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NEET Biology Organisms And Population Ageing And Death

NEET Biology Organisms And Population Ageing And Death Growth

• Growth: It refers to the augmentation in size and mass of an organism resulting from the synthesis of protoplasmic and apoplastic components. The event occurs when anabolism predominates in the overall metabolic process. There are three types of growth.
• Auxetic growth: In this instance, the volume of the organism expands due to the proliferation of body cells without an increase in the number of cells. The quantity of cells is predetermined in the majority of bodily regions. This sort of growth occurs in worms, rotifers, and a category of early chordates known as tunicates.
• Multiplicative growth :In this scenario, the cell count grows while the average cell size remains constant. All occurring decisions are mitotic. It frequently manifests in embryos and is a defining feature of the prenatal development of higher vertebrates.
• Accretionary growth refers to the mitotic division of reserve cells to augment and substitute the depleted differentiated cells.
• The various cells in the post-embryonic phase lose their ability to divide, resulting in this form of growth, for example. Development of epidermal cells from the Malpighian layer.
• Appositional growth: it entails the accumulation of new layers onto already established layers. It is a distinctive way of growth for stiff materials.

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NEET Biology Organisms And Population Ageing And Death Growth Rate

All creatures develop at a certain rate and cadence. The growth is a noticeable and quantifiable increase in the bulk of living material, which can be assessed by weighing at intervals.

Furthermore, the growth rate is variable, as organisms develop at distinct rates throughout different intervals. Rapid growth occurs throughout prenatal and teenage stages, which then decelerates during juvenile and post-adolescent phases, ultimately ceasing thereafter.

Organisms And Population Ageing And Death NEET Notes

NEET Biology Organisms And Population Ageing And Death Growth Curve

The growth of an animal organ for a definite period when plotted against time forms a S-shaped Sigmoid curve. it is called a growth curve.

• An analysis of the Sigmoul curve shows ills’ glow it is slow in llu[•Birds and mammals stop growing when they have attained a certain characteristic age and size.
• it has been found that the factors that check the unlimited growth of animal tissues are many and varied. One such mechanism is the intrinsic antagonism between the factors that regulate the process of proliferation.
• The initial and final weight of an individual for any period of tune is lowed absolute prow lit. l.i Cell uniw3 Grow the old cells’ events during the inter of the cell cycle.
• During this phase, new materials such as nucleic acids, proteins, and protoplasmic bodies were formed. interphase is completed in three phases G, S and G, phases. Cell growth is an utmost important factor in the growth of multicellular animals. Cell growth leads to the division of cells also. Cell growth cannot be measured because of the small size and location of the cell.

1. Pattern Of Growth:

• Isometric growth: in this pattern of growth, an organ grows at the same mean rate as the rest of the body c.y. fishes and certain insects like locusts.
• Allnnictric growth: in this pattern of growth, an organ grows at a rate different from that at which the body grows mammals.

2. Methods Of Growth: Growth in animals is accomplished by several methods.

The most important of these are:

• Protoplasmic synthesis: Through this process, the growing animal synthesizes new l4ing matter from available food materials. The new raw materials are obtained from the digestion and absorption of complex food materials such as proteins, carbohydrates and lipids.
• Uptake of water: The amount of water that accumulates in the animal body during growth and development is enormous.
• intercellular deposition; Large-scale intercellular deposition of non-living matter occurs during growth. These substances consist mostly of jelly, fibres or the ground substances of cartilage and bone.

Organisms And Population Ageing And Death NEET Notes

NEET Biology Organisms And Population Ageing And Death Hormonal Control Of Growth Rate in Man

• Thymosin hormone, released by the thymus gland, affects growth during the ages of 10 to 13 years (childhood).
• This era is characterized by sluggishness. Thyroxine and somatotropic hormone (STH) enhance development rate throughout late childhood.
• Growth accelerates throughout puberty (ages 14 to 18 years) due to heightened secretory activity of the pituitary and other endocrine glands.
• In males, testosterone regulates the development of secondary sexual organs and accessory sex traits, whereas in females, progesterone and estrogen perform similar functions.

NEET Biology Organisms And Population Ageing And Death Growth Factors

1. Epidermal Growth Factor (EGF): it stimulates epithelium to undergo mitosis – EGF is produced under the scab and is also produced in the sal4ary glands.
2. Fibroblast growth Factor (FGF): it stimulates the division of endothelial cells to heal the injured blood vessels.
3. Platelet-der4ed Growth Factor (PGF): it stimulates the mitosis of fibroblasts at the injured site to fill in the damaged area under the blood clot.

Measurement of Growth

• The amount of growth, an animal undergoes is expressed in terms of absolute growth or relative growth.
• The absolute growth rate is the increase in growth per unit of time.
• The relative growth rate is a relative increase in growth per unit of time. Comparisons of relative growth rates show many interesting patterns in animal growth.

Grow th Arresting Factors

• Birds and mammals stop growing when they have attained a certain characteristic age and size.
• it has been found that the factors that check the unlimited growth of animal tissues are many and varied. One such mechanism is the intrinsic antagonism between the factors that regulate the proliferation process.
• Another check on growth is cell destruction. Another mechanism is the hormonal cessation of growth in the long hones.

NEET Biology Organisms And Population Ageing And Death Regeneration

Regeneration, The ability of a living organism to replace out parts, regrow cast tY organs and transform the entire body from small fragments of it is called regeneration.

Categories of animal regeneration :

1. Restorative regeneration.
2. Restorative regeneration.

1. Restorative regeneration:  It is a common phenomenon amongst invertebrates and vertebrates. in sponges, an entire sponge may regenerate and form a group of a few cells. Similarly in Hydra, small pieces containing both germ layers may regenerate into new organisms.

Different Animal groups and their Regenerative body parts

Ageing And Death In Organisms NEET Study Material

2. Reparative regeneration: It is quite common in the case of invertebrates and vertebrates. Amongst vertebrates, it is best observed in the Axolotl larva which can replace its tail, limbs and eyes. Tadpole the frog also shows a similar type of regeneration. Lizards can regenerate their tails but they are without bones. L4er in man has great power of reparative regeneration.

• Physiological regeneration: Replacement of cells of the body which are worn out due to constant activities.
• Compensatory hypertrophy: The regeneration of internal organs by enlarging one of the paired organs in case one is lost accidentally e.g. kidney
• Heleromorphosis: Regeneration that produces a part different from a lost part, e.g. crayfish.
• Mechanism of regeneration: given by T.H. Morgan

1. Morphallaxis: It is the reconstruction of an entire animal from a small fragment by reorganization of the existing cells.
2. Epimorphosis: It replaces a lost organ of the body by the proliferation of new cells from the surface of the injured part.

NEET Biology Organisms And Population Ageing And Death Ageing

• Gerontology: The field of developmental biology which deals with the study of the process of ageing is known as gerontology. it is the progress or deterioration in the structure and functions of cells, tissues and organs of the organism with time. it leads to death.
• Ageing: it is progress4e deterioration in this structure ami functions of cells, tissues, of pans ami organ systems. There is a progress decline in metabolism’s ability to replace worn-out cells, repair damaged tissues and resistance to diseases.

As old age progresses, skin becomes dry, and wrinkled, hair falls off, the body assumes a stooping posture, bones become brittle, and muscles, skin and cartilage become less elastic. Ageing affects the blood-vascular system. Sense organs like an ear. eyes etc. lose their intensities and kidney tubules are no more efficient
in the production of normal urine.

1. The heart pumps 35% less blood and sends 20% and 58% less blood to the brain and kidneys.
2. Oxygen carrying capacity of blood reduces.
3. The formation of new RBCs from the bone marrow slows down.
4. Calcium accumulates in the blood.

Cellular changes during ageing

1. There occurs reduction in tbe granular endoplasmic reticulum, partial degeneration of mitochondria (According to Rafsksy and Brarrows i958) and accumulation of lipofuscin granules.

1. Somatic mutations occur in, tbe cells of l4er, brain, heart and stomach.
2. Certain enzymes like aldolase, acctyl-cholincstrase, lactase dehydrogenase, glucose 6- phosphate dehydrogenase show reduced act4ities.
3. The number of chromosomes changes from the normal. Thus there are changes in DNA structure. in mice, dog and man, with increase in age, the l4er cells exhibit increased number of chromosomal aberrations,
4. Cellular membranes come to have calcium deposition, (According to Shock and Strehler i962) thus do not show select4e permeability.
5. Due to storage of certain pigments, the rate of cell d4ision decreases.

Extracellular changes: Extracellular changes include structural and functional changes in collagen.Collagen is most abundant extracellular protein which with ageing becomes less permeable, less flexible and insoluble. These changes interfere the normal functioning of the cells and induce the ageing.

Changes at the organ level include structural changes in the skin, muscles, bones etc. and also physiological changes in the vital organs like the heart, brain, kidney etc

NEET Biology Organisms And Population Ageing And Death Theories Of Ageing

1. The exact reason behind ageing is not clearly understood, and it is considered a cyclic phenomenon in one’s life. Several hypotheses have been proposed to explain the reason for ageing. They are as follows :
2. According to one view, free radicals accumulate with age which brings about oxidant reactions resulting in the deterioration of collagen and elastin etc. The oxidation of unsaturated fats results in the impairment of cell membranes in their select4e permeability.
3. The immunity system breaks down since the capacity of the formation of lymphocytes by bone marrow is lessened.
4. Ageing reduces the sensibility and effectiveness of the nervous control over the endocrine glands.
5. The high rate of metabolism results quickening of old age. probably CrT in,hc coded message of DNA increases due to old age which affects proper protein synthesis.
6. The tendency of ageing is intrinsic i.c. an organism will undergo ageing at a rat determined by the nature of genes.

Whatever views have been proposed, even today the understanding of the reasons for old age remains vague.

Ageing And Death In Organisms NEET Study Material

Degrowth and death factors which result in degrowth

• The rate of breakdown surpasses that of synthesis reactions within the body.
• Internal reserves, shown as fat in adipose tissue, are metabolized to supply energy for essential living functions.
• Proteins from the living materials are also utilized for energy production.
• All these variables contribute to the depletion of living matter and lead to degrowth.
• Lipofuscin is the pigment associated with aging.
• With aging, there is a decrease in body weight by 12%, brain weight by 15%, and liver weight by 37%.
• The basal metabolic rate is 20%, the speed of nerve impulses is 5%, and the renal blood flow is 40%. to the brain is 80%. Consequently, there are few lymphocytes.

NEET Biology Organisms And Population Ageing And Death Death

it is a biological event which is due to a permanent breakdown in body functioning usually occurring due to a lack of oxygen supply to tissues. The cells stop normal functioning. it is an inescapable event of life.

Symptoms of clinical death: Symptoms of clinical death are Heartbeat, pulse and respiration stop 2 Pupils become fixed, remain dilated and do not respond to light.

Two main categories of causes of death

1. Weakening of tissues and vital organs: Weakening of tissues and vital organs, such as the heart, liver, kidney etc. result in physiological and metabolic disorders of irreversible nature. Sudden blockage of blood supply to the heart, and brain causes instantaneous death.
2. Due to ageing, there is a gradual breakdown in the immune system. Thus due to loss of body resistance, in old age man becomes susceptible to infectious diseases.

• Considerable growth occurs during the late embryonic or foetal period in the case of mammals.
• Replacement of old worn-out cells, metamorphosis and regeneration are the three main categories of post-embryonic development.
• Post-embryonic developments are characterised by growth, morphogenesis and differentiation finally. Ageing is also a post-embryonic stage.
• Animals grow at different rates at different periods of life.
• The human embryo is i50 /rm at the time of implantation and grows to about 50 cm during the gestation period.
• Growth may be auxetic or multiplicat4e accretionary. Fibroblast growth factors (FGFs) control cell proliferation in the development of limbs in chick, and insulin-like growth factors (iGFs) have a role in prenatal and postnatal growth of mammals. Growth hormone (Gil) secreted in the anterior lobe of the pituitary plays an important role in growth during childhood.
• Hydra and planaria have a capacity for regeneration. Nematodes show very low regenerat4e ability.
• Glial growth factors (GGFs) and other factors such as (FGFs iGFs) control amphibian limb regeneration.
• Compensatory regeneration: In the case of compensatory regeneration, the cells of l4er or kidney d4ide do not form an undifferentiated mass of cells or tissues, rather produce cells similar to themselves and maintain their function.
• Epimorphic regeneration: In the case of epimorphic regeneration as in Salamander, dedifferentiation occurs, and then these cells divide to form blastema which later on transforms into a correctly patterned limb structure.
• Reparative regeneration: The power of repairing only some body cells e.g. skin layer: gut lining: RBCs of blood etc.
• Morphallactic regeneration: The formation of the whole body from a body fragment by reorganizing the existing cells, e.g. Formation of components body of Hydra from a fragment.

Population Ageing And Death NEET Biology Notes

Changes in the weights of human body parts from birth to adulthood:

Life Span Of Selected Animals:

NEET Biology Organisms And Population Ageing And Death Quanta To Memory

• Vladimir Korenchevsky-Father of gerontology
• Werner Syndrome is a syndrome with signs of advanced ageing in the 20s.
• Eutyly: When the number of cells is constant both for the entire life and specific organs e.g. Ascaris.
• Nucleopycnosis: It is the shrinkage and condensation of chromatin leading to the death of the nucleus.
• Heteromorpliosis: it is a case when the regenerated part is different from the lost part.
• There are 60 quadrillion cells in an average adult human body weighing 60 kg but only 2 quadrillion in an infant.
  From the age of about 30 years, the human body becomes functionally less efficient by about 0.8% every year.
• The nucleus shrinks and stains deeply with advancing age. This is due to condensation of chromatin and leads to cellular death. Such a degenerat4e process is called nuclear pyknosis
• By the age of 75 years, the number of uriniferous tubules is reduced to half in men.
  Japanese have the highest life expectancy limit. The average life of a Japanese woman is 8i.5 years while that of a man is 76.2 years Regeneration was discovered by Trembley in Hydra.
• When reserve food material is utilised in the body, the process is called degrowth.
• in ascidian tadpole Example larva of Herdmcmia) there occurs retrogress4e metamorphosis.
• Maximum power of autotomy (self-mutilation) is found in holothurians (echinoderms). These organisms can throw off their internal visceral organs whenever threatened by a predator. in mammals, external body parts are not regenerated.
• But mammals have a great capacity to regenerate some of the internal organs. L4er has the maximum capacity of regeneration. Similarly, if one kidney is removed, the other enlarges and takes over the function of the lost kidney. Such a reparat4e regeneration is known as compensatory hypertrophy.

NEET Biology Organisms And Population Ageing And Death Questions

Question 1. Which one of the following is (rue during ageing?

1. Decrease in blood urea and GFR
2. increase in calcium content of arteries and cartilage
3. Decrease in cholesterol content of cornea and lens
4. Decrease in calcium content of arteries and cartilage.

Answer: 2. increase in calcium content of arteries and cartilage

Population Ageing And Death NEET Biology Notes

Question 2. in human beings the growth in height becomes nearly constant after the age of:

1. 15 years
2. 20 years
3. 30 years
4. 40 years.

Answer: 2. 20 years

Question 3. Which one of the following statements is correct concerning a test tube baby?

1. Fertilization of the egg is affected outside the body; the fertilized egg is then placed in the womb of the mother where the gestation is completed
2. Fertilization of the egg and growth of the embryo arc affected in a large test tube
3. A prematurely born baby reared in an incubator
4. Fertilization of the egg is affected in the female
5. Genital tract; the fertilized egg is then taken out and grown in a large test tube.

Answer: 1. Fertilization of the egg is affected outside the body; the fertilized egg is then placed in the womb of the mother where the gestation is completed

Question 4. The science of ageing is called :

1. Chronology
2. Odontology
3. Gynaecology
4. Gerontology.

Answer: 4. Gerontology.

Question 5. Ageing in many mammals including man may be due to:

1. Adverse changes in the environment
2. interaction between hereditary factors
3. Malnutrition and stress
4. All of the above.

Answer: 4. All of the above.

Question 6.Degenerat4e changes occur during :

1. Metamorphosis only
2. Parthenogenesis
3. Ageing only
4. Both in metamorphosis and ageing.

Answer: 4. Both in metamorphosis and ageing.

Question 7. As a person becomes old, a degenerat4e process sets in the body which causes:

1. A gradual alteration in the connect4e tissue components only
2. Increases the collagen content of the connect4e tissues
3. And increases the mucopolysaccharides content of most of the connective tissue.
4. Both in metamorphosis and ageing.

Answer: 4. Both in metamorphosis and ageing.

Organisms And Population Ageing And Death NEET Question Bank

Question 8. The growth in an animal includes:

1. increase in size
2. increase in weight
3. Synthesis of new proteins
4. All.

Answer: 4. All.

Question 9. The growth rate in most of the animals is:

1. Sigmoid for all organs
2. Linear for all organs
3. Uniform for all organs
4. Different for different organs.

Answer: 4. Different for different organs.

Question 10. The pigment of ageing is:

1. Haemoglobin
2. Hacmocyanin
3. Melanin
4. Lipofuscin.

Answer: 4. Lipofuscin.

Question 11. With the advancement of age, the hair of males starts thinning due to :

1. Falling of hair
2. Low ATP formation
3. Reduced rate of protein synthesis
4. None of the above.

Answer: 3. Reduced rate of protein synthesis

Question 12. The most accepted theory of ageing is :

1. Death of brain cells
2. Non-functioning of a – cells in the pancreas
3. Less RBC in blood
4. Non-functioning of thymus gland.

Answer: 4. Non-functioning of thymus gland.

Question 13. The growth rate in childhood is controlled by :

1. Thymosine
2. Thyroxine
3. Oestrogen
4. Progesterone
5. Testosterone.

Answer: 1. Thymosine

Question 14. Which is not connected with the theory of ageing?

1. Wear and tear
2. Neurohormonal changes
3. Epimorphosis
4. Metabolic rate
5. Somatic mutation.

Answer: 3. Epimorphosis

Question 15. Growth is an irreversible process found at :

1. Subcellular growth
2. Cellular growth
3. Organ growth
4. All of the above.

Answer: 4. All of the above.

Organisms And Population Ageing And Death NEET Question Bank

Question 16. In animals, chalones are substances responsible for:

1. Regeneration
2. Ageing
3. Development
4. Parthenogenesis.

Answer: 2. Ageing

Question 17. Growth in l4ing being is called :

1. Accretion
2. intussusception
3. Aggregation
4. interaction.
5. Accumulation.

Answer: 1. Accretion

Question 18. if Hydra is broken into pieces:

1. Hydra will die
2. Hydra will undergo sexual reproduction
3. Some fragments will form a complete Hydra
4. Every fragment will grow into a complete Hydra

Answer: 4. Every fragment will grow into a complete Hydra

Question 19. Formation of the whole body from a fragment is:

1. Cpimorphosis
2. Morphallaxis
3. Epigenesis
4. Auxetic growth.

Answer: 2. Morphallaxis

Question 20. The correct sequence of growth curve for bacteria is:

1. Lag. log, stationary’ and decline
2. Lag. log, decline and stationery
3. Stationary, lag. log, decline
4. Decline, lag and log phase.

Answer: 2. Lag. log, decline and stationery

Question 21. Semilog of per minute growing bacteria is plotted against time. What will be the shape of the graph?

1. Ascending straight line
2. Sigmoid
3. Hyperbolic
4. Descending straight line.

Answer: 1. Ascending straight line

Question 22. Senescence is inhibited by :

1. Ethylene
2. Gibberellic acid
3. Cytokinin
4. Abscisic acid.

Answer: 3. Cytokinin

Question 23. In which phase proteins for spindle Fibre formation are synthesized?

1. G-phase
2. G-phase
3. S-phase
4. Anaphase.

Answer: 3. G-phase

Question 24. The maximum life span of a dog in years is :

1. 5
2. 10
3. 15
4. 20.

Answer: 4. 20

Ageing And Death In Organisms NEET Mcqs

Question 25. In the somatic cell cycle :

1. In Gjphase DNA content is double the amount of DNA present in the original cell
2. DNA replication takes place in S-phase
3. A short interphase is followed by a long mitotic
4. Phase.

Answer: 2. DNA replication takes place in S-phase

Question 26. The maximum growth rate occurs in :

1. Senescent phase
2. Stationary phase
3. Lag phase
4. Exponential phase.

Answer: 4. Exponential phase.

Question 27. Four healthy people in their twenties got involved in injuries resulting in damage and death of a few cells of the following. Which of the cells are least likely to be replaced by l4ing cells?

1. Osteocytes
2. Malpighian layer of skin
3. Liver cells
4. Neurons.

Answer: 4. Neurons.

Question 28. Based on cellular mechanisms there are two major types of regeneration found in the animals. Which of the following is the correct example of the type mentioned?

1. Morphallaxis- Regeneration of two transversely cut equal pieces of a Hydra into two small Hy draws.
2. Epimoiphosis – Replacement of old and dead erythrocytes with new ones.
3. Morphallaxis – Healing up of a wound in the skin.
4. Epimorphosis – Regeneration of crushed and filtered out pieces of a Planaria into as many new Planar- cans.

Answer: 1. Morphallaxis- Regeneration of two transversely cut equal pieces of a Hydra into two small Hy dras.

Question 29. Ageing of an animal’s body is associated with deterioration in its :

1. Connect4e tissue
2. Glandular tissue
3. Epithelial tissue
4. Both 1 and 2.

Answer: 2. Glandular tissue

Question 30. The modern idea about ageing is that our body slowly loses the power of defence against the invasion of germs and pathogens, this process starts with the
the disappearance of which organ?

1. Spleen
2. Thymus gland
3. Pituitary gland
4. Parathyroid gland.

Answer: 2. Thymus gland

Question 31. Match the items in Column I with Column II and choose the correct alternatives :

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

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

Question 32. Which endocrine gland becomes inactive in old age?

