NEET Biology Cell Structure and Function MCQs

Question 1. Engulfing of food materials or foreign bodies is called:

1. Pinocytosis
2. Pinocytosis and phagocytosis
3. Mitosis
4. Phagocytosis.

Answer: 4. Phagocytosis.

Question 2. The total thickness of the plasma membrane proposed by Robertson is:

1. 5Å to 20Å
2. 20Å to 35Å
3. 50Å to 75Å
4. 75Å to 100Å

Answer: 4. 75Å to 100Å

Question 3. The main function of the plasma membrane is to :

1. Regulate the flow of material into and outside the cell
2. Maintain the cell shape and size
3. Control all cellular activities
4. Store cell material.

Answer: 1. Regulate the flow of material into and outside the cell

Question 4. In a fluid mosaic model of the cell membrane, the extrinsic proteins are :

1. Attached to intrinsic proteins but can be separated easily
2. Superficially present but cannot be separated easily
3. Superficially present and can be easily separated
4. Attached to intrinsic proteins but cannot be separated easily.

Answer: 3. Superficially present and can be easily separated

Cell Structure And Function Mcq For Neet

Question 5. The one end of the phospholipid in the cell wall of plants is hydrophobic, which means:

1. It has no affinity for metabolites
2. It has no affinity for water
3. It has no affinity for solutes
4. None of the above.

Answer: 2. It has no affinity for water

Question 6. Amoeba, a single-celled organism, has a specialized structure called a contractile vacuole whose function is to collect excess water frorn the cell and discharge the water into the environment. From this infor-mation you can deduce that amoeba live in an environment that is (hypotonic) to the interior solution of amoeba. Thus, you would expect to find amoebas living in :

1. A freshwater pond
2. The ocean
3. Great salt lake
4. A bottle of unpasteurized milk.

Answer: 1. A freshwater pond

Question 7. We know that the Golgi body discharges substances from the cell by fusing of vesicles with the plasma membrane and subsequent opening of what was the interior of the vesicle to the outside environment. This is an example of:

1. Exocytosis
2. Endocytosis
3. Active transport
4. Facilitated diffusion.

Answer: 1. Exocytosis

Question 8. The selective transfer of particles through the cell membrane is an important factor in the process of:

1. Cytoplasmic streaming
2. Homeostasis
3. Nuclear transfer
4. Mechanical digestion.

Answer: 2. Horneostasis

Neet Mcqs On Cell Organelles With Answers

Question 9. The plasma membrane consists of three layers arranged :

1. Protein layer, phospholipid layer, and protein layer
2. The phospholipid and two protein layers
3. The two protein layers and the phospholipid layer
4. The protein layer, the phospholipid layer, and the fat layer.

Answer: 1. Protein layer, phospholipid layer, and protein layer

Question 10. The bordered pits are characteristics of:

1. Ferns
2. Gymnosperms
3. Angiosperms
4. Cycads.

Answer: 2. Angiosperms

Question 11. The torus of simple and bordered pits is made up of :

1. Suberin
2. Glttcose
3. Cutin
4. Phospholipids.

Answer: 1. Suberin

Question 12. Membrane functions are carried out by :

1. Carbohydrates
2. Lipids
3. Metalion
4. Proteins.

Answer: 4. Proteins

Question 13. The integrity of the membrane is maintained by :

1. Ionic bonds
2. Covalent bonds
3. Hydrophilic action
4. Hydrophobic attractions.

Answer: 3. Hydrophilic action

Question 14. According to the fluid mosaic model, the fluidity of a cell membrane is due to :

1. Lipid
2. Proteins
3. Glycoproteins
4. Glycolipids.

Answer: 1. Lipid

Question 15. Regarding cellular membranes one of the following is incorrect?

1. Membranes are selectively permeable but a solute’s electrical polarity and other physical characteristics may affect its ability to enter or leave.
2. Water-soluble substances pass through more rapidly than lipids and lipid-soluble substances.
3. Generally smaller molecules pass through cellular membrane more readily than larger molecules.
4. None of the above.

Answer: 2. Water-soluble substances pass through more rapidly than lipids and lipid-soluble substances.

Question 16. The counter pressure exerted by the cell wall tends to oppose :

1. Turgor pressure
2. Osmotic pressure
3. Solvent pressure
4. Diffusion pressure.

Answer: 1. Turgor pressure

Cell Structure And Function Neet Previous Year Questions

Question 17. Ion channels have been discovered by :

1. Singer and Nicholson
2. Nehar and Sakmann
3. Gamier
4. Robinson and brown.

Answer: 2. Nehar and sakmann

Question 18. The most abundant lipid in a cell membrane is:

1. Phospholipid
2. Cholesterol
3. Steroid
4. Cutin.

Answer: 1. Phospholipid

Question 19. Glycoproteins are known to play an important role in cell recognition. The specificity of this recognition is provided by:

1. Lipid portion of glycoproteins
2. Lipids are in the least proportion
3. Oligosaccharide portion of glycoprotein
4. Proteins are in the least proportion.

Answer: 3. Oligosaccharide portion of glycoprotein

Question 20. According to the fluid mosaic model, which one is true?

1. Oligosaccharides and lipids are held by non-covalent interaction
2. Components of the plasma membrane can be dispersed by detergents
3. Lipids and proteins are amphoteric
4. Polar groups of proteins are directed towards the lipid bilayer.

Answer: 4. Polar groups of proteins are directed towards the lipid bilayer.

Question 21. When a group of cells is placed in a salt solution whose concentration is more than their cell sap :

1. The cytoplasm with its plasma membrane expands
2. The cytoplasm with its plasma membrane shrinks up
3. The cytoplasm comes out through the plasma membrane
4. The cytoplasm remains in position.

Answer: 2. The cytoplasm with its plasma membrane shrinks up

Question 22. Which of the following structures of the cell is dead?

1. Cell wall
2. Nucleus
3. Plasma membrane
4. Mitochondria.

Answer: 1. Cell wall

Question 23. An Electron microscope has revealed that the cell wall is made up of several layers of :

1. Cavities
2. Microfibrils
3. Plasmodesmata
4. Myonemes.

Answer: 2. Microfibrils

Question 24. Plasmalemma prevents escape of na+ and k+ to :

1. Disrupt neighboring cells through desmosomes
2. Maintain electrostatic neutrality of cells
3. Maintain cell sap
4. All of the above.

Answer: 1. Cause disruption in neighboring cells through desmosomes

Cell Structure And Function Neet Previous Year Questions

Question 25. The cell wall is a permeable membrane can be best deducted from the passage of water and mineral salts from:

1. The root hair into cortical cell
2. The pericycle cells into the tracheal elements
3. The cortical cells are into tracheal elements
4. The soil into the root hair.

Answer: 4. The soil into the root hair.

Question 26. In the fluid mosaic membrane model, the phospholipid bilayer:

1. Is sandwiched between two protein layers
2. Have proteins embedded in it
3. Lies on top of a single protein
4. Is covered by a single protein.

Answer: 2. Has proteins embedded in it

Question 27. The structure in the ce1l bounded by the single membrane is :

1. Chloroplast
2. Peroxisome
3. Ribosome
4. Mitochondria.

Answer: 2. Peroxisome

Question 28. Plasma membranes of adjacent cells become thicker at certain regions. They are called :

1. Desmosomes
2. Terminal bars
3. Infoldings
4. None of the above.

Answer: 1. Desmosomes

Question 29. The middle lamella is made up of :

1. Protein
2. Cellulose
3. Calcium and magnesium pectate
4. Lignin.

Answer: 3. Calcium and magnesium pectate

Question 30. The cell wall in plants is composed of :

1. Chitin
2. Lipids
3. Xylan
4. Cellulose.

Answer: 4. Cellulose.

Question 31. The cellulose layer during the formation of the cell wall is secreted by the outer cytoplasm as :

1. Primary wall
2. Secondary wall
3. Tertiary wall
4. None of the above.

Answer: 1. Primary wall

Cell Organelles And Their Functions Mcq Neet 

Question 32. All membrane processes, such as pumping and channeling of molecules are carried out by :

1. Lipids
2. Carbohydrates
3. Nucleic acids
4. Proteins.

Answer: 4. Proteins.

Question 33. Plant cells can usually be distinguished from animal cells because only plant cells possess:

1. Cell wall and mitochondria
2. Goigi bodies and central vacuole
3. Celt wall and central vacuole
4. Chromosome and mitochondria.

Answer: 3. Celt wall and central vacuole

Question 34. If you were given a non-polar- membrane, which of the following would you expect to diffuse through it with the most ease :

1. CO2 phenylalanyl
2. Glycine
3. Lead atom
4. Proteins.

Answer: 1. CO2 phenylalanyl

Question 35. Membranes are found within :

1. Cytoplasm, chloroplasts and mitochondria
2. Chromosomes, nuclei, and mitochondria
3. Cytoplasm, nuclei, and starch grains
4. Chromosomes, chloroplasts, and starch grains.

Answer: 1. Cytoplasm, chloroplasts and mitochondria

Question 36. Which of these factors affects the movement of substances through the plasma membrane?

1. Permeability of the membrane
2. Size of diffusing particles
3. Membrane proteins
4. A1l the above.

Answer: 4. A1l the above.

Question 37. Endocytosis refers to :

1. Phagocytosis
2. Pinocytosis
3. Phagocytosis and pinocytosis
4. Mitosis.

Answer: 3. Phagocytosis and pinocytosis

Question 38. The plasma membrane is selectively permeable. It shorts maximum permeability to:

1. K+
2. Nh4+
3. Na+
4. Ca++

Answer: 1. Nh4+

Question 39. Pinocytosis and active transport are similar because both processes:

1. Depends directly upon cyclosis within a cell
2. Require the expenditure of energy
3. Are types of circulation
4. Increase the absorbing surface of- cell.

Answer: 2. Require the expenditure of energy

Question 40. Most living cells acquire unwanted compounds either by absorption from their surroundings or as by-products of chemical activities. Cells would die if such compounds are accumulated in the cytoplasm or nucleus. Hence mechanisms have evolved to affect their removal. It is accomplished by developing a system of:

1. Membranes such as endoplasmic reticulum
2. Pores in the mernbrane of nucleus
3. Semipermeable cell membrane surrounding the nucleus
4. Vacuoles.

Answer: 2. Pores in the membrane of the nucleus

Cell Organelles And Their Functions Mcq Neet 

Question 41. The term osmosis refers to the diffusion of :

1. Energy
2. Water
3. Glucose
4. Positive electric charges.

Answer: 2. Water

Question 42. The function of the intracellular membrane is to:

1. Establish several compartments within the cell
2. Provide the neat spatial organization of enzymes and pigments
3. Provide a system of channels for the distribution of nutrients within cell
4. All the above

Answer: 4. All the above

Question 43. Amphipathy means:

1. Presence of hydrophobic and hydrophilic groups in the same molecules.
2. Hydrophobic
3. Hydrophilic
4. Isotonic.

Answer: 1. Presence of hydrophobic and hydrophilic groups in the same molecules.

Question 44. An import of energy is required for which of the following:

1. Diffusion
2. Osmosis
3. Facilitated diffusion
4. Active transport.

Answer: 4. Active transport.

Question 45. Microvilli are :

1. Finger-like projections on cell surface responsible for ultra absorption of liquids.
2. Finger-like projections of nuclear membrane responsible for obtaining nutrients for the nucleus
3. Hair-like structures on the cell surface responsible for the sense of touch
4. Secondary finger-like projection on the intestinal villi.

Answer: 1. Finger-like projections on cell surface responsible for ultra absorption of liquids.

Question 46. The simplest and most common mechanism by which substances move across the cell wall is:

1. Active transport
2. Metabolically coupled transport
3. Diffusion
4. Osmosis.

Answer: 3. Diffusion

Question 47. Continuity of cytoplasm from cell to cell is maintained through:

1. Middle lamella
2. Plasmodesmata
3. Endoplasmic reticulum
4. Cell membrane system.

Answer: 2. Plasmodesmata

Question 48. Which pair of structures are usually found in both plant and animal cells?

1. Cell membrane and nucleolus
2. Cell membrane and cell wall
3. Nucleolus and chloroplast
4. Nucleus and cell wall.

Answer: 1. Cell membrane and nucleolus

Question 49. Tonoplast is a differentially permeable membrane surrounding the:

1. Mitochondria
2. Cytoplasm
3. Vacuole
4. Nucleus.

Answer: 3. Vacuole

Question 50. Singer and Nicholson model of plasma membrane differs from Robertson’s model in the :

1. Arrangement of lipid layers
2. Arrangement of proteins
3. Absence of proteins in the Singer model
4. Number of lipid layers.

Answer: 2. Arrangement of proteins

Question 51. Which of the following does not pass across membranes by simple diffusion?

1. O2
2. H+
3. Co2
4. H2O.

Answer: 2. CO2

Question 52. All are membrane-bound cell organelles except:

1. Sphaerosome
2. Lysosome
3. Ribosomes
4. Chloroplast.

Answer: 3. Ribosomes

Question 53. Sialic acid is a constituent of:

1. Cell membrane
2. Cell wall
3. Tonoplast
4. Chromosome.

Answer: 2. Cell wall

Question 54. Beetroot does not lose color in freshwater This is because :

1. The plasma membrane is permeable
2. The plasma membrane is impermeable to pigment
3. The plasma membrane and cell wall are permeable
4. Both the plasma membrane and cell wall are impermeable.

Answer: 2. Plasma membrane is impermeable to pigment

Question 55. Cellulosic cell walls can be specifically stained by

1. Zinc chloride
2. Phloroglucinol
3. Methyl blue
4. Sudan 4.

Answer: 1. Zinc chloride

Cell Organelles And Their Functions Mcq Neet 

Question 56. The plan of cell wall formation is determined by:

1. Golgi bodies
2. Er
3. Microtubules
4. Nucleus.

Answer: 1. Golgi bodies

Question 57. Which of the following is not a form of endocytosis?

1. Monocytosis
2. Phagocytosis
3. Pinocytosis
4. Receptor-mediated cytosis.

Answer: 1. Monocytosis

Question 58. The process by which a cell secretes macromolecules by fusing a transport vesicle to a plasma membrane is:

1. Pinocytosis
2. Endocytosis
3. Phagocytosis
4. Exocytosis.

Answer: 4. Exocytosis.

Question 59. Membrane potential is caused by unequal distribution

1. Ions
2. Isotopes
3. Fatty acids
4. Glucose

Answer: 1. Ions

Question 60. The cell wall is the secretion of:

1. Middle lamella
2. Plasmalemma
3. Cytoplasm
4. Plasmodesmata

Answer: 3. Cytoplasam

Question 61. The cell wall is thin in :

1. Xylem
2. Collenchyma
3. Cytoplasm
4. Parenchyma.

Answer: 4. Parenchyma.

Question 62. Animal cells do not have cell walls because:

1. They are adapted to move their body
2. They have muscles and nerves
3. They have to change the size of their body during locomotion
4. All correct.

Answer: 4. All correct.

Cell Structure And Function Mcq For Neet

Question 63. The smallest structural unit of the cell wall is :

1. Fibril
2. Microfibril
3. Micelle
4. Middle lamella.

Answer: 3. Micelle

Question 64. Unripe fruits are hard, due to :

1. Tannins in the cell wall
2. Middle lamella
3. Plasmodesmata
4. All of these.

Answer: 2. Middle lamella

Question 65. The cell wall in bacteria and cyanobacteria is made up of :

1. Murein or mucopeptide
2. Peptidoglycan and amino sugars
3. Cellulose
4. Chitin.

Answer: 2. Peptidoglycan and amino sugars

Question 66. The hemicellulose in the cell wall acts as :

1. Filler substance
2. Binding microfibril
3. Strengthening cellulose
4. All of these.

Answer: 2. Binding microfibril

Question 67. A micelle is made up of :

1. 250 Microfibril
2. 100 Cellulose chains
3. 20 Macrofibrils
4. 3000 Cellulose chains.

Answer: 2. 100 Cellulose chains

Question 68. Mineral elements of the middle lamella are/are :

1. Calcium pectate
2. Magnesium picrate
3. Manganese
4. Both 1 and 2.

Answer: 4. Both 1 and 2.

Question 69. The cell wall of the fungus contains :

1. Pectin and cellulose
2. Cellulose and chitin
3. Chitin and pectin
4. Chitin and silica.

Answer: 2. Cellulose and chitin

Question 70. Torus is related to:

1. Bordered pits in the cell wall
2. Receptacle of lotus
3. Both correct
4. Both wrong.

Answer: 3. Both correct

Question 71. Symplast:

1. Is the living component of the cell
2. Consists of cytoplasm and cell membrane
3. Both correct
4. Only 2 Is correct.

Answer: 3. Both correct

Question 72. The cell wall is absent in some plant cells like:

1. Zoospores
2. Gametes
3. Pplo
4. All correct.

Answer: 4. All correct.

Question 73. Intussusception is shown by a primary cell wall. It is :

1. Deposition of cell wall materials from inside to cause growth
2. Deposition of wall materials from outside as layers
3. Hardening of cell wall
4. None of these.

Answer: 1. Deposition of cell wall materials from inside to cause growth

Question 74. A pit is an unthickened area in the cell wall. It lacks:

1. Primary wall
2. Middle lamella
3. Secondary wall
4. Cell wall and cell membrane.

Answer: 3. Secondary wall

Question 75. The term cell membrane was given by :

1. Nageli
2. Singer and Nicholson
3. Robertson
4. Plower.

Answer: 1. Nageli

Cell Structure And Function Mcq For Neet

Question 76. The main amino acids in the cell membrane are :

1. Arginine and lysine
2. Arginine and leucine
3. Arginine and tryptophan
4. Arginine and glycine.

Answer: 1. Arginine and lysine

Question 77. Carbohydrate molecules attached to lipid and protein molecules from glycocalyx (extraneous coat). These carbohydrates are usually :

1. Monosaccharides
2. Polysaccharides
3. Oligosaccharides
4. Starches.

Answer: 3. Oligosaccharides

Question 78. Fluid mosaic model explains :

1. A bilipid layer in between 2 protein layers
2. A layer of proteins on one side and a bilayer of lipids on the other side
3. 2 Lipid layers and 1 protein layer
4. A phospholipid layer with proteins between and on both sides of the lipid layer.

Answer: 4. A phospholipid layer with proteins between and on both sides of the lipid layer.

Question 79. Cellular recognition and adhesion are facilitated by components in plasmalemma. These are :

1. Lipids
2. Proteins
3. Both a and b
4. Glycolipids and glycoproteins.

Answer: 4. Both a and b

Question 80. The plasma membrane of an animal cell is composed of:

1. Lipids, proteins, oligosaccharides
2. Lipids, proteins, proteins, polysaccharides
3. Lipids, proteins, disaccharides
4. Lipids, proteins, monosaccharides.

Answer: 1. Lipids, proteins, oligosaccharides

Question 81. Na+- k+ pump is found in membranes of many cells like nerve cells. It works against an electrochemical gradient and involves an integral protein ATPase. For each molecule of ATP used :

1. 3 Ions of na+ are pumped out and two k+ ions are taken
2. 3 Ions of na+ are taken in and 2k+ are pumped out
3. 2 Ions of na+ are thrown and 3k+ are absorbed
4. 3 Ions of Na+ are pumped out.

Answer: 1. 3 Ions of na+ are pumped out and two k+ ions are taken

Question 82. The cell membrane shows maximum permeability :

1. K+
2. Nh4+
3. Na+
4. Ca++.

Answer: 1. K+

Question 83. Who among the following proposed unit membrane model for cell membrane?

1. Davson and Danielle
2. Robertson
3. Singer and Nicholson
4. Metchnikoff.

Answer: 2. Robertson

Question 84. The cell membrane is absent in :

1. Sperm
2. Bacteria
3. Lysosomes
4. None of these.

Answer: 4. None of these.

Question 85. Which process requires energy?

1. Bulk transport
2. Pinocytosis
3. Exocytosis
4. All of these.

Answer: 4. All of these.

Neet Mcqs On Cell Organelles With Answers

Question 86. Pinocytosis was first reported by Edward in Amoeba. It is absent in:

1. Bacteria
2. Blue-green algae
3. Prokaryotes
4. All of these.

Answer: 4. All of these.

Plant Anatomy (Meristem Plant Tissues Anatomy Of Root Stem And Leaf)

Meristem

Meristem. A meristematic tissue consists of a group of cells which have the power of division. The word meristem lias its origin from the Greek word ‘meristos’ which means divisible. (Nageli, 1058)

They comprise isodiametric immature cells that are undergoing division and expansion.

• They are densely organized to eliminate intercellular gaps.
• The cells are predominantly spherical and possess slender walls encasing them.
• Each cell comprises a conspicuous nucleus and thick protoplasm.
• Vacuoles in the cell are typically missing; when present, they are rather tiny.
• During cell division, the initial nucleus undergoes mitotic division into two nuclei, followed by cytokinesis, culminating in the production of two daughter cells.
• Proplastids are present in lieu of plastids.
• Metabolic activity is elevated.
• The cambium cells are elongated and contain vacuoles.

Read and Learn More NEET Biology Notes

Anatomy Of Flowering Plants Neet Notes

Anatomy Of Flowering Plants Neet Notes

1. Types Of Meristem Based On Development It is of three types :

1. Promeristem
2. Primary meristem
3. Secondary meristem.

• Promeristem. It is made up of a group of meristematic cells that represent the youngest stage of a growing organ. It is the earliest stage of the primary meristem.
• Primary Meristem. Promeristem gives rise to primary meristem. By the rapid cell divisions, the cells of primary meristem get differentiated into different tissues. Cells of this meristem divide in three or more planes.
• Secondary Meristem. It develops at a later stage in the development of an organ. It is always lateral in position.

2. Meristematic Tissue-Based On Function: The first formed meristem (Promeristem) gets differentiated into the following three regions :

1. Protoderm (gives rise to epidermis).
2. Procambium (gives rise to phloem, xylem and cambium).
3. Ground meristem (forms cortex, pericycle, medullary rays, pith, hypodermis and
   endodermis).

3. Types Of Meristem Based On Location The Body. According to location in the body meristems are of three types:

1. Apical meristems
2. Intercalary meristems
3. Lateral meristems.

• Apical Meristem. They are present at the apices of the stem, root and branches. These are responsible for increasing the length. Many cells form the apical meristems. However, in pteridophytes, one cell constitutes the meristem. It includes both pro-meristem and primary meristem.
• Intercalary Meristems: These are the parts of apical meristems, which get separated from the apex due to the development of permanent tissue in between. Intercalary meristems are found at the base of leaves above the nodes For Example. grasses, Equisetum, or below the nodes For Example. Mint. It increases the length of internodes and is finally consumed.
• Lateral Meristem. It is formed literally from the procambium strands i.e., cambium present between the xylem and phloem and the cork cambium of roots and stems. The cells divide only in the criminal plane and thus they add to girth. This type of meristem shows its activity after some time in plant organs.

4. Mcrislemulic Tissue-Based Oil Plane Of Cell Division:

• Mass Meristem. Here cells divide in all the planes thus increasing in volume. It can be noticed in the meristem of the cortex, pith etc.
• Plant Meristem. The cells divide in two planes. They form flat surfaces by increasing the area of organs For Example. Leaf formation.
• Rib Meristem. The cells divide only in one plane For Example., the formation of filaments in algae.

5. Based On Obesogens

• Dermatogen (forms piblcma and root cap in dicots),
• Periblem (forms cortex and endodermis), and
• Plcrome (forms pericyclic. vascular strand and pith.).

Anatomy of Flowering Plants – Important Notes for NEET Theories of Apical Meristem. Regarding the apical meristem, there are three theories:

1. Apical Cell Theory Was Formulated By Nagcli (1858). According to the apical cell theory or Nagcli ( 1858), the apical meristem is made up of a single apical cell in all plants. This is also called “Single-cell theory”.
2. Histogen Theory Proposed By Hanstein (1870). According to the history theory of Hanstein ( 1870), the apical meristem is divisible into three zones, i.e. outer dermatogen, middle problem and inner plenty. Dermatogen gives rise to epidermis, periblem to cortex and the pleronte to stele.
3. Tunica Corpus Theory Was Formulated By Schmidt (1924). According to the tunica corpus theory of Schmidt (1924), the apical meristem is made up of two zones i.e. tunica and corpus. The tunica zone is outer in position and its cells divide only anticlinally. On the other hand, the corpus zone is central in position and its cells divide in many planes. Tunicacorpus theory is the most accepted theory of apical meristem.
4. Korpe Kappe Theory (Schcupp, 1917). It deals with the organisation of the root apex, i.e. It has two parts. Kappe or cap and Korpe or body. Both show T-type division, upright or inverted.

Anatomy of Flowering Plants – Important Notes for NEET  Quiescent Centre

Clowes (1961) has shown the occurrence of an inactive centre in many roots called a quiescent centre. It is the region of low mitotic activity which occupies the central region of the root apex, For Example., between the root tip and meristem. In the quiescent centre, there is little synthesis of protein DNA and RNA.

The root apex is differentiated into 3 regions-

1. Protoderm (future epidermis),
2. Cortical initials (future cortex) and
3. Vascular cylinder. A group of initials at the apex produce cells on both sides.

Those towards the axis form the epidermis, cortex and vascular cylinder, while those away from the axis form the root cap. The Histogen involved in the formation of the cap (caiyptrogen) is derived from dermatogen.

Anatomy Of Flowering Plants Neet Notes

Neet Biology Anatomy Of Plants

They are arranged in the following four ways :

1. Ranunculus Type. There is a single set or layer of initials that gives rise to all parts.
2. Casuarina Type. Two sets or layers of initials-inner forming the central part, outer forming cortex, root cap and epiblema.
3. Common Dicot Type. Three sets or layers of initials, one forming root cap and epiblema, second cortex and third central cylinder.
4. Common Monocot Type. Four sets of initials, one (caiyptrogen) forming root cap, second epiblema, third cortex and fourth central cylinder.

Stem A place Meristem (Vetictatlve Shoot Apex)

It is a multicellular, dome-shaped or conical structure which is protected by young leaves produced by it. New leaves and axillary buds are produced periodically on the flanks.

• The period between the origin of two successive leaves is called plastoehron. The meristem forms three derivatives- protoderm (produces epidermis of stem and leaves).
• Procambium (forms vascular strand) and ground meristem (ground tissues like mesophyll of leaves, hypodermis, cortex. endodermis, pith, etc).

Anatomy of Flowering Plants – NEET Questions Permanent Tissue

Permanent Tissue. They are composed of mature cells which after undergoing complete growth, have assumed a definite shape, size and function. They have the power of division. Depending upon origin, permanent tissue is of two kinds:

1. Primary tissue consists of evils derived from the primary meristem and
2. Secondary tissue haring cells derived front secondary meristem.

The permanent tissue is of two types depending upon constitution i.e., simple tissue (one type of cells) and compound tissue (two or more than two types of cells.)

