cycle within the same cell, which now has NADPH and ATP available from light-dependent reactions.

• CAM represents Crassulacean acid metabolism. The Crassulaceae is a family of flowering succulents. In CAM plants stomata open during night only and is an adaptation of xerophytic succulents. Photosynthesis in such cases is usually not as efficient as in C₃ or C₄ plants, but it allows the CAM plants to live under stress-
• Isolated chloroplasts can carry out CO₂ reduction provided the leached substances are externally supplied to them.
• This was proved by D.I. Arnon and his associates.
• Dark reactions can occur in light as well as in the dark.
• The temperature coefficient (Q₁₀) is defined as the ratio of the velocity of a reaction, at a particular temperature to that at a temperature 10°C lower.
• For a physical process, the value of Q₁₀ is slightly greater than one.
• For photochemical reactions, the value of Q10 is one.
• For a chemical reaction, the value of Q₁₀ is two or more i.e., with the rise of 10°C temperature, the rate of chemical reaction is doubled.
• The difference between C₄ plants and CAM plants is that in C₄ plants two cycles are separated by different leaf cells (i.e. in mesophyll cells and bundle sheath cells) whereas in CAM plants both pathways are found in mesophyll cells both being separated by time.

NEET Biology Photosynthesis And Translocation Of Organic Solutes Quanta to Memory

Chi C—C₃₅ H₃₂ O₅ N₄ Mg (Mol. wt.) = 712. Phytol absent it is present in brown algae + diatoms.

Chl d—C₅₄ H₇₀ O₆_ N₄ Mg (Mol. wt. 895) red algae

Bacteriochlorophyll a—C₅₅ H74 O₆ N₄ Mg (Mol. wt. 911)

• Chi a : Chi b = 2.5-3.5 : 1
  For sun plant 5.5: 1 [For heliophyte)
  For shade plant 1:4:1 [For sciophyte]
• Chlorophyll absorbs more of blue light than red light. 40% (Blue) 30% (Red) For Chi a 48% (Blue) 20% (Red) —For Chi b
• Bacteriochlorophyll-b found in Rhodopseudomonas is not yet known.
• Chlorobium Chlorophyll-old name of bacterioviridin
• Carotenoid-lipochrome. Fat-soluble, light not necessary.
• Calvin gave a molecular model of the chloroplast.
• Discovered by Wakineroder as a provitamin of carrot types – a, b, g and carotene, phytotene, neurosphere.