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

Answer: 3. Thymus

Ageing And Death In Organisms NEET Mcqs

NEET Biology Organisms And Population Ageing And Death Self Assessment Test Unit Reproduction

Question 1. A low statements describing certain features of reproduction are given below :

1. Gametic fusion takes place

2. Transfer of genetic material takes place

3. Reduction division takes place

4. Progeny has some resemblance with parents Select the options that are true for both asexual and sexual reproduction from the options given blow:

1. 1 and 3
2. 2 and 3
3. 2 and 4
4. 1 and 3

Answer: 3. 2 and 4

Question 2. The term ‘clone cannot be applied to offspring formed by sexual reproduction because :

1. Offspring do not possess exact copies of parental DNA.
2. DNA of only one parent is copied and passed on to the offspring
3. Offspring are formed at different times
4. DNA of parent and offspring are completely different.

Answer: Offspring do not possess exact copies of parental DNA.

Question 3. Amoeba and Yeast reproduce asexually by fission and budding respectively, because they are :

1. Microscopic organisms
2. Heterotrophic organisms
3. Unicellular organisms
4. Uninucleate organisms

Answer:  3. Unicellular organisms

Question 4. A few statements about sexual reproduction are given below :

1. Sexual reproduction does not always require two individuals
2. Sexual reproduction generally involves gametic fusion.
3. Meiosis never occurs during sexual reproduction
4. External fertilisation is a rule during sexual reproduction.

Choose the correct statements from the options below :

1. 1 and 4
2. 1 and 2
3. 2 and 3
4. 1 and 4

Answer:  2. 1 and 2

Question 5. A multicellular, filamentous alga exhibits a type of sexual life cycle in which the meiotic division occurs after zygote formation. The adult filament of this alga has

1. Haploid vegetative cells and diploid gametangia
2. Diploid vegetative cells and diploid gametangia
3. Diploid vegetative cells and haploid gametangia
4. Haploid vegetative cells and haploid gametangia

Answer:  4. Haploid vegetative cells and haploid gametangia

Organisms And Population Ageing And Death NEET Notes

Question 6. The male gametes of rice plants have i2 chromosomes in their nucleus. The chromosome number in the female gamete, zygote and the cells of the seedling will be respectively.

1. 12, 24. 12
2. 24, 12, 12
3. 12. 24.24
4. 24, 12. 24

Answer: 3. 12. 24.24

Question 7. Given below are a few statements related to external fertilization. Choose the correct statements.

1. The male and female gametes arc formed an<i released simultaneously

2. Only a few gametes are released into the medium.

3. Water is the medium in a majority of organisms exhibiting external fertilization.

4. Offspring formed as a result of external fertilization have a better chance of survival than those formed inside an organism

1. 3 and 4
2. 1 and 3
3. 2 and 4
4. 1 and 4

Answer:  2. 1 and 3

Question 8. The statements given below describe certain features that are observed in the pistil of flowers.

1. Pistil may have many carpels

2. Each carpel may have more than one ovule

3. Each carpel has only one ovule

4. Pistil has only one carpel

Choose the statements that are true from the options below :

1. 1 and 2
2. 1 and 3
3. 2 and 4
4. 3 and 4

Answer:  1. 1 and 2

Question 9. Which of the following situations correctly describes the similarity between an angiosperm egg and a human egg?

1. Eggs of both are formed only once in a lifetime
2. Both the angiosperm egg and the human egg are stationary
3. Both the angiosperm egg and human egg are motile and transported
4. Syngamy in both results in the formation of zygote

Choose the correct answer from the options given below:

1. 2 and 4
2. 1 and 4
3. 3 and 4
4. 1 and 4

Answer:  2. 1 and 4

Question 10. The appearance of vegetat4e propagules from the nodes of plants such as sugarcane and ginger is mainly because:

1. Nodes are shorter than int models
2. Nodes have meristematic cells
3. Nodes are located near the soil
4. Nodes have non-photosynthetic cells

Answer: 2. Nodes have meristematic cells

Question 11. Which of the following statements, supports the view that elaborate sexual reproduction process appeared much later in the organic evolution?

1. Lower groups of organisms have a simpler body design

2. Asexual reproduction is common in lower groups

3. Asexual reproduction is common in higher groups of organisms

4. The high incidence of sexual reproduction in angiosperms and vertebrates.

Choose the correct answer from the options given below:

1. 1 and 2
2. 1 and 3
3. 2 and 4
4. 2 and 3

Answer: 3. 2 and 4

Organisms And Population Ageing And Death NEET Notes

Question 12. Offspring formed by sexual reproduction exhibit more variation than those formed by asexual reproduction because:

1. Sexual reproduction is a lengthy process
2. Gametes of parents have qualitat4ely different genetic composition
3. Genetic material comes from parents of two different species
4. The greater amount of DNA is involved in sexual reproduction.

Answer:  3. Gametes of parents have qualitat4ely different genetic composition

Question 13. Choose the correct statement from among the following:

1. Dioecious (hermaphrodite) organisms are seen only in animals
2. Dioccies organisms are seen only in plants
3. Dioecious organisms are seen in both plants and animals
4. Dioecious organisms are seen only in vertebrates.

Answer: 4. Dioecious organisms are seen only in vertebrates.

Question 14. There is no natural death in single-celled organisms like Amoeba and bacteria because :

1. They cannot reproduce sexually
2. They reproduce by binary fission
3. The parental body is distributed among the offspring
4. They are microscopic

Answer: 2. They reproduce by binary fission

Question 15. There are various types of reproduction. The type of reproduction adopted by an organism depends on :

1. The habitat and morphology of the organism
2. Morphology of the organism
3. Morphology and physiology of the organisms
4. The organism’s habitat, physiology and genetic makeup

Answer:  1. The habitat and morphology of the organism

Question 16. Identify the incorrect statement.

1. In asexual reproduction, the offspring produced are morphologically and genetically identical to the parent
2. Zoospores are sexual reproduct4e structures
3. In asexual reproduction, a single parent produces offspring with or without the formation of gametes
4. Conidia are asexual structures in the Penicillium

Answer: 4. Conidia are asexual structures in Penicillium

Question 17. Which of the following is a post-fertilisation event in flowering plants?

1. Transfer of pollen grains
2. Embryo development
3. Formation of flower
4. Formation of pollen grains

Answer: 4. Formation of pollen grains

Question 18. The number of chromosomes in the shoot tip cells of a maize plant is shall be :

1. 20
2. 10
3. 40
4. 15

Answer:  3. 40

Question 19. Among the terms listed below those that are not correct names for a floral whorl are :

1. Androecium
2. Carpel
3. Corolla
4. Sepal
   1. 1 and 4
   2. 3 and 4
   3. 2 and 4
   4. 1 and 3

Answer:  3. 2 and 4

Question 20. The embryo sac is to ovule as is to an anther.

1. Stamen
2. Filament
3. Pollin grain
4. Androecium

Answer: 3. Pollin grain

Question 21. In a typically complete, bisexual and hypogynous flower, the arrangements of floral whorls on the thalamus from the outermost to the innermost is.

1. Calyx, corolla, androecium and gynoccium
2. Calyx, corolla, gynoecium and Androecium
3. Gynoecium, androecium, corolla and calyx
4. Androecium, gynoecium, corolla and calyx

Answer:  1. Calyx, corolla, androecium and gynoecium

Question 22. A dicotyledonous plant bears flowers but never produces fruits and seeds. The most probable cause for the above situation is:

1. The plant is dioecious and bears only pistillate flowers
2. The plant is dioecious and bears both pistillate and staminate flowers
3. Plant is monoecious
4. The plant is dioecious and bears only staminate flowers.

Answer: 4. Plant is dioecious and bears only staminate flowers

Question 23. The outermost and innermost wall layers of microsporangium in an anther arc respectively :

1. Endothecium and tapetum
2. Epidermis and endodermis
3. The epidermis and middle layer
4. Epidermis and tapetum

Answer: 4. Epidermis and tapetum

Question 24. During microsporogenesis, meiosis occurs in :

1. Endothecium
2. Microspore mother cells
3. Microspore tetrads
4. Pollen grains

Answer:  2. Microspore mother cells

Question 25. From among the sets of terms g4en below, identify those that are associated with the gynoecium.

1. Stigma, ovule, embryo sac, placenta
2. Thalamus, pistil, style, ovule
3. Ovule, ovary, embryo sac, tapetum
4. Ovule, stamen, ovary, embryo sac

Answer: 1. Stigma, ovule, embryo sac, placenta

Question 26. Starting from the innermost part, the correct sequence of parts in an ovule is:

1. Egg, nucellus, embryo sac, integument
2. Egg, embryo sac, nucellus, integument
3. Embryo sac, nucellus, integument, egg
4. Egg, integument, embryo sac, nucellus.

Answer: 2. Egg, embryo sac, nucellus, integument

Question 27. From the statements g4en below choose the option that is true for a typical female gametophyte of a flowering plant :

1. It is 8-nucleate and 7-celled at maturity

2. It is free-nuclear during the development

3. It situated inside the integument but outside the nucellus

4. It has an egg apparatus situated at the chalazal end

1. 1 and 4
2. 2 and 3
3. 1 and 2
4. 2 and 4

Answer: 3. 1 and 2

Question 28. Autogamy can occur in a chasmogamous flower if:

1. Pollen matures before the maturity of the ovule
2. Ovules mature before the maturity of pollen
3. Both pollen and ovules mature simultaneously
4. Both anther and stigma are of equal lengths.

Answer: 3.  Both pollen and ovules mature simultaneously

Question 29. Choose the correct statement from the following :

1. Cleistogamous flowers always exhibit autogamy
2. Chasmogamous flowers always exhibit geitonogamy
3. Cleistogamous flowers exhibit both autogamy and geitonogamy
4. Chasmogamous flowers never exhibit autogamy

Answer: 1. Cleistogamous flowers always exhibit autogamy

Ageing And Death In Organisms NEET Study Material

Question 30. A particular species of plant produces light, non-sticky pollen in large numbers and its stigmas are long and feathery. These modifications facilitate pollination by:

1. Insects
2. Water
3. Wind
4. Animals

Answer: 3. Wind

Question 31. From among the situations given below, choose the one that presents both autogamy and goitnogamy.

1. Monoecious plant boating unisexual flowers
2. Dioecious plant carrying male or female  flowers
3. Monoecious plant with bisexual flowers
4. Dioecious plant with bisexual flowers

Answer:  3. Monoecious plant with bisexual flowers

Question 32. In a fertilised  Sac the haploid. diploid anti tnploul stntctutvs atv :

1. Syergid, zygote and primary endosperm nucleus
2. Synergid ,antipodal and polar nuclei
3. Amiposlal, synergid and primary endosperm nucleus
4. Synergid, polar nuclei and zygote.

Answer: 1. Syergid, zygote and primary endosperm nucleus

Question 33. In an embryo sac. the cells that degenerate after fertilisation arc :

1. Syncrgids and primary endosperm cell
2. Synergids and antipodals
3. Antipodals and primary endosperm cell
4. Egg and antipodals

Answer: 2. Synergids and antipodals

Question 34. While planning for an artificial hybridization programme involving dioecious plants, which of the following steps would not be relevant:

1. Bagging of the female flower
2. Dusting of pollen on the stigma
3. Emasculation
4. Collection of pollen

Answer:  3. Emasculation

Question 35. In the embryos of a typical dicot and a grass, true homologous structures are :

1. Coleorhiza and coleoptile
2. Coleoptile and scutellum
3. Cotyledons and scutellum
4. Hypocotyl and radicle

Answer: 2. Coleoptile and scutellum

Question 36. The phenomenon observed in some plants wherein parts of the sexual apparatus are used for forming embryos without fertilisation is called :

1. Parthenocarpy
2. Apomixis
3. Vegetat4e propagation
4. Sexual reproduction

Answer:  2. Apomixis

Question 37. In a flower, if the megaspore mother cell forms megaspores without undergoing meiosis and if one of the megaspores develops into an embryo sac, its nuclei would be :

1. Haploid
2. Diploid
3. A few haploid and a few diploid
4. With varying ploidy.

Answer: 2. Diploid

Question 38. The phenomenon wherein, the ovary develops into a fruit without fertilisation is called :

1. Parthenocarpy
2. Apomixis
3. Asexual reproduction
4. Sexual reproduction

Answer: 1. Parthenocarpy

Question 39. Choose the incorrect statement from the following :

1. In birds and mammals, internal fertilisation takes place
2. Colostrum contains antibodies and nutrients
3. Polyspermy is prevented by the chemical changes in the surface of the egg
4. In the human female implantation occurs almost seven days after fertilisation

Answer:  3. Polyspermy is prevented by the chemical changes in the surface of the egg

Question 40. Identify the wrong statement from the billowing ;

1. High levels of oestrogen trigger the ovulatory phase
2. Oogoninl cells start to proliferate and g4e rise to ova in regular cycles from puberty onwards.
3. Sperms released from seminiferous tubules arc poorly motile/non-mobile
4. Progesterone levels are high during the post-ovulatory phase of the menstrual cycle.

Answer:  2. Oogoninl cells start to proliferate and g4e rise to ova in regular cycles from puberty onwards.

Question 41. Spot the odd one out from the following structures concerning the male reproductive system :

1. Rate lists
2. Epididymis
3. Vasa efferentia
4. Isthmus

Answer: 4. Isthmus

Question 42. Seminal plasma, the fluid part of semen, is contributed by,

1. Seminal vesicle

2. Prostate

3. Urethra

4. Bulbourethral gland

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

Answer: 2. 1, 2 and 4

Question 43. Spermiation is the process of the release of sperm from:

1. Seminiferous tubules
2. Vas deferens
3. Epididymis
4. Prostate gland

Answer: 1. Seminiferous tubules

Question 44. A mature Graafian follicle is generally present in the ovary of a healthy human female around :

1. 5 – 8 days of the menstrual cycle
2. 11-17 days of menstrual cycle
3. 18-23 days of the menstrual cycle
4. 24 – 28 days of the menstrual cycle

Answer:  2. 11-17 day of menstrual cycle

Ageing And Death In Organisms NEET Study Material

Question 45. The acrosomal reaction of the sperm occurs due to :

1. Its contact with zona pellucida of the ova
2. Reactions within the uterine environment of the female
3. Reactions within the epididymal environment of the male
4. Androgens produced in the uterus

Answer: 1. Its contact with zona pellucida of the ova

Question 46. Which one of the following is not a male accessory gland?

1. Seminal vesicle
2. Ampulla
3. Prostate
4. Bulbourethral gland

Answer: 2. Ampulla

Question 47. The immature male germ cell undergoes division to produce sperm by the process of spermatogenesis. Choose the correct one concerning the above.

1. Spermatogonia have 46 chromosomes and always undergo meiotic cell division
2. Primary spermatocytes d4ide by mitotic cell d4ision
3. Secondary spermatocytes have 23 chromosomes and undergo second meiotic division
4. Spermatozoa are transformed into spermatids

Answer: 3. Secondary spermatocytes have 23 chromosomes and undergo second meiotic division

Question 48. Match between the following representing parts of the sperm and their functions and choose the correct option.

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

Answer: 2. a-4 b-3 c-1 d-2

Question 49. Which among the following has 2.3 chromosomes?

1. Spermatogonia
2. Zygote
3. Secondary oOcyte
4. Ogonia

Answer: 3. Secondary oOcyte

Question 50. Match the following and choose die correct options :

1. Trophoblast 1. Embedding of blastocyst in the endometrium
2. Cleavage2. Group of cells that would differentiate as embryo
3. Inner cell mass 3. The outer layer of the blastocyst attached to the endometrium
4. Implantation 4. Mitotic d4ision of zygote Options

Answer: 2. Cleavage2. Group of cells that would differentiate as embryo

Question 51. Which of the following hormones is not secreted by the human placenta?

1. HCG
2. Estrogens
3. Progesterone
4. LH

Answer: 4. LH

Question 52. The vas deferens receives duct from the seminal vesicle and opens into the urethra as :

1. Epididymis
2. Ejaculatory duct
3. Efferent ductule
4. Ureter

Answer: 2. Enaculatory duct

Question 53. Urethral meatus refers to the following:

1. Urinogenital duct
2. Labia minora
3. Eimbriac
4. Infundibulum
5. Isthmus

Answer: 4. Infundibulum

Question 57. The method of directly injecting sperm into the ovum assisted by reproduct4e technology is called :

1. GIFT
2. ZIFT
3. ICSI
4. ET

Answer: 3. ICSI

Question 58. Increased iMR and decreased MMR in a population will:

1. Cause a rapid increase in the growth rate
2. Result in a decline in the growth rate
3. Not cause a significant change in the growth rate
4. Result in an explos4e population

Answer: 3. Not cause a significant change in growth rate

Question 59. Intensely lactating mothers do not generally conce4e due to the:

1. Suppression of gonadotropins
2. Hypersecretion of gonadotropin
3. Suppression of gametic transport
4. Suppression of fertilisation

Answer: 1. Suppression of gonadotropins

Question 60. Sterilisation techniques are generally foolproof methods of contraception with least side effects. Yet, this is the last option for the couples because :

1. It is almost irreversible

2. Of the misconception that it will reduce sexual urge/ dr4e

3. It is a surgical procedure

4. Of lack of sufficient facilities in many parts of the country

Choose the correct option :

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

Answer: 4. 1, 2, 3 and 4

NEET Biology Plant Growth and Development Basic Features Of Development

• Growth: It is a biological phenomenon involving an increase in the quantity of metabolically active protoplasm, accompanied by an increase in cell number cell size or both.
• Reproduction: The process of producing the young ones of one’s type is called reproduction.
• Development: It is the development of a small, simple one-celled zygote into a large complex-celled adult plant or animal.
• Embryonic or Pre-natal period: It is the period of development of an animal from fertilization to the hatching or birth stage.
• Post-embryonic or Post-natal period: It is the period of changes or transformations which occur in an animal from hatching or birth up to death.
• Ontogeny: The total of events and progressive changes which transform a fertilized egg into a mature individual capable of reproducing is known as ontogeny.
• Reproductive unit: It is is unit produced from either one parent or two parents which undergo a series of developmental changes to give rise to the body of offspring which resembles the parent.
• Gamete: It is the structure produced by the male or female individual through meiosis (gametogenesis) in the sex organs, which takes part in fertilization to form a zygote.
• Zygote: It is the sexual fusion product of male and female gametes.
• Embryo: It is the stage of life history between fertilization and the hatching or birth of a young one. It is derived from the fertilized egg or zygote. The embryo is diploid. It is formed as a result of fertilization and subsequent changes.
• Blastogenesis: The process of development of the progenies from reproductive units such as fragments and buds is called blastogenesis. The process is common in those individuals who are produced by asexual reproduction.
• Embryogenesis: The process of development of the embryo from the zygote produced by the fusion of male and female gametes in sexual reproduction is called embryogenesis. This process occurs in individuals who reproduce by sexual reproduction.

Read and Learn More NEET Biology Notes

• Gametogenesis: The production and differentiation of male and female haploid gametes from gonads.
• Fertilization: The union or syngamy of haploid nuclei of male and female gametes to form a diploid zygote is called fertilization.
• Cleavage and Blastula: A series of repeated mitotic divisions of an egg that form a cluster of balls of cells (blastomeres) is called blastula.
• Gastrulation: The morphogenetic movements of cells of the blastula to give rise to germinal layers, ectoderm, endoderm and mesoderm is called gastrulation. The embryo thus formed with archenteron is called gastrula.
• Growth: Growth is a permanent increase in the synthesis of new nuclear material and cytoplasm.
• Differentiation: It refers to events by which parts become different from one another. It may be morphological, chemical, behavioural, or differentiation.
• Spermatogenesis: The process of formation of sperms from the sperm mother cell of the testis. It involves the following phases:

Plant Growth And Development NEET Notes

Multiplication phase: The sperms are formed from the sperm mother cells, present in the germinal layer of seminiferous tubules of the testis. Some of the mother cells enlarge and divide mitotically to form spermatogonia.

1. Growth phase: Some of them enter a period of growth and are called primary spermatocytes which are diploid.
2. Maturation phase: These cells divide meiotically to form two haploid, secondary spermatocytes. Each secondary spermatocyte again divides. Thus one primary spermatocyte forms four haploid spermatids.

• Spermiogenesis (Spermateliosis): The process of conversion of spermatid into motile spermatozoa is called spermiogenesis.
• It involves movements of cell organelles characteristics of mature sperm such as shrinking of nucleus forming the head, Golgi complex gathering in front of nucleus forming acrosome, change in centriole as distal centriole from the axial filament, mitochondria form spiral sheath and middle piece.
• All these changes are aimed at keeping the spermatozoa small, light and motile. Oogenesis. The process of formation of the ovum from the ovum mother cells of the ovary. It is similar to spermatogenesis and completed in three phases viz. multiplicative phase, growth phase and maturation phase.

Similarities between Spermatogenesis and Oogenesis:

1. Both processes start with primordial germ cells derived from the germinal epithelium of gonads and occur inside the gonad.
2. Both the processes are completed in three phases i.e. multiplication, growth and maturation and show meiosis in the maturation phase.
3. Both processes produce haploid gametes.

Difference Between Spermatogenesis and Oogenesis:

NEET Biology Plant Growth and Development Structure Of Ovum

In all the animals, ova arc single-celled. The ovum is surrounded by a primary membrane called vitelline membrane which is produced after the release from the ovary, the secondary and tertiary membranes are secreted by the Graafian follicle or lining of the oviduct. These layers may be albuminous as in amphibians or may be porous, calcareous as in birds.

• Most animal eggs are spherical or oval, non-motile but on close examination it is noted that one pole is different from the other. The pole from which polar bodies are given off is called the animal pole while the opposite is termed as vegetal pole.
• Thus it is said to have polarity. Thus various cytoplasmic substances are unequally distributed along the axis. The nucleus, also called a germinal vesicle having a chromatin network is bounded by a nuclear membrane.
• It also contains prominent nucleolus. All animal eggs contain some reserve material to provide food called yolk. The cytoplasm of the ovum is called ooplasm. It lacks a centrosome but contains cortical granules derived from Golgi bodies in its peripheral region termed as cortex.

NEET Biology Plant Growth and Development Functions Of Ovum

1. It contributes female’s haploid set of chromosomes.
2. After fertilization, forms a zygote which gives rise to young animals by development.
3. Egg Membranes Protect The Developing Embryo.
4. The eggs are of different sizes. The smallest egg is that of the mouse (0.075 mm) find the largest is that of the ostrich bird (175 mm).