Kinds Of Simple Permanent Tissue.

• Parenchyma
• Collenchynta
• Sclerenchynta.

1. Parenchyma. Oval, spherical polygonal or isodiametric cells with thin cell walls. often with intercellular spaces.

• Parenchyma is modified into
• Chlorenehyma. These cells have chloroplasts and hence take part in photosynthesis. The Chlorenehyma of the leaf is called mesophyll. It is often differentiated into palisade parenchyma (columnar chlorenehymatous cells) and spongy parenchyma (irregular chlorenchyma cells enclosing air spaces),
• Aerenchyma. Network of star-like parenchyma cells enclosing large air cavities, For Example., aquatic plants.
• Epidermis. Cutinised parenchyma cells form a covering layer. A distinct layer of cutin or cuticle may occur on the outside,
• Guard Cells. They are a pair of specially thickened small reniform or dumb-bell cells which can create a pore in between them due to differential swelling,
• Prosenchyma. Elongated fibre-like parenchyma.

Anatomy Of Flowering Plants Mcq For Neet

• The tissue takes pan in the storage of food, slow conduction and turgidity of softer pans.
• It is the major ground tissue that occurs inside the stem and root as cortex and pith, the pulp of the fruit.
• The endosperm of the seed, parts of vascular tissues, leaf interior, etc. The epidermis is made of modified parenchyma cells.

2. Collenchyma. The tissue of cells with thick cellulose cell walls, especially at the angles of the cells is called collenchyma. It is abundant in climbing stems. It occurs in the hypodermis of dicot stems and petiole.

Depending upon the place of thickening, collenchyma is of three types:

• Lamellate (Lamellar). Thickening on tangential walls For Example., the stem of a Sunflower,
• Lacunate. Thickening on the walls bordering intercellular spaces, For Example.. stem of Tagetes. Tomato. Datura.
• Angular. Thickening at the angles. For Example.. stem of Cucurbita.

Flowering Plant Tissue Structure Neet

Anatomy of Flowering Plants – NEET Questions Collenchyma Functions.

• It provides mechanical support.
• It provides elasticity while allowing plant organs to grow in size.
• The cells may store food as well as manufacture food.

3. Sclerenchyma. It is made up of hard and lignified tissue consisting of fibres and sclereids. Its function is also supportive.

1. There are two types of sclerenchyma cells
2. Long, flexible with tapered ends (fibres) and
3. Usually rough and spherical sclereids or stone cells.

Sclerenchymatous fibres. Individually, fibres are quite strong due to lignified walls. When these groups are together, their strength is greatly increased.

• Therefore, these can provide mechanical support to the tissue in which these are found. Fibres are commonly found in the pericycles of stems, forming a solid tissue protecting the vascular bundles of dicots.
• These also surround the vascular bundles of monocots and quite often, they form a layer in the cortex below the epidermis of stems or roots. These also occur in the xylem and phloem.

Anatomy of Flowering Plants – NEET Questions Sclerenchyma Commercial Fibres

1. Surface fibres For Example. cotton, calotropis, and coir (coconut).
2. Bast Fibres For Example. Hemp, Linum. Jute, Sun hemp.
3. Leaf Fibres For Example. Agave, Murs.

Steroids are usually singly or in groups in the plant body, especially in the phloem, fruit walls and in the pulp of fruits and seeds, Sclereids provide rigidity to the structures in Which these are found.

The graininess of the fruits like guava and pears is due to the occurrence of stone cells in soups in their pulp. The ssalls of sclereids are very’ thick, and highly lignified so that lumen is greatly reduced.

Sclerites-Sclereids occurring singly are called idioblastic sclereids or spicular cells or sclerites.

Anatomy of Flowering Plants – NEET Questions Sclereids Are Of The Following Five Types

1. Brachysdereids (Stone cells). Isodiametric sclereids resembling parenchyma in shape. found soft parts of plants.
2. Macrosdereids (rod cells or Malpighian cells). Columnar b shape, forming palisade-like epidermal layer b seed coats of peas and beans and epidermis of onion.
3. Osteosclereids (prop cells). Bone-like sclereids, columnar with dikted ends For Example. leaves and seed coat of many monocots. hr.
4. Astrosclereids-star-like (stellate) sclereids For Example. Nymphaea leaves, stem and leases of Thea. (tea).
5. Trichosclereids (or Trichoblasts or Internal hairs) are Long, hair-like, sometimes branched sclereids For Example. leaves of Olea and aerial roots of Monsiera.

Anatomy of Flowering Plants – NEET Questions Sclereids Functions

The function of sclerenchyma is to provide support and mechanical strength to the plant. Therefore, its distribution in plants is related to be physical stress which different organs have to face.

Sclereids Compound Tissue

Sclereids is two types, i,e. xylem and phloem.

Anatomy of Flowering Plants – NEET Questions Xylem

The xylem is a permanent complex conducting tissue. It is also called wood. It is concerned with the upward conduction of water and minerals.

Xylem is a group of cells which are similar b origin and function but of more than one type b structure. On be basis of development, the xylem consists of two primary xylem and a secondary xylem.

Primary Xylem. It is differentiated into :

1. Protoxylem. It is the first formed part and consists of annular and spiral tracheids and vessels.
2. Metaxylem. It is formed later and consists of scalariform, reticulate and pitted tracheids and vessels.

The Primary Xylem Is Of Three Types based on be relation between the protoxylem and metaxylem.

Three forms are:

1. Exarch.
2. Endarch
3. Mesarch

The secondary xylem is formed from vascular cambium during secondary growth. It may consist of annual rings. Each annual ring is made up of autumn wood and spring wood.

Anatomy of Flowering Plants – NEET Questions Elements Of Xylem

Xylem is composed of the following four different kinds of elements:

1. Tracheids
2. Vessels
3. Xylem parenchyma
4. Xylem fibres.

1. Tracheids. These are elongated (1-6 mm) tube-like dead single cells with hard, thick and lignified walls. Their end walls are tapered and overlap with adjacent tracheids. When mature, babies are dead with empty lumens.

Neet Important Questions Anatomy Of Flowering Plants

Water can pass through empty lumens and passes from tracheid to tracheid through ‘pits’ in beer walls. However, angiosperms have relatively fewer tracheids, and vessels are more common b bese plants.

Anatomy of Flowering Plants – NEET Questions Depending Upon Thickenings, Tracheids Are Of The Following Type

1. Annular,
2. Spiral,
3. Reticulate,
4. Scalariform and
5. Pitted (simple pits or bordered pits).

2. Vessels. These are characteristic conducting units of xylem m angiosperms. These are very long (l-6m) tubular structures formed by be fusion of several cells (called vessel elements) end to end in a row.

The vessel elements are similar to tracheids, except bats are shorter and wider than be latter. Vessels are exceptionally long in Eucalyptus.

3. Xylem Parenchyma. Parenchymatous cells associated with the xylem together constitute the xylem parenchyma. The cells are living, thin-walled and abundant. These are mainly involved in the short-distance transport of substances as well as the storage of sugars, starch and lipids.

4. Xylem Fibres. Sclerenchymatous fibres present in the xylem are called xylem fibres. These occur abundantly in woody dicots. These do not conduct water. Thus, these have thicker walls and narrower lumens than xylem vessels and are, therefore, stronger and provide additional mechanical strength to the xylem.

Anatomy of Flowering Plants – NEET Questions Phloem

It is a permanent complex tissue. It is meant for the conduction of food materials. Phloem occurs throughout the plant body along with the xylem. Phloem is of three types based on its position i.e. External phloem present outside the xylem. Internal phloem present inner to xylem and Interxylary or included phloem present within the secondary xylem.

Phloem is made up of four types of cells :

1. Sieve tubes
2. Companion cells
3. Phloem parenchyma
4. Phloem fibres.

1. Sieve Tubes. These are long, slender, tube-like structures involved in the transport of solution of organic solutes like sucrose throughout the plants.

• These are formed by end-to-end fusion of cells called sieve tube elements or sieve elements. Rows of these cells develop in the apical meristem together with the primary xylem.
• The walls of sieve tube elements are made up of cellulose and pectic substances, as in parenchyma cells, but their nuclei degenerate and are lost as they mature. The cytoplasm is confined to a thin peripheral layer.
• Two adjoining end walls of neighbouring sieve elements form a sieve plate. Originally plasmodesmata passed through the walls, but later on, these pores enlarged, so that the walls looked like a sieve allowing the flow of solution from one element to the next.

2. Companion Cells. A thin-walled elongated cell called a companion cell is associated with each sieve tube. Both are connected by simple pits.

Each companion cell is living and contains dense protoplasm and a large elongated nucleus. The sieve tube elements do not have a nucleus, but they remain living, being dependent upon the adjacent companion cell.

3. Phloem Parenchyma. These are parenchymatous cells found in the phloem. These are living and often cylindrical. These are absent in most of the monocots. These mainly store food materials.

4. Phloem Fibres. Phloem fibres are similar to sclerenchyma fibres and provide mechanical support. Phloem fibres of plants like jute, flax and hemp are retted in water and extracted for making ropes and coarse textiles. Sclereids are more frequent in older phloems.

Secondary Growth In Flowering Plants Neet – NEET Questions Types of Vascular Bundles

• Vascular Bundle. A strand-like part of the plant vascular system (conducting system) containing xylem and phloem. the xylem and phloem may be separated by the fascicular
  cambium. the following types of vascular bundles are found in plants.

1. Conjoint Vascular Bundle. When phloem and xylem axes are present on the same radius, i.e. they are laterally placed to each other. It is of two types

1. Collateral and
2. Bicollateral.

• Collateral Vascular: If a strip of cambium is present between the phloem and xylem, they are called open bundles. If cambium is absent they are called closed bundles. If above the conjoint bundle, a sclerenchyma fibre is present the bundle is called fibrovascular bundle.
• Bicollateral Vascular Bundle. When in a collateral bundle, the problem is present both above and below the xylem bundles on the same radius. One group of phloem faces the pericycle and the other group faces the pith. This is seen in the Cucurbita stem and the cambium twice between both phloem groups lying above and below the xylem.

2. Radial Vascular Bundle. When the xylem and phloem lie on different radii alternating with each other, as in roots, the bundle is called radial.

Anatomy Of Dicot And Monocot Plants Neet

3. Concentric Vascular Bundle. When the xylem is surrounded by phloem or vice versa, the vascular bundle is called concentric.

If the xylem is surrounded by phloem it is called a concentric amphicribal vascular bundle (Hydrocentric) i.e. Ferns (Lycopodium, Selaginella). But when a phloem is surrounded by a xylem, it is called a concentric amphivasal vascular bundle (Leptocentric) Example. Dragon plant (Dracaena) and Dagger plant (Yucca).

Anatomy Of Flowering Plants Chapter 6 Special Tissues

They are commonly secretory or excretory tissue For Example. laticiferous tissue and glandular tissue.

1. Laciceferous Or Laticiferous Tissues Or Laticifers

It is concerned with the secretion of latex or an emulsion or oils, alkaloids, resins, proteins and sugar. It consists of thin-walled, elongated branched ducts. The laticifers are of two types

• Latex vesseLs
• Latex celLs.

These occur irregularly distributed in the mass of parenchymatous cells.

• Latex Cells are called simple laticifers or non-articulated laticifers which may be unbranched or may be branched profusely but do not fuse to form a network quite common in the members of families Apocynaceae, Asclepiadaceae, Euphorbiaceae and Moraceae (For Example. milkweed. Euphorbia, Ficus etc.).
• Latex Vessels (Articulated laticifers) are formed by the union of latex cells (hence called compound Laticifers also) and are quite common in the family Papaveraceae (poppy family), Caricaceae (Papaya family), Compositae, Musaceae (banana family)

2. Glandular Tissue. They are isolated secretory structures which may be unicellular or multicellular. Example

1. Nectar-Secreting glands.
2. Nectar (or honey) is a sugary substance secreted by the nectar gland or nectaries which may be floral (present in flower) or extra floral (on vegetative parts).
3. Water-Secreting Structures (Water Stomata or Hydathodes) are present along the margins and apices of leaves. The exudation of water through these is called guttation.
4. Osmophores. They secrete essential oil.
5. Chalk Or Gland cells secrete salts For Example. Tamarix.

Simplified Notes On Anatomy Of Flowering Plants For Neet

Sachs (1975) distinguished three types of tissue systems in plants

1. Epidermal tissue system,
2. Ground tissue system,
3. Vascular tissue system.

1. Epidermal Tissue System

• It consists of the epidermis, the outermost layer of cells covering the entire surface of the plant body and epidermal outgrowths.
• The Epidermis of the stem, leaves and floral parts originate from the surface layer of the shoot apical cistern.
• In roots, the epidermis originates either from an independent Set of Initials or has a common origin with the root cap and cortex. It is called epithelia or piliferous layer, it may bear root hair.

In most of the angiosperms, it is single-layered (uniseriate), but in some (like leaves of Nerlum, Ficus, Olearulcr etc.) it is made up of two or more layers (multiseriate).

• Epidermal cells are living, thin-walled, with a large central vacuole and thin peripheral cytoplasm. These are compactly arranged without intercellular spaces. The basic function of the epidermis is to protect the plant from desiccation and infection.
• The epidermal cells secrete a waxy substance called cutin, which forms a layer of variable thickness (the cuticle) within and on the outer surface of its all walls. It helps in reducing the loss of water by evaporation and also checks the entry of pathogens.
• In Xerophytes, the cuticle is thick; in mesophytes, it is moderately thick; and is absent in hydrophytes. It is also absent in roots and underground parts.

Epidermal outgrowths are called trichomes (hairs or scales). The hair-like extensions may be unicellular or multicellular and serve a variety of functions.

In roots, Unicellular hairs are called root hairs, these absorb water and mineral salts. In stems, these are multicellular. Trichomes are epidermal outgrowths. Scales are flattened epidermal outgrowths.

Stomata occur in the epidermis of aerial parts. Depending upon the distribution of stomata, the leaves are

• Apple-Mulberry Type. Hypostomatic stomata only on the lower surface.
• Potato Type. Most common, amphistomatic but more on the lower surfaces,
• Oat Type. Amphistomatic, equal on two surfaces,
• Nymphaea Type. Epistomatic—only on the upper surface,
• Potamogeton Type. Astomatic or with nonfunctional stomata.

2. Ground Tissue System:

It comprises the internal structure of organs, excluding the circulatory system. The ground tissue system in leaves is referred to as mesophyll. It is categorized into hypodermis, cortex, endodermis, pericycle, pith, and medullary rays.

• The hypodermis imparts strength. The cortex is involved in food storage. In certain stems, the cells possess chloroplasts and are also photosynthetic.
• The cortex of immature roots transports absorbed water and minerals inward.
• The endodermis, the innermost layer of the cortex, contains Casparian strips in roots.
• In dicot stems, it is referred to as a starch sheath.
• The endodermis is lacking in the stems of monocots. The pericycle constitutes the external boundary of vascular tissues. It is unilayered in roots and multilayered in stems.

3. Vascular Tissue System:

It consists of a vascular strand or cylinder. The latter is made up of some vascular bundles. Vascular bundles are radial in roots and conjoint in other parts.

Plant Tissues And Anatomy Neet Questions

Anatomy Of Flowering Plants Chapter 6 Anatomy Of Root

Internal Structure of Dicot Root

A primary root arises from the radicle of the seed. It is generally cylindrical in outline and possesses the following structures, from outside towards the inside of the transverse section of the root:

1. Epiblema Or Piliferous Layer. It is the outermost layer which is made up of compactly arranged thin-walled parenchymatous cells. From epidermal cells, arise thin-walled tubular outgrowths called root hair. Due to the presence of root hair, the epiblema layer is also called as piliferous layer. The Epiblema layer is responsible for the absorption of water and minerals from the soil.
2. Cortex. Inner to epiblema is a multilayered cortex which is made up of thin walled cells. The cells of the cortex store food. These cells also conduct water from epiblema to internal tissue.
3. Endodermis. The innermost layer of the cortex is known as the endodermis. The endodermis consists of barrel-shaped cells with Casparian strips on their anti-clinal walls. Opposite to the protoxylem, the cells are thin-walled and called passage cells. Passage cells allow the free movement of water and minerals from the cortical cells in the xylem bundles.
4. Pericycle. Inner to endodermis is a layer of pericycle. From the pericycle arise lateral roots and also vascular cambium which brings about secondary growth in the root.
5. Vascular Bundle. Inner to pericycle are found 2-6 vascular bundles with alternating xylem and phloem. According to number, the root may be diarch, triarch, tetrarch and pentarch.

In the xylem, the protoxylem is outside and the metaxylem is towards the centre of the root. Such a xylem is called an exarch.

• Phloem is present in between two xylem bundles. Phloem consists of sieve tubes, companion cells and phloem parenchyma.
• Dicot root shows secondary growth. Cambium develops from pericycle and conjunctive parenchyma, and a ring of cambium is formed which cuts off the secondary xylem on the inner side and the secondary phloem on the outer side.

Anatomy Of Flowering Plants Chapter 6 Internal Structure of Monocotyledonous Root

The transverse section of the monocot root shows the following structures. There is no distinction between young and old monocot roots as there is no secondary growth in monocot rool The various layers of tissues are as follows:

1. Epiblema Or Piliferous Layer. It is the outermost layer which consists of thin-walled cells. Some cells produce root hair. It is meant for the absorption of water.
2. Cortex. Inner to epiblema is a multilayered cortex consisting of compactly arranged cells. It is meant for protection and storage of food.
3. Endodermis. It is single-layered and lies inner to cortex. The cells are barrel-shaped with Casparian strips on their radial walls. Opposite to protoxylem, endodermal cells are thin-walled and called passage cells.
4. Vascular Strand. It consists of several (8 or more) alternate radial xylem and phloem bundles. The vascular bundles are arranged in the form of a ring with a pith in the centre.
   • The xylem Is Exarch with a protoxylem towards the outside and a metaxylem towards the centre. Xylem elements are rounded. The xylem provides mechanical strength and is meant for the conduction of water and minerals.
   • The Phloem Alternates With The Xylem. The two are separated by conjunctive parenchyma. Phloem is meant for translocation of organic food.
5. Pith. Pith is present in the centre, consisting of parenchymatous cells. Pith stores food.

Anatomy Of Flowering Plants Chapter 6 Anatomy Of Stem

Structure Of Dicot Stem

A young dicot stem in the transverse section shows the following structures from the periphery towards the centre.

1. Epidermis
2. Cortex
3. Endodermis
4. Pericycle
5. Vascular bundles
6. Pith.

Structure Of Monocot Stem

In the monocot stem, there is no distinction between the cortex and the pith. There is ground tissue in which vascular bundles are scattered. The transverse section of Maize stems shows the following structures:

1. Epidermis
2. Ground tissue.
3. Vascular bundles.

Anatomy Of Flowering Plants Chapter 6 Anatomy Of Leaf

Internal Structure Of A Dicotyledonous Leaf Or Dorsiventral Leaf of Helianthus or Chenopodium can be studied under the following heads :

1. Epidermis. In the transverse section, there are upper epidermis and lower epidermis. The epidermis is single-layered. The cells of the epidermis are colourless and secrete a waxy layer of cuticle.

• In the epidermis are numerous minute apertures called stomata. Each stoma has two kidney-shaped guard cells. Stoma opens in the leaf in a sub-stomatal cavity.
• Besides guard cells, there are two specialised cells called subsidiary cells or accessory cells. The guard cells regulate the opening of a stoma.

Plant Tissues And Anatomy Neet Questions

2. Mesophyll. In between the upper and lower epidermis, there is chloroplast containing photosynthetic tissue called mesophyll. Mesophyll is divided into two parts:

1. Palisade parenchyma
2. Spongy parenchyma.

• Palisade Parenchyma. It is present below the upper epidermis and consists of closely packed elongated cells. The cells contain abundant chloroplasts and are arranged in 2-3 layers.

The compactness of the cells of this layer reduces the transpiration. The main function of palisade tissue is to manufacture carbohydrates during photosynthesis.

• Spongy Parenchyma. It is present below palisade tissue and consists of loosely arranged irregularly shaped cells with large intercellular spaces in between them.

Spongy parenchyma is in contact with the atmosphere through stomata. Its function is transpiration and exchange of gases for respiration and photosynthesis. In addition, spongy parenchyma is photosynthetic in function.

3. Vascular System. There are many vascular bundles. Each vascular bundle is surrounded by a layer of parenchymatous cells called a bundle sheath. Each vascular bundle has a xylem towards the upper epidermis and a phloem towards the lower epidermis.

The xylem is meant for the conduction of water and minerals while the phloem is meant for the translocation of food. Cambium is absent in the leaf, so there is no secondary growth in the leaf.

Structure of A Monocotyledonous Leaf Or Isobilateral Leaf Grass Or Zea Mays.

The transverse section of a monocot leaf shows the following parts:

• Epidermis. It consists of a closely packed single layer of cells. Some cells in the epidermis are large, and thin and contain water and are called bulliform cells. In epidermis are present stomata. Each stoma has two dumbbell-shaped guard cells.
• Mesophyll. There is no distinction between palisade and spongy parenchyma. The mesophyll consists of similar types of cells rich in chloroplast. There is no distinction between palisade and, spongy parenchyma. The main function of mesophyll is photosynthesis.
• Vascular System. The vascular bundles are present in a row. Each vascular bundle is surrounded by a sclerenchymatous bundle sheath. In the vascular bundle xylem is towards the upper epidermis and the phloem towards the lower epidermis. There is no cambium. So vascular bundle is closed.

Secondary Growth

Secondary Growth is growth brought about by secondary meristem. It may be classified into two types:

Normal And Anomalous. Growth brought about by fascicular cambium is called normal. Secondary growth of vasculature brought about by extra fascicular cambium (arising either in the pith or cortex) is called anomalous.

• In dicots, secondary growth is seen in the vascular cylinder as well as in the cortex. Vascular cambium produces secondary vascular tissue while cork cambium produces periderm tissue.
• In monocots vascular bundles are closed, thus there is no secondary growth. In some monocots, Dracaena, Yucca, Aloe, Agava, and Sanserveria, secondary growth occurs.

Anatomy Of Flowering Plants Chapter 6 Steps Of Secondary Growth

• Secondary growth results from the activities of the cambium and cork cambium.
  The cambium is a lateral meristem that is one cell thick radially.
• It consists of fusiform initials and ray initials. It may be multi-storeyed or single-storeyed.
• A cambium ring consisting of intra- and interfascicular cambial strips is established.
• It generates secondary xylem internally and secondary phloem externally. Additionally, secondary medullary rays are produced on both sides.
• The secondary xylem and phloem form a vertical and a horizontal system. The latter in both instances consists of ray parenchyma.
• The secondary medullary rays consist of upright and reclining cells. The rays might be either homocellular or heterocellular. They can be homogeneous or heterogeneous, and uniserate, biserate, or multiserate.
• The growth throughout the spring and fall seasons results in spring and autumn woodlands, respectively. The two types of wood form the annual ring. The age of the plant can be approximated by counting the annual rings.
• The wood can be either porous or non-porous, with the porous category further classified as ring porous or diffuse porous.
• The paratracheal parenchyma generates balloon-like formations known as tyloses within the tracheary components.

The wood is thereafter categorized into a narrow, light-hued region known as sapwood or alburnum, and a dark-hued, large region referred to as heartwood or duramen.

• The sapwood is physiologically active, facilitating the ascent of sap. The heartwood has more resistance than sapwood. Reaction wood develops as a response to stress. It could be either tension wood or compression wood.
• The extra-stellar zone expands when a cork cambium (phellogen) develops in the cortex or epidermis.
• The phellogen generates cells outside that undergo suberization to produce cork (phellem). The cells on the inner side remain thin-walled and constitute the secondary cortex (phelloderm).
• The three layers, namely phellem, phellogen, and phelloderm, collectively form the periderm. Non-suberized cells of phellem are referred to as spheroids.
• All tissue external to the vascular cambium is referred to as bark. The tissue external to the innermost phellogen forms the outer bark or rhytidome, while the remaining tissue is classified as the inner bark.
• The bark can be scaly, papery, ring-shaped, or exhibit intermediate characteristics.
• Commercial cork is derived from Quercus suber. The initial layer is referred to as a virgin cork. It is lightweight, robust, flexible, a poor conductor of heat and electricity, and impermeable to liquids and gasses.
• A wound, once created, is promptly filled with cork cells known as wound cork, produced by the activity of phellogen.
• A lenticel develops at the stomatal site. The sub-lenticular cells serve as the complimentary cells. A phellogen is established, generating new complimentary cells and protective layers.
• When branches accelerate in the stem as a result of secondary growth, nodes are generated.

Anatomy Of Flowering Plants Chapter 6

Plant tissue may be classified into two main groups i.e. meristematic tissue and permanent tissues.

1. According to position, the meristem is of three types i.e. apical, intercalary and lateral.
2. The apical meristem lies at the apex of both stem and root.
3. Various types of trichomes are
   • Simple
   • Unicellular,
   • Multicellular
   • Multicellular with protuberance and
   • Multicellular
   • Branched and
   • Stinging and
   • Glandular
4. In a dicot root, there are 2 to 6 xylem bundles while in monocots there are more than six.
5. Latex of Carica papaya (papaya) contains papain. Latex of poppy yields opium which contains the alkaloid morphine.
6. Latex of Bananas contains tannin.
7. Though Hevea brasiliensis (Para rubber) and Manihot glaziovi belong to the family Euphorbiaceae, these contain latex vessels (not latex cells).
8. Latex cells are found in Cannabis, Vinca minor and Urtica dioica. Para rubber and Indian rubber are obtained from the latex of Hevea brasiliensis and Ficus elasticatively.
9. Aristolochia And Bougainvillea show anomalous secondary growth.
10. The periderm is a secondary protective tissue that replaces the epidermis during secondary growth. It consists of phellogen (cork cambium) which produces phellem towards the outside and phelloderm towards the inside.
11. Endodermoid. The term is used by some authors for endodermis or starch sheath of young stems because of the absence of Casparian strips.
12. Leaf Primordium. Develops from a lateral protrusion or leaf buttress. It grows initially by an apical meristem (permanent in ferns) and then by intercalary meristem.
13. The leaf consists of only primary tissues. Secondary growth is limited to wound healing.
14. The epidermis which covers the upper surface of the leaf is called the adaxial epidermis while that which covers the lower surface is known as the abaxial epidermis.
15. In grasses and Equisetum, silica is present in the epidermal cells.
16. Epidermal cells containing cystoliths are called lithocysts.
17. The epidermis of garlic (Allium sativum), scales and seeds of peas and beans are made up of sclereids.
18. Usually, epidermal cells are colourless, but hydrophytes and sciophytes, contain chloroplasts and are hence, green.
19. Cork is light, highly compressible and does not catch fire.
20. In the deserts; 60 cm. high plant Aerva persica plant can have a tap root system reaching a depth of 6 metres.
21. Apoplast. The non-living parts (For Example. xylem, cellulose, intercellular space, etc.) of the plant are called apoplast.
22. Symplast. Living parts (cytoplasm-containing cells) of the plant.
23. Sclerenchymatous patches of the pericycle outside the vascular bundles are called bundle caps.
24. Lateral roots arise endogenously from the pericycle cells.
25. Medullary vascular bundles are found in the stems of Mirabilis, Boerhaavia, Amaranthus, etc. The plants show anomalous secondary growth.
26. Abscission. It involves the formation of a special parenchymatous layer called abscission or separation layer at the base of the organ and a layer of suberised thick-walled ‘cork’ cells called a protective layer over the mother axis. Degeneration of cells of abscission or separation layer causes abscission.