NEET Biology Plant Growth and Development Types Of Eggs

1. Types of eggs based on amount or yolk.

1. Alecvithal cups. Yolk absent c.g. Mctathcrian and cutlierian mammals.
2. Leithal eggs. Eggs contain yolk. They are of three types.
   1. Microlcoithal or olipolceithul Eggs: Microlcoithal Eggs contain very small amounts of yolk
      • Examples: Hydra, and sea urchin. Amphioxus, Tunicatcs.
   2. Mesolccithal Eggs: Mesolccithal Eggs contain a moderate amount of yolk
      • Examples: Earthworm, Dipnoi fishes, and amphibians.
   3. Macrolecithal or mepalecithal or polylccithal eggs: Macrolecithal Eggs contain large quantities of yolk
      • Examples: birds, fishes, reptiles, prototherian mammals and insects.

2. According to the distribution of yolk:

Eggs are of the following types

1. Home-lethal or Isolecithal eggs have evenly distributed yolk
   • Example: Porifers, Amphioxus, Echinodemiates.
2. Heterolecithal Or Anisolecithal Eggs:  Have Localized Yolk.
   • They Are Of The Following Types
     1. Telolecithal eggs: Telolecithal eggs in amphibians— yolk concentrated towards one side.
     2. Meiolecithal eggs: Meiolecithal eggs of birds and reptiles are large and yolk occupies the entire ooplasm.
     3. Centrolecithal eggs: Centrolecithal eggs in insects have yolk in the centre with cytoplasm forming a thin layer around.

3. Types Of Eggs According To Covering:

1. Cleidoic eggs. These eggs are fully laden with yolk and surrounded by albumen and water-proof shells made up of calcium
   • Example: Eggs of reptiles and birds.
2. Non-cleidoic eggs: Non-cleidoic eggs In such a shell is absent.

4. Types Of Eggs According To The Type Of Development:

1. Determinate or mosaic eggs. In such eggs, cleavage is of a determinate type and each part of the egg has a definite fate
   • Examples: Porifers, Platyhelminthes, annelids, arthropods and molluscs.
2. Indeterminate or regulative eggs. In this type, each early blastomere on separation from others may give rise to a complete embryo
   • Example: echinoderms and chordates.

Phases Of Plant Growth NEET Biology

NEET Biology Plant Growth and Development Egg Membranes Or Coats

Eggs possess unique coats beside the plasma membranes. They safeguard the eggs from predators and physical harm while supplying nourishment.

1. The primary membrane secreted by the egg is the vitelline membrane.
2. The secondary membrane is constituted by follicular cells of the ovary that encase the ovum. Chorion in the egg of Herdmania and zona pellucida in the mammalian egg.
3. Tertiary membrane produced by the oviduct’s gland. Jelly-like coating around the eggs of fish and amphibians, together with albumen, shell membranes, and the shell encasing the eggs of reptiles and birds.

NEET Biology Plant Growth and Development Structure Of Mammalian Sperm

Structure. A mammalian sperm is a minute, microscopic, flagellated and motile gamete with no nutritive material, protective envelopes and most cell organelles like ribosome, endoplasmic reticulum, etc. It is formed of four parts, each performing a specific function:

1. Head: The shape of the head varies in different mammals. It is generally oval and flat (in man, bull, rabbit). The head is formed of two parts :

• Acrosome (Gr. Akron = extremity; soma = body):  It is a small pointed structure present at the tip of the nucleus. It is formed from a part of the Golgi body of the spermatid. During the sperm entry, the acrosome secretes a lytic enzyme called hyaluronidase which helps in the penetration of the ovum.
• Nucleus: It is generally long, narrow and pointed but is flat and oval in human sperm. It is formed by condensation of nuclear chromatin of spermatid and loss of RNA, nucleolus and acidic proteins. Chemically, the nucleus is formed of deoxyribonucleoprotein (DNA + basic proteins). It is the carrier of genetic information.

The acrosome and anterior half of the nucleus are covered by a fibrillar sheath galea.

 2. Neck: It is the smallest part of spermatozoan and may be indistinct. It is formed of two centrioles perpendicular to each other and is formed from the centrosome of the spermatid.

• Each centriole is a microtubular triplet structure having a 9 + 0 arrangement. The proximal centriole lies in a depression in the posterior surface of the nucleus and is perpendicular to the main axis of the sperm. The distal centriole is along the longitudinal axis of the sperm.
• Centrioles form a spindle for the first cleavage of the zygote. Distal centriole acts as a basal body and gives rise to the axoneme of the sperm tail.

 3. Middle piece: It lies behind the neck and is cylindrical in human sperm.

• It is formed of a mitochondrial spiral called nebenkern around the proximal part of the axoneme.
• The middle piece is a powerhouse of sperm.
• The posterior half of the nucleus neck and middle piece of sperm is covered by a sheath called a manchette.
• Tail (Flagellum) It is the longest part of sperm. It is slender and tapering.

It comprises two parts: Central contractile and microtubular, axoneme or axial filament, and outer protoplasmic sheath.

• Axoneme is formed of 11 proteinous microtubules arranged in a 9 + 2 manner.
• Sometimes, a ring centriole may be present at the junction of the middle piece and flagellum.
• The tail shows lashing movements which provide a forward push to the sperm.

 4. Viability: It is the period up to which the sperm can fertilize an ovum. The viability of human sperm is about 24 hours.

NEET Biology Plant Growth and Development Fertilization

Fertilization. It is a fitness by which male and female gametes come close and fuse to form a zygote. The union of two gametes is termed syngamy and the intermixing of nuclei is amphimixis.

Steps Involved in fertilization are :

1. Encounter of spermatozoa and ova: It may occur inside the body (internal fertilization) or outside the body(external fertilization).
2. Capacitation and contact. Sperm (antifertilizin) and ovum (fertilizin) show fertilizin- antifertilizin reaction which is highly specific for a species.
3. Acrosome reaction and penetration: Golgi bodies of acrosome secrete enzymes.
   hyaluronidase which dissolves the membranes of the ovum so that materials of sperm can penetrate.
4. Activation of ovum: Immediately after the apical tip of the acrosomal tubule touches the egg plasma membrane, a fusion of both membranes takes place and a single continuous mosaic membrane is formed.

Thus plasma membrane of both gametes becomes continuous and forms a zygote. At this time certain changes occur in the cytoplasm of the egg which are collectively termed as activation of the ovum. It includes the following events.

1. Fertilization cone formation: Coming in contact with the acrosomal filament of spermatozoan, the cytoplasm of the egg bulges forward to produce a conical projection, the fertilization cone. It gradually engulfs the spermatozoan.
2. Cortical reactions and fertilization membrane formation: It may differ from one group of animals to the other, but, in most groups, it fundamentally culminates into the formation of a membrane, called fertilization membrane, outside the egg plasma membrane. This membrane blocks the entrance of late-arriving spermatozoa.
3. Metabolic activation: Following metabolic changes occur in the egg at the time of fertilization.
4. Changes in the plasma membrane: The permeability of the egg plasma membrane increases for the molecules of water, glycol and ions of K+, P04-3 etc. Its electrical potential becomes more positive in the beginning but more negative later on.
5. Ionic changes: The concentration of cations such as Na+, Ca++ and K+ changes during fertilization.
6. Changes in coenzyme: During fertilization, the inactive enzyme NAD-kinase becomes active and changes NAD into NADP and NADPH by phosphorylation.
7. Respiratory changes: Fertilization increases the rate of respiration in those eggs in which maturation is completed before fertilization (e.g., sea urchin) and decreases in those eggs in which fertilization occurs at the first maturation division (e.g., Chaetopterus).The respiratory rate increases for the release of more ATP.
8. Change in the rate of protein synthesis: During fertilization, the inhibitor enzymes are removed to initiate an action of protein synthesis.
9. Initiation of mitosis: It takes place due to the following agencies :

Immediately after fertilization, the rate of DNA synthesis increases many- folds and so also the uptake of cytoplasmic DNA Polymerase enzyme, which is required in the biosynthesis of DNA. The sperm introduces its centriole and by contributing a second centriole it initiates the formation of a spindle.

Plant Growth Regulators NEET Study Material

• Migration of pronucleus and amphimixis: To perform the act of amphimixis, the sperm nucleus has to perform two activities i.e., it has to become pronuclei and to migrate v from the site of penetration to the site of amphimixis. The fusion of male and female pronuclei is termed amphimixis.
  • Significance Of Fertilization:

1. 1. 1. It stimulates the egg to complete its maturation.
      2. The fusion of male and female pronuclei in fertilization restores the diploid number of chromosomes and activation of secondary oocytes results in a mature form of ovum. The ovum which is in a quiescent state with a low metabolic rate restores its normal metabolic activity.
      3. Fertilization initiates cleavage or segregation.
      4. The combination of the chromatin material from two different parents forms the physical basis of biparental inheritance and variation.
      5. The centriole of sperm initiates the first division of zygote timelines and further entry of sperm is checked by the fertility/action membrane.

Ovipary, Vivipnry and Ovovivipnry:

• Osipary: It is the development of an embryo inside its egg delivered outside the body. The fertilization may be external or internal.
• Vivipnry: It is the development of an embryo inside the uterus of a female connected using the placenta. The fertilization is internal. The female gives birth to the young one.
• Ovovivipnry: The phenomenon of retaining eggs and the development of embryos in the body till birth without forming any organic connection for obtaining extra nourishment i.e. no placenta formation. Fertilization is internal.

NEET Biology Plant Growth and DevelopmentCleavage

Cleavage: The series of divisions that occur inside the fertilized egg or zygote to transform it into a multicellular body called blastula is called cleavage. They produce blastomeres.

Characteristics of Cleavage:

1. Cleavage divisions are mitotic and occur one after the other. However, the rate depends upon species, amount of yolk and temperature.
2. During cleavage, growth does not take place and the size and volume of the embryo remain the same and the size of blastomeres is reduced.
3. The nuclear and cytoplasmic ratio becomes very low for the zygote and as a result cleavage increases.
4. During cleavage general shape of the embryo does not change.
5. All blastomeres divide simultaneously during early cleavage.
6. For rapid nuclear division, there is a great increase in the synthesis of DNA.
7. O2 consumption increases during cleavage.

The cleavage division differs from ordinary mitotic division in the following ways :

1. The cleavage division is not followed by the growth of daughter cells before they divide but during ordinary mitotic division, each division is followed by a growth of daughter cells before the next division starts.
2. The rate of cleavage depends in different species on temperature but during mitosis, it is not so.
3. During cleavage nuclear and cytoplasmic ratio is changed.
4. During cleavage, the blastomeres divide simultaneously but in ordinary mitosis all the daughter cells divide approximately at the same time.
5. The cleavage differs from ordinary mitosis of large-sized zygotes, and it is meant basically to reduce the size of blastomeres.

Pattern of Cleavage: Three common patterns of cleavage are radial, bilateral and spiral cleavage.

1. Radial cleavage: In radial cleavage, the successive cleavage planes cutting straight through the egg are at a right angle to one another. The resultant blastomeres become symmetrically, exposed around the animal-vegetal axis. Such type of cleavage occurs in sponges, coelenterates and a few molluscs.
2. Bilateral cleavage: In this pattern of cleavage, the blastomeres are so arranged that the right and left sides become apparent, e.g., Cephalopods, a few Echinoderms and Vertebrates.
3. Spiral cleavage:  In this pattern of cleavage, the furrows are so formed that the blastomeres are arranged in a spiral manner around the animal-vegetal axis e.g., Flatworms, annelids and molluscs.

Planes Of Cleavage During cleavage, different cleavage furrows may divide the egg into different planes.

1. Meridional plane. Cleavage furrow passes through the centre of the animal-vegetal axis and bisects both the poles of the egg. e.g., Frog.
2. Vertical plane. Cleavage furrow passes in a direction from the animal pole towards the vegetal pole. For. first cleavage furrows of Amin calva and chick.
3. Equatorial plane. It bisects the egg at right angles to the main axis and halfway between the animal and vegetal poles, e.g…… first cleavage plane of eggs of higher mammals.
4. Latitudinal plane. It is similar to equatorial, but it courses through the cytoplasm on either side of the equatorial plane, e.g., the third cleavage planes of Amphioxus and frog.

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Types of cleavage: The amount and pattern of distribution of yolk determine the type of cleavage. It is of the following types :

• Holoblastic cleavage: In alecithal, isolecithal and slightly telolecithal eggs, the zygote and the blastomeres divide completely. It results in a cocloblastula i.e., a blastula with a central cavity called the blastocoel. Holoblastic cleavage is of two types
• Equal holoblastic cleavage: The cleavage produces approximately equal-sized blastomeres throughout. It occurs in alecithal eggs of rabbits and microlecithal eggs of sea squirts, amphioxus, marsupials and other placental mammals.

• Unequal holoblastic cleavage: This cleavage in later divisions gives rise to unequal blastomeres, small micromeres and large megameres. It occurs in telolecithal eggs of bony fishes and amphibians.
• Meroblastic Cleavage: In this type of cleavage, division occurs only in the small amount of metabolically active cytoplasm. The yolk remains undivided. It is found in macrolecithal eggs. It is of two types :
• Discoidal Cleavage: It is confined to the active cytoplasm located at the animal pole and occurs in isolecithal eggs of reptiles, birds and egg-laying mammals. It results in a blastula called a disco blastula.
• Superficial Cleavage: It occurs in the centrolecithal eggs of insects. The nucleus placed in the centre of the yolk divides repeatedly to form many daughter nuclei which migrate to the peripheral yolk-free cytoplasm. It then cleaves into many uninucleate blastomeres arranged around the yolk. It results in a superficial blastula consisting of single-layered epithelium enclosing yolk instead of blastocoel.

Significance of cleavage:

1. It produces a large number of cells from a single-celled zygote by repeated divisions and results in the formation of the embryo. , .•
2. It prepares the embryo for the migration of cells to their fixed position during gastrulation.
3. Preparation and initiation of the process of cell differentiation.

NEET Biology Plant Growth and Development Gastrulation

Gastrulation. It is a phase of embryonic development during which cell movements establish the three primary germinal layers and initiate morphogenesis.

The most important features of gastrulation in all animals are :

1. Complex but orderly and irreversible morphogenetic movements involving large masses.
2. The rhythm of cellular division is slowed down.
3. Growth if any is insignificant.
4. The nuclei become more active.
5. Formation of archenteron surrounded by endoderm.
6. The type of metabolism changes and the rate of oxidation is intensified.
7. Chemodifferentiation starts with the synthesis of new proteins.

• Epiboly: It involves stretching and spreading movements of ectoderm-forming cells to surround the embryo except at one pole called the blastopore.
• Emboly: It is the shifting or migration of the cells in such a way as to form internal layers of the mesoderm and endoderm of the embryo. It can occur by five methods.

1. 1. Invagination: It is the simplest type of emboly. In this method, the vegetal pole side of the blastula simply caves in or pushes into the interior e.g. Amphioxus and Invertebrates.
   2. Involution: It is the active rolling in of the endodermal and mesodermal cells from the surface to the interior through blastopore e.g., Frog.
   3. Ingression:  It is the proliferation of cells from the inner surface of the blastoderm into blastocoel which gets filled up with new cells and results in the formation of solid gastrula. The archenteron appears later on by splitting up of internal mass of cells. It may be unipolar as in Obelia or apolar as in Hydra.
   4. Delamination: Separation of sheets of cells to form two layers called epiblast and hypoblast e.g. chick, mammals.
   5. Convergence: It involves the migration of blastomeres from the outer surface towards the blastoporal lips.

NEET Biology Plant Growth and Development Fate Of There Germinallayers

Germinal layers:

Ectoderm, Mesoderm and Endoderm are the three primary germinal layers of the embryo as all the organs differentiate and develop from these layers.

NEET Biology Plant Growth and Development Morphogenesis And Nieekrentlation

Every living organism starts its life from a one-celled structure, a zygote, formed by a union of male and female gametes. From this one-celled stage, a multicellular stage is established by groups of processes of which morphogenesis and differentiation are outstanding.

Morphogenesis: It involves the formation of various structures in an individual organism resulting in the establishment of a young one.

There are two main processes of morphogenesis, namely growth and form:

1. Growth: Molecular growth increases the size of the individual cell. The mitotic division of cells, the most significant process of growth involves the increase in the number of cells and eventually the increase in bulk and complexity of the organism.
2. Form: The growth leads to the form of an individual plant or animal. The resultant of growth establishes various structures and organs. When a structure or an organ has reached its maximum limitation of size, further growth stops. The form is determined by polarity and symmetry. Polarity is of the three dimensions. In an organism one exerts dominance.

The head exerts dominance over the rest of the body. Due to polarity, there is a differentiation of anterior, posterior, right and left sides. Symmetry is the regularity of the arrangement of parts in an organism.

Differentiation: This involves the operational and functional components of development. The zygote divides repeatedly finally establishing millions of cells all having the same types of genes. Yet these cells differentiate into various organs. A group of cells at an early stage maintain certain functions while in the later part of life take up different functions.

Up to a stage the cells are capable of giving rise to any structure i.e. totipotent and after a time when a cell produces special types of cells, there cannot be any further transformation of the cell. The final stage reaches specialisation so that the cell is set apart to perform a definite function.

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Cell differentiation may come about in three methods :

1. The developing differences among cells might be the result of progressive changes in gene action. Further, gene activity patterns might change differently in different cells resulting in differentiation.
2. While the gene action might remain constant, the cytoplasmic operations may become progressively altered.
3. Nuclear and cytoplasmic changes might occur reciprocally.
4. The differentiation may start from the molecular level leading to cellular differentiation.

NEET Biology Plant Growth and Development Formation Of Three Germinal Layers In Mammal

Development of three germinal layers. In viviparous mammals, fertilization occurs internally.

The subsequent processes transpire during the creation of the three germinal layers:

1. Cleavage:

The zygote undergoes holoblastic cleavage in the fallopian canal.

2. Morula:

A compact sphere of cells is generated through successive cleavage divisions.

3. Blastula:

(Blastodermic vesicle or Blastocyst) A chamber known as the blastocoel emerges in the developing embryo. The blastodermic vesicle is encased by an external cellular layer known as the trophoectoderm. The blastodermic vesicle exhibits an interior aggregation of cells resulting from differentiation. This aggregation of cells is referred to as the inner cell mass.

4. Gastrulation:

At this stage, the morphogenetic movements of the cells, such as epiboly and emboly, occur in small aggregates or sheets.

Consequently, three germinal layers are established:

1. Endoderm
2. Mesoderm
3. Ectoderm

1. Development of Endoderm:

Certain cells from the inner cell mass undergo delamination.

• Cells migrate in layers or aggregates within the blastocoel. These represent the prospective endodermal cells.
• These cells organize themselves as the second layer, situated between the inner and outer layers of the blastodermic vesicle.
• The blastocoel vanishes, and a new hollow emerges. The newly formed cavity is referred to as the archenteron.
• The residual mass of embryonal knob cells becomes convoluted and systematically organized to create an embryonic disc.

2. Formation or mesoderm:

The cells at the caudal end of the embryonic disc initiate proliferation and subsequently detach from the disc to produce mesoderm.

3. Development of ectoderm:

 Following the detachment of mesodermal cells from the embryonic disc, the remaining cells in the disc organize into a separate layer, forming the ectoderm.

NEET Biology Plant Growth and Development Placenta

• Placenta: A vascular organ that unites the foetus to the wall of the uterus in all mammals except marsupials and monotremes is called the placenta and its formation is plantation.
• Structure or Kpithelio-shoring placenta: Epitheliochorial is the simple and basic type of placenta formed in marsupials, pigs, horses, etc. In this case, some of the components are derived from the uterine wall of the mother while the other parts are derived from the foetus itself.

1. 1. Maternal components are (a) mucous membranes of the uterine wall (b) uterine connective tissue (maternal mesenchyme) (c) endothelium of maternal blood capillaries.
   2. Foetal components are A wall of foetal blood capillaries and foetal connective tissue. Foetal chorionic epithelium.
   3. Functions of the placenta:  The placenta serves primarily as an organ that permits the interchange of material earned in the blood of the mother and foetus. The main functions are :
   4. Nutrition: Supply of nutrient materials to the foetus. Respiration. Supply of 02 to the foetus and receive C02 back from it. Excretion. Fluid nitrogenous waste products escape through the placenta. Barrier. The placenta is a barrier-like semipermeable membrane.
   5. Storage: The placenta stores fat, glycogen and iron for the embryo before die formation of the liver. Hormonal function. The placenta secretes extra-ovarian hormones estrogen and progesterone in females during pregnancy that serve to maintain the foetus.

Classification of the placenta: The placenta is of five types depending upon the number of tissue layers that separate the foetal blood from maternal blood.

Epitheliochorial placenta (all six layers) e.g. horse, pig and donkeySyndesmochorial placenta (five layers present, uterine epithelium eroded e.g., cow, goat, sheep Endotheliochorial placenta (four layers present-uterine epithelium and connective tissue eroded) e.g. dog and catHaemochorial placenta (three layers present-material three layers eroded) e.g, primates including human andHaemoendothelial placenta (all the maternal and two foetal tissue layers eroded) e.g. rodents and rabbits.

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Types of placentae according to the distribution of villi on chorion.

1. Diffuse placenta: Chorionic villi remain scattered all over the surface of the chorion e.g., pig, horse, lemur.
2. Cotyledonary placenta: The villi are found in groups or patches e.g. cattle, sheep, deer
3. Zonary placenta: The villi are developed in the form of a belt or girdle e.g. cats, dogs Discoidal placenta. The villi continue developing only on one side e.g. mouse, rat, human, monkey.
4. The placenta is of three types, viz. Allantoic, yolk sac and chorionic placenta: about the foetal membrane that takes part in its formation.

NEET Biology Plant Growth and Development Vitellogenesis

The synthesis of yolk is termed vitellogenesis. Recent investigations have revealed that yolk is not necessarily synthesized in oocytes but produced elsewhere in some extra ovarian tissue such as fat bodies in insects.

• In fishes, amphibians and also in gastropod molluscs, its synthesis takes place inside modified mitochondria.
• In other vertebrates, yolk is produced in liver cells. It is transported to the ovarian follicle by blood in the soluble form. From these cells of the follicle, the oocyte takes the yolk by pinocytosis.
• The Golgi complex and endoplasmic reticulum of oocytes transfer these yolk components to modified mitochondria and convert them into insoluble forms.

1. 1. Composition of yolk: The yolk is the reserve food material in the egg. It is composed of proteins, phospholipids and neutral fats. The yolk may be a protein yolk if it contains mainly protein. If the yolk consists mainly of phospholipids, neutral fats and small fats, it is termed a fatty yolk. Both kinds of yolk are present side by side in the eggs but protein yolk is the main constituent of many invertebrates and chordates.
   2. Utilization of yolk: In the isolecithal eggs Example: frog) the yolk gets distributed to all the daughter cells at the time of cleavage. However, at later stages, some cells may have more yolk due to unequal division. The yolk is broken down into simpler substances and utilized in the synthesis of new protoplasmic constituents.

In the acrolectal egg of birds, the yolk is absorbed by diffusion in the early stages. Later on, a yolk sac develops around the yolk mass from mesoderm and endoderm. Blood vessels called vitelline arteries and veins connect the yolk sac with the heart. The enzymes from the yolk sac digest the yolk into soluble form, which is then taken to the heart and vitelline veins and then distributed to all parts of the developing embryo.

NEET Biology Plant Growth and Development Hereditary Defects

• Teratology: It is the branch of developmental biology which deals with the study of abnormal development during embryogenesis. The ways and means by which abnormal developments occur during embryogenesis are called teratogenesis.
• List of hereditary defects, Colour blindness harelip (Cleft plate Clubfoot Hole in the heartAbsence of hands, feet, arms or legs (Meromelia) Right half body normal and left like dwarf (Achondroplasia) Mongolism Phenylketonuria Albinism Alkaptonuria Haemophilia Polydactyly Cat cry syndrome (at) Turner’s syndrome and Klinefelter syndrome.
• Identical twins: The twins are of the same sex and are identical in all respects including appearance, size and behaviour.
  The identical twins are monozygotic because they develop as a result of fertilization of the single ovum by a single sperm but the zygote divides into two halves and each half gives rise to a child. Each gets attached to the same placenta.
• Fraternal twins: The fraternal twins are dizygotic as they are produced due to the fertilization of two different eggs. They may or may not belong to the same sex. They may or may not resemble each other.
• Normally the ovaries release a single egg at a time or if two eggs are released both may be fertilized and then may develop into two separate individuals, thus fraternal twins develop from two different zygotes, hence termed dizygotic twins. They are connected to the uterine wall by a separate placenta.
• Conjoined twins: Twins are generally normal babies, but some twins may be abnormal in shape, structure or development. Some twins may be fused wholly or in part, such fused twins are called conjoined twins. The degree of union may be slight or extensive. Union is by heads and upper trunk.

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NEET Biology Plant Growth and Development Important Notes

1. Spermiogenesis: The process of conversion of a spermatid into a functional spermatozoan by the process of differentiation of specialization is called spermiogenesis or spermioteliosis.
2. Sertoli cells: These are indifferent cells situated in the lining of seminiferous tubules which provide nourishment to the differentiating spermatozoa. Sperms’s head is kept embedded in Sertoli cells for this purpose.
3. External fertilization: The fusion of male and female gametes takes place outside the body of a female animal.
4. Internal fertilization: The fusion of male and female gametes takes place inside the body of a female animal.
5. Amnion: A thin extra-embryonic membrane forms a closed sac around the embryo in birds, reptiles and mammals.
6. Amniota: A collective term for the reptiles, birds and mammals, all of which have an amnion.
7. Anamniote: Any animal of which the amnion is absent during embryonic development.
8. Amniotic fluid: A substance that fills the amnion to protect the embryo from shock and industry.
9. Amniocentesis: A procedure during pregnancy by which the abdominal wall and foetal membrane are punctured with a cannula to withdraw amniotic fluid.
10. Amphimixis: The union of nuclei of egg and sperm in sexual reproduction.
11. Allantois: A fluid-filled, sac-like extraembryonic membrane lying between the chorion and amnion of reptiles, birds and mammals.
12. Allantochorion: The extraembryonic membrane is formed by the fusion of the outer wall of allantois and with the primitive chorion.
13. Chemo-difTerentiation: It is the chemical differentiation of cells of the embryo during development.
14. Cyto-differences: It is the differentiation of cells ol ciuluyo dining development.
15. no-dinViviilintlon: It location of the tissue mill also ballots ns histogenesis.
16. Orgnn-dinVivntlntlon: It is tot million of guns limit the embryo.
17. Kmhnoule Murillo: The supply of required materials which are essential for the synthesis of unit ami and other compounds ami for the production of energy during the development of the embryo is called embryonic nutrition. The materials required are amino acids, minerals and oxygen.
18. Diapause: The sexual rest period in insects is called diapause.
19. Kmlometrium: Glandular mucous membrane lining of the uterus.
20. Genome: The set of all different chromosomes found in each nucleus of a given species. A haploid nucleus has one genome.
21. Germinal vesicle: Nucleus of the animal oocyte during the period of cytoplasmic growth.
22. Gestation period: Length of time from conception to birth in viviparous animals.
23. lactation: Production of milk.
24. Monoccious:fUiscxual or hermaphrodite).
25. Mullerian Duct: Oviduct of female gnathostome vertebrate.
26. Neoteny: Persistence of the form of a larva or any other stage (larva becomes sexually matured.)
    • Example: Axolotl Larva of Salamander in Amphibians
27. Nidicolous birds: Those which hatch undeveloped.
28. Nymph: Young states of exopterygote insect.
29. Oxytocin: A hormone secreted by the posterior lobe of the pituitary gland which causes labour pains (contraction of uterine muscles.).
30. Secondary sexual characters: A characteristic of animals which differ between the two sexes.
31. Seminal vesicles: Organs which store sperm in males (cf).
32. Spermatheca. Organs which store sperm in female ($).
33. Syngamy:Union of gametes is termed syngamy.
34. Testosterone: A principal male hormone.
35. Urethra: Duct leading from the urinary bladder of mammals to the exterior.
36. Uterus masculinus: A sac-like structure dorsal to the bladder in male mammals.
37. Vitelline membrane:  Primary egg membrane secreted by the egg.
38. Yolk plugs: A mass of macromeres which closes the blastopore in the developing embryo

• Colostrum. The first milk which comes out from the mother’s mammary glands just after childbirth is known as colostrum. It is rich in calories and proteins. It contains antibodies.
• On average human ejaculate of 3 – 4 ml of semen contains 80-100 million spermatozoa.
• Virus infection of the mother e.g. by the rubella (German measles) virus or exposure to certain chemicals may cause malformation in the developing embryo. Such agents are called teratogens.  All the systems in a developing foetus are formed by the three months of pregnancy.
• cv During further development after three months, there was growth and a few minor structural modifications. Extra-embryonic membranes include the yolk sac, amnion, chorion and allantois.
• Yolk sac is also found in like certain fishes Example: Scoliodon), bony fishes and a few amphibians
• Example: Necturus having an egg.
• Amnion, chorion and allantois are formed only in am- niote embryos as their development occurs on land either inside the egg or in the uterus of the mother.
• These are not formed in amniotes as their development occurs in water so there is no problem of desiccation, supply of oxygen and removal of wastes. c& Amnion is an innermost embryonic membrane and never participates in placenta formation.
• c& Chorion is an outermost embryonic membrane and always participates in placenta formation.
• Polarity. The existence of a definite axis in the egg and the embryo is called polarity. In the egg, polarity is indicated by the position of the nucleus and the yolk.
• Inducers (Organizers). The cells that induce or control die developmental fate of the neighbouring cells in an embryo are called inducers or organizers.
  c& Inductors. These are the chemicals which the inducers release to guide the fate of the adjacent cells.

NEET Biology Plant Growth and Development Quanta To memory

• Identical twins:  Twins are the term used to describe the delivery of two or more infants in a single birth. These may be identical twins, monozygotic twins, fraternal, dizygotic, or non-identical twins.
• Siamese siblings: Conjoined twins are joined at the pelvis, chest, kick, and face. These are monozygotic and have been surgically separated for the first time in Siam.
• In the process of frog oogenesis, a single oogonium generates a single ovum and only two polar bodies.
• In mammals, a fertilization membrane is not formed; however, die enzymes that are released following the formation of the zona pellucid neutralize sperm receptors, preventing any additional sperm from binding to them.
• Transformation: Metamorphosis is the term used to describe the process by which a juvenile individual undergoes a transformation into a morphologically and physiologically distinct adult. There are two varieties of it.
• Metamorphosis that is retrogressive: The transformation of an advanced larva into a degenerate adult, such as Merdmania. Sacculina.
• Metamorphosis in progress: When a simplified larva transitions into an advanced adult, such as a frog.
• Martinis are complimentary: A male and a female heifer that were sexually underdeveloped were united.
• Fate diagram: Diagram illustrating presumptive or potential regions on the blastula’s surface.
• This is accomplished through the utilization of specific essential stains, including neutral red, Nile blue sulphate, and Bismarck brown. It was initially prepared by W. Vogt in 1929.

Stages Of Embryonic Development in Human

NEET Biology Notes For Reproductive Health

• Health is affected by the Following :

1. Genetic disorders.
2. Infection.
3. Lifestyle including Food and water.
4. Physical exercises.

• Genetic disorders: these are inborn errors. these are deficiencies with which a child is born. such as mongolism. genetic disorders also include deficiencies or defects which a child inherits From birth.
• Reproductive health: it means total well-being in all aspects of reproduction i.e. physical, emotional, behavioural and social.
  • A society with people having physically and Functionally normal reproductive organs and normal emotional and behavioural interaction among them in all sex-related aspects is called a reproductively healthy society.
  • Reproductive and Child Health Care (RCH) programmes are carried out at the National Level to look after these problems.
• Sex education: Sex education is concerned with creating awareness among people about reproductive organs, adolescence and associated changes, safe and hygienic practices, and sexually transmitted diseases including AiDS.
• Significance of Reproductive Health in a Society: A reproductively healthy society’ survives in a normal way. Reproductive health ensures that all individuals in the reproductive age group are Fertile and able to carry on the human race Further.
• Individuals should be educated about reproduction-related aspects like controlled population, absence of sex abuses and sex-related crimes in society and enable people to think and take up necessary steps to build up a reproductively healthy society.
• Aspects of reproductive health need to be given special attention in the present scenario: ConFerring upon the demands of the present situation of our country, the following aspects of reproductive health should be given special attention :

Reproductive Health Neet Important Points

1. Control of the human population.
2. Creation of awareness about reproduction-related aspects among people including sex education to students.
3. implementation of various action plans to attain reproductive health.
4. Continued research on reproduction-related areas.
5. Measures of birth control.

• Sex education should be encouraged in schools:  Sex education should be encouraged in schools to give the right information to young minds to save them From myths and misconceptions about sex-related aspects.
  • Proper information about reproductive organs, adolescence and related changes, safe hygienic sexual practices, and sexually transmitted diseases like AiDS would help people to lead a reproductively healthy life
  • Thus sex education is necessary to make society reproductively healthy.
• Reproductive health in our country has tremendously improved in the past 50 years and the Following are some areas of improvement.
  • Improved Medical Facilities available For the treatment of diseases.
  • Rapid decline in death rate.
  • Success oF programmes like Family planning and Reproductive and Child Health Care Programmes.
  • Increased awareness among people about reproduction-related aspects.
• RCH programmes also include providing medical Facilities and care to persons about problems like menstrual irregularities, pregnancy-related aspects, MtP, StD, birth control and infertility.

Read and Learn More NEET Biology Notes

NEET Biology Reproductive Health Objectives OF RCH

1. creating awareness about canon* reproduction-related problems.
2. Providing Facilities and support to the building, up a reproductively healthy society.
3. Providing audio-usual and print media support to various government and non-government organisations.
4. Educating the people and providing the right information to them From myths and mis- mis-misconceptions
5. Providing project education regarding reproductive organs, adolescence and related changes, and safe and hygienic sexual practices.
6. Providing information regarding the danger of sexually transmitted diseases, AiDS etc.

Various contraceptive options:

Various contraceptive options are available now such as natural/ traditional, barrier, and lUDs. pills, injectables, implants and surgical methods. though there are certain ill-elFects For some of these methods, they are not very significant. they have to be used under strict medical guidance and supervision only.

Different types oF lUDs:

Different types oF lUDs are presently available such as the non-medicated IUDs example. i-pipes loop), copper-releasing lUDs (CUt, CU 7, Multiload 375) and hormone-releasing ones (Progestasert, LNG-20)

Functions:

IUDs increase phagocytosis oF sperms within the uterus and the Cu ions released by some suppress sperm motility and the Fertilising capacity oF sperms. the hormone-releasing iUDs. in addition, make the uterus unsuitable For implantation and the cervix hostile to the sperm.

Advantages:

IUDs are ideal contraceptives For Females who want to delay pregnancy and space children. it is one of the most widely accepted methods of contraception in India.

Oral Contraceptives:

• The oral administration of low dosages of progestagens or progestagen-estrogen combos constitutes an alternative contraceptive strategy utilized by females.
• They are administered in tablet form, commonly referred to as ‘pills.’ Pills must be taken daily for two consecutive days, preferably between the first five days of the menstrual cycle.
• Following a 7-day interval (during which menstruation transpires), the procedure must be resumed in the same sequence until the intended duration of contraception is achieved. They impede ovulation and implantation, as well as modify the quality of cervical mucus to obstruct or delay the entry of sperm.
• Pharmaceuticals demonstrate high efficacy with little adverse effects and are widely accepted by females.

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Advantages of Saheli:

A‘Saheli’, the new oral contraceptive For females contains a non-steroidal preparation called ‘centchroman’. it is a ‘once a week’ pill with very Few side effects and high contraceptive value.

Medical termination of Pregnancy:

• Medical termination of Pregnancy (MTP) is the intentional termination of pregnancy before Full term. MtP is legalised in our country with certain strict conditions to avoid its misuse. MTP is generally performed to get rid oF unwanted pregnancies due to rapes, casual relationships etc.
• It is also used in certain cases when the continuation of the pregnancy could be harmful or even fatal to either the mother the Foetus or both. MTPs are formed by qualified medical professionals preferably during the First trimester.
• Avoiding sexual intercourse with unknown/multiple partners, and using oF condoms during coitus are some of the simple tips to avoid contracting STDs.
• inability to conceive or produce children even after 2 years of unprotected sexual cohabitation is called infertility. Various methods are now available to help such couples.

• Population:  Population is defined as a group of organisms or the same species within which individuals may change genetic information occupying a particular space.
• Demography: Demography deals with the statistical study of the population.
• The population has characteristics which are a Function of the whole group and not of the individuals these are population density, birth rate, death rate, potential oF dispersion and growth Form.
• The population is defined as the total number of individuals of a species present lit a particular area: lie enemies in a population have some common characteristics, share a common pone pool and are capable of interbreeding among themselves to produce let tile ollspimgs
• Aim of Population Study: The alarming rise in the human population has created many scrum problems, l herblore, population education has been introduced into the school and college curricula. Population education is aimed at making students aware of the following:

1. 1. consequences of uncontrolled population growth such as environmental pollution, depletion of natural resources, extinction of species, etc ;
   2. Benefits oF lowering population growth rate to the biosphere ;
   3. advantages of a small Family to humans ;
   4. growth, distribution and density of population ;
   5. relation oF population to the standards oF liFe.

• Aspects of Demography.

1. Demography: The scientific study of the human population is called demography. it deals with three phenomena :
   1. 1. Changes in population, i.e., growth or decline.
      2. Composition of the population, i.e., age groups, and sex ratios.
      3. Distribution of the population in space.

• Demographic study is carried out through census, and registration of births and deaths.
• Census: Census is the counting of population, age and sex of individuals, marital status, number of children per couple, number of dependents, number of earning hands, education, literacy, mother tongue, religion, race, occupation, type of employment, mortality, etc.
  • India, census is undertaken every ten years, for example, i97i, i98i, i99i. it takes over one year For the completion oF census. The Census of our country was carried out in February 2001 it is over one billion.
• Population density: Population density of a species is the number of individuals of a species per unit area or volume example, the number of animals per square kilometre; the number of trees per acre of a Forest etc. For instance, the number of people per square kilometre in 1991.
  • If the total number of individuals is represented by the letter N and the number oF units oF space by the letter S, the population density D can be obtained as D = N/S.
• Consequences OF Higher Population Density

Neet Reproductive Health Chapter Notes

As the population density increases in a country beyond its means; it brings the following problems:

1. Per capita income comes down
2. Natural resources like land, minerals, wood, Fuel, etc. decrease
3. general health goes down
4. The large population of a country is the result of having large Families and the quality of life deteriorates accordingly.

Birth or Natality rate:

It is often measured as the number of births per 1,000 individuals in a population annually. It increases both the population size and population density.

• The national average birth rate in India is roughly 28.6 births per 1,000 inhabitants each year. Kerala has the lowest birth rate among Indian states at 18 per 1,000, whilst Uttar Pradesh has the highest at 34.8 per 1,000.
• The total number of live births in a year is equal to the mid-year population multiplied by the mortality rate.
• It is the opposite of the birth rate. It is sometimes measured as the number of deaths per 1,000 residents in a population per year
• It is often measured as the number of births per 1,000 individuals in a population annually. It increases both the population size and population density.
• The national average birth rate in India is roughly 28.6 births per 1,000 inhabitants each year. Kerala has the lowest birth rate among Indian states at 18 per 1,000, whilst Uttar Pradesh has the highest at 34.8 per 1,000.
• The total number of live births in a year is equal to the mid-year population multiplied by the mortality rate.
• It is the opposite of the birth rate. It is sometimes measured as the number of deaths per 1,000 residents in

Difference between Natality Rate And Mortality Rate

• Population growth: Population growth is determined by several individuals added to the population by births (natality) and immigration (entry of individuals of the same species into an area From outside). it increases the population size. the number of individuals lost From the population by deaths (mortality) and emigration (departure of individuals of the same species From one area to outside). it decreases the size of the local population but the species spreads to new areas.
  • If more individuals are added than lost, the population will show positive growth.
  • But if more individuals are lost than added, then the population shows negative growth.
  • But if the two rates are equal, then the population will become stationary and is called zero growth.
  • Population growth = (Births + immigration) – (Deaths + emigration).
    Migration involves the two-way movement of a whole population From one area to another area. Migration is not considered as a Factor determining the population size.
• Growth Rate: it is the increase in the number of individuals per unit time per unit number of individuals due to natality being higher than mortality. in other words, the growth rate is the difference in the birth rate and death rate in a population. the growth rate of the human population is 2%; 0.8% in developed countries and 2.5% in developing countries.
  it is i.7% in India as per census oF 200i.
• Reasons for an overpopulation

1. 1. Religious Beliefs. Certain religions Forbid Family planning. Saudi Arabia and the United Arab Emirates have a population growth rate of 3% despite being among the richest and most educated countries.
   2. Education: It is found that population growth is inversely related to the degree and percentage of education. Over 50% of the Indian citizens are illiterate. Most of them believe that a higher number of children are a blessing to God.
   3. Early Marriage: In most developing countries, marriages are solemnised at an early age between i5-20 years.
   4. Child-Labour. In many families, children are asked to work to earn a livelihood. Such Families consider a larger number of children to be an asset.
   5. Decreased Mortality: The death rate has Fallen in most countries including India mostly due to the spread of medical Facilities and awareness of care For Infants.
   6. increased Average Life Span: The average life span of human beings is steadily rising in most countries. it has reached a Figure of more than 75 years in developed countries and around 56 years in developing countries like India.
   7. incidence of Epidemics: they have come down due to the increased spread of health services and, the stress of government and civic agencies on sanitation and vaccination.
   8. Famine and Floods. Previously innumerable deaths used to occur due to these two reasons Advancement of technology has made it possible to Forecast impending disasters and take preventive as well as remedial measures.
   9. increased Facilities. Every government pays special attention to building Facilities like transportation, health services, proper storage and distribution of Food, housing and other Facilities For the poor

Reproductive Health Neet Previous Year Questions

Major Disadvantages OF Large Families :

The major Disadvantages OF Large Families are

1. 1. The mother may suffer From ill health due to Frequent pregnancies.
   2. Economically weak parents cannot maintain their standard of living.
   3. Children do not get nutritious Food, proper clothing, proper medical Facilities and good education.
   4. over the health of the mother leads to less attention to children.
   5. Overcrowding leads to problems of sanitation, sewage, transportation, environmental and noise pollution, and various socio-economic problems related to juvenile delinquency and crime.

• Disadvantages of Large Population

1. 1. Deficiency oF the essential commodities oF liFe viz. Food, clothes and shelter.
   2. Depletion of resources.
   3. Unemployment.
   4. Poverty.
   5. StriFe among different groups.
   6. Lack of interest towards life.
   7. Crime and addictions.
   8. Abortion.
   9. Restrict the Family to two children.

• Family Planning”.The main objective of family planning or family welfare programmes is to prevent the fertilization of the dead ovum by the male sperm and stop the increase in population growth by various methods, such as contraceptives, intrauterine devices, vasectomy and tubectomy.
• Contraceptives (Anirudh) for males and intrauterine devices, loop for females are used to avoid pregnancy. Vasectomy is the method of sterilizing a male by surgical operation of the sperm duct or vas deferens. Tubectomy is the method of sterilizing a female by the surgical operation of fallopian tubes. Whatever the method employed, it must take care of the health of the persons concerned.
• Because of the family planning methods, the birth rate in India is reduced to some extent. The government gives incentives to those who adopt family planning.
• Ways of Family Planning

1. 1. Late marriage for young persons.
   2. Increase in the sources of recreation to divert the attention from sex.
   3. The couple should not mate between the 8th and 18th day from the start of the menstrual cycle.
   4. Use of contraceptives.
   5. Sterilization
   6. Use of drugs.
   7. Strife among different groups.
   8.  Crime and addictions

• Population Control

Population explosion can be checked by two methods—population education and birth control.

• Population Education

The knowledge about the relationship between population size and the availability of resources For the welfare of the society is called population education.