Anatomy Of Flowering Plants Chapter 6

Vessels are an advanced type of conducting element and are characteristically found in angiosperms. Some primitive vessel-less angiosperms belong to the families—Winteracae, Trochodendraceae and Telracentraceae. Some pteridophytes (Selaginella, Pteridium) and gymnosperms (Gnetum) have got vessels.

1. Wood without vessels is homozygous while the one with vessels is heterozygous.
2. Gymnosperms With Vessels. Members of group gnetales.
3. Pteridophytes With Vessels. Occasional in species of Selaginella, Dryopteris, Marsilea, etc.

Fibres present outside the xylem are called extrasolar fibres. They may be cortical, pericyclic (or perivascular) or phloem (bast) fibres.

1. Except xylem parenchyma, the xylem is a dead tissue.
2. Sieve tubes were first discovered by Hartig (1837).
3. In phloem, companion cells and sieve tubes arise from the same mother cell.
4. Slime plugs are dense funnel-shaped structures formed by the coagulation of slime bodies on sieve plates.
5. conifers (gymnosperms), albuminous cells are found-analogous to companion cells.

Since companion cells and sieve tubes arise from the same mother cell, these are called sister cells.

1. Knot. As the stem grows in thickness, the bases of branches become embedded in the secondary xylem and thus knots are formed. The buried portion can neither grow in diameter nor can be pushed outward.
2. When a log is cut vertically, the branch embedded in it as a knot, is cut transversely.
3. P-proteins are proteinaceous structures present in sieve tubes and are believed to be responsible for
4. Movement of materials through the cell,
5. Sealing of pores after wounding.
6. Bhojpatra is derived from the bark of Betula utilis.

The waxy substance associated with the walls of cork cells is suberin and the phenomenon of impregnation of cell walls with suberin is called suberisation.

1. Cutin forms a continuous layer on the epidermis, which is known as a cuticle.
2. The formation of the cuticle is called cuticularization.
3. Apical cell theory was proposed by Hofnieister (1857) and supported by Nageli.
4. Histogen theory was given by Hanstein (1868) and supported by Strassburger.
5. Heartwood. Most abundant in Mulberry but absent in Poplar and Willow.
6. There is no distinction between heart wood and sap wood in Salix, Populus, etc.
7. In Morus, Taxus, the heartwood is most abundant and the sapwood zone is quite thin.

Heartwood is dark-coloured due to the deposition of extractives and is considered durable.

1. Heartwood is the dead primary or old xylem. Most Durable Soft Wood. Cedras deodara.
2. Most Durable Wood. Teak (Tectona grandis).
3. Lightest Wood. Ochroma pyramidale ( = 0. lagopus).
4. Heaviest Wood. Guaiacwn officinale. In India Acasia sundra.
5. The bark of Cinnamomum leylanicum (Dalchini) is used as a flavouring material.
6. In Angiosperms vessels are present along with tracheids.
7. In the sieve tube nucleus is absent.

Neet Important Questions Anatomy Of Flowering Plants

Companion cells occur only in Angiosperms and are absent in Pteridophytes and Gymnosperms.

1. Phloem parenchyma is absent in monocots.
2. Xylem cells are polygonal in dicots and oval in monocots.
3. Normally no secondary growth in monocot stems except anomalous secondary growth in Dracaena, Yucca etc.
4. In monocots, grafting is not successful due to closed and scattered vascular bundles.
5. In a hollow-hearted plant, the growth of the plant is not affected.
6. Wound healing and secondary growth are controlled by secondary meristems.

Swollen exogenous protuberances on the growing apices are leaf primordia.

1. Sieve elements are living enucleated structures.
2. Tissue builder zones are three in the shoot apex and four in the root apex.
3. Raphides are the crystals of calcium oxalate.
4. Amphivasal is where the xylem surrounds the phloem.
5. Clayptrogen histogen forms a root cap.

Climatic variations are almost zero in seashore plants therefore cambium has uniform activity without demarcation of annual rings.

1. The leaf consists of only primary tissues. Secondary growth is limited to wound healing.
2. Leaf primordium develops from a lateral protrusion or leaf buttress. It grows initially as apical meristem (permanent in ferns) and then by intercalary meristem.
3. The epidermis which covers the upper side of the leaf is called the adaxial epidermis.
4. The epidermis which covers the lower surface is called the abaxial epidermis.
5. Cells of bark i.e. cork of phellem cells are made up of impervious suberin.
6. After the formation of phellem, the stomata are obliterated and new proes are formed which are lens-shaped hence lenticels.

NEET Biology Plant Anatomy Multiple Choice Questions And Answers

Question 1. Meristematic cells have:

1. Large prominent nucleus and dense cytoplasm
2. No intercellular spaces
3. Rounded shape
4. All the above.

Answer: 4. All the above.

Question 2. The cells or tissues of plants which have lost the power of division are called:

1. Meristematic
2. Permanent
3. Protoderm
4. Promeristem.

Answer: 2. Permanent

Question 3. Promeristems can be distinguished from primary meristems by:

1. Their apical position
2. By their power of active division
3. The presence of a large prominent nucleus
4. All the above.

Answer: 4. All the above.

Question 4. The undifferentiated cells are present in:

1. Maple tree root system
2. Sepals of geranium flower
3. Cambium of oak
4. Root of Raphanus.

Answer: 3. Cambium of oak

Read and Learn More NEET Biology Multiple Choice Question and Answers

Question 5. The tip of the root apical meristem is capped by the histogen, known as:

1. Dermatogen
2. Periblem
3. Calyptrogen
4. Plerome.

Answer: 3. Calyptrogen

Vascular Tissues MCQs For NEET

Question 6. Meristematic cells are:

1. Thin-walled, isodiametric, nucleate and less protoplasmic
2. Thin-walled, isodiametric, nucleate and densely protoplasmic
3. Thick-walled, isodiametric, non-nucleate and densely protoplasmic
4. Thick-walled, isodiametric, nucleate and less protoplasmic.

Answer: 2. Thin-walled, isodiametric, nucleate and densely protoplasmic

Question 7. The root apical meristem is subterminal because it:

1. Is covered by root hairs
2. Is covered by the root cap
3. Has many corpus cells
4. Is covered by tunica cells.

Answer: 2. Is covered by the root cap

Question 8. Cork cambium is a:

1. Promeristem
2. Lateral meristem
3. Intercalary meristem
4. Ground meristem.

Answer: 2. Lateral meristem

Question 9. Primary vascular tissues are derived from:

1. Protoderm
2. Procambium
3. Ground meristem
4. Calyptrogen.

Answer: 2. Procambium

Questions Question 10. The epidermis in the stem is produced from:

1. Protoderm
2. Procambium
3. Ground meristem
4. Calyptrogen.

Answer: 1. Protoderm

Question 11. The pith in the stem is derived from:

1. Protoderm
2. Procambium
3. Ground meristem
4. Plate meristem.

Answer: 3. Ground meristem

Vascular Tissues MCQs For NEET

Question 12. Epiblema in roots is derived from :

1. Protoderm
2. Procambium
3. Ground meristem
4. Calyptrogen.

Answer: 1. Protoderm

Question 13. The histogen concept was proposed by:

1. Schmidt
2. Nageii
3. Hanstein
4. Strassburger

Answer: 3. Hanstein

Question 14. The lateral meristem is responsible for:

1. Increasing height
2. Increasing thickness
3. Increasing tissue
4. None of the above.

Answer: 2. Increasing thickness

Question 15. The tissue is made up of thin-walled rectangular cells responsible for the secondary growth:

1. Cortex
2. Xylem
3. Cambium
4. Pith.

Answer: 3. Cambium

Question 16. Root cap in dicots is formed from:

1. Ground meristem
2. Procambium
3. Protoderm
4. Calyptrogen.

Answer: 4. Calyptrogen.

Vascular Tissues MCQs For NEET

Question 17. Intercalary meristems are derived from:

1. Permanent tissue
2. Secondary meristem
3. Lateral meristem
4. Apical meristem.

Answer: 4. Apical meristem.

Question 18. Secondary meristems are derived from:

1. Apical meristem
2. Intercalary meristem
3. Lateral meristem
4. Permanent tissues.

Answer: 4. Permanent tissues.

Plant Anatomy MCQs For NEET

Question 19. The vascular cambium of the root is an example of meristem:

1. Apical meristem
2. Intercalary meristem
3. Secondary meristem
4. Root apical meristem.

Answer: 3. Secondary meristem

Question 20. Tunica corpus theory was proposed by:

1. Hanstein
2. Schmidt
3. Nageli
4. Hofmeister.

Answer: 2. Schmidt

Question 21. Dermatogen is tissue formed by apical meristem and it develops into:

1. Pith
2. Vascular bundles
3. Epidermis
4. Cortex.

Answer: 3. Epidermis

Question 22. Grass stem elongates by the activity of:

1. Cambium
2. Intercalary meristem
3. Apical meristem
4. Primary meristem.

Answer: 2. Intercalary meristem

Plant Anatomy MCQs For NEET

Question 23. The concept envisaging three distinct zones of cells of new tissue builders at the stem and root apices is known as:

1. Meristem theory
2. Histogen theory
3. Dermatogen theory
4. Tunica colpus theory.

Answer: 2. Histogen theory

Question 24. Which of the following clogs the cavity of the xylem vessels?

1. Tyloses
2. Cystoliths
3. Hydathode
4. Raphides.

Answer: 1. Tyloses

Question 25. Carnbium which produces cork is known as:

1. Phelloderm
2. Phellogen
3. Phellern
4. Periblem.

Answer: 3. Phellern

Plant Anatomy MCQs For NEET

Question 26. When we peel the skin of a potato tuber, we remove:

1. Epidermis
2. Periderm
3. Cuticle
4. Sapwood

Answer: 2. Periderm

Question 27. In which meristem do you see cell divisions occurring in all planes?

1. Lile meristem
2. Plate meristem
3. Lateral meristem
4. Ground meristem.

Answer: 4. Ground meristem.

Question 28. Which is the first wall layer formed by dividing plant cells and occurring between subsequently formed cell walls of daughter cells?

1. Primary wall
2. Secondary wall
3. Middle lamella
4. Cellulose layer.

Answer: 3. Middie lamella

Question 29. The fascicular cambium in a dicotyledonous stem is a meristematic tissue referred to as :

1. Apical
2. Lateral
3. Primary
4. Intercalary.

Answer: 2. Lateral

Important MCQs On Plant Anatomy NEET

Question 30. Which new tissues of the plant body originate in the apical meristems?

1. Parenchyma
2. Collenchyma
3. Sclerenchyma
4. Secondary.

Answer: 1. Parenchyma

Question 31. Intercalary meristems are present in the following:

1. Nodai region
2. Internodal region
3. Bryophytes
4. The nodal region is close to the base of the plant.

Answer: 1. Nodai region

Question 32. The basic differences between a vessel and a tracheid are:

1. Types of pits
2. Size and types of pits
3. Perforations on end walls
4. Length wall thickness and lignification.

Answer: 3. Perforations on end walls

Question 33. Which is not true about the sclereids?

1. These are parenchymatous cells with thick lignified cell wall
2. They are elongated and flexible and their ends are tapering
3. Generally, they are found in the rind of drupe fruits and pulp of guava and pear
4. They are also called stone cells.

Answer: 2. They are elongated and flexible and their ends are tapering

Question 34. Primary growth of a tree:

1. Occurs through the activities of apical meristems
2. Occurs through the activity of a vascular cambium
3. Occurs through the activity of the root cap
4. Occurs only in the first year of the tree’s life.

Answer: 1. Occurs through the activities of apical meristems

Important MCQs On Plant Anatomy NEET

Question 35. Secondary xylem and phioem are laid down by:

1. Apical meristems
2. Axillary meristems
3. Vascular cambium
4. Cork cambium.

Answer: 3. Vascular cambium

Question 36. Which of the following would not secrete a cuticle?

1. Leaf epidermis
2. Stem epidermis
3. Root epidermis
4. Xerophytes.

Answer: 3. Root epidermis

Question 37. One year’s growth in length of a young woody shoot is the distance between successive:

1. Rings of bud scale scars
2. Leal scars
3. Branches
4. Axillary buds.

Answer: 1. Leal scars

Question 38. Anatomically jute fibres are:

1. Vertical fibres
2. Pith fibres
3. Xylem fibres
4. Phloem fibres.

Answer: 4. Phloem fibres.

Plant Tissues MCQs For NEET

Question 39. Xylem that is not conducting water is called:

1. Heartwood
2. Sapwood
3. Springwood
4. Summerwood.

Answer: 1. Heartwood

Important MCQs On Plant Anatomy Question 40. Intercalary meristem is seen in:

1. Maize
2. Ficus
3. Cabbage
4. Cucurbita.

Answer: 1. Maize

Question 41. Tunica and corpus organization occurs in:

1. Lateral meristem
2. Root apex
3. Shoot apex
4. Intercalary meristem.

Answer: 3. Shoot apex

Question 42. Tree trunk increases in girth because of the cell division activity in:

1. Epidermal tissues
2. Supporting tissues
3. Meristematic tissues
4. None of the above.

Answer: 3. Meristematic tissues

Plant Tissues MCQs For NEET

Question 43. In the root, the maximum growth occurs:

1. In the presence of high-temperature
2. In the presence of light
3. At the apex
4. Behind the apex.

Answer: 4. Behind the apex.

Question 44. Chlorenchyma cells are:

1. Chlorophyll-containing sclerenchyma cells
2. Chlorophyll-containing epidermis
3. Chlorophyll-containing parenchyma
4. Chlorophyll-containing phloem.

Answer: 3. Chlorophyll-containing parenchyma

Question 45. Sclerenchyma cells are mostly:

1. Living cells
2. Dead cells
3. Pat of xylem vessels
4. Part of pericycle.

Answer: 2. Dead cells

Question 46. Abnormal secondary growth due to accessory cambia is found in:

1. Helianthus
2. Cucurbita
3. Dracaena
4. Maize.

Answer: 3. Dracaena

Plant Tissues MCQs For NEET

Question 47. Secondary meristems are set apart from primary meristems in that they:

1. Are responsible for secondary growth
2. Increase the size of the state
3. From the cork and secondary vascular tissue
4. Always arise in permanent tissue.

Answer: 4. Always arise in permanent tissue.

Question 48. In amphiphilic siphonostele, phloem is:

1. Internal to xylem
2. External to xylem
3. Surrounded by xylem
4. On both sides of the xylem.

Answer: 4. On both sides of the xylem.

Question 49. The science of dendrochronology is applied to determine:

1. The age of trees
2. Date of archaeological objects
3. Ecological succession of trees
4. Tree-like concept of evolution.

Answer: 1. The age of trees

Xylem And Phloem MCQs For NEET

Question 50. Cork of commercial value is obtained from:

1. Quercus
2. Mango
3. Pines
4. Cedrus deodara.

Answer: 1. Quercus

Question 51. The first event during the secondary growth of dicot root is the division of:

1. Cambial initial between xylem and phloem
2. Pericyclic cells external to primary xylem
3. Conjunctive cells form circular cambium
4. Parenchyma cells are internal to the primary phloem.

Answer: 3. Conjunctive cells to form circular cambium

Question 52. Collenchyma mainly forms:

1. Hypodermis
2. Epidermis
3. Phloem
4. Inner cortex.

Answer: 1. Hypodermis

Question 53. Xylem and phloem in plants are concerned with conduction like arteries and veins. Yet unlike the arteries and veins, together they cannot be termed a circulatory system because:

1. No liquid moves through these elements
2. Gases are not transported by these tissues
3. Plants lack the heart to pump
4. Movement is not in a circular manner from one to the other.

Answer: 4. Movement is not in a circular manner from one to the other.

Xylem And Phloem MCQs For NEET

Question 54. Xylem parenchyma occurring in association with vessels is known as:

1. Paratracheal xylem parenchyma
2. Apotracheal xylem parenchyma
3. Syntracheal xylem parenchyma
4. Associated xylem parenchyma.

Answer: 1. Paratracheal xylem parenchyma

Plant Anatomy MCQs Question 55. Angular collenchyma is found in:

1. Althea
2. Cucurbita
3. Lactuca
4. Salvia.

Answer: 2. Cucurbita

Question 56. Youngest layer of secondary xylem is adjacent to:

1. Cortex
2. Pith
3. Cambium
4. Pericycle.

Answer: 3. Cambium

Question 57. External protective tissue of plants are:

1. Pericycle and cortex
2. Epidermis and cork
3. Cork and pericycle
4. Cortex and epidermis.

Answer: 2. Epidermis and cork

Question 58. Angiosperms have:

1. Tracheids only
2. Vessels absent
3. Vessels present
4. Sieve tubes are absent.

Answer: 3. Vessels present

Xylem And Phloem MCQs For NEET

Question 59. Fusiform initials form:

1. Tracheary elements
2. Phloem parenchyma
3. Vascular rays
4. Ray parenchyma.

Answer: 1. Tracheary elements

Question 60. Which of the following lies in between the bark and wood of a tree trunk?

1. Cork cambium
2. Phloem
3. Vascular cambium
4. Primary cortex.

Answer: 3. Vascular cambium

Question 61. Plant fibres can originate from:

1. Phloem, xylem, epidermis and sclerenchyma tissues
2. Xylem, epidermis and sclerenchyma tissues
3. Phloem, xylem and sclerenchyma tissues
4. Xylem, phloem and epidermis tissues.

Answer: 1. Phloem, xylem, epidermis and sclerenchyma tissues

Question 62. Sieve tubes are best suited for translocation because they:

1. Possess no end wall
2. Are broader than long
3. Possess a broad lumen and perforated wall end
4. Possess bordered pits.

Answer: 3. Possess a broad lumen and perforated wall end

NEET Botany Structural Organization MCQs

Question 63. Promeristem is found in:

1. Embryo
2. Root apex
3. Shoot apex
4. All of the above.

Answer: 1. Embryo

Question 64. Which of the following do not have a nucleus but are still living?

1. Sieve tubes
2. Trachea.
3. Companion cell
4. Phloem fibres.

Answer: 1. Sieve tubes

Question 65. Abundant root hairs are present in:

1. Eichhornia
2. Hydrilla
3. Commelina
4. Pistia.

Answer: 1. Eichhornia

Question 66. The cell layer located at the periphery in the cross-section of the root is called:

1. Endodermis
2. Epiblema
3. Pericycle
4. Xylem.

Answer: 2. Epiblema

Question 67. Lateral roots arise from the:

1. Endodermis
2. Epidermis
3. Pericycle
4. Pith.

Answer: 3. Pericycle

Question 68. The endodermis is the innermost layer of the:

1. Xylem
2. Phloem
3. Cortex
4. Cambium.

Answer: 3. Cortex

Question 69. Casparian strips occur in:

1. Endodermis
2. Epidermis
3. Pericycle
4. Cortex.

Answer: 1. Endodermis

Question 70. Radial vascular bundles occur in:

1. Stems
2. Dicot stem
3. Monocot stem
4. Monocot root.

Answer: 4. Monocot root.

NEET Botany Structural Organization MCQs

Question 71. Well-developed pith is found in:

1. Monocot root and monocot stem
2. Monocot root and dicot stem
3. Monocot stem and dicot root
4. Dicot root and dicot stem.

Answer: 2. Monocot root and dicot stem

Question 72. Protoxylem lacunae are characteristic features of:

1. Climbers
2. Underground stem
3. Vascular bundles of the stem of grasses
4. Cladode.

Answer: 3. Vascular bundles of the stem of grasses

Question 73. The centrifugal arrangement of the xylem is called:

1. Monarch
2. Diarch
3. Polyarch
4. Exarch.

Answer: 4. Exarch.

Question 74. The xylem in the monocot root is:

1. Monarch
2. Diarch
3. Triarch
4. Polyarch.

Answer: 4. Polyarch.

Question 75. Cortex in the monocot root constitutes:

1. Parenchymatous cells
2. Collenchymatous cells
3. Sclerenchymatous cells
4. Companion cells.

Answer: 1. Parenchymatous cells

Question 76. Root hairs are:

1. Acellular
2. Unicellular
3. Multicellular
4. Multicellular and unicellular.

Answer: 2. Unicellular

Question 77. Monocot root differs from dicot root in having:

1. Scattered vascular bundles
2. Well developed pith
3. Endarch vascular bundles
4. Open vascular bundles.

Answer: 2. Well-developed pith

Question 78. The main function of xylem is:

1. Protection
2. Storage of food
3. Conduction of water and minerals
4. None of the above.

Answer: 3. Conduction of water and minerals

NEET Botany Structural Organization MCQs

Question 79. Vascular cambium in dicot root develops from:

1. Endodermis
2. Pericycle
3. Conjunctive parenchyma
4. Both (2) and (3).

Answer: 4. Both (2) and (3).

Important MCQs on Anatomy of Flowering Plants Question 80. Vessels are characteristic of:

1. Angiosperms only
2. Gymnosperms only
3. Pteridophytes only
4. None of the above.

Answer: 1. Angiosperms only

Question 81. Root hair arises from:

1. Pericycle
2. Endodermis
3. Cortex
4. Epiblema.

Answer: 4. Epiblema.

Question 82. Tyloses are found in:

1. Secondary xylem
2. Secondary phloem
3. Callus tissue
4. Cork cells.

Answer: 1. Secondary xylem

Question 83. After secondary growth, the copies in the dicot root:

1. Remains intact
2. Is completely sloughed away
3. Is largely lost
4. Is converted to cork.

Answer: 3. Is largely lost

Question 84. Monocot root differs from dicot root in:

1. Showing no secondary growth
2. No hairs
3. No cambium
4. All the above.

Answer: 3. No cambium

NEET Botany Structural Organization MCQs

Question 85. Exarch xylem is found in:

1. Root
2. Stem
3. Leal
4. Rachis.

Answer: 1. Root

Plant Anatomy MCQs Question 86. Stem and flrots olqucifeme grow due to actiraty of:

1. Cortex
2. Cambium
3. Phloem
4. Endoderm.

Answer: 2. Cambium

Question 87. Pith is absent or reduced in:

1. Dicot root
2. Dicot stem
3. Monocot stem
4. Monocot root.

Answer: 1. Dicot root

Question 88. Two to five xylem bundles are found in:

1. Monocot root
2. Monocot stem
3. Dicot stem
4. Dicot root.

Answer: 4. Dicot root.

Question 89. Maximum amount of growth in roots occurs due to :

1. Auxins
2. Root cap region
3. Presence of light
4. Darkness.

Answer: 1. Auxins

Question 90. The tip of the root apical meristem is covered by a root pocket in:

1. Brassica
2. Eichhornia
3. Petunia
4. Wheat.

Answer: 2. Eichhornia

Question 91. Raphides are:

1. Starch
2. Silica
3. Calcium carbonates
4. Calcium oxalate.

Answer: 4. Calcium oxalate.

Question 92. Raphides are found in:

1. Citrus
2. Colocasia or monocots
3. Nerium
4. Mango.

Answer: 2. Colocasia or monocots

Question 93. If the heartwood region of the plant is removed or decays:

1. The root will die first
2. Shoot will die first
3. Root and shoot die together
4. Neither root nor shoot till die.

Answer: 4. Neither root nor shoot till die.

Question 94. In the dicot stem the vascular bundles are:

1. Not found at all
2. Closed and show sclerenchymatous bundle sheath
3. Arranged in a ring
4. Are scattered in the ground tissue.

Answer: 3. Arranged in a ring

Question 95. In a dicot stem, the vascular bundle is:

1. Concentric
2. Collateral
3. Excentric
4. Radial.

Answer: 2. Collateral

Vascular Tissues MCQs For NEET

Question 96. The most common type of ground tissue is:

1. Epidermis
2. Collenchyma
3. Parenchyma
4. Sclerenchyma.

Answer: 3. Parenchyma

Question 97. Mark the openings on a tree trunk for respiration:

1. Stomata
2. Hydathode
3. Lenticels
4. Cracks.

Answer: 3. Lenticels

Question 98. In monocots vascular bundles are:

1. Open
2. Closed
3. Bicollateral
4. Radial.

Answer: 2. Closed

Plant Anatomy MCQs Question 99. Growth rings determine:

1. Age
2. Length
3. Breadth
4. Number of branches of a plant.

Answer: 1. Age

Question 100. Vascular bundles are arranged in a ring in:

1. Dicot stem
2. Dicot root
3. Monocot stem
4. Monocot leaf.

Answer: 1. Dicot stem

Animal Kingdom Non-Chordate Phyla Classification Of Animal Kingdom

There are about 1.2 million animal species which show a great diversity of life. Though the animals are metazoans like the plants they differ from plants in several characteristics like the absence of plastids, cell wall, and central vacuole; and having centrosomes in the cells.

These are exclusively heterotrophic and are mostly holozoic in their nutrition. These also pass through certain larval stages during their development.