1. 1. the students should be convinced about the relationship between overpopulation and unemployment.
   2. the citizens should be told how the large size of the population is eating away at the resources of the state and the reasons For the limited availability of health care, education Facilities and other welfare schemes.
   3. People should be made aware of how a large number of children eat away the meagre resources of the Family with nothing left For bad days, how large Families rely on indebtedness to meet emergencies.
   4. How child bread earners do not improve the conditions of the Family, how uneducated children remain a burden on society, etc. they should be convinced that a small Family can live comfortably even with meagre resources.
   5. Mass Media of Communication. Radio, television, newspapers, magazines, hoardings and posters should be employed to spread the message of Family planning and birth control and its advantages.
   6. The future of mankind depends on the stabilisation of the human population at a level that ensures the necessities of life, employment and happiness.
   7. The law about marriageable age should be widely published and strictly enforced (2 years For boys and 8 years For girls). In developed countries, women marry at the age of 25-35.
   8. As far as possible. miss should bo laid on (hr mini Ftlnln% ul ilic women. Women 2veing higher Mvia! Matu is perfect for small Families. Stub women gc2nnlly matiy late.
   9. Remove the Mi|vititionv ami wrong beliefs in the society higher number oF children hong ihvl’s pill connected with the earthly or heavenly prosperity.

The various methods of birth control

1. Use oF Contraceptives means prevention oF conception ;
   The following contraceptives are popular :

• • Diaphragm: Hie vaginal diaphragm is a rubber cup stretched over a collapsible metal spring coil. it is designed to fit over the cervix, i.e. the mouth of the uterus which prevents Fertility or conception.

• • Condom: The condom is a sheath oF rubber which Fits on the erect penis. it is put on the penis beFore it is introduced into the vagina during intercourse.
  • Jellies, creams and Foams: Several different spermicidal jellies, creams and Foams are available For use as contraceptive agents. These jellies, creams and Foams are inserted into the vagina Five to FiFteen minutes beFore ejaculation takes place.

Reproductive Health Neet Short Notes Download

Introduction oF copper ‘t’: or loop in the Female uterus prevents the entry oF sperms in the uterus iUD (intra-uterine device).

1. Oral contraceptives. these are popularly known as “pills” and are combinations of synthetic sex hormones which suppress the production of ovum. these pills alter the ovulation cycle.
2. Sterilization. it is the surgical technique by which the passage of sperm or ovum is discontinued. Both men and women can be sterilized without losing their ability to function sexually.
   • Vasectomy: In men, the sterilization procedure is called vasectomy.
   • tubectomy: In women, part of the Fallopian tube is cut and tied.
   • Laparoscopy: it is the mechanism of tying the oviducts or tubal ligation and hence blocking them with the help of an instrument called a laparoscope. Because oF ligation, the ovum cannot pass into the uterus nor the sperm reach the egg For Fertilization.
3. Medical termination of pregnancy (MTP). it is the cessation of pregnancy by surgery, suction or by other means.
4. Other measures

• • Abstinence: Abstaining From intercourse.
  • Coitus interrupts: It involves the withdrawal of the penis From the vagina beFore ejaculation occurs.
  • Zero ‘O’ method: This is a natural effective and practical method where the woman has to Find Herself in the Fertile and infertile period, by keeping a close watch on the uterine charge. the safest period to avoid pregnancy is From the beginning of mucus discharge next Four days after the discharge has stopped.

NEET Biology Reproductive Health Questions From Competitive Examinations

Question 1. Which of the following is a convincing reason for Kuion’s growth as a country?

1. High birth rate
2. Low mortality rate
3. Low population of old people
4. High population of young children.

Answer: 4. High population of young children.

Question 2. If the rate oF addition oF new members increases concerning the individual host oF the same population, then the graph obtained has :

1. Declined growth
2. Exponential growth
3. Zero population growth
4. None of these.

Answer: 2. Exponential growth

Question 3. Copper-t prevents :

1. Ovulation
2. Fertilization oF egg
3. Implantation
4. Both B and C.

Answer: 4. Both B and C.

Question 4. Which is related to males?

1. Oral pill
2. tubectomy
3. Vasectomy
4. None of these.

Answer: 3. Vasectomy

Question 5. Study oF population trends is:

1. Kalography
2. Psychobiology
3. Biography
4. Demography.

Answer: 4. Demography.

Reproductive Health Ncert Notes For Neet

Question 6. July 11 is :

1. World Environment Day
2. World Population Day
3. World AIDS Day
4. World Education Day.

Answer: 2. World Population Day

Question 7. A method of birth control is :

1. GIFt
2. Zift
3. IVF-Et
4. IUDs

Answer: 4. IUDs

Question 8. What is the Function of copper t?

1. Prevents mutation
2. Prevents Fertilization
3. Prevents zygote Formation
4. B and C.

Answer: 4. B and C.

Question 9.In the production oF test tube babies:

1. Fertilization is external and Foetus Formation is internal
2. Fertilization is internal and Foetus Formation is external
3. Fertilization and Foetus Formation are external
4. Fertilization and Foetus Formation are internal.

Answer: 1. Fertilization is external and Foetus Formation is internal

Question 10. Certain characteristic demographic Features of developing countries are :

1. High Fertility, high density, rapidly rising mortality rate and a very young age distribution.
2. High infant mortality rate, low Fertility, uneven population growth and a very young age distribution.
3. High mortality, high density, uneven population growth and a very old age distribution.
4. High Fertility, low or rapidly Falling mortality rate, rapid population growth and a very young age distribution.

Answer: 4. High Fertility, low or rapidly Falling mortality rate, rapid
population growth and a very young age distribution.

Question 11. Oral contraceptives are prescribed in Females to check :

1. Ovulation
2. Fertilization
3. Implantation
4. Entry oF sperms in the vagina.

Answer: 1. Ovulation

Question 12. Zero growth means :

1. Natality is zero
2. Natality balances mortality
3. Natality is less than mortality
4. Natality is more than mortality.

Answer: 2. Natality balances mortality

Question 13. The following is a technique for direct introduction of gametes into the oviduct:

1. MtS
2. Et
3. IVF
4. Post.

Answer: 3. IVF

Question 14. Which of the following is a mechanical barrier used in birth control:

1. Loop
2. Copper-t
3. Diaphragm
4. Dalcon shield.

Answer: 3. Diaphragm

Question 15. Which of the following is the most sparsely populated state of India?

1. Manipur
2. Arunachal Pradesh
3. Rajasthan
4. Meghalaya.

Answer: 2. Arunachal Pradesh

Question 16. Maximum growth rate occurs in :

1. Lag phase
2. Exponential phase
3. Stationary phase
4. Senescent phase.

Answer: 2. Exponential phase

Reproductive Health Neet Syllabus Coverage

Question 17. In a population, the condition at which the rate of addition of new members is more than the rate of individuals lost indicates :

1. Zero population growth
2. Exponential growth
3. Fluctuating growth
4. Declining growth
5. None of these.

Answer: 2. Exponential growth

Question 18. The growth curve is normally :

1. J-shaped
2. V-shaped
3. S-shaped
4. C-shaped.

Answer: 3. S-shaped

Question 19. The greatest biological problems Faced by human beings are:

1. Population explosion
2. Depletion of the ozone layer
3. Depletion of natural resources
4. Land erosion.

Answer: 1. Population explosion

Question 20. The formula For exponential population growth is:

1. dl/clN = rN
2. c/N/rN = dt
3. rN/r/N = dt
4. dN/dt = rN.

Answer: 4. dN/dt = rN.

Question 21. Human population growth is :

1. Lag
2. Stationary
3. Exponential
4. None of these.

Answer: 3. Exponential

Question 22. Which of the Following birth control measures can be considered the safest?

1. the rhythm method
2. the use oF physical barrier
3. termination oF unwanted pregnancy
4. Sterilization techniques.

Answer: 2. the use of a physical barrier

Question 23. Write one of the Following concretely mulched Sexually transmitted Diseases (S tD) with its pathogen.

1. AIDS—Fiacillus anthraeis
2. Syphilis—7’irponcma
3. pallidumUirlhcrilis—Entamoeba gingivalls
4. Gonorrhoea—Leislimania donovani.

Answer: 2. Syphilis—7’irponcma

Question 24. lire most important component of contraceptive pills is: .

1. Progesterone
2. Growth hormone
3. Thyroxine
4. Luteinising hormone.

Answer: 1. Progesterone

Question 25. Chancroid is a sexually transmitted disease caused by :

1. treponema
2. Haemophilus
3. Nlisseiria
4. Chlamydia
5. trichomonas

Answer: 4. trichomonas

Question 26. Which of the following causes abortion in ladies?

1. Viruses
2. Bacteria
3. Mycoplasma
4. None of these.

Answer: 3. Mycoplasma

Question 27. Which one of the following statements is incorrect about menstruation?

1. At menopause in the Females, there is an especially abrupt increase in
   gonadotropic hormones
2. the beginning of the cycle of menstruation is called menarche
3. During normal menstruation about 40 ml of blood is lost
4. the menstrual Fluid can easily clot.

Answer: 4. the menstrual Fluid can easily clot.

Reproductive Health Neet Notes 

Question 28. Consider the statements given below regarding contraception and answer as directed thereafter:

(1)Medical termination of pregnancy (MTP) during the First trimester is generally safe

(2)Generally chances of conception are nil until the mother breast-feeds the Infants up to two years.

(3) Intrauterine devices like copper-t are effective contraceptives.

(4)contraception pills may be taken up to one week after coitus to prevent conception.

Which two of the above statements are correct?

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

Answer: 1. 1,3

Question 29. Given below are Four methods (a-d) and their modes of action (i-iv) in achieving contraception. Select their correct matching From the Four options that Follow.

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

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

Question 30. Medical termination of Pregnancy (M l P) is considered a sale tip to how many weeks of pregnancy?

1. Eight weeks
2. Twelve weeks
3. Eighteen weeks
4. Six weeks.

Answer: 2. twelve weeks

Question 31. Which one of the Following is the most widely accepted method of contraception in India, at present?

1. Cervical caps
2. tubectomy
3. Diaphragms
4. BJDs (Intrauterine devices).

Answer: 4. BJDs (Intrauterine devices).

Question 32.  The test-tube Baby Programme employs one of the following techniques?

1. Intra uterine insemination (IUI)
2. Gamete intra Fallopian transfer (GIFt)
3. Zygote intra Fallopian transFer (Z1Ft)
4. Intra cytoplasmic sperm injection (ICSI).

Answer: 3. Zygote intra Fallopian transfer (Z1Ft)

Question 33. What is the Figure given below showing in particular?

1. Uterine cancer
2. tubectomy
3. Vasectomy
4. Ovarian cancer.

Answer: 2. tubectomy

Question 34. Which of the following is wrongly matched?

1. IUI – semen collected From the husband or donor is artificially introduced either into the vagina or into the uterus.
2. GIFt – transFer oF embryos with more than 8 blastomeres into the Fallopian tube.
3. ICSI – sperm directly injected into the ovum.
4. ZIFt – transFer oF embryos with up to 8 blastomeres into the Fallopian tube.
5. tVF – Fertilization outside the body in almost similar conditions as that in the body.

Answer: 2. GIFt – transFer oF embryos with more than 8 blastomeres into the Fallopian tube.

Question 35. One of the legal methods of birth control is :

1. By abstaining From coitus From day 10 to 17 oF the menstrual cycle
2. By having coitus at the time of daybreak
3. A premature ejaculation during coitus
4. Abortion by taking an appropriate medicine.

Answer: 4. Abortion by taking an appropriate medicine.

Question 36. Which of the following cannot be detected in developing

1. Foetus by amniocentesis ?
2. Sex of the Foetus
3. Down syndrome
4. Jaundice
5. Klinefelter syndrome

Answer: 3. Jaundice

Question 37. Artificial insemination means:

1. Transfer oF sperms oF husband to a test tube containing ova
2. Artificial introduction oF sperm to a healthy donor into the vagina
3. Introduction oF sperms to a healthy donor directly into the ovary
4. Transfer oF sperms oF a healthy donor to a test

Answer: 2. Artificial introduction oF sperm to a healthy donor into the vagina

NEET Biology Animal Reproductive System

• Embryology: It is the study of events and changes that take place from fertilization to the hatching or birth of an individual and includes the changes of the prenatal period only.
• Developmental Biology: It is the study of the ontogenic development process by which organism undergoes changes in their structure and physiology during their entire life and includes the entire changes from fertilization to death.
• Reproduction: The process of producing the young ones of its type is called reproduction.

NEET Biology Animal Reproductive System Forms Of Reproduction

Asexual and Sexual reproduction are the two main forms of reproduction in animals.

• Asexual Reproduction: It is a type of multiplication in which an offspring is formed from a specialized or unspecialized part of the parent without the formation and fusion of sex cells and the process is termed blastogenesis.

Basic features of asexual reproduction:

1. Only one parent is involved.
2. All the cell divisions are mitotic.
3. All the offspring are genetically similar to the parent.
4. The reproductive unit is a fragment or specialized part of the parent.

Read and Learn More NEET Biology Notes

The different ways of asexual reproduction are :

• Budding, fission, fragmentation, plastotomy, etc. Budding may be external ExamplePorifers and Hydra) or internal Example Spongilla).
  • Fission may be binary Example Euglena) or multiple (Plasmodium)
    Fragmentation Example Earthworm), Sporulation ExampleAmoeba) Another asexual method is either androgenesis or gynogenesis.
• Sexual Reproduction: It is a type of reproduction that takes place through the formation and fusion of gametes and form zygotes and undergoes division to form an embryo, the process is termed embryogenesis.

Reproductive System In Animals NEET Notes

Types Of Sexual Reproduction

Basic features of sexual reproduction

1. Development of male and female organs.
2. Meiosis occurs in the life cycle.
3. Production of a large number of male and female gametes.
4. Motility of male gametes.
5. Hie two types of gametes fuse and they produce a diploid structure called a zygote.
6. A zygote produces an embryo by different changes.
7. Only the mature individuals can produce the gametes.

NEET Biology Animal Reproductive System Sexual Reproduction In Humans

The reproductive system is formed of primary sex organs, viz. testes and ovaries, which produce haploid gametes by meiosis.

• Secondary sex organs, organs that perform important functions in reproduction but neither produce gametes nor secrete sex hormones, are called secondary sex organs, Example prostate and seminal vesicles, Cowper’s glands in male and fallopian tubes, and also produce sex hormones uterus and vagina in the female.
• Accessory sex organs are the distinct structures or characters that distinguish the sex of a species in appearance viz. facial hair, broad larynx, etc. in males and breasts in females.

NEET Biology Animal Reproductive System Male Reproductive System

It is formed of testes present in the scrotal sacs; epididymis to store the sperms; vasa deferentia for conduction of sperms and penis as an intromittent organ. Testis consists of numerous coiled seminiferous tubules (crypts). Each is lined by germinal epithelium formed of germ cells and Sertoli (nurse) cells. Germ cells produce spermatozoa which obtain nutrition from the sertoli cells.

• The interstitial cells (Leydig’s cells) of the testis produce the male sex hormone, testosterone. Secondary sex glands of males include a prostate, two seminal vesicles, and two Cowper’s glands. The secretion of these glands, along with the sperms, form the semen.
• The human male reproductive system includes the testes, epididymis, vasa deferentia, seminal vesicle, prostate gland, urethra, bulbourethral gland, and intromittent organ penis.
• The Testes (Spermaries) or Male Gonads
• In the embryo, the testes develop along the posterior wall of the abdomen. Shortly before birth, they descend into a fleshy sac scrotum which hangs away from the body wall between the thighs. The penis and scrotum together constitute the male external genitalia.
• If the testes do not descend, sterility occurs because normal sperm production is inhibited by internal body temperature, hence a cooler temperature is required. Temperature in the scrotum is about 2 to 3° C cooler than those in the abdomen. Failure of the testes to descend into the scrotal sac is called cryptorchidism.
• In the wall of the scrotum, there is a layer of smooth muscle, the dartos muscle, which responds to changing temperature. In the cold, this muscle contracts, and the testes are drawn closer to the abdomen for warmth, while heat causes the muscles to relax and the testes descend further for cooling.
• Internally, the testes are subdivided roughly into many compartments, each of which contains tightly coiled tubules, the seminiferous tubules, where sperms are produced by spermatogenesis from sperm mother cells.
• Along the outer wall of these tubules, are specialized cells, called spermatogonia.
• Surrounding the spermatogonia and the developing sperm are large cells called Sertoli cells. These cells provide protection, support, and nourishment to the developing sperm. Sertoli cells provide a barrier that protects sperm from an attack by the body’s immune system.
• After puberty, millions of sperm mature each day. A male continues to make sperm from puberty until death, though the number of living sperm arc reduces with age.
• Each ejaculation releases semen (a volume of fluid containing up to 300 million
  sperm). If a male releases fewer than 60 million sperm is usually considered infertile.

Reproductive System In Animals NEET Notes

NEET Biology Animal Reproductive System Transport Or Sperms

• Maturing spends are washed down in scmmilcnnis mimics by scaling Irom Sertoli cells and begin a long journey that may end in lentil/nylon.
• From die tubules, (be sperms enter the epididymis, then the vas deferens, and eventually the urethra. Along the way. three accessory glands – the seminal vesicles i.e., And the bulbourethral glands, contribute secretions.
• Together with the sperm, these secretions form semen. Tint semen is a thick whitish fluid that contains fluid from accessory glands.
• In each testis, the epididymis is a long coiled tube, where the sperm can be stored while they mature. The wall of the epididymis contains smooth muscle which can contract rhythmically to propel the sperm into the vas deferens during ejaculation

NEET Biology Animal Reproductive System Female Reproductive system

It comprises a pair of ovaries, two fallopian tubes, a uterus, and a vagina. Each ovary is encased by germinal epithelium composed of germ cells that develop into primary follicles.

• A primary follicle transforms into a Graafian follicle due to the action of FSH. Ovulation is regulated by luteinizing hormone (LH). The ovaries secrete estrogens and progesterone hormones.
• The fallopian tubes transport the ovum to the uterus, which serves as the site for fetal development throughout gestation, while the vagina functions as the delivery canal. The vulva is the external genitalia of females.
• Breasts are secondary sexual characteristics in females. Their size is contingent upon ovarian estrogens throughout puberty and lactogenic hormone following parturition.

NEET Biology Animal Reproductive System Female Gonads The Ovaries

The paired ovaries produce an egg each month. Ovaries lie on the lateral wall of the upper pelvic cavity and are held in position by supportive ligaments.

• Each ovary’ is covered with a layer of germinal epithelium. Within this covering, there are small sac-like structures, called ovarian (Graafian) follicles.
• These follicles pass through different stages of development: primary follicles, secondary follicles, and mature follicles.
• The small primary follicle consists of a single layer of cells and contains an immature ovum. The follicle cells support and protect the developing ovum and also produce the hormone estrogen, which maintains a woman’s secondary sex characteristics.
• The larger secondary follicle develops from the primary follicle and supports the maturation of the ovum.
• The next stage is the graafian follicle which has several layers of cells and a fluid-filled cavity surrounding the developing ovum.
• The immature ovum released from the Graafian follicle is called ovulation. Ovulation occurs about once a month. After ovulation, the follicle structure changes into a hormone-secreting structure, the corpus luteum, before degrading.
• The development of the follicle and the release of an immature ovum at ovulation are both initiated and controlled by follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland. The ovum will become completely mature only if it is fertilized by a sperm.
• At the time of birth, a female baby has about 500000 primary oocytes. During her life, she will make no more, most of them will degenerate before puberty. Only about 500 will develop sufficiently to be released by ovulation.

NEET Biology Animal Reproductive System Oviducts (Fallopian tubes)

The two oviducts transport the secondary oocyte to the uterus. One end of each tube attaches to the uterus, while the opposite end develops into a funnel-shaped structure known as fimbriae, which loosely encircles the ovary. Fertilization often transpires in the proximal portion of the fallopian tube.

NEET Biology Animal Reproductive System Uterus

The uterus is a hollow pc. un-shaped muscular urgim. where the fertilized ovum grows and develops.

• It is Emily covered the peritoneum mid-the cavity is lined by endometrium llieuicuis consisting of men: the hotly (expanded upper portion; the lathis (consoled rental pot lion) and the cervix.
• The ss. ill ol the Julius contains three distinct layers. The oilier thin covering ipcritoneunO is an eontinumion of die peritoneal membrane. ‘The middle link layer (myometrium) contains smooth muscles.
• The inner lining, called endometrium contains abundant blood vessels and glands to nourish and protect the embryo.
• li fertilization occurs, the early embryo burrows into this layer through a process called implantation. If fertilization and implantation, do not occur, portions of this layer are shed and replaced every month during the menstrual cycle.

Animal Reproductive System NEET Study Material

NEET Biology Animal Reproductive System Vagina

• The vagina is a flexible muscular tube extending from the cervix to the body’s exterior. The female genitalia are collectively called the vulva.
• The vulva includes two sets of fleshy folds called labia, the mons pubis, and the clitoris.
• The female reproductive system has five major functions.

1. 1. It produces and transports the female gametes and receives the sperm of the male.
   2. It provides a site for fertilization.
   3. It supports, protects, and nourishes the development of the fertilized egg, embryo, and fetus.
   4. It provides a birth canal for the newborn infant.

• In addition to these reproductive functions, the female produces milk from mammary glands to nourish the newborn child.
• The primary organs that accomplish these tasks are a pair of ovaries, a pair of uterine tubes (oviducts or fallopian tubes), a uterus, and the vagina.

NEET Biology Animal Reproductive System The Menstrual Cycle

NEET Biology Animal Reproductive System Puberty

It is the period of sexual maturity. It comes between 13 to 16 years in the male and between 10 to 14 years in the female.

It is controlled by testosterone in the male and estrogens in the female. It is characterized by the development of secondary sexual characters.

• Precocious puberty: Normally a woman’s fertile life starts from the age of puberty (about 13 years), but under some abnormal conditions like high levels of sex hormones (LH and FSH), menstruation starts at an earlier age than normal, it is called precocious puberty.
• Orgasm in females: During intercourse, under the influence of various stimuli, the female becomes excited. The clitorial and genital folds swell and the vaginal wall secretes a moist lubricating fluid.
  • The breasts swell and the nipples become erect. Orgasm is associated with the contraction of the vaginal wall. At orgasm, the cervix drops down into the upper portion of the vagina and creates a syringing action on the pool of semen.
• Parturition: It is a process of expulsion of a fetus from the uterus. It starts at the end of pregnancy. It takes place by the rhythmic contractions and propulsion movements of the uterine wall.
  • The cervix becomes soft and dilates at that time. The tire fetus is pushed down into the genital passage. Generally, the head comes out first. If legs come first then the baby is called a breech baby.
  • The period of the year when an animal may breed is called breeding season For Example autumn for sheep and spring and autumn for bitches. The estrous cycles run only’ during the breeding season in monoestrous animals.
  • The estrous cycles run throughout the year in polyestrous animals Example Cow, Buffalo.
  • The suspension of the estrous cycle in female animals throughout the non-breeding season is called the state of anoestrum.

Animal Reproductive System NEET Study Material

NEET Biology Animal Reproductive System Memory Points

• Cow and buffalo are continuously breeding animals.
• The ovum or egg is the largest cell of the body.
• Monarch. The onset of the menstrual cycle in females is termed menarche.
• Most birds possess only the left ovary and the left oviduct for conveying the ovum released from the ovary, the right ovary and right oviduct being rudimentary vestiges.
• The left oviduct leads to a swollen tube called a shell gland. When the egg reaches here through the oviduct, the shell gland deposits calcium salts on it to form the eggshell.
• Uterine milk. Nutritive endometrial secretion.
• Miscarriage or Abortion. Loss of embryo due to breakdown of endometrium due to lowering of progesterone secretion from corpus luteum.
• Colostrum. ‘I the fluid released from the nipples a few days after parturition. It is ri(h in protein globulin and low in fat. It transfers antibodies from mother to baby.
• Mali-, have high IJMK due to greater activity.
• Vitellogenesis. Synthesis of yolk in primary oocyte during prophase.
• The side of the ovum that extrudes polar bodies is known as an animal pole and the opposite side is a vegetal pole.
• In a woman’s loiillily period of 32 yours, about 13 eggs mnlurr ouch year .mil on about eggs have chance In reach maturity.
• Ovulation in human female lakes placed on Mill clay of menstrual cycle which is 28 a. 2-day cycle.
• Ovulation. Release of ovum during the menstrual cycle is due To a large concentration of 11 on the Mill day of the menstrual cycle.
• Menstrual bleeding is caused due to the reduction in concentration of both estrogen and progesterone especially progesterone During the first trimester of pregnancy, the corpus luleum secretes the progesterone hormone which maintains pregnancy.
• Chorionic gonadotropin is secreted from the placenta which is formed during pregnancy only.
• At the time of parturition (Childbirth), the hormone secreted is relaxin, which relaxes the pubic ligaments and helps in childbirth.
• The ovaries contain 2 million or more primary oocytes 6 months before birth about a million at the time of birth and only 400,000 remain by the time of puberty.

NEET Biology Animal Reproductive System Important Terms

1. Microgamete:  (sperm) small-sized, haploid, motile gamete that is deficient in stored nutrients is a tanned microgamete.
2. Macroganiete:  (Ovum or female gamete). It is large-sized, non-motile, haploid, laden with nutrients is called macrogamete.
3. Isogamy:  The fusion of similar gametes is called isogamy. e.g Monocystis.
4. Anisogamy:  The fusion of gametes that are different in form, size, and behavior is termed anisogamy, such gametes are termed heterogametes, e.g. frogs, human
5. Estrous Cycle:  It consists of a few days of estrous (heat) followed by a few days of anoestrous. There is no bleeding and endometrium is reabsorbed.
6. Semen:  It is a fluid which is usually ejaculated only after the penis has been stimulated during sexual excitement. It contains sperms (about 200-400 million per 3 ml.), secretions of various reproductive glands, fibrinogen, thromboplastin, and calcium citrate.
7. Corpus tuteum:  The ruptured Graafian follicle after ovulation is called corpus Iuteum and secrete progesterone hormone into blood.
8. Spermatic cord:  It is an elastic cord that passes through the inguinal canal and is attached to the testis.
9. The gubernaculum Mesometriun: is a fibromuscular tissue that binds the testis with the scrotal sac.
10. Sertoli cells:  Sertoli cells = Nurse cells = subtesticular cells. •
11. Graafian follicleMesometriun: discovered by Regnier de Graff.
12. Antrum:  Antrum fluid-filled space in Graafian follicle
13. Mesometriun:  Mesometriun Fold of peritoneum lining which encloses the uterus and vagina
14. Mesovarium:  Fold of the peritoneal membrane that surrounds the ovary in frog
15. Mesosalpinx:  The fold of the peritoneal membrane that surrounds the fallopian tube.
16. Mesorchium: The fold of the peritoneal membrane surrounds the testes in frogs.

In male frogs, nuptial pads are found at the metacarpals of 1st digit of the forelimb. These are also known as copulatory pads.

• The two fundamental methods of reproduction are asexual and sexual reproduction.
• Monocystis, Plasmodium, and Paramecium are acellular protists that reproduce sexually.
• Pseudopodiosporcs. During multiple fission in cysted amoeba many minute amoebae are formed termed pseudopodiospores.
• Gemmules are formed as internal buds (endogenous) covered by opaque envelopes in porifers such as Spongilla.
• Conjugation in Paramecium. It is the gametic nuclei fusion between two conjugating individuals through the cytoplasmic bridge.
• Animals with ability are termed as Hermaphrodite
  The development of an unfertilized ovum into a new individual is called parthenogenesis.
• The mature follicles are termed Graafian follicles. Rete-testis are cuboidal epithelium lined channels from which arise 10-20 fine tubules termed ductules efferent- tia.
• Mesovarium. The peritoneal membrane by which ovaries are suspended from the wall of the pelvic cavity.
• Cumulus oophorus. A heap of granulosa cells by which oocyte adheres to the wall of the follicle.
• Corpus lutcum. The granulose cells and interstitial cells form a mass of large yellowish conical cells after ovulation.
• c& Follicular atresia. Follicles in the ovaries that undergo regression and disappear due to death and are disposed of by phagocytes during the reproductive years of females are referred to as follicular atresia.
• Hormonal control of the male reproductive system  The hypothalamus has ultimate control of the testes’ sexual function because it secretes a hormone called gonadotrophic releasing hormone (GnRH) that stimulates the anterior pituitary to produce the gonadotrophic hormones.
• There are two gonadotrophic hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH), in both males and females. In males, FSH promotes spermatogenesis in the seminiferous tubules which also release the hormone inhibin. Inhibin acts to inhibit luteinizing hormone secretion by the anterior pituitary gland.

Animal Reproductive System NEET Study Material

• LH in males is sometimes given the name Interstitial cell-stimulating hormone (ICSH) because it controls the production of testosterone by the interstitial cells, scattered in the spaces between the seminiferous tubules.
• All these hormones are involved in a negative feedback relationship that maintains the constant production of sperm and testosterone.
• Testosterone is the main sex hormone in males. It is essential for the normal development and functioning of the male reproductive organs. Testosterone is also necessary for the maturation of sperm.
• Testosterone brings about and maintains the male secondary sex characteristics that develop at the time of puberty. It is responsible for the greater muscle strength of males, and this is the reason some athletes take supplemental amounts of anabolic steroids which are either testosterone or related chemicals.
• Hormonal control of the female reproductive system Mature females produce two sex hormones: estrogen and progesterone. Both are produced in the ovary by the specialized cells.

• During puberty, the anterior pituitary begins releasing LH and FSH together, L.H. and FSH stimulate the ovaries to produce estrogen and progesterone.
• Estrogen is responsible for the development of secondary sexual characteristics and for cyclic changes in the vaginal epithelium and endothelium of the uterus.
• Estrogen is also responsible for contour changes in the pelvis and the distribution of fat under the skin. Progesterone is a steroid hormone produced by the corpus lutein and placenta.
• Progesterone is responsible for changes in uterine endometrium in the second half of the menstrual cycle preparatory for the implantation of the blastocyst, development development of the maternal placenta, and implantation of mammary glands.

Hormonal Control of Menstrual Cycle. Gonadotropin-releasing hormone (GnRH) also called gonadotropin-releasing Factor (GnRF), is secreted by the hypothalamus of the brain, which stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

FSH stimulates the ovarian follicles to produce estrogens during the proliferative phase. LH stimulates the corpus luteum of the ovary to secrete progesterone.

1. The menstrual phase is caused by the reduction of progesterone and estrogens.
2. The proliferative phase is caused by the increased production of estrogens.
3. LH causes ovulation.
4. The secretory phase is caused by increased production of progesterone.

Capacitation: The sperms in the female’s genital tract are made capable of fertilizing the egg by secretions of seminal vesicles, prostate gland, and Cowper’s glands present in the semen itself. This process is called capacitation of sperms. It takes several (5 – 6) hours and involves n change in the properties of the membrane covering the acrosome.

1. Sperm lysins
2. Hyaluronidase
3. Corona penetrating enzyme
4. Fertilizin is a chemical that is released by acrosome during fertilization.

Reproductive System In Animals NEET Biology Notes 

NEET Biology Animal Reproductive System Quanta To Memory

Menstrual Cycle

• The menstrual Phase is caused by the reduction of progesterone and estrogens
• The proliferative phase is caused by increased production of estrogen
• LH causes ovulation
• The secretory phase is caused by an increase in progesterone

Fertilization 

• Physico-chemical event
• Site-Ampullary -Isthmic junction
• Insemination (single ejaculate contains 300 million sperm)
• The arrival of secondary oocyte stage
• Capacitation of sperms
• Acrosomal reactions
• Sperms Entry
• Karyogamy
• Activation of egg

Placenta

• The Chorionic Placenta Foetal part, chorion, and material part of the decidua basalis
  • Nutrition
  • Respiration
  • storage
  • Excretion
  • Barrier
• Endocrine Role- Oestrogen, progesterone, HCG Relaxin hp

NEET Biology Animal Reproductive System Questions From Competitive Examinations

Question 1. Which set is similar :

1. Corpus luteum – graafian follicles
2. Sebum – Sweat
3. Bundle of His – Pacemaker
4. Vit. B – Niacin.

Answer: 1. Corpus luteum – Graafian follicles

Question 2. The temperature of the scrotum which is necessary for the functioning of
the testis is always below body temperature. This difference is:

1. 2°C
2. 3°C
3. 4°C
4. 6°C

Answer: 1.2°C

Question 3. Bartholin glands are situated :

1. On either side of the vagina in humans.
2. On either side of the vas deferens in human
3. On the sides of the heads of some amphibians
4. At the reduced tail ends of birds.

Answer: 1. On either side of the vagina in humans.

Reproductive System In Animals NEET Biology Notes 

Question 4. The menstrual cycle is affected by :

1. Progesterone only
2. LH only
3. LH + FSH + oestrogen
4. Oestrogen only.

Answer: 3.LH + FSH + oestrogen

Question 5. The preparation of sperm before entry into the ovum is called

1. Insemination
2. Maturation
3. Capacitation
4. Fertilization.

Answer: 3. Capacitation

Question 6. The oocyte is liberated from the ovary under the influence of LH, after completing ;

1. Meiosis and before liberating polar bodies
2. Meiosis-I and before liberating polar bodies
3. Meiosis
4. Meiosis after the release of the polar body.

Answer: 4. Meiosis after the release of the polar body.

Question 7. Which is correct about human embryonic development?

1. Cleavage divisions bring about a considerable increase in the mass of protoplasm In the school division.
2. one of the two elastomers usually divides a little sooner than the second
3. With more cleavage division, the resultant blahs- come Ivconie larger and larger
4. Cleiv age division results in a hollow ball of cells called the month

Answer: 2. one of the two elastomers usually divides a little sooner than the second

Question 8. The number of chromosomes in a mature gamete gets halved during :

1. Formation of first polar body
2. Formation of second polar body
3. Meiosis 2
4. Division of secondary oocyte and spermatocyte.

Answer: 1. Formation of first polar body

Question 9. Frog’s testes do not possess :

1. Interstitial cells
2. Seminiferous tubules
3. Sertoli cells
4. Seminal vesicles.

Answer: 3. Sertoli cells

Question 10. In oogamy, fertilization involves :

1. A large non-motile female gamete and a small non-motile male gamete
2. A large motile female gamete and a small non-mo- tile male gamete
3. A small non-motile female gamete and a large motile male gamete
4. A large non-motile female gamete and a small motile male
   gamete,

Answer: 4. A large non-motile female gamete and a small motile male gamete,

Reproductive System In Animals NEET Exam Preparation

Question 11. In human females, ovulation occurs during the menstrual cycle :

1. At the end of the proliferative phase
2. In the middle of the secretory phase
3. Just before the end of the secretory phase
4. At the beginning of the proliferative phase.

Answer: 1. At the end of the proliferative phase

Question 12. Nebenkem is a part of:

1. Human ovum
2. Human sperm
3. Fetus
4. Graafian follicle.

Answer: 2. Human sperm

Question 13. Yellow-colored milk secreted by cattle soon after the birth of a calf is called :

1. Cholesterol
2. Colostrum
3. Chyme
4. Chyle.

Answer: 2. Colostrum

Question 14. In the diagram of the section of the Graafian follicle, different pans are indicated by alphabets. Choose the answer in which these alphabets have been correctly matched with the parts they indicate.

1. A =Membrana granulosa: B = Theca interna;
C = ovum; D = Cumulus rooms: E = Antrum;
F = Theca externa

2. A= Theca externa; B = Theca interna; C = ovum;
D = Mcmbrana granulosa; E = Antrum ;
F = Cumulus oophorus

3. A = Theca externa; B = Theca interna;
C = ovum; D = Cumulus oophorus; E = Antrum ;
F = mcmbrana granulosa

4. A = Membrane granulosa; B = Theca externa ;
C = Ovum ; D = Cumulus rooms ; E = Antruin ;
F =Theca interna

Answer: 3. A = Theca externa; B = Theca interna;
C = ovum; D = Cumulus oophorus; E = Antrum ;
F = mcmbrana granulosa

Question 15. Ovulation in the human female normally takes place during the menstrual cycle :

1. At the beginning of the proliferative phase
2. At the end of the proliferative phase
3. In the mid of the secretory phase
4. Just before the end of the secretory phase.

Answer: 2. At the end of the proliferative phase

Question 16. In which of the following organisms testes descend into the scrotum in the breeding season but in non-breeding season?

1. Frog
2. Kangaroo
3. Shrew
4. Bat.

Answer: 4. Bat.

Question 17. The proliferation of endometrium of the uterus is controlled by :

1. Relaxin
2. Oxytocin
3. Progesterone
4. Oestrogen
5. Luteinizing.

Answer: 4. Luteinizing.

Question 18. The type of placenta in sharks is

1. Allantoic
2. yolk sac
3. Hemophilia
4. Syndesmochorial.

Answer: 2. yolk sac

Reproductive System In Animals NEET Exam Preparation

Question 19. Which cell organelle is absent in human sperm?

1. ER
2. Mitochondria
3. Nucleus
4. Centrioles.

Answer: 1. ER

Question 20. The origin of the kidney and ureter in Rcina Grinch is

1. All mesodermal
2. All endodermal
3. Ectodermal and mesodermal
4. Mesodermal and endodermal.

Answer: 1. All mesodermal

Question 21. Which of the following is ‘immortal’?

1. Somatic cells
2. Glomerular cells
3. Genu cells
4. Cells of pituitary.

Answer: 3. Genu cells

Question 22. Grey crescent is an area :

1. At the point of entry of sperm into the ovum
2. At the animal pole
3. Just opposite to site of sperm entry into the ovum
4. At the vegetal pole.

Answer: 3. Just opposite to the site of sperm entry into the ovum

Question 23. Wolffian duct forms :

1. Epididymis
2. Oviduct
3. Ejaculatory duct
4. Urethra.

Answer: 1. Epididymis

Question 24. A cross-section at the midpoint of the middle piece of a human sperm will show:

1. Centriole, mitochondria and 9 + 2 arrangement of microtubules
2. Centriole and mitochondria
3. Mitochondria and 9 + 2 arrangement of microtubules
4. 9 + 2 arrangement of microtubules only.

Answer : 3. Mitochondria and 9 + 2 arrangement of microtubules

Question 25. Which one of the following events is coevally inches with the lime period in a normal menstrual cycle?

1. Release of egg = 5 days
2. Endometrium regenerate = 5-1O days
3. Endometrium secretes nutrients for implantation:11-18days
4. Rise in progesterone:1-15days

Answer: 3. Endometrium secretes nutrients for implantation:11-18days

Reproductive System In Animals NEET Previous Year Questions

Question 26. if the mammalian ovum fails to be fertilized, which one of the following is unlikely?

1. Corpus him will disintegrate
2. Hsitogen secretion I’m decreases
3. Primary follicle starts developing
4. Progesterone secretion rapidly declines.

Answer: 3. Primary follicle starts developing

Question 27. In which one of the following sets of animals do all four give birth to young ones?

1. Lion. hat. whale, ostrich
2. Platypus, penguin, bat, hippopotamus
3. Shrew, bat. cat, kiwi
4. Kangaroo, hedgehog, dolphin, loris.

Answer: 4. Kangaroo, hedgehog, dolphin, loris.

Question 28. Roth corpus lutcum and macula lutea are :

1. Found in human ovaries
2. A source of hormones
3. Characterized by a yellow color
4. Contributory in maintaining pregnancy.

Answer: 3. Characterised by a yellow color

Question 29. Sertoli cells are regulated by (the pituitary hormone known as:

1. LSI
2. GII
3. Prolactin
4. LI I.

Answer: 1. LSI

Question 30.Withdrawal of which of the following hormones is the immediate cause of menstruation?

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

Answer: 4. Progesterone

Reproductive System In Animals NEET Previous Year Questions

Question 31. In the cloning of cattle, a fertilized egg is taken out of the mother’s womb, and :

1. In the eight-cell stage, cells are separated and cultured until small embryos are formed which are implanted into the womb of other cows.
2. In the eight-cell stage, the individual cells are separated under an electrical field for further development in culture media.
3. From this upload eight identical twins can be produced
4. Die egg is divided into 4 pairs of cells which are implanted into the womb of other cows. ‘

Answer: 1. In the eight-cell stage, cells are separated and cultured until small embryos are formed which are implanted into the wombs of other cows.

Question 32. In the human female, menstruation can be deferred by die administration of:

1. Combination of FSH and LH
2. Combination of estrogen and progesterone
3. FSH only
4. LH only

Answer: 2. Combination of estrogen and progesterone

Question 33. In humans, at the end of the first meiotic division, the male germ cells differentiate into the :

1. Spermatids
2. Spetmnlogniiili
3. Ptimiity spcim.isocyclic
4. Secondly spcimaiocylcH.

Answer: 4. Secondnty spcimaiocylcH.

Question 34. Which of the following sliilemeiil’. is incorrect about nicnslriinlion?

1. The menstrual fluid can easily clot
2. During normal menstruation about 40 ml. of blood is lost
3. The beginning of the cycle of incnslrucation is called menarche
4. At menopause in the female, there is an especially abrupt increase in gonadotropic hormones.

Answer: 1. The menstrual fluid can easily clot

Question 35. Which one of the following statements about human sperm is correct?

1. The sperm lysins in the acrosome dissolve the egg envelope
   facilitating fertilization.
2. Acrosomc serves as a sensory structure leading the sperm toward the ovum
3. Acrosomc serves no particular function
4. Acrosomc has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilization.

Answer: 4. Acrosomc has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilization.

Question 36. The signals for parturition originate from :

1. Placenta as well as a fully developed fetus
2. Oxytocin released from the maternal pituitary
3. Fully developed fetus only
4. Placenta only.

Answer: 1. Placenta as well as fully developed fetus

Reproductive System In Animals NEET Previous Year Questions

Question 37. Sertoli cells are found in :

1. The adrenal cortex secretes adrenaline
2. Seminiferous tubules provide nutrition to germ cells
3. Pancreas and secrete cholecystokinin
4. Ovaries and secrete progesterone.

Answer: 2. Seminiferous tubules and provide nutrition to germ cells

Question 38. Which of the following is characteristic of the 27th day of the menstrual cycle?

1. Stasis of blood in the basal straight arteries of the endometrium
2. Constriction of the coiled spiral arteries
3. Increased proliferation of the endometrium
4. Increased edema of the functional spongy layer of the endometrium.

Answer: 2. Constriction of the coiled spiral arteries

Question 39. In the male reproductive system :

1. Spermatozoa pass in order through efferent ductules, rete testis,
   and ductus epididymis.
2. The ductus deferens, seminal vesicle, and prostate- all have smooth muscle in their walls.
3. the seminal vesicle is the main source of acid phosphatase in the semen
4. The prostate gland is a site where the maturation of sperm occurs.

Answer: 2. The ductus deferens, seminal vesicle, and prostate- all have smooth muscle in their walls.

Question 40. The figure given below depicts a diagrammatic sectional view of the female reproductive system of humans. Which one set of three parts out of I-Vl have been correctly identified?

1. (2) Endometrium. (3) Infundibulum, (4) Fimbriae
2. (4) Ovitlucal funnel, (5) Utenis, (6) Cervix
3. (3)Infundibulum, (4) Fimbriae, (5) Cervix
4. (1) Perimetrium,(2) Myometrium. (3) Fallopian lube.

Answer: 3. (3)Infundibulum, (4) Fimbriae, (5) Cervix

Question 41. The testes in humans are situated outside the abdominal cavity inside a pouch called the scrotum. The purpose served is for:

1. Maintaining the scrotal temperature lower than the internal body temperature
2. Escaping any possible compression by the visceral organs
3. Providing more space for the growth of epididymis
4. Providing a secondary sexual feature for exhibiting the male sex.

Answer: 1. Maintaining the scrotal temperature lower than the internal body temperature

Question 42. If for some reason, the vasa efferentia in the human reproductive system get blocked, the gametes will not be transported from :

1. Ovary to uterus
2. Epididymis to vas deferens
3. Testes to epididymis
4. Vagina to the uterus.

Answer: 3.Testes to epididymis

Question 43. The luteal (secretory) phase of the menstrual cycle is characterized by all of the following:

1. Coiling or sacculation of endometrial glands
2. Decreased amounts of progesterone in the blood plasma
3. The presence of a functional corpus luteum
4. Atresia of some ovarian follicles.