Classification Of Animal Kingdom For NEET Criteria Of Classification

Habitat Mode of living and orientation of the body

• Aquatic. Those animals which live in water.
• Marine. Those animals which live in seawater.
• Freshwater. Those live in waters other than sea water Exampleponds, drains, ditches, lakes, rivers, slow or fast running streams, etc.
• Amphibious. Those animals which can live on land as well as in water, Examplefrog.
• Terrestrial. Those that live on land Exampleman, lizards, etc.
• Aerial. Those animals which can live in the air, Examplebirds and bats.
• Zooplanktons. These float on the water’s surface and are drifted by water currents Example small crustaceans like Daphnia, Cyclops, etc.
• Nektons. These swim actively in a sea or a lake Examplemost of fishes. Zooplanktons and the nektons which live in open waters, are collectively called pelagic animals.
• Benthos. These live on the bottom of water bodies Examples, are corals, echinoderms, etc.
• Out of these, sponges and corals are fixed to the substratum and are called sedentary or sessile animals.
• Neustons are animals floating or swimming in surface waters. Neritic are the animals found in coastal waters.
• Terrestrial animals. These animals live on land. They are again of the following types:
• Scansorial animals. These climb the walls, rocks, etc. Examples are lizards, flying squirrels, etc.
• Aerial animals. These can go in the air Examplemost for insects and birds, bats, etc.
• Cursorial animals. These are fast-runners Examplehorse, rabbits, lions etc.
• Pelagic. Living in the surface water of the sea.
• Arboreal. Those animals which live on trees and catch hold of tree branches Examplemonkeys.
• Burrowing (Fossorial). Those animals that form burrows in the sand or soil, for example – earthworms, snakes, some fishes, etc.
• Cave dwelling. Those which live in caves, for example- Lions and some fishes.
• Solitary. Those animals that live alone or single individually Exampleman, cats, dogs, etc.
• Colonial. Those which form colonies to live together, for example- Bees, ants, some coelenterates, (Physalia, Obelia), porifers (Sycon), etc Sedentary. These are fixed animals attached to substratum Example sponges, obelia, and
  most coelenterates.
• Free swimming. They swim actively in water. Sessile. These animals do not possess stalk. Sub-sessile. They possess stalk.
• Orientation of body
• Oval shaped. The shape of the body is like an egg.
• Cylindrical. The shape of the body is long and spherical, resembling a cylinder.
• Elongated. The body is long.
• Oblong. The body is oval and long (oval + long)
• Depressed body Dorsoventrally flattened body.
• Laterally compressed. Pressed laterally.
• Abond. Located away from, or on the opposite side of the mouth.
• Adoral. Located on the same side of the body surface as the mouth.

Body Segmentation

• Metamerically segmented body. A linear repetition of body parts is known as a segmentation (metamerism) example. Pheretima.
• Somite. Each repeated unit is somite.
• Appendages. Body pints protrude from the main body and serve in locomotion, feeding, mating, etc.

Skeleton

• Exoskeleton. Skeleton, which lies outside the body, for example- scales, feathers, nails, hairs, etc. It protects the body.
• Endoskeleton. Skeleton which lies inside the body, supports and protects internal organs, composed of cartilage or bone.

Detailed Notes On Non-Chordates Classification For NEET

Formation of mouth

• Protostonies. In most of the phyla (Platyhelmithes, Annelida. Arthropoda, Mollusca, and smaller groups), a tired mouth is formed in front of the blastopore of the embryo. These are called protostomes.
• Deuterostomes. In echinoderms, hemichordates, and chordates, the mouth arises remote front of the blastopore, and the latter becomes the anus.

Mode of running

Unguligrade

• Running on the tips of digits Example Horse, Rhinoceros, Ass, Zebra, Giraffe, etc.
• Plantigrade Walking on the palm of sole
• Digitigrade—Walking on toes Example Cat, Dog.

Level of organization

• Cellular organization. The animal body is formed of many cells but the cells show no coordination to form tissues Example sponges.
• Tissue organization. The animal body is formed of many cells that coordinate for the specific function and form four types of tissues Example epithelial tissue, connective tissue, muscular tissue, and nervous tissue Example coelenterates like Hydra.
• Organ-system organisation. The body is multicellular and cells coordinate to form tissues, organs, and systems Examples from flatworms to mammals.

Symmetry

Asymmetry- When the animal cannot be cut into two halves Example Amoeba. Radial or Biradial Symmetry. The radially symmetrical animals are mostly spherical or cylindrical. These can be cut into two halves, if we cut them through any radius of the animal, for example, most of the coelenterates and all the echinoderms.

Radial symmetry is again of the following types:

1. Tetramerous Radial symmetry. When in radial symmetry, the body parts are arranged in fours or multiples of four Example Jellyfish.
2. Pentamerous Radial symmetry. When in radial symmetry, the body parts are arranged in five or multiples of five Example echinoderms.
3. Hexamerous Radial symmetry. When in radial symmetry, the body parts are arranged in sixes or multiples of six Example Sea anemone. In sea anemones, the body can be divided into two similar parts only by one or two vertical planes and have biradial symmetry.
4. Bilateral symmetry. When the animal can be cut into two exactly equal and similar halves by one plane only Example Platyhelminthes to Chaetognatha and also vertebrates.

Sides in a Bilaterally Symmetrical Animal.

• Anterior side. It is that side of the body which is kept forward during locomotion.
• Posterior side. It is that side of the body that is opposite to the anterior side of the body.
• Dorsal side. It is the upper side of the body which is away from the substratum during locomotion.
• Ventral side. (L. Venter = belly). It is the lower side of the body which is towards the substratum during locomotion.
• Lateral sides. The right and left sides of the body are called lateral sides.

Body cavity

• Coelom. The body cavity is bounded externally by the parietal layer of the peritoneum and internally by the visceral layer of the peritoneum.
• Coelomate (Eucoelomate). The animals that possess true coelom. (True coelom is a cavity between the body wall and visceral organs and must be formed from mesoderm) Example Bryozoa.

Based on origin, coelom is of two types :

• Schizocoel. When coelom is formed by splitting of mesoderm Example annelids, arthropods, and mollusks. The animals having schizocoelic coelom are grouped in Schizocoela.
• Enterocoel. When coelom is formed from the enteron ofgastrula Example echinoderms and chordates. Such animals are grouped in Enterocoela. Acoelomate. These organisms lack coelom. They include all members up to phylum Platyhelminthes.
• Pseudocoelomata Animals in which false coelom is present. Body cavity, if present, develops from blastocoel, for example- Rotifera, Nematoda. Haemocoelomatas.
• In Arthropods and mollusks, the true coelom is reduced and the body cavity is filled with blood and is called hemocoel, and animals are termed haemocoelomates.

Modes of Respiration

Modes of excretion

• Ammonotclism. When the main nitrogenous waste is NH3 the animals excreting ammonia are called ammonotelic animals. The water loss from the body along with ammonia is 300-900 ml/gm of NH3. It is found in aquatic animals Example Protozoans, sponges, coelenterates, crustaceans, echinoderms, and bony fishes.
• Ureotelism. The main nitrogenous waste is urea and the animals possessing it are called ureotelic animals. The loss of water along with urea is comparatively less. It is 50ml/ gm of urea. It is found in amphibians, mammals, and cartilage fishes.
• Uricotelism. The main nitrogenous waste is uric acid and animals possessing it are called uricotelic animals. Water loss is quite less and is just lOml/gm of uric acid. It is expelled as a semisolid paste. It is found in reptiles, birds, and insects.
• Mollusks like Limnaea, Unio, etc. are amniotic (expel amino acids) while certain bony fishes (especially teleosts) have trimethylamine as nitrogenous waste.

Cold-blooded or warm-blooded

1. Homeothermal or Endothermic (Warm-blooded animals).
2. In this, body temperature Is constant and does not change with the change in environmental temperature Example birds and mammals.
3. Homeothermal Or endothermic (Cold-blooded animals). In this, body temperature is not constant and changes with changes in environmental temperature.

These defend themselves in two ways:

1. Hibernation (Winter-sleep). In this, animals hide themselves in winter months and become inactive Example amphibians (frog; and lizards.
2. Aestivation (Summer-sleep). In this, animals hide in shady areas during hot summer months. amphibians.

Detailed Notes On Non-Chordates Classification For NEET

Blood Vascular System

1. Open type circulation Example Arthropods, mollusks.
2. Closed type circulation Example. Annelids and most of chordates.

Body Plan

1. Cell aggregate
2. Blind sac and
3. Tube in a tube body plan

Number of germ layers

• Diploblastic animals. In sponges and coelenterates, gastrula has two layers, outer ectoderm, and inner endoderm, so they are called diploblastic animals, for example, Porifers and coelenterates.
• Triploblastic animals. From flatworms to mammals, gastrula larva has three germ layers, outer ectoderm, middle mesoderm, and inner endoderm. So these are called triploblastic animals, for Example Platyhelminthes onward all phyla.

Reproduction

• Monoecious.When one individual of a species possesses both the male and female reproductive organs Example Pheretima, Taenia, Fasciola, etc. Hermaphrodite. It is a synonym or duplicate name of monoecious.
• Dioecious. When male and female reproductive organs are borne by separate individuals, the situation is called dioecious, for example- Man, Pila, Prawn, etc.
• Sexual dimorphism. If we can distinguish male and female individuals of a species by looking at their external features only, the phenomenon is called sexual dimorphism. Or, Males and females possess different shapes.
• PoIymorphism.The occurrence of at least tv/o, usually several, radically different body forms within colonial or social organisms.
• In unisexual animals, sperms and ova are derived from different animals, called cross-fertilization, In some bisexual animals, sperm and ovum of some animals fuse, called self-fertilization Example in Taenia.
• But in some bisexual animals, cross-fertilization occurs due to conditions: protandrous and protogynous. In protandrous conditions (Proto = first, android = male), testes mature earlier than ovaries Example leech, earthworm, etc.

In protogynous conditions (Proto =first, gynae = female), ovaries mature earlier than testes Example Scypha, and Herdmania (Sea squirt).

• Polygamy. When one male lives in the company of many females Example Struthio.
• Holoblastic Cleavage. The cleavage of the egg is complete; for example—in many invertebrates, amphioxus, amphibians, and mammals.
• Meroblastic Cleavage. The egg divides incompletely due to too much yolk in it The cleavage is confined to a limited portion of the egg, for example, Squids, insects, many fishes, reptiles, and birds.
• Metamorphosis. The larva undergoes certain changes to become adult, this process is called metamorphosis.
• Progressive Metamorphosis. When the larva is simple and becomes complex in the adult stage, for example- the Tadpole of a frog changes into an adult. Retrogressive Metamorphosis. When the larva is complex and more advanced than the adult.
• It loses its certain characters, for example –
• Ascidians. The larva has a well-developed notochord and nerve cord while these structures are absent and reduced respectively in adults.
  • Monogenetic life cycle. When a parasite completes its life cycle in a single host Example Ascaris.
  • Digenetic Life cycle. When a parasite completes its life cycle in two hosts.
  • Pheromones. Secretions of glands are released in the air. These generally act as sex attractants.
  • Autotomy. The ability of self-amputation.
  • Regeneration. Ability to make up lost parts.

Classification Of Animal Kingdom For NEET Phylum Porifera

Unique features

• The canal system consists of pores, canals, and chambers facilitating the continuous flow of water for nourishment, respiration, excretion, and reproduction.
• Cellular organization within the body.
• Lack of oral cavity and gastrointestinal tract.
• Choanocytes, also known as collar cells, line the diverse passageways and spongocoel.
• Existence of spicules, spongin fibers, or both.
• The free-swimming larvae, termed parenchymula (Lcucosolenia & Clathrina) and amphiblastula (Sycon), function as a primary mode of dispersal for this predominantly sessile phylum.

Classification Of Animal Kingdom For NEET Cells Of Sponges

• Choanocytes (also known as “collar cells”) flagellated cells which function as the sponge’s digestive system, are remarkably similar to the protistan choanoflagellates.
• The collar is composed of microvilli and is used to filter particles out of the water.
• The beating of the flagella of choanocytes’ creates the water current that enters the spongocoel.

• Pinacocytes. Form the pinacoderm, the outer epidermal layer of cells. This is the closest approach to true tissue in sponges.
• Porocytes. Tubular cells make up the pores in the sponge body through the mesohyl.
• Myocytes. Modified pinealocytes control the size of die and pore openings and thus (lie water flow.
• Archaeocytes (or microcytes). They are totipotent cells that can transform into. They also have a role in nutrient transport and sexual reproduction.
• Sclcrocylcs. Secrete calcareous or siliceous spicules that reside in the mesohyal.
• SpoiRocyles. Secrete spongin, collagen-like fibers which make up the mesophyll.
• Collcncytcs. Secrete collagen.
• Spicules. Stiffened rods or spikes made of calcium carbonate or silica are used for defense.
• Sensory anil nerve cells are absent in sponges.
• Spongioblasts. Spongin-fibre-secreting cells of sponges.
• Out of these, myocytes are derived from the dermal layer, while other amoebocytes are derived from the gastral layer.
• Cells are arranged in a gelatinous non-cellular matrix called mesohyal.

Position of Chomocytes

• Line the spongocoel in the Ascoiioid canal system.
• Line the radial canals in the Syconoid canal system.
• Line the flagellated chambers in the Lcticoitoid canal system.
• In the cavity of Eupleclella, a pair of crustaceans- Venusta spongicola lives till death.
• Prosopylc: An aperture between the incurrent and radial canal of Scypha.
• Apopyle: An aperture between a radial canal and an excurrent canal of Scypha.
• Geniniulation: Formation external buds in sponges.
• Gentmule: An internal bud of Spongilla. II is formed by a coat of spicules. It helps in perennation. Spicules- kinds.
  1. Rod-like or (long, short spear or club-like (excites)
  2. Three-rayed or Triradiate
  3. Tetaradiate
  4. Six rayed.
• Chemical nature.
• Calcareous or siliceous
• Costliest bath sponge – Spongia officinalis (natural sponge)
• Spongilla colony. Green in color.
• Gemmules are endogenous buds of sapodilla and help in asexual reproduction
• Euspongia. brown
• Spongia and Hippospongia provide bath sponges of commercial value
• The largest sponges belong to the class Demospongiae. A tropical logger-head sponge (Spheciospongia) forms a mass of over a meter in height and diameter
• Sponges are the lowest metazoans and arc placed in sub-kingdom Parazoa.
• Parazoology. Scientific study of sponges.
• Robert Grant. Coined the term Porifera.
• Ellis: Recognised the sponges as animals.
• The dermal ostia of sponges are analogous to mouths, while the osculum is analogous to the anus.
• The Mesogloea of the sponge is known as mesohyal or mesenchyme.
• Spongilla is a common and widely distributed freshwater sponge,
• Ieucosolenia is one of the simplest sponges.

Reproduction in sponges

Asexual reproduction

• By budding External/Exogcnous In budding, numerous archaeocytes collect at the surface and the placoderm bulges out to receive them. The bud so formed grows in an adult individual, ft either remains attached to the parent individual or gets detached and attached nearby to develop into an independent colony.
• Formation of gemmules (Internal/endogenous buds) All freshwater and some marine sponges (Ficulina, Tethya, Suherites, etc.) have a regular and peculiar mode of asexual reproduction by internal buds, called gemmules (Gr., gemma, bud).
• These eventually detach and develop into new individuals. Gemmules enable the sponges to tide over unfavorable conditions, such as excessive cold or draught, because they can withstand freezing and considerably greater degrees of desiccation than adult sponges.
• Fission-In some sponges, multiplication takes place by fission, throwing off parts of the body. The sponge is hypertrophied over a limited area, developing a line of weakness.
• Along this weak line, splitting occurs and a part is separated from the main parental body which develops into a new individual. By budding, this new individual takes the form of a colony.
• Formation of reduction bodies Another very unusual method of asexual reproduction is the formation of reduction bodies. Most freshwater and marine sponges disintegrate in adverse circumstances.
• The ailing sponge will usually collapse leaving small rounded balls, called reduction bodies.
• Each body consists of an internal mass of amoebocytes, covered externally by a pinacoderm. When favorable conditions return, these reduction bodies grow into completely new sponges.

Classification Of Animal Kingdom Non Chordates NEET Notes

Sexual Reproduction

• Sperms and ovum arc are derived from archaeocytes or choanocytes which undergo gametogenesis.
• Sperms are released outside through outflowing water and make their way into another sponge along with the ingressing water.
• Sperms arc carried by sperm-transit cells to the ovum.
• Fertilization is internal.
• The development includes amphiblastula or parencliymula larva.
• Amphiblastula is a hollow, oval larval stage, characteristic of many calcareous sponges (Example Scypha). Anterior one-half of amphiblastula bears flagella, whereas the posterior half does not.
• The parenchymula is a solid, oval, or flattened larval stage. It is characteristic of some calcareous, hexactinellid, and most demosopongians. The entire outer surface bears flagella.
• With the help of external flagella, the motile larvae escape from the parental body and swim for a few hours to many days. Finally, they settle down, become attached to some solid object, metamorphose, and grow into adults.

Classification Of Animal Kingdom For NEET Phylum-Coelenterata—(Cnidaria)

Unique features

1. Tissue level of organization.
2. Special kinds of stinging cells or cnidoblasts are meant for offense, defense, and food catching.
3. Diploblastic, radially symmetrical, and mostly show polymorphism.
4. The epidermis surrounds the cnidarian’s ‘stomach’ or gastrovascular cavity which functions as both mouth and anus. It is used both to ingest food and excrete waste.
5. It also serves along with the mesogloea as a hydrostatic supporting skeleton. Firm skeletons are only found among polyps, which produce lime for that purpose.
6. The gastrovascular system plays a role in the digestion and dispersion of food and the removal of metabolic waste.
7. It surrounds the gastrovascular cavity as well as its extension in the tentacles of polyps. Thus the gastrovascular system serves two separate functions, digestion, and transport.
8. Digestion is both intracellular and intercellular or extracellular.

Classification Of Animal Kingdom For NEET Kinds Of Nematocysts

• Penetrants or Stenoteles. They are the largest.
• Volvent or desmosomes. They are the smallest, used only for obtaining food.
• Small glutinanLs or Alrichous or his, Butt absent and help in fixing loan object.
• Large glulinants or Ifolotrichous isorhiza. The long thread is open at the free end. They slick to an object.

Classification Of Animal Kingdom For NEET Hydra

Features of Hydra

• It is a fixed animal and is found attached to submerged weeds and stones. Though it is fixed, it can move about when required. If disturbed, it contracts to a small spherical or oval mass.
• It is carnivorous as its food consists of small crustaceans and larvae of insects.
• Digestion is intercellular as well as intracellular.
• Hydra has a slender tubular body and exhibits distinct radial symmetry. The body is extremely contractile and length varies from 10 to 30 mm.
• The lower end of the tubular body is closed and this side is designated as the aboral or proximal end. This side of the body is named a foot or basal disc.
• It is used as a structure for attachment to the substratum and it helps in locomotion.
• The opposite end (the distal or oral end) is free and possesses the opening of the mouth, situated at the summit of a conical elevation called the hypostome or manubrium.
• The manubrium is usually surrounded by several tentacles. The tentacles are fine hollow processes and help in catching food.
• The mouth leads into the coelenteron which occupies the interior of the body. It is continuous with the cavities of the tentacles.
• The epidermis and Gastrodermis are the two cellular layers of the body wall of Hydra. In between these two layers is also present a non-cellular jelly-like mesogloea.
• The epidermis is the outer protective layer and cellular. It forms nearly one-third of the thickness of the body wall. It consists of the following types of cells:
  • Epitheliomuscular cells or
  • Musculoepithelial cells
  • Interstitial cells
  • Cnidoblasts or Nematoblasts
  • Nerve cells
  • Sensory or receptor cells
  • Germ cells.
• Nematocysts are of 4 types i.e. Penetrant (Stenotele), Volvcnt (Desmoneme), Glutinant streptoline (Holotrichous isorhiza), and Glutinant steroline (Atrichous isorhiza).
• Gastrodermis. It forms nearly two-thirds of the thickness of the body wall. It is always found forming the lining of the gastrovascular cavity. It consists of five types of cells:
  • The nutritive muscular cells
  • The secretory cells
  • The sensory cells
  • The nerve cells
  • The interstitial cells.

Classification Of Animal Kingdom For NEET Useful Information

• Leukart Gave the term coelenterata.
• Peyssonel (1723): Reported the animal nature of coelenterates.
• Coelenterates are commonly called cnidarians due to the presence of cnidoblasts, so the study of coelenterates is called cnidology.
• Coelenterata name is due to the presence of the coelenteron cavity.
• Obelia is a trimorphic and marine colony.
• Planula larva is formed during the life cycle of Obelia.
• Coelenteron is present which is known as a gastrovascular cavity.
• Cell differentiation and Physiological division of labor are distinct in Hydra.
• Digestion is extracellular as well as intracellular.
• Respiratory organs, Blood, vascular system, and excretory organs are absent.
• The epidermis and Gastrodermis are cellular layers and are separated by mesogloea.
• Mesogloea is the non-cellular layer that is secreted by the epidermis and gastrodermis.
• Obelia and Aurelia show an alternation of generation and phenomenon of metagenesis.
• The main stem of Obelia is called the stolon which gives rise to hydrorhiza which is attached to a substratum.
• Most probably Triclwplax represents the most primitive living metazoans.
• Totipotent interstitial cells are the characteristic of Hydra.
• When development starts, obelia is a monomorphic form having polyp only but later due to the development of blastostyle it becomes a dimorphic colony and finally medusae but over the blastostyle in a mature colony, then it becomes a trimorphic colony.
• Some coelenterates can paralyze people swimming in the seas. ‘Sea wasp’ a coelenterate is one of the most poisonous animals.

Metagenesis. In the life cycle of Obelia, there is regular alternation between fixed polypoid and free swimming medusoid phases, both of which are diploid. Such an alternation between two phases is called metagenesis.

In metagenesis, the adult polyp forms male or female medusae (diploid) asexually.

There are three principal asexual events:

• Budding Strobilation occurs when a medusa forms on the higher (oral) end of the polyp, and is common among scyphozoa finally, complete metamorphosis, from polyp to medusa form can also occur.
• Some coelenterates that show polymorphism are Obelia, Physalia, and Velella. Physalia shows excessive polymorphism having gastrozooids, dactylozooids, and gonozooids.
• In India, medusae of Aurelia are commonly found in coastal waters of Madras.
• In the development of Aurelia (a jellyfish), both planula (larva) and ephyra (larva) are present.
• Obelia. Seafur, a marine, sedentary, and trimorphic colonial coelenterate.
• It has 3 types of zooids: nutritive and flower-like polyp enclosed in a hydrotheca; long and cylindrical mouthless blastostyle enclosed in a gonotheca; and umbrella-like dust with gonads and developed as a bud on the blastostyle. It is commonly called zoophyte due to its plant-like appearance.
• Corals are skeletons secreting anthozoans, while sea anemones are anthozoans with skeletons.
• Coral reefs. A coral reef is a ridge in the sea and is formed of skeletons of the coelenterates called corals. It is mainly formed of skeletons of stony corals like Madrepora but is impregnated by skeletons of Millipore and Tubipora.

It is mainly formed of calcium carbonate. These are of 3 types (by Hyman, 1940):

• Fringing reefs. These extend from the shore up a distance of 400 meters into the sea.
• Barrier reefs. These run parallel to the shore but are separated from slower by a water body called a lagoon. The largest barrier reef Great Barrier Reef in the north-east coast of Australia and is 1920 km long.
• Atoll. It is circular coral surrounding a quiet water body called a lagoon. It is also called Coral Island.
• In India, Lakshadweep islands are formed of coral reefs.
• These are mainly found in warm (70°F) and shallow waters of tropical seas. The Pacific northeast of Australia is called the Coral Sea.
• Corallite is the skeleton of an individual coral, while coenosteum is the colonial skeleton and is called corallum when it is branched.
• Corallium rubrum. Also called red coral (moonga), while Meandrine is commonly called brain coral.
• Rhizostoma. A polytomous scyphozoan with many mouth-bearing structures called scapulets.
• Aurelia. Three larval stages in the life cycle: Planula (ciliated for dispersal), Scliyphistoma (represents reduced polypoid stage and forms ephyrae by transverse fission called strobilation), and ephyrae.

Important Non-Chordates NEET Questions With Answers

Classification Of Animal Kingdom For NEET Phylum—Acnidaria Or Ctenophora

• Phylum Ctenophora was established by Hatschek (1839).
• Phylum Ctenophora is also called Aaiidaria as these lack cnidoblasts.
• Gastrodes parasiticum is only an endoparasitic ctenophore.
• Mesogloea ofctenoplwres is of collenchyma nature (with many cells).
• Ctenophora is a small phylum of marine coelenterates like free swimming and biradially symmetrical animals having 8 meridional rows of ciliary comb ribs.
• They are popularly called comb jellies, sea combs, and sea gooseberries.
• Cnidoblast are absent except Eucldora rubra.
• They possess phagocytes or light-producing structures, therefore are luminescent.
• Tentacles, when present, are solid and possess adhesive cells called colloblasts (= lasso cells).
• Ctenophores are acoelomates.
• The body plan is intermediate between the blind sac and tube within the tube.
• Animals are usually monoecious. An immature ciliated stage larva called cydippid larva is found in some forms.
• Ctenophoria has two classes- denticulate (with tentacles), Example Hormiphora, and nuda (without tentacles), Example Beroe.

Classification Of Animal Kingdom For NEET Phylum- Platyheminthes

General Characters of Phylum Platylielmintlies

• Body form. Body dorsoventrally flat, unsegmented leaf or ribbon-like.
• Germ layers. Triploblastie animals, with three germ layers ectoderm, endoderm, and mesoderm.
• Habitat. Mostly parasites with some five living forms.
• Symmetry. Bilaterally symmetrical.
• Level of Organisation. Body organization is at the level of organ and organ-system grade.
• In parasites, forms suckers and hooks are present lor attachment to host tissues.
• Body cavity. True body cavity absent i.c. acclimate.
• Incomplete alimentary canal present. In the alimentary canal, the mouth is present but the anus is not present. In some endoparasites alimentary canal is absent.
• Respiration is aerobic in free-living forms and anaerobic in endoparasites.
• Excretion is mainly ammonotelic. For excretion special cells called flame cells or protonephridia are present.
• Nervous system. Due to capitalization, a nerve ring is present.
• Sense organs. Photoreceptors are present in free-swimming forms.
• Reproduction. The reproductive system is highly developed and bisexual. It is an adaptation of a parasitic mode of life.
• The life cycle is usually complicated. It is again an adaptation to a parasitic mode of life

Classification Of Animal Kingdom For NEET Parasitism

It is an association between different species in which one is benefited and the other is harmed. The organism which is benefited is called a parasite and the other that suffers is termed a host. It is interesting to note that hosts can live without parasites but parasites cannot survive without hosts.

Types of parasites

1. Temporary or partial parasites. These are animals that spend a brief period of their life as parasites and a major part as free-living forms.
   1. Examples: The Glochiditim larva of freshwater mussel is ectoparasitic on fishes for a short period, whereas the adult mussel is free living.
   2. Hymenoptera larvae are parasitic on caterpillars, whereas the adults are free-living.
2. Permanent parasites. They are parasites throughout their life.
3. Ectoparasite (External Parasite). They live on the surface Example Diplozoon indicum parasites on the gill of freshwater fishes.
4. Endoparasites. Many live inside the host’s body Example Taenia in the intestine, Paragonitim in the lungs, Polystomium in the urinary bladder Fasciola hepatica in the liver, and Schistosoma in the blood. They live in the host body, within the cells. (Cytozoic), tissue (histozoic) or cavities (coelozoic).
5. Monogenetic parasites (life cycle). Life history completed in a single host. Example Polystomum and Diplozoon.
6. Non-pathogenic parasites. They do not cause any diseased conditions in the host body.
7. Digenetic parasites. These parasites require two hosts to complete their life cycle.
8. The host in which the parasite grows into its adult phase is called final, definitive, or primary while the one that simply serves to transmit the parasite from one definitive host to the other is called intermediate, secondary, or vector host.
9. Accidental parasites. These are swallowed accidentally.

Examples: Soil and freshwater nematodes.

1. Mode of infection of helminth parasite
2. Swallowing of contaminated food.
3. Boring through skin Example Schistosoma.
4. Direct contact Example Diplozoon.

Adaptations of helminth parasite

Morphological Adaptation

1. Loss of organs. Locomotory organs, digestive organs, sense organs.
2. Continuation of pre-existing features. Thin flat body, shelled egg.
3. Development of new structure. Adhesive organs tegument, sucking pharynx, cyst wall around infective larvae.

Non-Chordates Classification NEET Previous Year

Physiological adaptations

1. Anaerobic respiration.
2. Secretion of anti-enzymes and mucus.
3. Evasion of the host’s immune system.
4. Chemotoxin
5. Excessive multiplication

Classification Of Animal Kingdom For NEET Fasciola Hepatica (Liver Fluke)

• Liver fluke lives as endoparasite in the bile ducts and canaliculi within the liver and remains attached by an oral and a ventral sucker (acetabulum).
• Upto 200 flukes may be present within a sheep. The mouth is situated in the oral sucker. No anus. Liver fluke is hermaphrodite (monoecious) but cross-fertilization takes place.
• There are two tests. Ovaries and vitelline glands are separate. Laurer’s canal is the temporary opening that receives the cirrus of the male during copulation.
• After fertilization eggs are laid in the bile ducts from where through the intestine they come out with the feces. The shell gland secretes the secretion which hardens to form the shell (capsule). Further development takes place in humidity.

Life Cycle of liver fluke

• The life cycle is digenetic, the primary host is sheep and the secondary host is a snail.
• Eggs enclosed in capsules develop into miracidium larva which hatches in water and enters into the body of a snail (in digestive glands).
• Miracidium will die if it does not reach a suitable host within 24 hours of hatching.
• It develops into sporocyst larvae which form at least two aerations of 5 to 8 media larvae.
• Each media larva forms 14 to 20 cercaria larvae by its ns cells. Cerearia larvae come out of the body of the snail and swim with their tail.
• After some time they get attached to leaves of water vegetation and become encysted to the next larva i.e. metacercaria.
• When sheep feed on aquatic vegetation, metacercaria reaches the alimentary’ canal, where the cyst is dissolved by digestive enzymes and cercaria reaches the liver through the bile duct and develops into adult flukes.
• It causes fascioliasis or liver rot, anemia, and excessive edema of the jaws. Heterogamv.
• A kind of alternation of generations in liver fluke, in which there are alternations between sexual phase represented by adult worms and parthenogenetic generations represented by media and cercariae larvae. Polyembryony.
• In Liver fluke, the germ cells present in larval form are not eggs but they are diploid cells derived by mitotic divisions from propagatory cells separated from zygote. Thus zygote produces many larvae. It is termed as polyembryony.

Classification Of Animal Kingdom For NEET Schistosoma Haematobium

Blood fluke

Commonly known as a blood fluke. It is a digenetic parasite, the primary host is man and the secondary host is Limnea (snail). It causes schistosomiasis or Bilharziasis. Males and females are separate. Females live in the gynaecophoral canal of males.

Classification Of Animal Kingdom For NEET Taenia Solium (Tapeworm)

1. This lives as an endoparasite in the digestive tract where it is anchored to its mucosa by its scolex and absorbs the host’s digested food.
2. It is found in all those parts where the pig is domesticated.

1. Its body is opaque, flat, long, and ribbon-like, measuring 2.8 meters on average.
2. The body is divided into Head (Scolcx), the unsegmented neck, and the segmented strobiln.
3. The head has 4 muscularsuckers and two rows of hooks around the rostellum. The hooks and suckers are meant for attachment. The strobila has about 800-900 segments known as probiotics. These proglottids at the posterior end are sexually mature and known as grnvids.
4. The gravids break off from the body and pass out with feces. This loss of gravity is made good by the neck which makes new proglottids.
5. The body walls consist of a cuticle that rests on the body musculature that binds mesenchyme.
6. Respiration is mainly anaerobic or anoxybiotic.
7. The excretory system consists of lateral longitudinal canals, secondary canals, capillaries, and flame cells.
8. Tapeworm is bisexual (hermaphrodite). Each proglottid has a large number of testes and a single bilobed ovary. Fertilization is internal and the zygotes are stored in a very much-branched uterus. There may be upto 30,000 zygotes present in the items of one gravid. The zygotes are covered with a thick layer of shell.
9. Life Cycle. The gravids break off (apolysis) from the body and pass out with feces.
10. If these feces are eaten by a pig, the zygotes reach into the alimentary canal of the pig. Each zygote produces an embryo with 6 hooks known as a Hexacanth embryo.
11. The hexacanth embryo along with the shell is known as the oncosphere. The shell gets dissolved in the intestine of the pig, the hexacanths come out.
12. These hexacanths pierce the wall of the intestine and enter into the bloodstream. The hooks disappear and each hexacanth embryo changes into a bladder-like structure known as a bladder worm (Cysticercus larva).
13. These larvae now settle into the voluntary muscles of pigs. If a man eats such a pork which is highly infested with bladder worms, they reach into the intestine of the man and one of the bladder worms develops into a Taenia.
14. Parasitic adaptation. Locomotory organs and digestive system absent Hooks and suckers present for attachment to host’s intestine Cuticle permeable for absorption of digested food from host’s intestine, Produces some anti enzymes which neutralize the enzymes and Taenia does not get digested itself, The osmotic pressure of the body fluids of Taenia is the same as that of man.
15. Because there is one Taenia found in the intestine of one person hence it is bisexual, It produces a very large number of ova because there is a lot of wastage of ova in the feces, and Sense organs are very much reduced.

Classification Of Animal Kingdom For NEET Taenia Saginatathe, Beef Tapeworm

Taenia saginata is comparatively longer than Taenia solium and the scolex does not have rostellum and hooks. It has 4 muscularsuckers only. There may be upto 2000 proglottids present in the body. The intermediate hosts are cows and buffaloes. It causes Taeniasis and cycticercosis.

Classification Of Animal Kingdom For NEET Important Information

Turbellarians (Planarians).

• Dugesia is with a triangular head with two auricles, while Planaria is with a truncated head.
• The pharynx is protrusible through the mouth.
• Rhabditis: Rod-like bodies in the epidermal cells. Their secretion is probably protective and adhesive in function.
• The Planarian eye is an inverse eye in which light has to pass through the photoreceptors and then fall on pigment cells.
• Bipalium: Only terrestrial planarian.
• Morpholactic regeneration. One part of the body can form the whole body.
• Neoblasts: Cells of planarians that help in regeneration.

Classification Of Animal Kingdom For Neet

Trematodes (Flukes).

• Schistosoma (Blood-fluke). It is the only unisexual fluke found in the veins of man. Female is present in the gynaecophoral canal (a groove on the ventral side) of males. It causes schistosomiasis characterized by intestinal disorders. It is also called Bilharzia.
• Opisthorcliis sinensis. Chinese liver fluke of man.
• Paragonimus. Lung fluke of man.

Fasciolopsis buski: Intestinal fluke of man.

• Monogenetic flukes. With a monogenetic life cycle, for Example Diplozoon (ectoparasite of gills of fishes), Gyrodactylus.
• Digenetic flukes. With two hosts in the life cycle Example Fasciola, Schistosoma, etc.
• Prohaptor. Anterior sucker of flukes.
• Opisthaptor. Posterior sucker of flukes.
• Amphistomous flukes. Fluke with 2suckers, one at each end of the body Example Paramphistomum.
• Fasciola is with two testesand one ovary. Miraridium and cercaria are in free-swimming stages, while sporocyst and redia are inside the snail.

Cestodes (Tapeworms)

• Taenia saginata (Beef-tapeworm). It is found in the small intestine of man. The secondary host is a cow. Human infection is by taking undercooked measly beef. Its scolex is without hooks and rostellum while strobila is formed of about 2,000 proglottids.
• Taenia has a bilobed ovary and about 200 follicular testes.
• The world population suffers more from Taenia saginata than T. solium due to more beef eaters.
• Bothria: Longitudinal groove-like adhesive organs of tapeworms.
• Suckers. Cup-like adhesive organs.
• Onchosphere. Encapsulated larvae are found in the uterus of gravid proglottids.
• Apolysis. Loss of gravid proglottids from the posterior end of the body.
• Strobilation. Formation of new proglottids from the neck, also called
  pseudometamerism.
• Echinococcus. Hydatid worm. Its hydatid cyst shows exogenous as well as endogenous budding. Parasite of small intestine of dogs, cats, etc. It has only 3-4 proglottids.
• Diphyllobothrium. Largest tapeworm (18 m).
• Hymemolepis. Dwarf tapeworm (2-4.5 cm). It is a monogenetic tapeworm of man.
• Dipylidum. Dog tapeworm.
• Scolex is the adhesive part of tapeworms.

Classification Of Animal Kingdom For NEET Phylum Aschelminthes

General characters of Phylum Ascheliminthes

• Body form. Cylindrical body but circular, in outline in cross-section.
• Germ layers Triploblastic animals with three germ layers.
• Habitat, Some are free living and many are ectoparasites and endoporasites of animals as well as plants.
• Level of organization. Body organization is at the level of an organ system.
• Symmetry. Bilaterally asymmetrical.
• The body is covered with thick, tough, and spiny cuticles.
• The epidermis is syncytial.
• In the body fixed number of cells are present.
• The alimentary canal is complete and straight.
• Circulatory system absent.
• Respiratory system absent.
• Respiration is aerobic in free-living forms and anaerobic in parasitic forms.
• Special types of sense organs known as phasmids are present.
• The nervous system is well developed with a nerve ring, ganglia, and nerve cords.
• The excretory system is simple, formed of specially shaped cells.
• Excretion is ureotelic.
• Reproduction. Sexes are separate with a well-developed reproductive system.
• Shows sexual dimorphism. Usually, females are longer than males.

Classification Of Animal Kingdom For Neet

Classification of Phylum Aschelminthes.

• Class Nematoda (Sub-class Phasmida).
• Phasmid present, pouch-like sense organs and act as chemoreceptors present] Dracunculus medinensis (guinea worm), Rhabditis.
• Sub-class Aphasmida. Phasmids absent Example Trilobius, Trichinella (Trichinia worms) Trichuris (whipworm)
• Class 2. Nematophora e.g, Paragordius,
• Class 3. Rotifera Example, Philondina, Rotaria.
• Class 4. Kinorhyncha Example Echinoderes.
• Class 5. Gastrotricha Example Chaetonotus, Macrodasys.
• Class 6. Pripaulida
• Class 7. Acanthocephala

(These classes are now treated as separate phyla)

Classification Of Animal Kingdom For NEET Ascaris Lumbricoides (The Round Worm)

• This is the common roundworm found as a parasite in the intestine of man and also in pigs, cattle, sheep, and squirrels.
• Sexes are separate and show sexual dimorphism. The male is comparatively smaller than the female. The male measures 15 to 30 cm long with the posterior end curved, whereas the female measures 20 to 40 cm long and straight. Cloacal aperture is present in males whereas in females separate anus and vulva are present.
• There are 4 distinct lines present on the body of Ascaris in the form of folds known as Epidermal cords. (Dorsal, Ventral, and two lateral cords).
• The mouth is situated at the anterior end surrounded by 3 lips known as Dorsal Lip and 2 Ventro-lateral lips. The lateral papilla and amphid are present on each ventrolateral lip.
• Amphid is the chemo and olfactory receptor.
• Excretory pores are present above 2 mm away from the anterior end.
• The body wall consists of a cuticle (non-cellular), syncytial ectoderm, and longitudinal muscle.
• Highly vacuolated, fluid-filled pseudocolor present.
• The alimentary canal starts from the terminal mouth surrounded by 3 lips. The mouth opens into the pharynx which is bulb-shaped and lined by cuticles. From the pharynx begins the intestine which leads into the narrow rectum which opens outside through the anus.
• The alimentary canal of Ascaris is mainly concerned with absorption ofthe food rather than digestion.
• The excretory system is more or less H-shaped. Two longitudinal excretory canals are joined by a transverse canal.
• Male reproductive organs consist of a single long and coiled thread-like testis that opens into the vas deferens of almost the same diameter.
• The vas deferens opens into a wide seminal vesicle. It leads into a narrow ejaculatory duct which opens outside through the cloaca. There are present a pair of pineal spicules which help during copulation.
• Female Reproductive Organs are didelphic i.e. double. There are a pair of thread-like ovaries. Each ovary continues into a slightly thicker tube known as the oviduct The two oviducts open into a broad and muscular utero. The two uteri join together and open into the vagina. The vagina opens outside through the female gonopore or vulva, which is situated on the ventral side about one-third of the length from the anterior end.
• Life History. The sperms of Ascaris are amoeboid which brings fertilization of eggs in the uterus.
• The fertilized eggs are covered with 3 layers. A female Ascaris lays about 15,000 to 200,000 zygotes each day in the small intestine of a man. These zygotes pass out with the human feces.
• The larvae are known as rhabdoid larvae or first stage juveniles which are formed within the zygotes.
• The first-stage juveniles still live within the eggshell and molt after 10 days to produce 2nd stage juveniles (infective stage about 0.2 to 0.3 mm long).
• After rupturing the shell, 2nd juveniles come out and wander in the body for 25 days, undergo second and third molting in the alveoli of the lungs, and by the time 4th stage juveniles are formed again and reach the alimentary canal where they grow into adults. In the intestine, they molt for the fourth time and grow into adults in about 2 to 3 months.

Classification Of Animal Kingdom For NEET Life Cycle Of Ascaris

Classification Of Animal Kingdom For NEET Wuchereria Bancrofcit

Human filarial worm

• It is predominantly located in tropical climates.
• Wuchereria is a dimorphic intercellular endoparasite of humans.
• Wuchereria inhabit the lymphatic arteries and lymph nodes of humans.
• Wuchereria bancrofti, sometimes referred to as Filaria bancrofti, induces elephantiasis disease (Filariasis).
• In filariasis, lymphatic tubes and glands become inflamed and clogged, resulting intissue enlargement due to the accumulation of lymphatic  fluid. Infection by Wuchereria (filaria) occurs via the Culex mosquito.
• The life cycle is digenetic in nature.
• Both male and female forms entwine with one another.
• Culex fatigans and Culex pipiens act as secondary hosts for Wuchereria.
• Female Wuchereria produce sheathed embryos known as microfilariae.
• Microfilariae are elongated, slender entities encased in a translucent sheath.
• Microfilariae enter the superficial blood circulation at midnight and are transmitted into the body of a mosquito (Culex) during the bite.
• Microfilaria transforms into sausage-shaped larvae within the thoracic musculature of mosquitoes.
• Microfilariae undergo two molts within the thoracic muscles of mosquitoes, transforming into elongated, slender forms.
• Long, slender microfilariae represent the infective stages that are subsequently transmitted within the primary host, namely humans.
• Significant pharmaceuticals include Antimony and Arsenic compounds, which eliminate both adult forms and microfilariae.
• The lifespan of Wuchereria is four to five years.

Ancylosloma (Hook worm)

• Ancylosloma is the worm of man.
• Ancylostoma is monogenetic.
• The Cloaca of the male is surrounded by a copulatory bursa. Hookworm causes Ancylostomiasis in which a person suffers from acute (severe) anemia.
• The free larval stage is found in the life cycle of hookworms.

Trichuris trichiura (whip worm). Endoparasite of caecum and large intestine of man. Heavy infection causes diarrhoea and anemia.

Rhabditis maupasi. A free living soil nematode.

Loa (Eye worm): Commonly found in subcutaneous tissue in Africans. These pass across the eyeball.

Enterobius (Oxyuris). Pinworm. An endoparasite of the large intestine of man. It is monogenetic. It causes enterobiasis characterized by sleeplessness, digestive and mental disorders, abdominal pain, etc.

Animal Kingdom Neet Previous Year Questions

Trichinella (Trichina worm). An intestinal endoparasitic worm ofman. Reservoir hosts are pigs, dogs, cats, etc. Larvae become spirally coiled in the voluntary muscles. It causes trichinosis characterized by nausea, muscular pain, etc.

Dracunculus (Guinea worm). An endoparasitic worm of subcutaneous tissue is digenetic and its secondary host is Cyclops. It causes guinea worm disease characterized by itching, diarrhea, nausea, vomiting, etc. It is the earliest known nematode and was earlier called the “Fiery Serpent.”

Classification Of Animal Kingdom For NEET Phylum Annelida

General characters of Phylum Annelida

• Triploblastic animals.
• Bilaterally symmetrical.
• Found in water and moist soil.
• Mostly free swimming, some are parasites
• True coelom is present for the first time in the animal kingdom. Coelom is shizocoel.
• True metameric segmentation is present.
• Annelids have a complete and straight alimentary canal.
• Annelids show tubes within the tube body plan.
• Locomotory organs are setae or parapodia or suckers.
• In the body wall, both circular and longitudinal muscles are present.
• Blood vascular system closed type.
• Respiratory pigment is hemoglobin, which is dissolved in plasma.
• Respiration either by moist body surface or parapodia or gills is present.
• Nephridia are present for excretion. Nephridia are metanephridia.
• The nervous system consists of a nerve ring, double, solid, ventral nerve cord, and segmental ganglia.
• Sense organs are of many types such as photoreceptors, olfactory receptors, etc.
• Sexes usually united i.e., hermaphrodite.
• Reproductive organs develop from coelomic epithelium.
• Development may be direct or indirect.
• The larva, if present, is a trochophore larva.

Unique features

1. Metameric segmentation
2. True coelom lined by mesodermal epithelium filled with coelomic fluid which acts as a hydraulic skeleton
3. Excretory and osmoregulatory structures are nephridia
4. The presence of circular and longitudinal muscles both in the body wall and wall of the gut
5. Closed circulatory system with respiratory pigment dissolved in plasma
6. Development may be direct or larva if present is trochophore larva.

Classification Of Animal Kingdom For NEET Important Information

Class Oligochaeta

• Chloragogen cells or yellow cells of earthworms are analogous to vertebrate liver cells.
• The brown color of earthworms is due to the pigment porphyrin present in the body wall and coelomic fluid.
• It protects the body from bright sunlight. Lumbricus is the earthworm of Europe and North America; Megascolex is found in South India while Eutypliaeus is found in the Gangetic plain of North India.
• Clitellar glands are maximum in clitellar segments and secrete ootheca.
• Setae are absent in the first, clitellar and anal segments.
• The coelomic fluid of earthworm is with five types of coelomocytes: Phagocytes (largest sized and most numerous); leucocytes, melanocytes, circular cells, and yellow cells.
• Yellow cells, also called chloragogen cells, store glycogen granules so are analogous to hepatocytes of the liver. Some suggest that these are excretory in function.
• Typlilosole: A large-sized fold in the middle part of the intestine and increases the face area of absorption.
• In earthworms, there are 4 pairs of hearts, one pair in each of the 7th, 9th, 12th, and 13th segments. The anterior two pairs of hearts are called lateral hearts, while the posterior two pairs of hearts are called latero-oesophageal hearts.
• Scptail nephridia of earthworm mid nephridia of Nereis arc called metanephridia as each opens In coelom by nephrostome.
• Earthworm In excretion (40% tire).
• In the nerve cord, there are 4 giant nerve fibers which help in reflex actions,
• Receptor organs of earthworms are formed of modified epidermal cells.
• The male reproductive system is formed of two pairs of testes (one pair In each of the 10th and Ith segments) and is enclosed in respective testes sacs (two in number). Prostate glands are one pair while accessory glands are 2 pairs (one pair in each of the 17th and 19th segments).
• The female reproductive system includes one pair of uncovered ovaries (in the 13th segment). Spermal Uecae is 4 pairs (one pair in each of the 6th, 7th, 8th, and 9th segments) and stores the sperms received during copulation.
• Tubifex (blood worm) A darkly red-colored oligochaete (with a large amount of hemoglobin in blood) that can survive even in a highly 02- deficient and polluted fresh-water body.

Animal Kingdom Neet Important Points

Class Polycliaeta

• Nuchal organs. Olfactory and chemosensory pits on prostomium behind the eyes. These help the worms to detect the prey.
• Gonads are temporary structures and develop only during the breeding season.
• Nephromixia. Nephridia which act as excretory as well as genital ducts. The term nephrotoxic was coined by Goodrich (1945).
• Epiloky. Transformation of a non-sexual into a sexual polychaete. The posterior part of the body with gonads and parapodia with leafy outgrowths and oar-like setae is called epitoke, while the anterior non-modified part is called matoke.
• Trochophore larva is with two ciliated bands: Prtotrocli and telotroch, which help in dispersal
• Aphrodite. Commonly called sea mouse, while Polynoe is called scale worm.
• In Eunice (Potato worm), epitoke is regenerated several times.
• Chactoplertis (Paddle worm) A tuberculous, marine polychacte. It has 3 fan-like notopodia in the middle part of the body which beat and maintain a water current.
• Arenicola (Lugworm), Amphitrite, and Tcrcbella are polychaetes that have gills for respiration.
• Nereis has a closed circulatory system but no heart.

Class Hirudinea

• luminaria granulosa (Indian cattle leech) :
• The skin of leech is with numerous mucus-secreting gland cells.
• A clitellum is formed by the 9th, 10th, and 11th segments during breeding season.
• Nephridiopores are 17 pairs (one pair on the ventral side of each of the 6th to 22nd segments).
• Leech has 3  jaws (jaw with a single row of denticles).
• Hirudin. An anticoagulant in the saliva of leech.
• The crop is the largest part of the gut. It is 10-chambered and stores the blood.
• True coelom in leech is reduced and enclosed in testes sacs and ovisacs.
• Leech has 17 pairs of nephridia and are of 2 types:
• 11 pairs of testicular nephridia (one pair in each from the 12th to 22nd segment).
• 6 pairs of pre-testicular nephridia (one pair in each of the 6th to 11th segments)
• Ciliated organs of nephridia have no excretory function but manufacture coelomic corpuscles of the haemo coelomic system.
• Leech is ammonotelic in excretion.
• Leech has 11 pairs of testis sacs, one pair in each segment from the 12th to the 22nd segment, but has only one pair of ovaries in the 11th segment.
• Spermatophore. Bundle of sperms.
• Pontobdella (skate sucker) is a marine leech that sucks the blood of skates, rays, and sharks.
• Hirtido medicinalis The medicinal leech of Europe is a fresh-water leech.
• Phlebotomy. Method of blood-letting to suck the impure blood by applying an icon-hungry leech to the skin.

Classification Of Animal Kingdom For NEET Phylum Arthropoda

General characteristics of Arthropods

• Habitat. Arthropods are found in all types of habitats. They may be aquatic or terrestrial the insects have taken to the aerial mode of life.
• Germ layers. Triploblastic i.c. ectoderm, mesoderm and endoderm.
• Symmetry. All arthropods show bilateral symmetry, having distinct dorsal, ventral, and lateral sides.
• Body plan. Like all higher animals arthropods show tube-within-tubc plan of the body.
• Level of organization organ system level.
• Exoskeleton. The body is covered by a chitinous exoskeleton which may be impregnated with calcium salts. Chitin is a polysaccharide. The chitinous exoskeleton is largely responsible for the success of arthropods to live on land, it protects the body and prevents the loss of water.
• Body Regions. The body is usually distinguished into the head, thorax, and abdomen.
• The presence of the head is an important advancement and is called cephalisation. In many species, the head and thorax are fused to form a cephalothorax, for Example, Prawn, and Crayfish.
• Segmentation. Arthropods are segmented externally. The segments in the anterior region get fused to form the head. However, the body cavity is not partitioned by septa.
• Jointed Appendages. The most important feature of the phylum is the presence of paired jointed appendages. They are modified according to their function. For example, insects have three pairs of jointed legs on the thorax which are used for walking, in crayfish and prawns they are modified for swimming. Some of them are specialised for feeding while others are applied for sensory and reproductive purposes.
• Wings. The insects are the only non-chordates that can fly due to the presence of two pairs of wings arising from the dorsal side of the thorax. However, some insects, for example, Silverfish and Head louse lack wings. The wings are simply outgrowths of the body wall.
• Digestive system. The alimentary canal opens at both ends of the body and is distinguished into three regions, the foregut, mid-gut, and hindgut.
• Body Cavity. The body cavity is called hemocoel. It lacks a regular layer of mesodermal lining and contains blood.
• Circulatory system. The circulatory system is of open type. The blood directly lies in the body cavity, and there are no closed vessels.
• Respiratory organs. Aquatic forms respire by gills. The terrestrial arthropods such as insects breathe employing certain branched tubular organs called tracheae which ramify throughout the body, and communicate to the outside by certain openings called spiracles.
• Excretory organs. The excretory organs in insects are the malpighian tubules. In crustaceans, the excretion is by green glands or antennary glands.
• Nervous system. It resembles that of annelids and consists of a brain and ganglionated ventral nerve cord.
• Sense organs. The sense organs are well developed. They include compound eyes for sight, and sensilla for smell, hearing, and taste.
• Reproduction. Arthropods reproduce only sexually. Sexes are separate, and the male and female are externally distinguishable.
• Fertilization is internal. Life history usually involves a larva or nymph. The larva (or nymph) later changes into an adult. The phenomenon is called metamorphosis.

Classification Of Animal Kingdom For NEET Unique Features

1. Jointed appendages are modified for performing various functions such as feeding, walking, flight, sensory; copulation, egg laying, etc.
2. The hard exoskeleton of chitinous plates for protection and also provides a hard surface for attachment of muscles
3. Tracheae for respiration in most eases. In other forms gills, book gills, and book lungs act as respiratory organs.
4. Malpighian tubules or coxal glands as excretory organs for excretion.
5. Compound eyes are formed of optical units called ommatidia.
6. Presence of hemocoel

Classification Of Animal Kingdom For NEET Mouth-Parts Of Insects

1. Biting and chewing type Orthopteran Example Grasshopper, cockroaches, crickets, silverfish, Booklice, bird lice, earwigs, termites, Hymenoptera, especially caterpillars, bedbugs, and beetles.
2. Piercing and Sucking
   1. Mandibles, Maxillae constitute needle
   2. Labium – hollow grooved channel Example Mosquitoes
3. Chewing and lapping type Example Honey bees
4. Sponging type Example houseflies and other flies
5. Siphoning type. Butterflies and moths.