Answer: 3. The presence of a functional corpus luteum

Question 44. The first movements of the fetus and the appearance of hair on its head are usually observed during which month of pregnancy?

1. Fifth month
2. Sixth month
3. Third month
4. Fourth month.

Answer: 1. Fifth month

Question 45. Hie second maturation division of the mammalian ovum occurs:

1. Until after the ovum has been penetrated by a sperm
2. Until the nucleus of the sperm has fused with that of the ovum
3. In the Graafian follicle following the first maturation division
4. Shortly after ovulation, the ovum makes entry into the fallopian tube.

Answer: 1. Until after the ovum has been penetrated by a sperm

Question 46. Which one of the following statements about morula in humans is correct?

1. It has far less cytoplasm as well as less DNA than an uncleaved
   zygote.
2. It has more or less an equal quantity of cytoplasm and DNA as in
   uncleaved zygote.
3. It has more cytoplasm and more DNA than an uncleaved zygote.
4. iDl It has an almost equal quantity of cytoplasm as an uncleaved zygote
   but much more DNA

Answer: 1. It has far less cytoplasm as well as less DNA than an uncleaved zygote.

Question 47. During the  (sperm to- genesis), the awesome arises by the accumulation of material in :

1. Mitochondria
2. The nucleus
3. The Golgi complex
4. The nuclear envelope.

Answer: 3. The Golgi complex

Question 48. Seminal plasma in human males is rich in :

1. Glucose and calcium
2. DNA and testosterone
3. Ribose and potassium
4. Fructose and calcium.

Answer: 4. Fructose and calcium.

Question 49. What is correct to say about the hormone action in humans?

1. Secretion of thymosin is stimulated with aging.
2. In females, FSH first binds with specific receptors on the ovarian cell membrane.
3. FSH stimulates the secretion of estrogen and progesterone.
4. Glucagon is secreted by P-cells of Islets of Langerhans and stimulates glycogenolysis.

Answer: 2. In females, FSH first binds with specific receptors on the ovarian cell membrane.

Question 50. In a normal pregnant woman, the amount of total gonadotropin activity was assessed. The result expected was:

1. High level of circulating HCG to stimulate endometrial thickening.
2. High levels of FSH and LH in the uterus stimulate endometrial thickening.
3. High level of circulating HCG to stimulate estrogen and progesterone synthesis.
4. High levels of circulating FSH and LH in the uterus stimulate the implantation of the embryo.

Answer: 1. High level of circulating HCG to stimulate endometrial thickening.

Question 51. Signals for parturition originate from :

1. Oxytocin released from the maternal pituitary
2. Placenta only
3. The fully developed fetus only
4. Both placenta as well as fully developed fetus.

Answer: 4. Both placentas as well as the fully developed fetus.

Question 52. The Leydig’s cells as found in the human body are the secretory sources of:

1. Intestinal mucus
2. Glucagon
3. Androgens
4. Progesterone.

Answer: 3. Androgens

Question 53. Which one of the following is not the function of the placenta? It:

1. Secretes estrogen
2. Facilitates removal of carbon dioxide and waste material from embryo
3. Secretes oxytocin during parturition
4. Facilitates supply of oxygen and nutrients to the embryo.

Answer: 3.Secretes oxytocin during parturition

Question 54. What is the correct sequence of sperm formation ?

1. spermatogonia, spermatocyte, spermatozoa, spermatid
2. Spermatogonia, spermatozoa, spermatocyte, spermatid
3. Spermatogonia, spermatocyte, spermatid, spermatozoa
4. Spermatid, spermatocyte, spermatogonia, spermatozoa

Answer: 3.Spermatogonia, spermatocyte, spermatid, spermatozoa

NEET Biology Sexual Reproduction In Plants

• Angiosperms are the most common vascular plants on Earth. The plant body is sporophyte, differentiated into true roots, stems and leaves. A flower is a reproductive organ. Stamen (part) has 2 anthers, and 4 pollen sacs, each pollen sac has tapetum and pollen mother cells. They produce haploid microspores (pollen grains) by microsporogenesis
• Carpel (part), the ovary possesses an ovule, and each ovule has two integuments, a nucellus and one megaspore mother cell. 4 haploid megaspores are produced by megasporogenesis.
• The main function of the flower includes the production of pollen grain and ovule, pollination, fertilization, development and dispersal of seeds and fruits.
• Embryology
• It is the study of the development of the embryo.
• It includes sporogenesis, fertilization and embryo formation. Sporogenesis. It is a mode of spore formation and involves meiosis. It is of two types microsporogenesis in the pollen sac of anther and megasporogenesis inside the ovule.
• Microsporogenesis. The mature anther is a two-lobed structure. It has four pollen sacs or microsporangia. The cavity of the microsporangium encloses a large number of The life cycle of an Angiospermic plant.

Read and Learn More NEET Biology Notes

• Encloses huge Mumbai to Microsoft mother cells, they are diploid. They undergo meiosis and each one of them produces 4 haploid cells or microspores that are arranged in distinct groups to tout or tetrad.
• These groups are surrounded by a common wall of spore mother cell, these microspores develop their wall within tetrad and later separate.

NEET Biology Sexual Reproduction In Plants Pollen Grain (Microspore)

It typically has a circular shape with a wall and an interior consisting of 2 to 3 cells. The wall comprises two layers: an exterior thick exline of spuropollenin and an interior thin inline of pectocellulose. Sporopollenin is an extremely durable lipidic compound associated with cutin. The exine is categorized into the inner endexine and the outer Kleine.

Sexual Reproduction In Flowering Plants NEET Notes

Ektexine is formed of three layers

1. Inner continuous foot layer
2. Middle discontinuous bacula layer and
3. Outer discontinuous tectum.

The tectum and bacula layers produce designs over the surface of the pollen grain. Exine is absent in certain areas called germ pores (if rounded) or germinal furrows (if elongated). Depending upon their number, the pollen grains are monocolpate, bioplate, tricolpate, etc.

• In monocots, the pollen grains generally possess one germinal furrow (monocolpate) while in dicots the pollen grains have generally three germ pores (tricolpate). The sculpturing, number and position of germ pores are characteristics of each species.
• The branch dealing with the study of pollen grain characteristics is known as palynology. Insect disseminated pollen grains have a covering of a yellow sticky substance called pollen kit. Internally the pollen grain has (/) tube or vegetative cell with a degenerating nucleus, vacuolate cytoplasm rich in starch and unsaturated oil and (n) one generative cell or two male gametes derived from it.

NEET Biology Sexual Reproduction In Plants Pollination

The process by which pollen is carried from the anther to the surface of the stigma in angiosperms is called pollination.

It is of two types :

1. The pollination of one plant by pollen from another individual is called cross-pollination ;
2. On the other hand, the pollination of a carpel by the pollen from the same flower or the same individual is called self-pollination.
   • The earlier information on the concept of pollination is available in the works of Herodotus, Theophrastus, Grew, Camerarius, Kolreuter etc.
   • The concept is divided into two categories: autogamy, involving one flower, and allogamy, involving two flowers.
   • Since this classification is genetically unsound, the concept is now divided into three categories autogamy, geitonogamy and xenogamy.
     1. Utogamy. It is the transference of pollen grains from the anther of a flower to the stigma of the same flower bisexual Example Pea, Wheat, Rice, etc.
     2. Geitonogamy. When pollen from one flower is deposited on the stigma of another flower bome on the same plant.
     3. Xenogamy. Pollination takes place between two flowers made by two separate plants of the same or allied species.

The contrivances which favour autogamy are homogamy and cleistogamy. In the latter case, self-pollination is the rule.

1. Homogamy. It is the condition in which anthers and stigmas in bisexual flowers attain maturity at the same time.
2. Cleistogamy. In cleistogamy, flowers never open to expose their sex organs and the pollens fall on the stigma of the same flower Example Commelina, Viola, Oxalis, Drosera etc. Cleistogamy is followed by geocarpy in plants like groundnuts (fruits are formed in the soil).
3. Bud Pollination. Pollination occurs in bud conditions, for example, in peas and wheat. The self-pollinated flowers develop many devices like a direct touch of anthers and stigma at maturity by bending the filament of stamen on the stigma (Mirabilis jalapa) or by curving the style on the anthers having terminal porous dehiscence (Solatium ).

Sexual Reproduction In Flowering Plants NEET Notes

In Vinca rosea the anthers are present at the mouth of the corolla tube and mature when the stigma passes through the mouth of the corolla tube, causing self-pollination. In sunflower self-pollination lakes are placed by the curving of the receptive surface of the stigma downward and inward, thus coming in contact with their pollen grain. This happens when cross-pollination fails in sunflowers.

NEET Biology Sexual Reproduction In Plants Contrivances Which Favour Allogamy

They are dicliny, self-sterility, dichogamy, herkogamy and heteromorphism. The contrivance best suited to allogamy is declined. The dichotomous flowers may be protandrous or protogynous. The heteromorphic flowers may lie dimorphic or trimorphic. The polymorphism may be due to heterostyly and or heterarchy.

1. Dicliny or Unisexunlity
   • Monoecious, Example. Maize, Cucurbits, Castor
   • Dioecious. Examples, are Carica papaya, Mulberry, and Cannabis.
2. Self-sterility or incompatibility: The pollen of a flower has no fertilizing effect on die stigma of the same flower, e.g., Passiflora, Malva, Potato.
3. Dichogamy. Male and female sex organs mature at different times.
   • Protandry. Anthers mature earlier dian die gynoecium, Example, China-rose, Lady’s finger. Foeniculum, Jasmium.
   • Protogyny. Carpels mature earlier than the stamens Example, the Four o’clock plant, Custard- apple.
4. Heterostyly. Two or more types of flowers concerning the length of the style and stamen arc formed, Example, Solatium, Oxalis, Lythrum, Primula.
5. Hereogamy. Male and female sex organs are so placed in a flower that the pollen grains die and they are unable to reach the stigmas in the same flower, for example, Carnation, Gloriosa, and Calotropis.

NEET Biology Sexual Reproduction In Plants Types Of Cross-Pollination Depending Upon Agencies

1. Anemophily. Small flowers are pollinated by wind. Plants produce enormous amounts of pollen Example. Oak, Betula, grasses, rice, bamboo, Pinus (Winged Pollen grains).

• Anemophilous flowers are small and inconspicuous; never coloured or showy; do not emit any smell and nor do they secrete any nectar.
• Pollen grains are produced in large quantities which are very small, dry, smooth and light so they can be easily disseminated by wind over a wide area, helping cross-pollination.
• Stigmas are hairy and branched to licit they may entangle the pollen grains floating in the air.

2. Hydrophily: Pollination through the agency of water is called hydrophily. When pollination occurs below the water level, it is described as hypohydrogamie and when it occurs at the die level of water, it is called epiliydrogamic.

• In plants like Potamugeton, Myriophyllum etc. when? the inlloirsociKT pmlnulcs mil of witter level, wind pollimilinn occurs.
• Hydmphilv is commonly seen in the members of Ceralopliyllncene, and Najiiclaecnc. Hvdiwharitaecac, Potumogetonuceue, Aponogctonucene etc. Hypohydrogumie pollination is seen in plants like Ccralopliyllum, Najas etc.
• An interesting pollination mechanism is seen in plants like Ruppia Maritime and Vallisncria spiralis. In Ruppia the flowers; are bisexual and protandrous. The anthers release pollen into the water and the grains float on the water’s surface.
• Now the peduncle and pedicel elongate till the stigma reaches the water surface and comes in contact with the floating grains. After pollination, the stalk contracts and the fruit matures under water. In Vallisncria, which is a rooted submerged aquatic plant, the male flowers are born in a spadix and the females are solitary.
• The male flowers are set free below water level but they open on the surface where they float. The pedicel of the female flower elongates till it reaches the water surface where it comes in contact with the pollen grains.

3. Zoophily. Pollination by the agency of animals.

1. Chiropterophily. Pollination by bats, Example, Anthocephcilus, Bauhinia, Kigelia pinnata, Adensonia (Boabab tree)
2. Ornithophily. Pollination by birds, for example, Bignonia, Erythrina indica, Bombax, Agave, and Grevillea.
3. Malacophily. Pollination by slugs and snails, Example, Arisaema. and other aroids.
4. Entomophily. Pollination by insects, for example, Jasmine, Rosa, and Magnolia.

Sexual Reproduction In Flowering Plants NEET Study Material

These flowers possess the following characteristic features :

• The insect-pollinated flowers are fragrant and omit scent and odour, for Example, Cestrum, Jasmine etc. Rafflesia gives out obnoxious and repelling odours.
• The insect-pollinated flowers are beautifully coloured. In flowers, most petals are brightly coloured.
• Sometimes, when flowers themselves are not conspicuous, other parts may become coloured and showy to attract the insects Example bracts in Bougainvillea, leaves in Euphorbia pulcherrima, one sepal in Mussaenda etc.
• The nectariferous glands produce nectar for feeding the visiting insects.
• Nectariferous glands are present at such positions on floral parts to encounter the anthers and stigmas.
• In Viola (pansy), markings on petals (nectar guides) are present which guide the insects to nectaries.
• In entomophilous plants, the pollen grains become sticky or spiny so that they may easily get attached to the bodies of visiting insects.
• To catch the pollen grains, the stigmas become sticky.
• Flowers become more conspicuous by grouping Example capitulum, corymb etc.
• In plants like Papaver, Rosa, Clematis etc. edible pollen grains are produced.
• Some of die pollen grains stick to the body of insects while feeding on the edible pollen grains.
• In orchid Ophrys, the shape and colour of the petals are like a female wasp. Male wasp mistakes the flowers of Ophrys for female wasp and tries to copulate, thus pollinating the flowers.
• In Yucca, Yucca-moth bores a hole in the ovary of the Yucca flower and lays its eggs in it. Then it collects pollen from several flowers and pushes the whole of the pollen down the hollow end of the stigma.
• Fertilization takes. place and seeds develop. Larvae feed on developing seeds.
• Some seeds remain unconsumed to propagate the species. Moth cannot survive without Yucca flowers and Yucca fails to reproduce sexually without moth.

NEET Biology Sexual Reproduction In Plants Development And Formation Of Male Gametes

Development of male gametophyte starts in pollen grains, while still present in the microsporangium or pollen sac (precocious germination). Microspore undergoes only two mitotic divisions.

• First mitotic division leads to the formation of a vegetative cell and a generative cell.
• The vegetative cell is also called the tube cell. These cells do not possess any cell wall and, hence are represented only by cell membranes. A temporary callose wall is laid down between the two cells (Groska-Bry-Lass, 1967).
• The callose wall spreads between the generative cells and the intestine to finally pinch it off.
• Soon, this callose wall dissolves and the generative cell lies freely in the cytoplasm of the vegetative cell. Generative cells may be elliptical, lenticular or even spindle-shaped.
• The cytoplasm contents of the generative cells are almost hyaline and do not possess much-stored food material. The large vegetative cell contains fat.
• starch and some type of protein granules. It is usually at this two-celled stage that pollen grains are liberated from pollen sacs of anther lobes.
• Rarely generative cells may further divide to form two male gametes. All these stages for the development of male gametophytes are grouped under pre-pollination stages.
• After the falling of pollen grains on the stigma, post-pollination changes occur.
• Pollen grain absorbs water and nutrients of the stigmatic secretion through its germ pores. The intine protrudes out through one of the germ pores or a germ furrow.
• The generative nucleus divides to form two male nuclei, which become surrounded by cytoplasmic masses and appear as distinct male gametes. Protruded intine forms pollen tube. The tube nucleus migrates to the pollen tube. The formation of male gametes can occur in vegetative cells or pollen tubes.
• Usually, generative cell comes down into pollen tubes and then divide to form the male gametes. The hindered region of the pollen tube is highly vacuolated. This region is plugged from the anterior part by the development of callose. The male gametophyte in angiosperms is highly reduced.
• Usually, there is a single pollen tube and pollen grains are termed monosphonous. In Malva, Althea and other members of the family Malvaceae and Cucurbitaceae, the condition is polysiphonous with as many as 14 pollen tubes.

NEET Biology Sexual Reproduction In Plants Megasporogenesis And Development Of The Female Gametophyte

The ovule develops as a small outgrowth from the tissue of the placenta, A single hypodermal cell in the nucellus starts functioning as an archesporium which, is also called a primary archesporial cell. This cell divides by a periclinal wall to form a primary parietal and sporogenous cell.

• The primary parietal cell undergoes repeated divisions forming a parietal tissue. The primary sporogenous cell functions directly as the megaspore mother cell which divides twice the first division being mciotic and the second mitotic, forming four haploid cells arranged in a row.
• Three of the upper cells degenerate and the remaining lowermost cell forms die functional megaspore. In the meantime, two integuments are disclosed from the base of the ovule, which envelops the mature ovule. ‘1 The megaspore represents the first cell of the female gametophyte.
• The megaspore nucleus divides thrice to give rise to eight nuclei. Four of the nuclei migrate to one pole and the remaining four die opposite jxilc; one nucleus from the cadi of the pole comes to lie in the centre of die embryo sac where the two lose together to form a secondary nucleus.
• The three nuclei at the base form the antipodal tells and the three nuclei at the apex organise into an egg apparatus, consisting of two synergies and an egg between them.
• The ovule is a rounded structure attached to the placenta by a stalk, die funicle, The place of attachment of the funicle to the body of the ovule is called a Lilium. Hie basal region of the ovule, where integuments arise, is termed a thalaza. ‘The lire ovule consists of integuments mid nucellus.

1. Orthotropous or atropous straight. ovule is erect. Funcile, and chalaza micropyle lie on the same verticle line e.g polygonum, Rumex
2. Anatropous or Inverted or resupinate. Ovule bends along the funnel. Micropyle lies close to the hilum. Micropyle and chalaza lie on the same vertical line Example Solanum, Anemone, Helianthus.
3. Amphitropous or Transverse. The ovule is placed transversely or at a right angle to its stalk, for Example, Lenina and some crucifers.
4. Campylotropous or Curved. Chalaza and micropyle do not lie in a straight line, for example, Capparis, Mustard, Pisum, and family Chenopodiaceae.
5. Circinotropous. This ovule is inverted at an angle of 360° so that the ovule again fir becomes orthotropous and coiled around by funiculus Example opuntia.
6. Hemianatropous. It is intermediate between ortho and anatropous types of ovules, for example, members of Primulaceae, Ranunculaceae and some crucifers.

Sexual Reproduction In Flowering Plants NEET Study Material

NEET Biology Sexual Reproduction In Plants Fertilization

The process of nuclear fusion between the male nucleus and an egg nucleus is referred to as fertilization. It produces a diploid zygote. The second male gamete amalgamates with the secondary nucleus. Double fertilization is a common occurrence.

• The pollen tube infiltrates the embryo sac. The pollen tube enters the embryo sac from many locations.
• These represent Porogamy: the ingress of the pollen tube through the micropyle.
• Illustration Lily chalazogamy refers to the introduction of the pollen tube through the chalazal end, exemplified by Juglans (walnut) and Casuarina. Mesogamy refers to the passage of the pollen tube through the funiculus or integuments. Example: Cucurbita, Populus.
• The apex of the pollen tube ruptures within the embryo sac, discharging both male gametes. One gamete penetrates the egg and amalgamates with its nucleus to create an oospore or zygote.
• The amalgamation of the male gamete with the ovum nucleus is referred to as fertilization.
• In angiosperms, the 8-nucleate Polygonum-type embryo sac comprises two polar nuclei centrally located. The polar nuclei amalgamate to create a diploid secondary nucleus (2N).
• The 2nd male gamete (N) of the pollen grain fuses with this secondary nucleus (2N) to form triploid endosperm (3N). This technique is referred to as twofold fertilization.

Endosperm

Endosperm is usually triploid and is formed as a result of triple fusion after fertilization. The endosperm provides food to the young embryo.

Three different types of endosperms have been reported in angiosperms

1. Nuclear endosperm
2. Cellular endosperm
3. Global endosperm.

Development of endosperm. Endosperm develops after double fertilization in angiosperms. It is triploid and develops from the primary endosperm nucleus.

It is meant to nourish the embryo. As the endosperm develops fully in the fertilized ovules, it may show the effect of genes present in the male gamete.

It is called Xenia. Endosperm development is accompanied by degeneration of the nucellus. Some food is also obtained from plants as well as the endothelium.

Types Of Endosperm

1. Nuclear endosperm. In nuclear endosperm development, the nucleus divides by free nuclear division, there is the appearance of the central vacuole, all the nuclei are pushed towards the periphery then starts cytokinesis and results in the formation of cells as in Capsella bursapastoics, but in coconut vacuole persists which is filled with fluid.
2. Cellular endosperm. In cellular endosperm every division is followed by cytokinesis, so endosperm is cellular from the very beginning Example Datura, Petunia.
3. Helobial endosperm. It is intermediate between cellular and nuclear endosperm. The first division is followed by. cytokinesis to form two unequal cells, a micropylar cell and a chalazal cell. Further divisions in each cell are free nuclear divisions. This type of endosperm is found in the order Helobiales.

The endosperm may persist in the seed or be consumed by the developing embryo. In the latter case, the food is generally stored in cotyledons. Ruminate or convoluted endosperm occurs in Areca (Betel nut) and Passiflora. The hard endosperm is found in Date, vegetable Ivory and Areca.

Embryo Development

The embryogeny (Crucifer /Onagrad type). The zygote or oospore divides by a transverse wall into an upper suspensor cell and a lower embryonal cell. The suspensor cell which lies towards the micropylar end, divides by transverse divisions to constitute 7-10 cells called suspensor.