Classification Of Animal Kingdom For NEET Metamorphosis In Insects

1. No metamorphosis or Ametabolous development Example silverfish, springtails egg Adult
2. Incomplete metamorphosis or hemimetabolous development
   • Egg → Naiad→ Adult
   • Example Mayflies, Dragonflies, stone flies
3. Gradual metamorphosis or paurometabolous development
   • Egg→ nymph → Moulting Adult
   • Example Grasshopper, Aphids, Stink bug
4. Complete metamorphosis or Holometabolous development
   • Egg → Larva Pupa → Adult
   • Example Housefly, Mosquito, butterfly

Animal Kingdom Neet Previous Year Questions

Hormonal Control

1. Brain hormone (BH) – (LIPID)
2. Activates the corpora cardiaca—a component of retrocerebral complex.
3. Prothoracicotrophic hormone (PTTH) is secreted in corpora cardiaca which in turn stimulates Prothoracic glands.
4. Prothoracic gland hormone (PGH) (Ecdysone) Trigger molting.
5. Juvenile hormone (JH)
6. Secreted by corpora allata (non-sterolic lipid). Promotes metamorphosis.

Larvae Of Crustaceans

1. Nauplius—Cyclops. Ii may give rise to intermediate larval forms
2. Mctanauplius—Apus
3. Protozoea—Penacus
4. Megalopa—True crab
5. Glamcothel—Hermit crab
6. Schizopod—Lobster
7. Cypris—Lcpas, Sacculus
8. Alima—Squilla
9. Phyllzosoma—Spiny lobster
10. Zoea.

Classification Of Animal Kingdom For NEET Economic Importance Of Insects

1. Poisonous Insects. Examples are Honeybees, wasps, hornets, fire ants, bed bugs, mosquitoes, and a few lepidopterous and other larvae.
2. Disease carriers
   1. Species of Anopheles spreads Malaria.
   2. Culex mosquitoes spread nematode worm Filaria which causes Filariasis.
   3. Stergomyia mosquitoes spread Yellow fever
   4. Taparus fly spread surra disease among horses and camels.
   5. African sleeping sickness by tse tse fly (Glossina)
   6. Housefly spreads diarrhea, cholera
   7. Fleas spread bubonic plague
   8. Bed bugs and Body Louse spreads Relapsing fever
3. Productive Insects
   1. Honey and bees wax by Honey Bee (Apis indica)
   2. Wax produced by scale insects
   3. Commercial silk by silkworms (Bombyx mori)
   4. Lac is produced by lac insect (Kerria laced)
   5. Shellac secreted by coccidae.
   6. Dyes and tannin are obtained from cochineal dried bodies of certain scale insects.
4. Insects in Medicines
   1. Cochineal Insect contains carminic acid concern, myricetin, fat, and fatty acids used for neuralgia and whooping cough.
   2. Browfly larvae are used in treating the decay of the tissue.
   3. Cantharidine oil obtained from blister beetle,
   4. Bods’ extracts of the cocoon of silk moth used for treating leucorrhoea,
   5. Bee venom is used for
      1. Arthritis and
      2. Antivenom for snake bite
      3. Honey. Natural Antiseptic used to cure ulcers.
      4. Bee wax. Base for ointments.

Classification Of Animal Kingdom For NEET Important Information

• Larvae of the genus Chironomus (an insect) are called blood worms. They have red blood. The red color of these larvae is due to hemoglobin.
• In coastal areas like Konkan Maharashtra of India, the red and black species of scorpions are deadly poisonous. Their venom is fatal.
• Honey is flower nectar mixed with the saliva of bees and is a natural antiseptic.
• Bees communicate by complex dance.
• Royal Jelly—a substance secreted by honey bee workers.
• Termites are social and polymorphic insects.
• Termites form large nests called crematoriums.
• Usually the larger an animal is, the longer it takes to grow up. One exception is the 17-year cicada (an insect), which spends a very long time as a larva.
• In spiders, the web is secreted by the last body segment.
• The thread of the spider web is stronger than steel thread.
• The endoskeleton is present in the head and thorax of the cockroach. The abdomen has no endoskeleton.
• In all insects the intervals between two eedysis (casting of skin) is known as the stadium and the form assumed by the young insect during a stadium is called an Instar.
• Mites are parasites of animals as well as plants
• Fireflies or glow worms bear light-producing organs upon their abdomen. Light is emitted at short intervals by both males and females as a visual signal to attract each other for copulation.
• Gambusia is a larvivorous fish that feeds on up larvae of mosquitoes.

Classification Of Animal Kingdom For NEET Selected Arthropods Class Crustacea

• Daphnia. Its body is covered by a bivalved carapace and is commonly called a water flea.
• Cyclops Commonly called one-eyed monster (with the simple median eye). The female is with ovisacs and carries the eggs. Serves as a vector of Dracunculus nematode.
• Cypris. Commonly called mussel shrimp. A microscopic fresh-water crustacean showing cutaneous respiration.
• Barnacles are sedentary crustaceans Example Liyas. Called a Ship or goose barnacle. A pedunculate crustacean. Carapace is with 5 calcareous plates.
• Balanus. Called Acorn or Rock Barnacle. A sessile crustacean. Carapace is with 5 calcareous plates.
• Sacculina. Called a root-headed barnacle. An ecotoparasite of crab and highly degenerated crustacean due to retrogressive metamorphosis. Induces the development of female characters in infested male crab, called parasitic castration. Squilla is commonly called mantis shrimp as preys upon small marine fishes, crustaceans, mollusks, etc.
• Palinums. Marine spiny or rock lobster as carapace with many spines, Edible.
• Eupagurus (Hermit crab): Shows proto-cooperation with sea anemone (Adamsia).
• Palacmon (Prawn).
  • P. carcinus is giant prawn (90 cm), while P. Lamarr is dwarf prawn (2.5-5 cm).
  • Statocysts (one pair) are organs of balance and lie in the basal segment of each
    antennule.
  • Epimeron. A scaly plate which joins an appendage with the pleuron.
  • Biramous appendage. An appendage in which a basal segment called
  • Protopodite gives two outgrowths: inner endopodite and outer exopodite.
  • Uniramous appendage: When protopodite gives rise only endopodite but there is no exopodite.
  • Cephalic appendages of Prawn are 5 pairs (one pair each of antennules, an tennae, mandibles, maxillidae and maxillae).
  • Thoracic appendages are 8 pairs (5 pairs of legs and 3 pairs of maxillipeds).
  • The digestive gland of crustaceans is hepatopancreas which combines the functions of the liver, intestine, and pancreas.
  • All the gills of Prawn are Phyllobranchcs (gill axis with 2 rows of leafy gill lamellae).
  • The heart of a Prawn is arterial as it receives and distributes oxygenated blood.
  • Prawn shows apposition or mosaic vision in bright light and superposition vision during dim light.
  • Prawn fishery: Capturing of prawns from natural resources as well as their culture.
  • Prawn is a rich source of proteins and A and D vitamins but has low fats. Pcnaeus indicus (about 23 cm. long) is the most important commercial prawn species in India.
  • Lobster tail. The abdominal region of spiny lobsters is used as food.
  • Central Marine Fisheries Research Institute is located at Narakkal (Cochin).
• Oniscus. Only terrestrial crustaceans.

Class Insecta

Sub-class Diplura

• Eleven segments in the abdomen of both immature and adult. Segmented antennae.
• Cerci present, Malpighian tubules absent or vestigial. Primarily wingless. A widely distributed order living in concealed habitats, often in the soil.
• Sub-class Protura Abdominal segments were added successively through post-embryonic growth, making a final complement of eleven segments plus a posterior telson.
• Antennae absent. Malpighian tubules are present but rudimentary. Primarily wingless. Minute, whitish insects widely distributed, found in moist litter, bark, etc.

Sub-class Collembola

• Abdomen with six segments only, usually with three sets of appendages, a ventral tube on segment 1, and a retaining hook on 3 which functions with a powerful springing organ on segment 4. No metamorphosis.
• The tracheal system is absent in most species. No malpighian tubules. Primarily wingless. Living in soil, leaf litter, decaying vegetable material, under bark, etc. Known as the springtails.

Sub-class Apterygota

• Primarily wingless. The metamorphosis from juvenile to adult is slight or absent.
• Mandibles have only a single point of articulation (except in the family Machilidae of the order Thysanura). Usually possessing pregenital abdominal appendages.

Animal Kingdom Neet Notes Pdf

Cockroach

• Indian cockroach, Blatta orientalis, is dark-colored and small-sized. Female Blatta has vestigial wings.
• The native place of Periplaneta is tropical Africa and not America.
• Burmeister (1838) : Gave the generic name Periplaneta.
• The mouth parts of the cockroach are downward called hypognathous heads.
• The neck, also called the cervical, is not a true body part but is an extension of the arthrodial membrane.
• The labrum is the upper lip, while the labium or second maxilla is the lower lip.
• The hypopharynx is the tongue hanging between the mouthparts.
• Each leg is formed of 5 podomeres. The last podomere is called tarsus.
• Fore wings are thick and leathery and act as tegmina or wing covers.
• Hind wings are the flight organs of cockroaches. Folded like Japanese fans.
• Anal cerci of cockroaches are with auditory receptors.
• The antennae of cockroaches are olfactory and tactile.
• Trichogen cells are seta-secreting cells of hypodermis.
• The rate of heartbeat is 49 times.
• The heart of a cockroach is tubular and 13-clambered.
• Cockroaches and other insects are uricotelic.
• Urate cells of the fat body show excretion by storage.
• Compound eyes show only apposition or mosaic vision. No superposition vision.
• Male cockroach has 3 gonapophyses, called phallomeres, and act as external genitalia.
• Female cockroach has 3 pairs of gonapophyses which act as an ovipositor.
• Each ovary is formed of ovarioles.
• The nymphal stage is called the instar, while the interval between two molts is called the stadium.
• Ecdysis is controlled by ecdysone, a steroid hormone produced by prothoracic glands.
• An adult insect is called an imago and is formed due to the absence of the juvenile hormone of corpora allata of the nymph.
• Cimex lecttilaris (Bed bug). It is an ectoparasite of man, nocturnal in activity, san granivorous (piercing-sucking mouth parts) in feeding, and is found in crevices of cots, etc. The body is sub-circular, flat, and wingless. Each leg ends in two claws. Its bite causes sleeplessness.
• It also spreads germs of typhoid, plague, kala-azar, relapsing fever, etc.
• Pediculus (Head louse). An ectoparasite of man; found glued to the body hair, sanguivorous in feeding with piercing-sucking type mouth parts; spreads typhus fever. The body is flat and wingless.
• antennae are reduced. Mouth parts are piercing-sucking type. Each leg ends into a single claw.
• Pteris (Butterfly). Cosmopolitan insect, diurnal in activity, feeds upon nectar with siphoning type mouth parts, female is oviparous.
• The development includes caterpillar larva and involves complete metamorphosis.
• The body is long and slender. The Head has knobbed antennae, compound eyes, and mouth parts. Thorax has 3 pairs of legs and 2 pairs of wings. The wings have black marks.
• Mayflies. The mayflies are soft-bodied insects with delicate, membranous wings bearing numerous veins and cross-veins, the hind wings much smaller.
• Adults are short-lived, with mouthparts vestigial, short bristle-like term.ro,
• 1 pair of long cerci with many segments, with or without a median caudal filament; adults uniquely preceded by a winged, pre-adult instar.
• Nymphs are aquatic, and active, with paired cerci and a median caudal process, and feathery tracheal gills in most abdominal segments; almost entirely herbivorous.
• Mierotreme (Tennile or white ant). A colonial, polymorphic, and social insect, found in nests called termitaria in woods, 5 castes in the colony (queen, drone, worker, soldiers, and nnsufes); show symbiosis with multiflagellate protozoan Triehonympha.
• Poccilocerus pietus (Ak Grasshopper). It is diurnal, herbivorous (on Ak leaves by chewing-type mouth parts), and flying and jumping (with large-sized senatorial metalegs).
• The female is oviparous and egg-containing cocoons are deposited inside the burrows with an egg-laying apparatus called an ovipositor. The development includes gradual metamorphosis. It produces sound by rubbing the forewings together.
• Crickets. Crickets are medium to large-sized insects, with large prothorax and usually jumping hind legs. Winged or wingless, forewings somewhat hardened to form wing covers (tegmina). Mouthparts mandibulate.
• Cerci is usually short and unsegmented. Females generally with well-developed ovipositor.
• Often with specialized auditor)’ and sound-producing (stridulating) organs. Most numerous in tropical regions, generally worldwide in distribution.
• Generally herbivorous, a few carnivorous.
• Sympctnnn (Dragonfly). It is a diurnal, good flier, and carnivorous (flies and mosquitoes) insect.
• The development includes an aquatic larva called naiad and incomplete metamorphosis. Each forewing has a black spot called pterostigma.
• It is also called a mosquito hawk.
• Damselflies. Damselflies are strong-flying, predacious insects with long, rather narrow wings bearing many veins and cross-veins, hindwings similar to or larger than forewings. The thorax is characteristically modified with legs moved forwards and wings moved backward by tilting the thoracic segments; the abdomen is long and narrow. Generally large insects; a fossil species had a wing span of over 60 cm. Nymphs aquatic, active, predator)’.
• Musea domcstica (Housefly). It is a diurnal and a good flier insect. It feeds upon liquid foods (saprophagous) with its sponging type mouth parts having a fleshy proboscis.
• Hindwings are reduced and are called halters. These act as balancers. The development includes legless maggot larva and complete metamorphosis.
• Aphis brassicae (Aphid). It is a serious plant pest of mustard. It sucks the plant sap with its piercing and sucking-type mouthparts.
• It shows a symbiotic relationship with the ants which are called ant corns. It secretes “honeydew” through their cornicles (honeydew tidies). Tire females are viviparous and reproduce by parthenogenesis.
• Stone pies. Tire stone flies are moderate to rather large, soft-bodied insects with membranous wings, folded over the back at rest, hindwing the larger with a large anal lobe. Antennae are long and hair-like; mouth parts are weak, and mandibulate.
• Abdomen usually with a pair of long cerci. Nymphs are aquatic, active, with long antennae and cerci, and tracheal gills on the thorax, sometimes on the head to abdomen; living only in well-aerated water, mostly vegetarian diet.
• Stick insect and leaf insect. The stick and leaf insects are large, usually of elongated form less commonly flattened, mimicking twigs or leaves. Prothorax is short, and mesothorax is often lengthened. Winged or wingless, forewing often short and hard, and Mouthparts mandibulate. Cerci is short and unsegmented. The ovipositor is small, and concealed. Predominantly tropical distribution; herbivorous.
• Silkmoth. A single cocoon of silkworm provides about 300 metres of silk thread and about 12500 cocoons provide about half a pound of silk. The rearing of silkworms on mulberry plants is sericulture.
• A female lays about 300-500 eggs. In temperate countries, female lavs diapause (dormant) eggs during winter. Caterpillar larva undergoes four molts.
• The pupa is also called chrysalis. India is second in the world in the production of mulberry silk. Central Silk Research Institute is located at Mysore (Karnataka)
• Honey bee. Mouth parts are chewing and lapping types adapted to suck nectar and to mold wax. Prolegs of worker bees with pollen brushes, mesolegs have pollen spurs while metalegs have pollen combs, pollen packers, and pollen baskets.
• Domestication of honey bees is called apiculture while boxes used are called apian/. Domesticated spp.
• include. A. indica (mainly used), A. dorsata, A.florea and A. mcllifera. Inscoutbees, waggle dance was first reported by Karl von Friesch (1956).
• Cicada (Seventeen-yearlocust). With opisthognathous (backward directed head). Not true locust as both pairs of wings are alike (no tegmina). Male producers a very loud and whistling sex call. The metamorphosis period extends upto about 17 years.
• Bugs. The bugs are small to large insects, usually with two pairs of wings, tire forewings of a harder consistency than the hind pair, either uniformly hardened (Homoptera) or with the apical part membranous (Heteroptera).
• Mouthparts modified for piercing and sucking; labium forming a grooved rostrum or snout, containing two pairs of piercing stylets (mandibles and maxillae).
• Many species feed on the sap or cell contents of plants, while others are predatory. Some are important vectors of plant and animal diseases. Distribution worldwide.
• Beetles. Forewings are completely thick and called elytra while hindwings are membranous for flight. Larva has only true legs and is called gnib Examples are Coccinella (Ladybird beetle), Scarabaeus (dung beetle), and Sitophilus (rice weevil — weevil is a grain beetle).

Other Arthropods

• Limulus (horseshoe crab). a living-fossil representative. it is a marine, fossorial, nocturnal, and carnivorous arthropod. locomotion is walking, swimming, and jumping type. body is divisible in cephalothorax (prosoma) and abdomen (opisthosoma).
• cephalothorax is covered by a horseshoe-shaped carapace and has one pair of chelicerae and 5 pairs of legs.
• abdomen has a long spike-like telson at the posterior end and is used for jumping. it is also called “living sil” (about 190 million years old).
• Ticks and mites are parasitic arachnids.
• Scorpion was picturized by Walt Disney in “Living Desert.”
• Mites. Sarcotes (Human itch mite).
• Ticks. Dermacentor (Dog tick), Exudes (Sheep tick), etc. Ticks act as vectors of rocky mountain fever, relapsing fever, etc.
• Muga silkworms feed on Moms.

Classification Of Animal Kingdom For NEET Phylum Mollusca

Characters of Phylum Mollusca

• Body form. The body is a differently shaped head with visceral mass and foot present.
• Habitat Molluscs are generally aquatic (marine as well as freshwater) some of them, for example, slugs and terrestrial while others, for example, Pila (Apple Snail) are amphibious, that is, live in water as well as on land.
• Germ layers. Mollusks are triploblastic animals showing the organ-system level of organization.
• Symmetry. They may be asymmetrical, for Example snails, or may show bilateral symmetry, for Example, Freshwater mussels and cuttlefish.
• Level of organization organ system level of organization.
• Body plan. They show a tube-within-tube body plan. The body cavity includes hemocoel and reduced coelom.
• Body division. The mollusks have soft bodies which are differentiated into three regions foot, visceral hump mass, and head.
• The head bears eyes and sensory tentacles. The foot is the locomotory organ. The visceral hump is the main part of the body and contains various viscera, mainly the alimentary canal, digestive glands, and the circulatory system.
• Mantle and Mantle cavity. The visceral mass is covered by a soft and generally leathery covering called mantle or pallium. Between the visceral hump and mantle lies the mantle cavity which contains the gills and some portions of digestive and reproductive systems.
• Shell. The presence of a hard shell outside the body is a characteristic feature of most die mollusks. The shell is formed of calcium salts and is secreted by the mantle. It varies in shape and size.
• It is spirally coiled in snails (conchs and couriers). In oysters and mussels, it is formed of two equal valves. The shell is light and internal in cuttlefish, while it is absent in some mollusks, for Example, slugs.
• Respiration. The organs of respiration include one or two pairs of gills for aquatic respiration. Aerial respiration through the pulmonary sac. Mantle also plays a role in the process.
• Circulatory system. It is well developed and is of open type.
• The nervous system is well developed. It consists of ganglia, connectives, and commissure.
• Excretion through the renal organ.

Unique features

• There are three body divisions i.e. Head, visceral mass, and ventral foot.
• Body covered by a soft delicate glandular membrane called mantle.
• The space between the mantle and the body is called the mantle cavity.
• Presence of a rasping organ called a radula.
• In most of the forms, the external shell is formed of calcium carbonate and conchiolin present.
• Kidneys are sac-like and open into the coelom at one end and into the mantle cavity at the other end.
• Hectocotylzed arm. The arm of the male cephalopod is modified for transferring spermatozoa into the body of the female’s mantle cavity.
• An octopus is a mollusk without a shell.
• The largest eye is of the Arhiteuthis (Giant) squid measures 15″ in diameter.
• Pearl oysters, the bivalves secrete the pearls.
• A living fossil was discovered in 1952 from a deep trench in the Pacific of Costa.
• Rica and Neopilina show metameric segmentation.
• The segmentation in Neopilina and the presence of trochophore larval stage suggest that mollusks have descended from the annelids.
• An average oyster filters about 3 liters of seawater per hour.
• The study of molluscs is called malacology and that of shells as conchology.
• The term ‘Mollusca’ was coined by Johnston.
• It is the Largest mollusc 55 feet (Giant squid). It is the largest invertebrate also.

• largest tentacles or arms
• Largest shell
• Smallest shell
• Largest snail
• Largest eye of mollusk
• Slowest moving snail
• Largest Octopus
• Largest gastropod
• The slowest growth in mollusk -Deep Sea clam.
• Torsion is the rotation of body points at an angle of 180° about the head and foot.
• The pallial complex is formed by all organs present in the mantle or pallial cavity.
• Mollusc is a first-rate pollution monitor.
• A slug ( a mollusk) is purely an air breather.
• Organs of Bojanus refer to the kidneys of the freshwater mussel.
• Keber’s organs also help in excretion in some giant squids and upload many tonnes in weight.
• The sea butterfly is a mollusk.
• Neopilina, considered a living fossil,
• Ordovician Period “Age of invertebrates” (also called “Age of Giant Mollusca”)
• Spire. All the whorl of the shell except the body whorl.
• Conchiolin: A horny albuminoid protein of shell.
• The innermost layer of the shell is called the hypostracum or nacreous layer or mother of Pearl.
• Nuchal lobes, also called pseudopodia, are formed of mantle. The left nuchal lobe acts as inhaled, while the right nuchal lobe acts as an exhalant siphon.
• Gilt, also called tedium, of Pila is monopetinate (with one row of gill lamel- ‘Iheff’Om gill axis) and pectinibranch.
• The hypobranchial gland is larger in males. Its secretion lubricates the penis and helps copulation.
• Osphradium is a bipectinate structure (with 2 rows of leaflets).
• Radula. A rasping organ in tire buccal mass and has many rows of teeth. The dental formula of each row is 2, 1, 1, 1, 2.
• The digestive gland is the hepatopancreas which performs the function of the liver, pancreas, and intestine.
• Pila has two chambered kidneys which act as a coelomoduct that connects the pericardial cavity (represents true coelom) to the outside.
• Pila is ammonotelic in water and ureotelic on land.
• Loligo (Squid or sea arrow). Similar to Sepia except that the fins are present only in the posterior half and meet posteriorly.
• Octopus (Devilfish). An octopod marine mollusk with 8 sucker-bearing arms but no tentacles. It kills the prey with its poisonous saliva. It has good learning power and can be trained.
• Nautilus has an external, coiled, and chambered shell. It floats by secreting a gas in the chambers. The animal lives only in the last chamber.

Classification Of Animal Kingdom For NEET Phylum Echinodermata

General Characters of Phylum Echinodcrmata

• All members are exclusively marine.
• Triploblastic animals.
• Larva is bilaterally symmetrical, adults become secondarily radially symmetrical (pentamerous symmetry).
• The body bears spines and calcareous ossicles.
• Coelom is cnterocoelic.
• No distinct heart is present.
• Classification of Echinodermata

• Locomotion takes place by tube feet.
• The water-vascular system is a characteristic feature of the phylum Echinodermata.
• The water vascular system helps in locomotion and respiration.
• In some echinoderms, respiratory trees, branchiae, or bursae are present for respiration.
• Coelom is in the form of the haemal system which is concerned with blood circulation. Points.
• The digestive system is simple, alimentary canal is complete.
• No special organs for excretion. Exclusively takes place by amoebocytes.
• Nervous system without brain or central nervous system.
• Sexes are separate.
• The great power of regeneration.
• Fertilization is external, in seawater.
• Development is indirect.
• Larva is pluteus or auricularia or bipinnaria.
• Bilaterally symmetrical larva metamorphoses into a radially symmetrical adult.

Important Information

• The term ‘Echenodermate’ was coined by J. Klein.
• The water vascular system of echinoderms is coelomic in origin.
• The endoskeleton is formed of calcareous dermal ossicles that have mesodermal origin.
• Larvae of echinoderms
  • Dipleura larva. It is the basic larva and all others are derived from it.
  • Bipinnaria larva. Larva of Asteroidea.
  • Auricularia. Larva of holothuroidea.
  • Ophiplecteus larva ophiuroidea. It is the larva of Echinopletcus
  • Doliolaria larva. Larva of sea lilies (Crinoidea)
• Largest starfish-Midgardiaxandaros
• Smallest starfish-Marginastcr carpets
• Aristotle’s lantern-wheel-like saw apparatus of Echinoidea.
• The starfish can open bivalves by attaching two arms with the help of tube feet to either side of a bivalve, pulling it apart. The bivalve tires and opens out.
• The stomach of the starfish is everted through the mouth and introduced into the open mollusk where it is partly digested before being ingested.
• Echinoderms predate on coral polyps also.
• Echinoderms flourished in the Cambrian period.
• Astcrias (Starfish)
• Commonly known starfish are Asterias, Pentaceros, Astropecten, Solaster, Heliaster, Asterina, etc.
• The mouth is also called actinostomc.
• Bivium. Two arms between which madreporite is present.
• Trivium. The remaining three arms of starfish.
• Pedicellariae of starfish are pedunculate and forcipate (with 2 jaws).
• The digestive glands of starfish are 5 pairs of pyloric eerie.
• Digestion is r.vtni corporeal (digestive juices released outside to digest prevent Tietlmnnn’s bodies Nine in number in starfish and probable form the phagocytic amoebocytes.
• Axial gland. Also called Hrougland. Suppose’ to K’ heart,
  The development includes diplexer, bipinnaria, and bracbiolaria larvae.
• The Tornaria larva was first of all discovered by J. Meiller in and was considered by him as the larva of echinoderms, after in 1850.
• Metschnik established that it is a larva of Balanoglossus clavigerus, The name Maria is given to it because of its habit of rotating in circles.

Classification Of Animal Kingdom For NEET Phylum-Hemichordata

Unique features

• Body soft, unsegmented, worm-like, bilaterally symmetrical.
• Triploblastic animals have an organ system level of organization and without appendages.
• The body is divided into proboscis, collar, and trunk which represents the inner tricoelomate organization.
• The digestive tract is complete, either straight with a terminal anus or 11 shape with an anus near the mouth.
• Buccal diverticulum or stomochord. Earlier regarded as notochord present in the proboscis as a hollow outgrowth of the alimentary canal.
• A dorsal heart with two longitudinal vessels (dorsal and ventral) interconnected by lateral vessels and sinuses open type of circulatory system.
• Respiration through one pair to many gill slits or general surface of the body.
  Excretion through proboscis gland or glomerulus.
• Sexes may be separate or united. Life history includes a free-swimming larval stage called tornaria larva.
• Examples-Balanoglossus (Acorn worm or Tongue worm)
• Affinities with chordates Resemblances. Presence of gill slits, dorsal hollow single, non-ganglionated nerve cord ‘and so-called notochord.
• Differences. No chordate character resembles in the true sense. Absence of head, paired app£rida£es. tail, endoskeleton, and presence of single-layered epidermis, Affinities, and echinoderms
• Both have poorly developed nervous system
• Both have the same pattern of coelom and open out and filled with water.
• The Larva of Balanoglossus named tornaria resembles the bipinnaria larva of starfishes

The cellular grade of organization can be observed in all protozoans. Animal cells are diverse in structure and function lack a rigid cell wall and are quite flexible. Based on the complexity of the organization metazoans are divided into two subkingdoms i.e. Parazoa and Eumetnzoa.

• Coelom formation in schizocoelomata takes place by the splitting of mesodermal pouches present on the lateral sides of the prospective gut and in enterocoelomata by the growth of lateral mesodermal pouches from the endoderm.
• The animal kingdom includes about 35 phyla of which
  11 are considered major phyla.
• About 99 percent of animals are invertebrates and the remaining represent vertebrates.
• Unicellular protists animals are included in protozoa and about 15,000 species are known.
• Locomotory structures of Protozoans are flagella, cilia, pseudopodia or absent as in sporozoa.
• Euglena, Amoeba, Paramecium, Noctilucn, and Elphidium are free-living protozoan, Monocystis, Entamoeba, Plasmodium, Trypanosoma and Giardin are parasitic protozoan.
• The size of theifiers ranges from l cm to l meters in length. Some members of porifers are radially symmetrical but huger ones are asymmetrical.
• Sponges reproduce asexually by fragmentation or budding.
• Sycon (scypha), Spongilla, Proterion (Neptune’s cup), Cliona (Dead man’s finger).
• Euspongia (Bath sponge) and Euplectellu aa common examples of sponges.
• Cnidarians exhibit two basic body forms, the Polyp (fixed and feeding) and medusa five swimming and reproductive Coclenterates (Cnidarians) show polymorphism.

NEET Biology Evolution Theory Of Evolution By Natural Selection

Recent study indicates that evolution refers to the alteration in the genetic makeup of a population resulting from the interplay of variations and natural selection.

• The notion of organic evolution was conceived by Darwin and Wallace.
• Aristotle posited that all living organisms can be systematically organized according to ascending complexity, with no gaps and no potential for positional alteration within the established hierarchy. The perspective on life is referred to as Scala Naturae.
• Evidence of evolution substantiates the occurrence of evolutionary processes. Notable proponents of organic evolution included Aristotle, Bacon, Kant, Buffon, and E. Darwin.
• The mutation hypothesis of evolution, proposed by de Vries, addresses certain limitations of Darwin’s theory.

NEET Biology Evolution Theories Of Evolution

The doctrines of organic evolution state that the world has evolved and not created as was believed earlier. Various theories have been put forward to explain organic evolution. Some of the important theories are as follows:

Read and Learn More NEET Biology Notes

1. Lamarck’s Theory of Inheritance of Acquired Characters (1744-1829): It is based on the following propositions.

1. Living organisms and their parts tend to increase in size continuously due to internal forces of life.
2. Production of a new organ in the body of organisms results from a new need for movement.
3. If an organ is used continuously and constantly, it tends to become highly developed, whereas its continuous disuse results in its disappearance.
4. Modifications produced or acquired during the lifetime of an individual are inherited.

• Lamarck’s Theory of Inheritance of Acquired Characters (1744-1829) Books written
  • Philosophic Zoologique
  • Organisation descerps vivont
  • Historic
  • Naturellecles Animax Sons Vertebrae.
• Lamarck’s Theory of Inheritance of Acquired Characters (1744-1829) Examples. Giraffes obtain their long necks by stretching them upwards to reach the available food in the form of leaves from tall trees. Eyes are reduced in moles because they live underground.
• Objections against Lamarckism. Lamarckism failed to meet the tests of observations. There is no evidence in support of the first proposition. The experiments conducted by Weismann in mice have discarded the law of inheritance of acquired characters.
• Neo-Lamarckism. A group of scientists Tower, Mendel, Morgan, Myar, and Smith have further studied Lamarckism and supported its modified form, which is known as Neo-Lamarckism.

2. Theory Of Catastrophism. Cuvier (1769-1832) is considered the father of modem palaeontology. Cuvier believed in the fixity of species. The occurrence of fossils of different rock strata was accounted on the basis of catastrophes. A succession of catastrophes have periodically destroyed all living things, followed each time by the successive creations of new and higher forms.

3. Theory Of Uniformitarianism. James Hutton (1878) and Charles Lyell (1932) established the concept of uniformitarianism which holds that slowly acting geological forces result in the formation of fossil-bearing rock strata.

4. Darwin’s Theory of Natural Selection ‘Descent of Man’ in 1871 – propounded by – Charles Darwin and Alfred Russel Wallace

Evolution Neet Notes

Summary Of The Theory Factors

NEET Biology Evolution Notes

Objections To Darwinism

1. The type of variations that provide the raw material for natural selection are generally non-inheritable.
2. It does not explain the effect of use and disuse and the presence of vestigial organs.
3. Darwinism explains the survival of the fittest but not the arrival of the fittest. Darwin also put forward a hypothesis of pangenes in order to explain the possible mode of inheritance of these variations.
4. According to pangenesis theory each and every cell of the body produces minute primordia which are known as gemmules or pangenes. The gemmules from all parts of the body are carried by the bloodstream to the gonads where these accumulate in the germ cells.

5. Weismann’s Theory of Continuity of Germplasm. According to this theory, the cytoplasm of the animal body is differentiated into somatoplasm and germplasm. The germplasm produces gametes which transmit the characteristics of the parents to the offspring. The remaining body of the organism is formed of somatoplasm.

6. Recapitulation Theory of Haeckel. Haeckel (1811) proposed that “ontogeny repeats phytogeny ”, that is, the development of the individual repeats the evolutionary history of the race, condensing some stages and eliminating others.

7. Isolation Theory. The role of isolation in evolution was first emphasized by M. Wagner. He stated that any factor or mechanism which separates the individuals of a species into groups, so that these are unable to intermingle and interbreed, constitutes the isolating mechanism and is helpful in the progress of evolution.

8. DeVries’ Theory of Mutation. De Vries suggested that variations which are important for evolution are sudden and large; which he called mutations or saltation

NEET Biology Evolution Notes

Salient Features Of The Mutation Theory: On the basis of his observations, Hugo de Vries (1901) put forward a theory of evolution, called mutation theory. The theory states that evolution is a jerky process where new varieties and species are formed by mutations (discontinuous variations) that function as the raw material of evolution. The salient features of mutation theory are

1. Mutations or discontinuous variations are the raw material of evolution.
2. Mutations appear all of a sudden. They become operational immediately.
3. Unlike Darwin’s continuous variations or fluctuations, mutations do not revolve around the mean or normal character of the species.
4. The same type of mutations can appear in a number of individuals of a species.
5. All mutations are inheritable.
6. Mutations appear in all conceivable directions.
7. Useful mutations are selected by nature. Lethal mutations are eliminated. However, useless and less harmful ones can persist in the progeny.
8. Accumulation of variations produces new species. Sometimes a new species is produced from a single mutation.
9. Evolution is a jerky and discontinuous process.

Theories Of Evolution NEET

Modern Synthetic Theory has evolved dm in; the last century through an accumulation of fuels and theoretical conclusions from a number of scientists, Dobzhansky (1937) emphasized the role of genetic changes in populations in the process of evolution. Julian Huxley and Ernst Mayr have explained the mechanism of origin of variations in higher animals,

1. Genetic Variations in n Population: Population is the unit of Involution
   • Mechanism Of Genetic Change
     • Gene mutation
     • Chromosomal aberrations
     • Recombination of genes
     • Hybridization
2. Natural Selection: It really means differential reproduction i.c. some members of a population reproduce at a higher rate and leave more surviving offspring in the next generation than others. The organisms that produce more offspring contribute a proportionately greater percentage of genes to the gene pool of the next generation.
   • What really matters in evolution is not how well or poorly the individuals can face the environment, but how many of their young ones survive to become parents of the next generation.
3. Speciation: Species are the group of actually or potentially interbreeding natural populations that are reproductive and isolated from other such groups. The formation of new species may be caused by the gradual drifting away of two or more populations of a single species until such time they cease to interbreed.

NEET Biology Evolution Factors Causing Genetic Divergence In The Populations

1. Mutations. These are the changes in the chemical constitution of the DNA in the chromosomes of an organism. Depending upon the mutation, selection will operate either for or against the mutated gene.
2. Recombination. Brings about new combinations of old genes present in the gene pool of a population as a result of interbreeding, crossing over at the time of meiosis, free assortment of genes at the time of gamete formation etc.
3. Genetic Drift Or Random Drift. In small populations, frequencies of particular alleles may change drastically by chance alone. Such changes in allele frequencies occur randomly, as if the frequencies were drifting, and are thus known as genetic drift. For this reason, a population must be large to be in Hardy-Weinberg equilibrium.
   • If the gametes of only a few individuals form the next generation, the alleles may by chance not be representative of die parent population from which they were drawn, for example when a small number of individuals are removed from a bottle containing many.
   • By chance, most of the individuals removed are blue, so the new population has a much higher population of blue individuals than the parent one had.

Mechanism Of Origin Of Species. There are two distinct ways in which new species arise from the pre-existing ones.

1. Speciation. Splitting of species into two or more species.
2. Transformation In Time. Transformation of the old species into new ones in due course of time.

• Geographical Speciation. The geographic isolation of a population of pre-existing species into sub-populations for a sufficiently long time produces genetic changes thus changing them into new species.
• Sympatric Speciation. It generally takes place due to a sudden new effective mutation occurring in a single individual.
• Role Of Hybridization And Polyploidy In Speciation: Generally the members of different species do not interbreed and produce fertile offspring. But sometimes, the individuals of two different but closely related species may interbreed to produce fertile young ones. This phenomenon is called hybridization.

Rapid Speciation Occurs By Polyploidy: Hybridization between even closely related species is prevented by a number of barriers. Examples. Polyploidy is uncommon in animals but about one-third of the plant species are polyploids example,

1. In wheat (2N=14), there are species with chromosome numbers 14, 28 and 42
2. In rose, there are species with 14, 28, 42 and 56 chromosomes.
3. Experimental formation of Raphanobrassica (Chromosome number = 36) by crossing radish (Raplianus, 2N=18) and cabbage (Brassica, 2N=18).

Isolation: It is the segregation of the population of a species into smaller units of individuals by certain mechanisms so as to prevent interbreeding among them.

Isolating Mechanism is the process of producing and maintaining reproductive isolation in a population. This can be brought about by mechanisms acting before or after fertilization.

Theodosius Dobzhansky suggested a classification of isolating mechanism

Theodosius Dobzhansky External Barriers: The premating mechanism prevents interspecific mating: Potential mates do not meet due to

1. Geographical isolation
2. Climatic isolation
3. Seasonal isolation
4. Habitat isolation
5. Isolation due to distance.
   • Potential mates meet but do not mate, it is ethological isolation
     • Copulation attempted by transfer of mates does not take place due to
     • Mechanical isolation
     • Physiological isolation

Theodosius Dobzhansky Internal Barriers: Post-mating mechanism. Reduce full success of interspecific isolation

1. Gametic Mortality. Sperms are transferred but eggs are not fertilized
2. Zygote. Eggs are fertilised but the zygote is inviable
3. Hybrid Inviability. Zygote produces F, a hybrid of reduced viability
4. Hybrid Sterility. Hybrid is produced but partially or completely sterile

Evolution NEET Important Questions

Kinds Of Isolation. They are given below:

1. Geographical Isolation. The various physical barriers, such as mountain ranges, rivers, deserts, water connections, etc; play an important role in the isolation of a population into units.
2. Isolation Due To Sheer Distance Apart. The members of a widely distributed species, which occupy a large extent of territory without natural barriers, may become isolated since they are unable to cover great distances. Thus the members of one part interbreed among themselves and do not reach other parts.
3. Climatic Isolation. The abrupt climatic differences in the range of distribution of species cause its separation into sub-units. The climatic factors may be temperature, moisture, mineral concentration and chemical composition of the surroundings.
4. Mechanical Isolation. Animals of different species are unable to interbreed due to the differences in size and structure.
5. Ecological Isolation. Due to different ecological habits, the organisms become isolated and interbreeding between them is prevented.
6. Physiological Isolation. Certain species are established only on the basis of some physiological differences developed between them. For example, in certain species of Drosophila mating is not possible among the members of different species. In Drosophila, the vaginal mucous membrane swells up after mating. This swelling lasts for a few hours if the mating is among the members of the same species, but continues for days if the mating is interspecific. This precludes the passage and eggs fail to come out.
7. Reproductive Isolation. In some species closely allied species are intersterile due to the differences in their copulatory organs. For example, in insects, the copulatory organs are developed on lock and key arrangement i.e., only one type of key fits into one definite pattern of lock.
8. Gametic Isolation. Interbreeding is prevented by gametic inviability. The sperms of one species are either unable to survive or poorly survive in the genital tract of the females of other species.
9. Hybrid Inviability. In other cases even if the gametes survive and bring about fertilization, the zygote is either unable to develop further or the embryo dies after developing for some time.
10. Hybrid Sterility. In some cases, the hybrid formed by the mating between different species is viable but is either sterile or produces fewer offspring, for example, Mules.
11. Changes In The Developmental Rhythm. Speed of development and length of life-cycle changes split up the species into groups and genera into species.
12. Psychic Isolation. Animals have a tendency to mate with like forms. They fail to copulate because of differences in mating behaviour and nest-building habits.

NEET Biology Evolution Neo Darwinism

Neo-Darwinism gains strength from a number of evidence like industrial melanism, the origin of DDT-resistant mosquitoes, geographical distribution of sickle cell anaemia etc.

Five Major Causes Of Evolutionary Changes Accepted By Neo-Darwinism

1. Gene mutation
2. Chromosomal mutations
3. Genetic recombination
4. Natural Selection
5. Reproductive isolation

G.L. Stebbins (1966—76) gave this theory in the present form as follows: Five factors have been identified as main bases

There are also accessory factors like gene migration and hybridization to increase genetic variability. Lastly, the chance factors (genetic drift) in a small population are also relevant in the evolution of the new species.

Evolution Class 12 Notes NEET

Neo Darwinism Examples

1. Industrial Melanism. Before the industrial revolution, the dull grey forms of peppered moth – Bistort betuJaria were dominant; the carbonara form (black) was rare because it was susceptible to predation by birds. The reason was that it was conspicuously visible while resting on tree trunks.
   • The Industrial Revolution resulted in large-scale smoke which got deposited on tree trunks turning them black. Now grey varieties became susceptible and the black forms flourished.
   • Replacement of coal by oil and electricity, reduced soot production – the frequency of grey moths increased again.
2. Drug Resistance. The drugs which eliminate pathogens become ineffective in the course of time because those individuals of pathogenic species can tolerate them, survive, and flourish to produce tolerant populations.
3. Sickle Cell Anaemia And Malaria. Individuals homozygous for sickle cell anaemia die at an early age. In heterozygous individuals, the cells containing abnormal haemoglobin become sickle- shaped. In fact, when RBC becomes sickle-shaped, it kills malarial parasites effectively so that these individuals are able to cope with malaria infection much better than normal people.
4. Favism, Glucose 6 phosphate dehydrogenase deficiency is a common abnormality in Negroids. Haemoglobin gets denatured and is deposited on the cell membrane. If such persons eat beans, haemoglobin is destroyed.

J. Lederberg And E. Lederberg provided experimental evidence for ‘selection* in bacteria. By using the replica plating technique, they demonstrated the processes of ‘selection* of antibiotic-resistant strains of bacteria.

Genetic Basis Of Adaptation: Lederberg’s Replica Plating Experiment is a good example of the genetic basis of adaptation.

1. After introducing penicillin, in the culture plate, it was found that some colonies were resistant to it. Bacteria acquired this ability due to mutations (preadaptive) which occurred before exposure to penicillin.
2. The new environment only selects such mutations.
3. Lamarckian explanation of this could be that the penicillin induced changes in some bacteria enabling them to grow in this medium. Thus these bacteria became adapted to live in a penicillin medium.
4. The Darwinian interpretation could be that the colonies had two types of strains: Penicillin-sensitive and penicillin-resistant arising by mutation. Before the use of penicillin, the suitable condition was for sensitive strain, hence after using penicillin they were wiped out, but was favourable for resistant strain. Thus natural selection operates here as advantageous to the resistant strain.

Evolution NEET Important Questions

Gene Frequency. Suppose two alleles A and A of a gene exist in a population. Suppose X individuals have genotype AA. Y have Aa, Z have aa. N (Total no. of individuals) = X + Y+ Z.

The no. of alleles would be 2 x N.

The ratio of A alleles (p) in population = \(\frac{2 X + Y}{2N}\) = \(\frac{X + 0.5 Y}{N}\)

This is called the gene frequency of A. Gene frequency of ‘a’ would be q = \(\frac{Y + 2 Z}{2N}\) = \(\frac{0.5 Y + Z}{N}\)

Selection Change. Over a period of time, the criteria of natural selection also change. As a result, the genetic composition and the direction of evolution also change.

NEET Biology Evolution The Hardy Weinberg Equation

Hardy-Weinberg Equation developed independently by G.H. Hardy, an English mathematician, and G. Weinberg, a German physician, in 1908, describes the relationship between allelic frequencies and genotypic frequencies in successive generations of a population that is at equilibrium is not evolving.

The Hardy-Winberg equation is p² + 2pq + q² = 1

where p = frequency of one allele (for example, A) at a locus

q = frequency of the alternative allele (for example, a) at the same locus

p² = frequency of the genotype homozygous for the allele present in frequency p (for example, A/A)

2pq = frequency of the heterozygous genotype (for example, A/a)

q² = frequency of the genotype homozygous for the allele present in frequency q (for example, a/a)

• If the frequency of one of the alleles (for example, p) is known, then the frequency of the other allele (q = 1 -p) can be known and the frequencies of the homozygous genotypes (p and q²) as well as those ofthe heterozygous genotype (2pq) can be calculated.
• Or, if the frequency of homozygous recessive individuals in the population (a/a, or q²) is known, then the frequencies of the allele (q) and the A allele (p or 1 – q) can be calculated.
• It is then possible to predict genotypic frequencies in the present and future generations. The Hardy-Weinberg principle states that the frequencies of alleles and genotypes remain the same from generation to generation- are not altered by genetic recombinations-provided that the following conditions hold.

1. No mutations
2. An infinitely large population (no genetic drift)
3. No emigration out of or immigration into the population (no gene flow)
4. Random matings between individuals (no assortative matings)
5. Equal reproductive success among the genotypes (no natural selection)

Illustration: An investigator has determined by inspection that 16% of the human population has a recessive trait. Using this information, we can complete all the genotype and allele frequencies for the population, provided the conditions for Hardy-Weinberg equilibrium are met.

Given: q² = 16% = 0.16 are homozygous recessive individuals.

Therefore, q = √0.16 = 0.4 = frequency of recessive allele

p = 1.0 – 0.4 = 0.6 = frequency of dominant allele

p² = (0.6)(0.6 = 0.36 = 36% are homozygous dominant individuals) 84% have the dominant phenotype

2 pq = 2(0.6)(0.4) = 0.48 = 48% are heterozygous individuals = 1.00-0.52 = 0.48

Present-Day Concept Of Evolution: A modified form of Darwin’s theory, lienee is often called Neo-Darwinism.

Also called the synthetic theory of evolution (synthesis of Darwin’s and Hugo de Vries’ theories). According to this theory, only genetic variations are inherited. It includes the following factors.

1. Genetic Variations in a population occur by mutations, genetic drift (elimination of gene of certain traits due to migration or death of a section of a population), geneflow (addition or removal of alleles when individuals enter or leave a population), gene recombination, hybridization, etc.
2. Heredity, i.e., the transmission of characters from parents to offspring plays an important role in the mechanism of evolution.
3. Natural Selection selects those members which have traits that enable them to grow up and reproduce at a faster rate. It is of four types:
   • Stabilizing Selection: Keeps population genetically constant and favours normal phenotypes whereas eliminates extreme variants.
   • Directional Selection: Produces a regular change within a population in one direction and favours non-average phenotypes.
   • Disruptive Selection: Favours extreme or more adaptable phenotypes hence poplution is disrupted into two groups.
   • Cyclic Selection: Maintains genetic differences in a population and fixes all the alleles of a gene pool.
4. Speciation occurs which is die formation of new species from existing ones by evolutionary means. It is of four types:
   • Multiplicative: Splitting of a species into new species which may be gradual (occurring in many generations) or instant (occurring in a single generation).
   • Phyletic: Replacement of one species by another without an increase in number.
   • Speciation By Fusion: Here two species merge into one.
   • Quantum: Speciation by reproductive isolation due to chromosomal rearrangements.
5. Reproductive Isolation i.e., prevention of interbreeding between populations of two different species is accomplished by either premating methods that may be mechanical, ethological, seasonal and gametic isolation or post-mating methods like incompatibility, hybrid sterility, etc. (post-mating).

• Mutations. A mutation is a random inheritable change in the genetic material. It may be due to changes in the structure of chromosomes, number of chromosomes, and gene mutation (Change in sequence of nucleotides).
  • Mutation is a recurrent event because a given length can undergo only a limited number of chemical changes if given enough time, each of these will appear again and again. Thus, in a hypothetical population in which all individuals are homozygous AA, the allele A will be eventually introduced by mutation.
• Mutations Are Regarded As Fountainheads Of Evolution. Recombination. During meiosis, crossing over causes reshuffling of gene combinations which provides new combinations of existing genes and alleles.
  • This is the essence of recombination. It may bring together the alleles that arose at different times and places. Recombination can occur not only between genes but also within genes resulting in the formation of a new allele. As it adds new alleles and a combination of alleles to the gene pool it is an agent of evolution.
• Gene Migration. Because few populations are completely isolated from other populations of the same species, usually some migration between populations takes place.
  • Therefore, members of a population may enter a  new population due to migration.
  • If the migrating individuals breed within the new population, the immigrants will add new alleles to the local gene pool of the host population. This is called gene migration.
• Genetic Drift (Or Wright’s Effect). Random change occurring in the allele frequency by chance alone is called genetic drift.
  • It is the change in the number and frequency of genes (alleles) that occurs by chance – and plays an important role in evolution.
  • It operates in small isolated populations by persistent in-breeding. As a result, some alleles become permanently fixed. While some alleles undergo change in their frequency and some others disappear completely.
  • When a species is split into many isolated populations without migration or mixing, its genetic composition is mainly determined by genetic drift.
  • In the case of Biston betulciria even though the grey moth was easily visible it was not that dark to escape predation.
  • Rather sometimes in areas with a high population of grey moths, birds used to prey on more black moths due to sheer chance.
• Founder Effect. When a population gets separated from the existing population it becomes the founder of a new population. This is called the founder effect which is the result of genetic drift i.e., by chance.
• Genetic Bottleneck. Wien in a season the one population leaves a few individuals of the population which become the founder of the new population then it will produce only a few genes by selection i.e. by chance new population emerges and it is similar to a bottle in which only certain population is allowed to flow as in the neck of the bottle.
• Gene Flow: Gene flow is the movement of alleles from one population to another. It can be a powerful agent of change because members of different populations may exchange genetic material. Sometimes gene flow is obvious, as when an animal moves from one place to another.
  • If the characteristics of the newly arrived animal differ from those of the animals already dire, and if the newcomer is adapted well enough to the new area to survive and mate successfully, the genetic composition of the receiving population may be altered.
  • Other important kinds of gene flow are not as obvious. These subtler movements include the drifting of gametes or immature stages of plants or marine animals from one place to another.
• Male Gametes of flowering plants are often earned great distance by insects and other animals that visit their flowers.
• Seeds may also blow in the wind or be carried by animals or other agents to new populations far from their place of origin.
• Gene flow may also result from the mating of individuals belonging to adjacent populations.
• Gene flow can alter the genetic characteristics of populations and prevent them from maintaining Hardy- Weinberg equilibrium.

Evolution NEET Revision Notes

Kinds Of Selections

1. Stabilising selection
2. Directional selection
3. Disruptive selection

Even low levels of gene flow tend to homogenize allelic frequencies among populations and thus keep the populations from diverging genetically.

• In some situations, gene flow can counter the effect of natural selection by bringing an allele into a population at a rate greater than that at which the allele is removed by selection.
• Migration is the movement of individuals from one population to another population.
• Emigration is the migration of individuals out of an area.
• Immigration is the migration of individuals into an area. AHopatric speciation. The speciation by the geographical separation of two populations and the divergence of the population.
• Sympatric Speciation. When a sub-population becomes reproductively isolated in the midst of its parent population this is called sympatric speciation.
• Balancing Selection. A heterozygous condition in sickle cell anaemia (H^A/H^S) survived the malarial condition and balanced the loss by sickle cell anaemia is called balancing selection.
• Biological Species concept. A sexually interbreeding population which is separated from other species by reproductive isolations.
• Evolutionary Species Concepts. An evolutionary species is a lineage evolving separately from others with its own unitary evolutionary role and tendencies.
• Convergent Evolution (Adaptive Convergence). The development of similar adaptive functional structures in unrelated groups of organisms is called convergent evolution. Example: Wings of insect, bird and bat.
  • Thus analogous organs show convergent evolution (adaptive convergence). When adaptive convergence is found in closely related species. It is called “Parallel Evolution” Example: development of running habit in deer (2-toed) and horse (1-toed with two vestigial splint bones.)
• Stabilizing Selection
  1. Stabilizing selection operates in a constant or unchanging environment.
  2. Stabilizing selection introduces homogeneity in the populations.
  3. Stabilizing selection favours average or normal individuals and eliminates over-specialised as well as less-specialized or less adapted individuals.
  4. Stabilizing selection checks the accumulation of mutations that may lower the fitness of species in unchanging environments.
  5. Stabilizing selection tends to arrest variance and evolutionary change.
  6. Stabilizing selection operates rarely because the environment is rarely constant.
     • Stabilizing Selection Examples
       1. Stabilizing selection in sparrows observed by H.C. Bumpus in 1S99.
       2. Stabilizing selection in Land Snails was observed by W.F.R. Weldon in 1901.
       3. Mortality of babies
       4. Stabilizing selection in red checkered moths (Panaxiadominula) observed by E.B. Ford.

NEET Short Notes On Evolution

Directional Selection:

This selection process functions in reaction to incremental alterations in environmental variables.

• It functions within the spectrum of phenotypes present in the population and applies selection pressure that shifts the mean phenotype towards a phenotypic extreme.
• When the mean phenotype aligns with the new optimal environmental conditions, stabilizing selection will prevail.
• This type of selection induces evolutionary change by creating a selection pressure that promotes the proliferation of novel alleles within the population.
• Directional selection underpins artificial selection, whereby the selective breeding of phenotypes exhibiting desirable qualities enhances the prevalence of those phenotypes in the population.
• D.S. Falconer conducted a series of tests in which he picked the heaviest mice from a population at six weeks of age and allowed them to inbreed. He also chose the lightest mice and permitted them to inbreed.
• This selective breeding based on mass led to the emergence of two populations: one exhibiting an increase in bulk and the other a decrease
• Following the cessation of selective breeding, neither group reverted to the original population mass of around 22g. This indicated that the artificial selection of phenotypic traits resulted in certain genotypic selection and a reduction of alleles within each population.