• The upper cell of the suspensor filament towards the micropylar end is called the historical cell, whereas the cell lying above the embryo cell is called hypophysis.
• The haustorial cell enlarges in size and attaches the suspensor to the tip of the embryo sac. The embryonal cell divides by a second longitudinal division at a right angle to the first and then by transverse division to form an octant or eight-celled embryo.
• Out of these eight cells, the lower four cells of octant away from the die suspensor give rise to the plumule and the two cotyledons, while dying above four cells of octant near the suspensor from the hypocotyl and stele of the radicle.
• Now this octant divides by a periclinal division to form an outer single-layered dermatogen from which arises the epidermis layer. The inner cells further divide to form periblem below’ die dermatogen and die central plerome. The periblem forms the cortex while the plerome gives the stele of the embryo.
• The lowermost cell of the suspensor, which lies just above die octant cells, is known as hypophysis. The hypophysis divides to give rise to the dermatogen and periblem of the radicle. A fully developed embryo of dicotyledons has an embryonal axis differentiated into a plumule, two cotyledons and a radicle.
• In die beginning embryo is globular. When two cotyledons differentiate from the sides with faint plumule in the centre, the embryo becomes heart-shaped. Now the embryo undergoes rest and the ovule is transformed into a seed.

Sexual Reproduction In Flowering Plants NEET Study Material

Monocot Embryogeny (Sagittaria Type)

The zygote or oospore divides transversely, producing a vesicular suspensor cell towards the micropylar end and an embryonal cell towards the chalazal end. The embryo cell divides transversely again into a terminal and a middle cell. The terminal cell divides vertically and transversely into a globular embryo. It forms a massive cotyledon and a plumule.

• The growth of cotyledon pushes the plumule to one side. Remains of second cotyledon occur in some grasses. It is called epiblast. The single cotyledon of monocots is called scutellum. It is shield-shaped and appears terminal.
• The middle cell gives rise to hypocotyl and radicle. It may add a few cells to the suspensor. Both radicle and plumule develop covering sheaths called coleorhiza and coleoptile respectively. They appear to be extensions of the scutellum.

Polyembryony

It is defined as the development of two or more embryos within an ovule. It was discovered by Leeuwenhoek in 1719 in orange. In angiosperms, the multiple embryos are produced in the following ways.

1. By fertilization of synergids or antipodal cells by sperms introduced in the pollen sac by additional pollen tubes, Example, Plantago, Poa, Allium
2. By cleavage of the single zygote or a young embryo into 2 or more parts, each of which develops into an embryo, For Example, members of Orchidaceae
3. One or more cells of the nucellus or integuments develop into embryos which soon project into the embryo sac and are nourished by the endosperm, For Example, Citrus, Mangifera, Eugenia
4. The occurrence of more than one embryo sacs which usually develop from the
   derivatives of a single or more than one megaspore mother cell, for example, Brassica,

• The flowers of Asteraccac ami Labiatae families are generally pollinated by bees and butterflies.
• The two cells are unequal. A large one is called a tube cell or vegetative cell and the small one is called a generative cell.
• This division occurs when microspores are still inside the pollen sac.
• Microspores are shed at this 2-celled stage. Later, the development of male gametophyte occurs after pollination.] The pollination by birds is common in coral trees, bottle brushes, Iiulca monospen and silk cotton trees.
• Hie pollination by bats is carried out in Adansonia and Kigelia. The wind-pollinated flowers are generally unisexual, as in coconut palm, dale palm, maize, and many grasses. Cannabis. Hydrophilv is common in water plants especially submerged ones, like Vallisneria, Ceratophyllum, Zostera

Differences between self-pollination and cross-pollination.

NEET Biology Sexual Reproduction In Plants Quanta To Memory

• Entomophily. In angiosperms, entomophily occurs in about 80% of the flowers. Pollen kit is characteristic of entomophilous pollen.
• Most of the entomophilous flowers are pollinated by members of Hymenoptera, Lepidoptera, Diptera and Coleoptera and only a few by other groups.
• An interesting pollination mechanism is seen in many plants. While Centaurea shows a piston mechanism for pollination, Salvia exhibits a lever mechanism.
• Pollination by water is called hydrophily. Pollination may occur below the water level (hypohydrogamic) or at the level of water (epihydrogamic).
• Translator Mechanism. In Calotropis and related plants, pollen grains are aggregated to form translators, each having two pollinia attached by a corpusculum. The translator is picked up and transferred by an insect visiting flowers for nectar”.
• Erythrina. It is pollinated by crows as well as squirrels.
• Adansonia. A flower bears 1500—2000 stamens.
• The effect of pollen grain on the characters of endosperm is called xenia.
• Sometimes pollen grains are present in a sac-like mass known as pollinium, for Example, Calotropis and Orchids etc.
• In some plants Example, Malva, and Althaea, 10-14 pollen tubes develop from the same pollen grain, but only one becomes functional.

Sexual Reproduction In Flowering Plants NEET Mcqs

NEET Biology Sexual Reproduction In Plants Questions From Competitive Examinations

Question 1. In the Kigcllia prenatal /Sausage tree, pollination is performed by :

1. Bats
2. Birds
3. Insects
4. Wind.

Answer: 1. Bats

Question 2. Apple growers usually keep bees in the orchard even though apples are usually wind-pollinated because :

1. Wind pollination results in apples of inferior quality
2. Insect pollination results in apples of superior quality
3. Wind pollination may fail at the right time and bees would bring about pollination in such a situation
4. Bees can inject honey into the apples and make them sweeter.

Answer: 3. Wind pollination may fail at the right time and bees would bring about pollination in such a situation

Question 3. Self-pollination means :

1. Occurrence of male and female sex organs in the same flower
2. Germination of pollen within the same anther
3. Transference of pollens from anther to stigma within the same flower
4. Transference of pollen from one plant to the stigma of a neighbouring plant.

Answer: 3. Transference of pollens from anther to stigma within the same flower

Question 4. Stigma is always rough and sticky in :

1. Entomophilous flowers
2. Anemophilous flowers
3. Hydrophilous flowers
4. All types of flowers.

Answer: 1. Entomophilous flowers

Question 5. Progeny resulting from cross-pollination :

1. Show greater genetic variability and are evolution- nary important
2. Homozygous and show phenotypic uniformity
3. Arc always sterile
4. Always show recessive characters.

Answer:  1. Show greater genetic variability and are evolution- nary important

Question 6. Maturation of stamens and pistils at different times in the same flower is called :

1. Dichotomy
2. Dichogamy
3. Heterospory
4. Heterostyly.

Answer: 2. Dichogamy

Question 7. Pollination by ants is :

1. Malacophily
2. Myrmccophily
3. Omithophily
4. Entomophily.

Answer: 2. Myrmccophily

Question 8. Some flowers possess pleasant odour and attractive colours for:

1. Hydrophily
2. Anemophily
3. Entomophily
4. All of the above.

Answer: 3. Entomophily

Question 9. Anemophily means :

1. Pollination by wind
2. Pollination by birds
3. Pollination by animals
4. Animal-loving plants.

Answer: 1. Pollination by wind

Sexual Reproduction In Flowering Plants NEET Mcqs

Question 10. Wind pollination is common in :

1. Legumes
2. Lilies
3. Grasses
4. Orchids.

Answer: 3. Grasses

Question 11. In which one of the following pollination is autogamous?

1. Geitonogamy
2. Xenogamy
3. Chasmogamy
4. Cleistogamy.

Answer: 4. Cleistogamy.

Question 12. Embryo sac is :

1. Microgametophyte.
2. Microsporangium
3. Megagametophyte
4. Megasporangium.

Answer: 3. Megagametophyte

Question 13. The 8-nucleate embryo sac is :

1. Monosporic
2. Bisporic
3. Tetrasporic
4. All the above.

Answer: 4. All the above.

Question 14. A mature male gametophyte is formed from pollen mother cell by :

1. One meiotic division
2. Two meiotic divisions
3. One meiotic and two mitotic divisions
4. Three meiotic divisions.

Answer: 1. One meiotic division

Question 15. Passage of pollen tube through micropyle while reaching the embryosac is :

1. Monogamy
2. Porogamy
3. Dicliny
4. Dichogamy.

Answer: 2. Porogamy

Question 16. The polygonum type of embryo sac is:

1. 8-nucleate
2. 16-nucleate
3. 24-nucleate
4. 32-Nucl

Answer: 1. 8-nucleate

Question 17. Tapetum occurs in:

1. 8-nucleate
2. Ovary Wall
3. Male gametophyte
4. Female gametophyte

Answer: 1. 8-nucleate

Sexual Reproduction In Flowering Plants NEET Mcqs

Question 18. Which one is produced as a result of double fertilization?

1. Seed
2. Fruit
3. Megaspore
4. Endosperm

Answer: 4. Endosperm

Question 19. A component of the female reproductive system is:

1. Stamens
2. Anther
3. Microscope
4. Embryo

Answer: 4. Embryo

Question 20. Mango and Guava ate propagated through.lt :

1. Tissue culture
2. Grafting
3. Stem cuttings
4. Layering.

Answer: 2. Grafting

Question 21. In a grafted plant, slock has 48 chromosomes while scion has 2d chromosomes. Idle chromosome numbers for root cells and eggs are :

1. 48and 24
2. 24and 24
3. 24and 12
4. 48 and 12.

Answer: 4. 48 and 12.

Question 22. Pollen grains are non-green due to :

1. Absence of plastids
2. Degeneration of plastids
3. Conversion of plastids into chromoplasts
4. Attraction of vectors.

Answer: 3. Conversion of plastids into chromoplasts

Question 23. The pollen grain of a tetraploid plant brings about fertilization in a diploid plant. The endosperm of the seed will be :

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

Answer: 3.  4

Question 24. Multinucleate condition is present in :

1. Quiescent centre
2. Maize
3. Meristematic tissue
4. Liquid endosperm of Coconut.

Answer:  4. Liquid endosperm of Coconut.

Question 25. If meiosis occurs inside pollen grain and egg nuclei, it will be :

1. Zygotic ineiosis
2. Gametic meiosis
3. Sporic meiosis
4. None of the above.

Answer: 2. Gametic meiosis

Sexual Reproduction In Flowering Plants NEET Exam Preparation

Question 26. Formation of the embryo from vegetative cells derived from the zygote is called :

1. Apoinixis
2. Adventive polyembryony
3. Apospory
4. Diploid polyembryony.

Answer: 2. Adventive polyembryony

Question 27. The formation of an organiser from a single, male gamete without fusion with an egg is an example of:

1. Parthenogenesis
2. Apogamy
3. Apospory
4. Parthenocarpy.

Answer: 1. Parthenogenesis

Question 28. Adventive embryonic in Citrus is due to :

1. Nucellus
2. Integuments
3. Zygotic embryo
4. Fertilized egg.

Answer: 1. Nucellus

Question 29. In grasses what happens in the microspore mother cell for the formation of mature pollen grains :

1. One meiotic and two mitotic divisions
2. One meiotic and one mitotic divisions
3. One meiotic division
4. One mitotic division.

Answer: 2. One meiotic and one mitotic division

Question 30. Which of the following statements is wrong :

1. Naked seeds are seen in gymnosperms
2. Pteridophyta produces endosperm
3. Basidiocarpous fruiting body of fungs
4. Capsule is the sporophyte

Answer: 2. Pteridophyta produces endosperm

Question 31. Double fertilization was given by :

1. Nawaschin
2. Maxwell
3. Einstein
4. Antony Hewert

Answer: 1. Nawaschin

Question 32. Hydroponics is :

1. Plant growth in mineral-deficient soil
2. Soil conservation
3. Plant growth under laboratory conditions
4. Plant growth in liquid culture medium.

Answer: 4. Plant growth in liquid culture medium.

Sexual Reproduction In Flowering Plants NEET Exam Preparation

Question 33. Number of nuclei present in common embryo sac tire :

1. Six
2. Eight
3. Twelve
4. Twenty-four.

Answer: 2. Eight

Question 34. Perisperm is :

1. Remains of nucellus
2. The outer part of the embryo sac
3. Degenerated synergid
4. Degenerated secondary nucleus

Answer: 1. Remains of nucellus

Question 35. In a flowering plant, archesporium gives rise to :

1. Only tapetum and sporogenous cells
2. Only the wall of the sporangium
3. Both the wall and the sporogenous cells
4. Wall and the tapetum.

Answer: 3. Both the wall and the sporogenous cells

Question 36. Pollen grains can tolerate extremes of temperature and desiccation because their exine consists of:

1. Cutin
2. Suberin
3. Sporopollenin
4. Close

Answer: 3. Sporopollenin

Question 37. The plant part has two generations, one within the other:

1. Seed
2. Germinated pollen grain
3. Embryo
4. Unfertilized ovule

Answer: 1. Seed

Question 38. Pollen tube usually enters the embryo sac :

1. Between one synergid and central cell
2. By knocking off antipodal cell
3. Through one of the synergids
4. Directly penetrate the egg.

Answer: 1. Between one synergid and central cell

Question 39. A plant root has 16 cells thus :

1. Gamete has 16 cells
2. Gamete has 8 cells
3. Endosperm has 16 cells
4. The endosperm has 8 cells.

Answer: 1. Gamete has 16 cells

Question 40. Which one of the following statements is correct?

1. Sporogenous tissue is haploid
2. Endothecium produces the microspores
3. Tapetum nourishes the developing pollen
4. The hard outer layer of pollen is called intine.

Answer: 3. Tapetum nourishes the developing pollen

Question 41. A diploid female plant is crossed with the tetraploid male. The ploidy of endosperm will be :

1. Tetraploidy
2. Diploidy
3. Triploidy
4. Pentaploidy.

Answer: 1. Tetraploidy

Question 42. Which of the following represents the edible part of the fruit of Litchi?

1. Pericarp
2. Mesocarp
3. Juicy aril
4. Endocarp.

Answer: 3. Juicy aril

Sexual Reproduction In Flowering Plants NEET Exam Preparation

Question 43. Through which cell of the embryo sac. does the pollen tube enter the embryo sac?

1. Egg cell
2. Central cell
3. Persistant synergid
4. Degenerated synergid

Answer: 4. Degenerated synergid

Question 44. Which one of the following mg represents an ovule, where the embryo sac becomes horse-shoe shaped and the funiculus and micropyle are close to each other?

1. uvinotiopous
2. Anatropous
3. Amphitropous
4. Atropous.

Answer: 3. Amphitropous

Question 45. Which is vivipary an undesirable character for annual crop plants?

1. It reduces the vigour of the plant.
2. The seeds cannot be stored under normal conditions for die next season.
3. The seeds exhibit long dormancy
4. It adversely affects the fertility of the plant.

Answer: 2. The seeds cannot be stored under normal conditions for die next season.

Question 46. In which one pair both dead plants can be vegetatively propagated by leal pieces?

1. Bryophyllum and Kalanchoe
2. Chrysandiemum and Agave
3. Agave and Kalanchoe
4. Asparagus and Bryophyllum.

Answer: 1. Bryophyllum and Kalanchoe

Question 47. In a type of apomixis known as adventive embryonic, embryos develop directly from the :

1. Nucellus or integuments
2. Synergids or antipodals in an embryo sac
3. Accessory embryo sacs in the ovule
4. zygote.

Answer: 1. Nucellus or integuments

Question 48. Double fertilization involves :

1. Fertilization of the egg by two male gametes
2. Fertilization of two eggs in the same embryo sac by two sperms
   brought by one pollen tube.
3. Fertilization of the egg and the central cell by two sperms brought
   by different pollen tubes.
4. Fertilization of the egg and central cell by two sperms brought by the same pollen.

Answer: 4. Fertilization of the egg and central cell by two sperms brought by the same pollen.

Question 49. In some plants anthers and sdgma grow and mature at the same time. This phenomenon is called

1. Homogamy
2. Syngamy
3. Allogamy
4. Fusion.

Answer: 1. Homogamy

Question 50. For the formation of a tetraspores embryo sac, how many megaspores mother cells are required?

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

Answer: 2. 2

Sexual Reproduction In Flowering Plants NEET Previous Year Questions

Question 51. The pollen sac in Cycas is called :

1. Megasporophyll
2. Megasporangium
3. Microsporophyl
4. Microsporangium.

Answer: 4. Microsporangium.

Question 52. Polygonum type of embryo sac is :

1. 8-nucleate and 7-celled
2. 8-nucleate and 8-celled
3. 8-nucleic and 8-called
4. 7-nuclcnlc ami 8 celled.

Answer: 1. 8-nucleate and 7-celled

Question 51. In die angiosperm ovule central cell of the embryo sac, before the entry of the pollen tube, contains;

1. A single haploid nucleus
2. One diploid and one haploid nuclei
3. Two Imploid polar nuclei
4. One diploid secondary nucleus

Answer: 4. One diploid secondary nucleus

Question 54. Xenia refer to :

1. Effect of pollen on stem
2. Effect of pollen on the taste of fruit
3. Effect of pollen on vascular tissue
4. Effect of pollen on endosperm.

Answer: 4. Effect of pollen on endosperm.

Question 55. Pollination by snails and slugs is known as :

1. Entomophilous
2. Omithophilous
3. Anemophilous
4. Malacophilous

Answer: 4. Malacophilous

Question 56. The arrangement of the nuclei in a normal embryo sac in the dicot plants is :

1. 2 + 4 + 2
2. 3 + 2 + 3
3. 2 + 3 + 3
4. 3 + 3 + 2

Answer: 2.  3 + 2 + 3

Question 57. Which one of the following is surrounded by a callose wall?

1. Male gamete
2. Egg
3. Pollen grain
4. Microspore mother cell.

Answer: 2. Pollen grain

Question 58. Male gametes in angiosperms are formed by the division of:

Generative cell

Vegetative cell

Microspore mother cell

Microspore

Answer: 1. Generative cell

Question 59. Eight nucleate embryo sacs are :

1. Always diasporic
2. Always tetraspores
3. Always monosporic
4. Sometimes monosporic, sometimes diasporic and sometimes tetraspores.

Answer: 4. Sometimes monosporic, sometimes diasporic and sometimes tetraspores.

Question 60. Double fertilization (or triple fusion) leading to initiation of endosperm in angiosperms, requires :

1. Fusion of 4 or more polar nuclei and the second male gamete only
2. Fusion of 2 polar nuclei and second male gamete only
3. Fusion of one polar nucleus and second male gamete only
4. All the above types of fusions in different types of angiosperms.

Answer: 2. Fusion of 2 polar nuclei and second male gamete only

Question 61. Many scientists consider viruses as living entities because these:

1. Respire
2. Can cause diseases
3. Reproduce (inside host)
4. Respond to tough environment.

Answer: 3. Reproduce (inside host)

Question 62. The mode of asexual reproduction in Hamlet and.

1. Formation of gametes
2. Endospore formation
3. Conjugation
4. Zoospore formation

Answer: 2. Endospore formation

Sexual Reproduction In Flowering Plants NEET Previous Year Questions

Question 63. Through which cell of the embryo sac. Does the pollen tube enter the embryo sac?

1. Egg cell
2. Central cell
3. Persistent synergid
4. Degenerated synergid

Answer: 4.Degenerated synergid

Question 64. Which one of the following represents an ovule, where the embryo w becomes horse-shoe shaped and funiculus and mu-ropy lc are close to each other?

1. Circinotropous
2. Antropous
3. Amphitropous
4. Atropous

Answer: 3. Amphitropous

Question 65. Which of the following represents the edible part of the fruit of litchi?

1. Pericarp
2. Mesocarp
3. Juicy aril
4. Endocarp.

Answer: 3. Juicy aril

Question 66. The study of pollen grain is called :

1. Etymology
2. Palynology
3. Paleobotany
4. M-taxonomy.

Answer: 2. Palynology

Question 67. Select the correct order of endosperm types :

1. Cellular, global, free nuclear
2. Cellular, free nuclear, global
3. Helobial, free nuclear, cellular
4. Free nuclear, cellular, and global
5. Free nuclear, global, and cellular.

Answer: 3. Free nuclear, cellular, and global

Question 68. Endosperm is consumed by developing embryo in the seed of:

1. Pea
2. Maize
3. Coconut
4. Castor.

Answer: 1. Pea

Question 69. Nucellar polyembryony is reported in species of:

1. Citrus
2. Gossypium
3. Triticum
4. Brassica.

Answer: 1. Citrus

Question 70. Filiform apparatus is a characteristic feature of:

1. Suspensor
2. Egg
3. Synergid
4. Zygote.

Answer: 3. Synergid

Question 71. What would be the number of chromosomes of the aleurone cells of a
plant with 42 chromosomes in its root lip cells?

1. 42
2. 63
3. 84
4. 21.

Answer: 2.63

Question 72. I lie genomic consists of many free pistils in the lower of

1. Tomato
2. Papaver
3. Michelia
4. Aloe

Answer: 3. Michelia

Question 73. Both autogamy and geitonogamy are prevented by:

1. Cucumber
2. Castor
3. Maize
4. Papaya.

Answer: 4. Papaya.

Question 74. An organic substance that can withstand environmental extremes eminently he pleaded that any enzyme is :

1. Spoiopollenin
2. Lignin
3. Cellulose
4. Cuticle.

Answer: 1. Spoiopollenin

Question 75. Plnccntnlion in tomato and lemon is :

1. Free central
2. Marginal
3. Axile
4. Parietal.

Answer: 3. Axile

Question 76. Which of these is a condition that makes flowers invariably
autogamous?

1. Dioccy
2. Self-incompatibility
3. Cleistogamy
4. Xenogamy
5. Syngamy.

Answer: 3. Cleistogamy

Question 77. Math the items in column I with those in column II and choose the correct answer.

1. 1- B; 2- C; 3- E; 4 – D; 5 -A
2. 1-A; 2 – C; 3 – B; 4 – D: 5 – E
3. 1 – B; 2 – C; 3 – A; 4 – D; 5 – E
4. 1 – B; 2 – D; 3 – E; 4 – A; 5 – C
5. 1 – C; 2 – D; 3 – E; 4 – A; 5 – B

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

Question 78. Megasporangium is equivalent to :

1. Fruit
2. Nucellus
3. Ovule
4. Embryo sac

Answer: 3. Ovule

Question 79. The advantage of cleistogamy is :

1. More vigorous offspring
2. No dependence on pollinators
3. Vivipary
4. Higher genetic variability

Answer:  2. No dependence on pollinators

Question 80. Perisperm differs from endosperm in :

1. Having no reserve food
2. Being a diploid tissue
3. Its formation by the fusion of a secondary nucleus with several sperms
4. Being a haploid tissue

Answer:  2.  Being a diploid tissue