Disruptive Selection. Fluctuating conditions within the environment may favour the presence of more than one phenotype in a population. It was studied in sunflowers.

NEET Biology Evolution Theory Of Evolution By Natural Selection Synopsis

The unit of evolution is the population. The unit of natural selection is individual (phenotype).

• An Isolating Mechanism is a means of producing and maintaining reproductive isolation within a population. This can be brought about by mechanisms acting before or after fertilisation. Theodosius Dobzhanskv suggested a classification of isolating mechanisms.
• Adaptive Radiations. Evolution of groups of animals in different directions.
• Of all the species that have ever lived more than 99% have gone extinct
• Danvin used the breeding of domestic animals, known as artificial selection as evidence of evolution. In artificial selection, humans are the selective agents, while in natural selection, the environment is the selective agent.
• Darwinism Fitness. In an individual it is a measure of its ability, relative to others in the population, to pass genes to the next generation.
• The branch of Biology that emerged from the synthesis of Darwinian Evolution and Mendelian genetics is called Population Genetics
• Parallelism is the adaptive convergence of closely related species in evolution.
• Genetic variation that parallels a gradient (for example, Rainfall) is called Cline.

Darwin regarded continuous variations to be more important since discontinuous variations being mostly harmful would not be selected again.

1. G6PD is an X-chromosome-linked trait. Clinical features
2. Drug-induced hemolytic anaemia, for example, sulphonamide, primaquine nitro furantin and phenacetin. Ingestion of the drug is followed by fever, malaise, prostration and passage of dark urine
3. Favism
4. Neo-natal jaundice Diagnosis is established by enzyme assay.

Evolution MCQs For NEET Biology With Answers

Question 1. Which one is the common point in Lamarckism and Darwinism?

1. Origin of the idea of organic evolution
2. Continuity of germplasm.
3. Mutation
4. The idea of evolution.

Answer: 4. The idea of evolution.

Question 2. Genetic drift is on account of:

1. Variation
2. Mutation
3. Increase in population
4. No change in population.

Answer: 3. Increase in population

Question 3. Reproductive isolation between segments of a single population is termed:

1. Allopatry
2. Population divergence
3. Sympatry
4. Disruptive isolation.

Answer: 3. Sympatry

Evolution – NEET Questions Question 4. The present Giraffe has a long neck as compared to its ancestors. According to the present-day view could be due to the:

1. Natural selection
2. Isolation
3. Speciation
4. Inheritance of acquired characters.

Answer: 1. Natural selection

Evolution Mcq For Neet

Question 5. The appearance of ancestral characters in the new bombs, such as the tail, multiple mammae etc. is known as:

1. Homologous
2. Analogous
3. Atavism
4. Vestigial.

Answer: 3. Atavism

Question 6. Nowadays Lamarckian theory is being reviewed in the light of the modern concept of evolution under the heading Neo-Lamarckism. Who proved that the genes are influenced by physical and chemical factors so that they bring remarkable changes to the offspring

1. Tower
2. Harrison
3. Hoffman
4. Both 1 and 2.

Answer: 4. Both 1 and 2.

Question 7. According to the Neo-Lamarckism:

1. Acquired characters influence the somatic cells
2. Acquired characters influence the chromosomes or genes
3. Somatic characters are not inherited while characters of gametes are inherited by the offspring
4. All the above three.

Answer: 2. Acquired characters influence the chromosomes or genes

Question 8. One of the following is most essential of evolution:

1. Mutation
2. Hereditary characters
3. Adaptations
4. Nature.

Answer: 1. Mutation

Question 9. Changes in genetic characters on accumulation, leading to the formation of new individuals is characteristics of:

1. Non-directional
2. Genetic drift
3. Divergent evolution
4. Macroevolution.

Answer: 3. Divergent evolution

Question 10. Radiations with successful adaptations in the case of insects over a major period are a result of the:

1. Microevolution
2. Genetic divergence
3. Mega evolutions
4. Macroevolution.

Answer: 4. Macroevolution.

Read and Learn More NEET Biology Multiple Choice Question and Answers

Question 11. The term used for similarity in organ structure seen in great diversity is:

1. Homology
2. Analogy
3. Symmetrical
4. Identical.

Answer: 1. Homology

Neet Mcqs On Evolution With Answers

Question 12. Darwinism fails to explain:

1. Usefulness of all organs
2. Retrogression
3. Progression
4. Presence of vestigial organs.

Answer: 4. Presence of vestigial organs.

Question 13. Fishes to mammals have a similar structure with respect to:

1. Forebrain alone
2. Midbrain alone
3. Hindbrain alone
4. All three regions.

Answer: 4. All three regions.

Question 14. Balancing selection promotes:

1. Homozygotes
2. Heterozygotes
3. Polyploids
4. Recessive traits alone.

Answer: 2. Heterozygotes

Question 15. Cladogenesis refers to:

1. Convergence of different genetic lines
2. Divergence of genetic lines from a common ancestor
3. Independent evolution
4. Formation of new species.

Answer: 2. Divergence of genetic lines from a common ancestor

Question 16. Allopatric speciation is due to:

1. Mutation
2. Geographical separation of population
3. Migration of members of a species from one to another population
4. Hybridization between closely related species.

Answer: 2. Geographical separation of population

Question 17. The most complex cellular structures are found in:

1. Bacteria
2. Algae
3. Protozoa
4. Fungi.

Answer: 3. Protozoa

Evolution Neet Previous Year Questions 

Question 18. The oldest fossil of a mammal is from the:

1. Permian period
2. Jurassic period
3. Triassic period
4. Cretaceous period.

Answer: 3. Triassic period

Question 19. Successful adaptation simply means:

1. An increase in fitness
2. Moving to a new place
3. Producing viable offsprings
4. Evolving new characteristics.

Answer: 3. Producing viable offspring

Question 20. The unit of evolution is now known to be the:

1. Individual
2. Family
3. Population
4. Species.

Answer: 3. Population

Question 21. The unit of natural selection is the:

1. Individual
2. Family
3. Population
4. Species.

Answer: 1. Individual

Question 22. The total collection of genes at any one time in a unit of evolution is called the:

1. Genotype
2. Gene pool
3. Multiple allelic groups
4. Demotype.

Answer: 2. Gene pool

Question 23. A change in the relative abundance of an allele (the allelic frequency) within a population, over a succession of generations is called:

1. Micro-evolution or adaptive evolution
2. Macro-evolution or speciation
3. Co-evolution
4. Phylogenetic evolution.

Answer: 1. Micro-evolution or adaptive evolution

Darwin’s Theory Of Evolution Mcqs Neet

Question 24. Micro-evolution can be measured by comparing observed allelic frequencies with those predicted by:

1. Chance
2. Hardy Weinberg equation
3. Mendelian ratios
4. All known environmental factors.

Answer: 2. Hardy Weinberg equation

Question 25. A potential danger to a population that has been greatly reduced in number is the following:

1. Loss of genetic viability
2. The tendency towards assortative mating
3. Reduced gene flow
4. Hardy Weinberg disequilibrium.

Answer: 1. Loss of genetic viability

Question 26. All alleles originate from:

1. Mutations
2. Cross-overs
3. Gene flow
4. Non-disjunctions.

Answer: 1. Mutations

Question 27. A beneficial allele increases more rapidly in frequency if it is:

1. Recently mutated
2. Rare
3. Dominant
4. Recessive.

Answer: 3. Dominant

Question 28. Sympatric speciation occurs most commonly in:

1. Mammals
2. Fishes
3. Amphibians
4. Birds.

Answer: 2. Fishes

Question 29. Reproductive isolation in sympatric speciation develops without a:

1. Change in chromosome number
2. Barrier to mating
3. Geographical barrier
4. The barrier to gene flow.

Answer: 3. Geographical barrier

Question 30. Darwin found that South American fossils are most similar to:

1. Australian fossils
2. Asian fossils
3. Living species of South America
4. Living species of North America.

Answer: 3. Living species of South America

Question 31. Darwin believed that a Giraffe has a long neck because:

1. A creator designed it that way
2. Catastrophes eliminated short-necked form
3. Its ancestors stretched their necks to get food
4. Ancestral Giraffes with slightly longer necks than others got more food and left more surviving offspring.

Answer: 4. Ancestral Giraffes with slightly longer necks than others got more food and left more surviving offspring.

Question 32. According to Darwin, two different areas within a continent have different species because they have different:

1. Evolutionary mechanism
2. Ancestors
3. Environments
4. Evolutionary times.

Answer: 3. Environments

Darwin’s Theory Of Evolution Mcqs Neet

Question 33. The population of Bi’s ton betularia changed from 1% dark 99% light individuals, 99% dark and 1% light individuals between 1848 to 1898. The selective agent causing the change was:

1. Humans
2. Toxins from smoke
3. Birds
4. Tree bark.

Answer: 3. Birds

Question 34. The most important evidence since Darwin bears on his theory has been the area of:

1. Palaeontology
2. Genetics
3. Comparative anatomy
4. Comparative embryology.

Answer: 2. Genetics

Question 35. Phylogeny describes a species:

1. Morphological similarities with other species
2. Reproductive compatibilities to other species
3. Evolutionary history
4. Geographical distribution.

Answer: 3. Evolutionary history

NEET Biology Evolution MCQs Question 36. Plants and animals of the Galapagos Islands resemble most closely the plants and animals of:

1. North America
2. South America
3. Asia
4. Australia.

Answer: 2. South America

Question 37. Similar traits resulting from similar selection pressures acting on similar gene pools are:

1. Coevolution
2. Convergent evolution
3. Divergent evolution
4. Parallel evolution.

Answer: 4. Parallel evolution.

Question 38. The process of evolution:

1. Is a continuous process
2. Is a discontinuous process
3. Was continuous in the beginning but discontinuous now
4. Was discontinuous.

Answer: 1. Is a continuous process

Question 39. Organic evolution means:

1. Life began in the sea
2. Fossils are old
3. Descent with modifications
4. Man descended from monkeys.

Answer: 3. Descent with modifications

Question 40. Evolution is generally:

1. Progressive
2. Retrogressive
3. Standstill
4. None of the above.

Answer: 1. Progressive

Question 41. Evolution means:

1. History of race
2. Development of race
3. History and development of race with variations
4. Progressive development of the race.

Answer: 3. History and development of race with variations

Question 42. Charles Darwin toured in a ship for 5 years. It was:

1. Vikrant
2. Alexander
3. Phillips
4. Beagle.

Answer: 4. Beagle.

Question 43. The modern theory of organic evolution is based on:

1. Genetic variation
2. Natural selection
3. Isolation
4. All the above three.

Answer: 4. All the above three.

Lamarck’s Theory Of Evolution Mcqs Neet

Question 44. Genetic variation arises by:

1. Recombination (crossing over)
2. Chromosomal aberrations
3. Mutation
4. All the above.

Answer: 4. All the above.

Question 45. Genes mutate by:

1. Substitution of a base
2. Addition of a base
3. Deletion of a base
4. All the above.

Answer: 4. All the above.

Question 46. The natural selection really means:

1. Struggle for existence
2. Differential reproduction
3. Survival of the fittest
4. Elimination of the unfit.

Answer: 2. Differential reproduction

Question 47. Salutations is the name given to:

1. Lethal variations
2. Blastogcnic variations
3. Continuous variations
4. Discontinuous variations.

Answer: 4. Discontinuous variations.

Question 48. The role of isolation in evolution is:

1. Creation of new species
2. Maintenance of an existing species
3. Evolutionary divergence
4. Extermination of a species.

Answer: 1. Creation of new species

Question 49. Which is the most important factor for the development of a new species?

1. Extensive inbreeding
2. Extensive outbreeding
3. Geographical isolation
4. None of the above.

Answer: 2. Extensive outbreeding

Question 50. There is more competition for survival between:

1. Different animals of the same niche
2. Some animals of the same niche
3. Different animals of different niche
4. Same animals of different niches.

Answer: 2. Same animals of the same niche

Question 51. Speciation depends on the sum total of adaptive changes preserved by:

1. Natural selection
2. Human conservation
3. Isolation
4. Environment.

Answer: 3. Isolation

Question 52. Separation of a variant population from the original population by a mountain is called:

1. Geographical isolation
2. Ecological isolation
3. Economical isolation
4. Temporal isolation.

Answer: 1. Geographical isolation

Question 53. The propounder of the theory of Natural Selection was:

1. Mendel
2. Darwin
3. De Vries
4. Lamarck.

Answer: 2. Darwin

Question 54. The doctrine of evolution is particularly concerned with:

1. Gradual changes
2. Environmental condition
3. Theory of special creation
4. Spontaneous growth.

Answer: 1. Gradual changes

Question 55. The theory of inheritance of acquired characters was proposed by:

1. Mendel
2. Darwin
3. Lamarck
4. De Vries.

Answer: 3. Lamarck

NEET Biology Evolution MCQs Question 56. Darwin was influenced by one of the following in proposing the theory of his natural selection:

1. Cell theory
2. Mendel’s Laws of Inheritance
3. Overflow of population
4. Malthus’s theory of population.

Answer: 4. Malthus’s theory of population.

Question 57. Organic evolution refers to:

1. Evolution of organs
2. Orderly changes based on plans of the past
3. Drastic changes with no resemblance to the past
4. Orderly changes over long periods.

Answer: 2. Orderly changes based on plans of the past

Question 58. Retrogressive evolution refers to:

1. Elimination of structural diversity
2. Elimination of behavioural traits
3. Reduction in structure of complex but primitive organisms
4. Degeneration of advanced organisms.

Answer: 3. Reduction in structure of complex but primitive organisms

Question 59. The various concepts such as conflict, struggle and survival were first introduced by:

1. Darwin
2. Heraclitus
3. Empedocles
4. Anaximander.

Answer: 1. Darwin

Question 60. De Vries worked on the plant:

1. Pisum
2. Lathyrus
3. Oenothera
4. Mirabilis.

Answer: 3. Oenothera

NEET Biology Evidence Of Evolution Relationship Among Organisms

Organic evolution is also stated as ‘Descent with modification’ (Darwin, 1859)

Empedocles (493—435 B.C.). Founder of the concept of Evolution.

Herbert Spencer (1820-1903). Coined the term evolution.

Biological evolution has given rise to a large number of different kinds of organisms.

NEET Biology Evidence Of Evolution Evidence In Support Of Evolution

The types of evidence which support organic evolution are, morphological, anatomical, embryological, palaeontological, biogeographical, physiological, and biochemical.

Read and Learn More NEET Biology Notes

NEET Biology Evidence Of Evolution From Taxonomy

Classification of animals both present and extinct is based upon their natural similarities and dissimilarities which establish their genealogical relationship and common ancestry.

Palaeobiological study helps in understanding and locating hydrocarbon sources.

Evidence Of Evolution NEET Notes

Palynofossils—the tiny microscopic spores, pollen, and other vegetal remains of the past—assist us in interpreting ancient environmental conditions favourable for organic matter accumulation and its conversion to fossil fuels by transformation and subsequent thermal alteration.

Genclogieal lice was first drawn by Lamarck (1809).

• The levels of classification are Phylum → Class → Order → Family → Genus → Species.
• All similar species are grouped together in one genus, all such genera in one family and so on.

Evolution Of Plants

• Diverse life processes, including energy transformation, macromolecule synthesis, genetic coding, and various biochemical reactions, exhibit similarities among diverse creatures.
• The parallels in biological processes reinforce the notion that every living being originated from a shared primordial ancestor and emerged through evolution.
• Evolutionary change is an essential trait of all living species.

NEET Biology Evidence Of Evolution Morphological And Anatomical Evidence

Body Organisation. Body of all multicellular animals: cell organelles → cells → tissues → organs → systems.

Vertebrate Organs. Certain organs (for example Heart) show gradual modifications.

• Fish’s Heart. 2 chambered (1 auricle + 1 ventricle)
• Amphibian’s Heart. 3 chambered (2 auricles + 1 ventricle)
• Reptilian Heart. Incompletely 4 chambered (2 auricles + partly divided ventricle).
• A crocodile is a reptile, but it has a 4 chambered heart with completely divided ventricles.
• Mammals And Aves. 4 chambered hearts (2 auricles + 2 ventricles).

Homologous And Analogous Organs NEET Biology

Homologous Organs. Organs which look different and perform different functions but have the same basic structure and origin are called homologous organs. They are evidence in support of divergent evolution Examples,

1. Forelimbs of vertebrates such as seal (flipper), bat (patagium), horse (forelimb), man (arm).
2. Thom of ‘glory of the garden’ ( Bougainvillea) and tendril of Passiflora. Both look different and help in climbing in a different manner. But both arise in the axillary position and are modified branches.
3. Insect Legs. They are used in squatting in mosquitoes, collection of pollen in bees, clinging in lice, grasping in praying mantis and digging in mole cricket. However, in each case, it has five parts – coxa, trochanter, femur, tibia and 1-5 jointed tarsus.
4. Insect Mouth Parts. They have a labrum, two mandibles and two pairs of maxillae. Mouth parts are specialised for chewing and biting in cockroaches, chewing and lapping in Honey bees, sponging in Housefly, piercing and sucking in Mosquito and siphoning in Butterfly.

Differences in homologous organs are examples of divergent evolution/adaptive radiation. The occurrence of similar types of biomolecules in various groups of organisms is called molecular homolog}’, for example, blood proteins in humans and apes, hormones in mammals, and Rubisco in plants.

Analogous Organs. Organs which have the same function and look superficially alike but are quite different in fundamental structure and embryonic origin are called analogous organs and support convergent evolution. Examples,

1. Wing of an insect and that of a bat.
2. Fins of fishes and flippers of whales have similar functions and are structurally quite different,
3. Stings of Honey bee and Scorpion have similar functions but are modifications of the ovipositor and last abdominal segment respectively,
4. Photosynthesis is performed by different structures in Wild peas (stipules). Australian acacia (petiole) and Ruscus (cladodes).

Connecting Links are the living animals which possess the characteristics of two different groups of animals known as the connecting links. Examples

1. Lung Fishes — connecting link between fishes and amphibians.
2. Resemblance With Fishes — paired fins, gills and dermal scales.
3. Resemblance With Amphibians — internal nares, 3 chambered heart single or double lung for breathing.
4. Egg Laying Mammals — spiny ant eater, duck-billed platypus. Link mammals with reptiles.

Mammalian Features — hair, mammary glands, diaphragm, single aortic arch.

Reptilian Features — lay large eggs, presence of cloaca, large coracoid in pectoral girdle.

Some Other Connecting Or Missing Links

Missing links are the extinct animals which possess characters of two different groups of animals.

Fossil Evidence Supporting Evolution NEET Study Material

Vestigial Organs. The organs which occur in reduced form and are useless to the possessor, but correspond to the fully developed functional organs of their ancestors called vestigial organs. For example, the Human body has about 90 organs which are vestigial.

1. Tail Bone (Coccyx)
2. Wisdom Tooth
3. Nictitating Membrane. (Plica semilunaris) also called the third eyelid. Used in cats, eels, pigeons and frogs for cleaning the cornea. In men, this function is carried out by the upper eyelid.
4. Auricular Muscles. Three in mammals such as dog, cow, rabbit etc. ( Anterior, superior and posterior).
5. Caecum And Vermiform Appendix

Examples In Other Animals

1. Whales. Whales possess vestigial pelvic girdle and vestigial ear pinna (reduced).
2. Pythons and Boas possess vestigial, greatly reduced pelvic girdles.
3. The splint bones of horses represent the vestigial second and fourth toe.
4. Eyes have become vestigial in deep sea-dwelling animals like crayfish, salamanders etc.

Examples Of Vestigial Organs Of Plants. Leaves are reduced to scales in Ruscus and Asparagus. Pistil is reduced in ray florets of sunflower.

Atavism (Reversion ). It is the reappearance of certain ancestral (not parental) structures which have either completely disappeared or greatly reduced.

NEET Biology Evidence Of Evolution Embryological Evidences

Embroyological Evidence includes similar early development; similar vertebrate embryos, temporary embryonic structures; recapitulation theory and development of certain organs.

• Development of all triploblastic animals starts from a zygote and undergoes similar processes to form gastrula having-3 primary germ layers (ectoderm, mesoderm and endoderm) which have the same fate in organogenesis.
• Early embryos of different vertebrates are similar in having similar structures like gill slits, notochord, tail etc. and are indistinguishable from one another. All these support organic evolution.
• It is also supported by recapitulation theory by Von Baer (modified into Biogenetic Law by Haeckel) which states “Ontogeny repeats phytogeny” example, a tadpole larva of the frog.

NEET Biology Evidence Of Evolution Palaeontological Evidence

Palaeontological evidence includes missing links; distribution of fossils in the rocks of different periods, ancestries of animals etc.

• Vinci (1452-1519) is regarded father of palaeontology. Palaeontological evidences are based on a comparative study of fossils of different animals. Fossils are the remains or impressions of harder parts of past animals preserved in sedimentary rocks or other media.
• The age of the fossil is determined either by C¹⁴ – dating technique or the amount of lead in a rock.

Radioactive Carbon Method: The radioactive carbon method was discovered by W.F. Libby.

• Half half-life of radioactive carbon is 5730 years which was found in very minute quantity i.e. 0.1 % in the atmosphere and continuously produced from cosmic ray bombardment on earth’s upper atmosphere.
• Living organisms absorb radioactive carbon (C¹⁴) throughout their life from the environment in the form of CO₂ and organic molecules which signal death.
• After the death of organism, C¹⁴ began to decay according to its half-life i.e., 573 x 10³ years. It means 100 grams C¹⁴ will remain 50 grams in 5.73 x 10³ years and 25 grams in another 5.73 x 10³ years.
• By measuring the amount of C¹⁴ in a fossil relate this amount with the amount of C¹⁴ in a living organism, the age of the fossil can be estimated.
• This method is useful only to determine the age of actual remains and useless for moulds, casts or impressions.
• The C¹⁴ Radioactive carbon method can be used to determine the age of younger fossils that are not older than 70,000 years.
• This method is used for dating not only fossils but also archaeological remains.

Fossil Evidence Supporting Evolution NEET Study Material

Radioactive Clock Method: This method was discovered by Boltwood (1907) and is based on the disintegrating property of radioactive elements. These elements disintegrate at a steady rate into a stable substance for example in the U²³⁸ – Pb²⁰⁶ method the following decay takes place.

Uranium²³⁸  → Radium²²⁶ →Polonium²¹⁸ → Lead²⁰⁶ → Polonium²¹⁰ → Astatine²¹⁸

• One-half of uranium238 atoms will convert into Lead206 after 4.5 billion years (4.5 x 10¹⁰ years).
• The age of the rock can be calculated by estimating the uranium and lead quantity.
• This method is used for igneous rocks containing minerals and is useless for determining the age of sedimentary rock and fossils directly.

It is based on the fact that the older rock is less radioactive.

Potassium-argon Method: The transformation of radioactive potassium K⁴⁰ to argon and rubidium to strontium has been used for dating fossil-bearing rocks of any age and any type. Due to the greater concentration of potassium in most rocks, it is a more accurate method of dating fossils than uranium, a relatively rare element.

• It is the latest method to estimate the age of fossils.
• The half-life of potassium is 1.3 x 10⁹ years.
• Ordinary potassium contains 0.01 % of radioactive isotopes which disintegrate into calcium and argon.
• The age of the earliest known fossil of hominids in East Africa has been estimated by this method recently.
• It is possible to date very old rocks i.e. over three billion years by this method. Electron spin resonance dating

Electron Spin Resonance (ESR) dating is a relatively new, more precise and most accurate method of dating. It is based on the fact that background radiation causes electrons to dislodge from their normal positions in atoms and become trapped in the crystalline lattice of the material.

• When odd numbers of electrons are separated, there is a measurable change in the magnetic field (or spin) of the atoms.
• Since the magnetic field progressively changes with time in a predictable way as a result of this process, it provides another atomic clock or calendar, that can be used for dating purposes. ESR is used mostly to date Calcium carbonate in limestone, coral, fossil teeth, molluscs and egg shells. This method can date quartz and flint.
• This method has been used by palaeontologists mostly to date samples from the last 300,000 years.

1. Missing Links. They are those extinct organisms which had the characteristics of two different groups of animals. These also show the path of evolution. Archaeopteryx (lizard-bird) is a missing link between the reptiles and the birds.
   • They are the transitional forms between two present-day groups of organisms, for example, Pteridosperms (Pteridophytes and gymnosperms).
   • Toothed birds Reptiles and birds.
   • Archaeopteryx (Wagner 1861)
   • Reptilian Characters—toothed jaws, non-pneumatic bones, keel-less sternum, free caudal vertebrae, free clawed fingers.
   • Avian Characters—Fore limbs forming wings, feathers, beak, rounded cranium, fused skull bones.
2. Geological Succession Of Fossils shows that fossils have become more in number and show gradually increased complexity from the earliest to recent rocks.
   • Dinosaurs were highly flourished, giant reptiles of the Jurassic period (Age of Reptiles) of the Mesozoic era. These became extinct probably due to the direct hitting of a comet or a meteorite having rich amounts of iridium and global cooling.
3. Geological Time Scale is the tabulated form showing the sequence and duration of different eras and periods with their dominant form of life. It was proposed by Giovanni Avaduina (1760). It has 5 principal eras: Archaeozoic; Proterozoic; Palaeozoic; Mesozoic and Coenozoic. Another era is Azoic 4200- 4600 million years ago in which no life existed.
4. Phylogeny is the evolutionary history of an organism. The Palaeontologists have traced the ancestries of horses, elephants, camels etc. The evolution of horses started in North America about 60 million years ago.
   • The original dawn horse (Eohippus) has passed through stages like an intermediate horse (Mesohippus), ruminating horse (Merychippus) and Pliocene horse (Pliohippus) to transform into a modern horse (Equus).
   • These stages confirm the occurrence of changes like an increase in height, a reduction in the number of functional digits and an increase in the size of the crown of the molars.

NEET Biology Evidence Of Evolution Type Of Fossils

1. Unaltered. Woolly mammoth buried in ice.
2. Petrified. Replacement of organic parts by mineral
3. Moulds and casts
4. Prints. Footprints, prints of leaves, stems etc.

Types Of Rocks

1. Igneous Rocks. Rocks which are formed by the solidification of the original molten earth are called igneous rocks.
2. Sedimentary Rocks. Rocks formed due to deposition and subsequent stratification of soil particles over a long period of time are sedimentary rocks.
3. Metamorphic Rocks. These rocks are sedimentary rocks that are changed by heat and pressure.

In passing from the earliest to recent rocks, the fossils become more numerous and also progress from simple to more complex types.

Geological Time Scale

NEET Biology Evidence Of Evolution Biogeographical Evidence

1. Biogeography. The study of the distribution of animals and plants in the world is called biogeography.
2. Pangaea. It is held that around the carboniferous period ( about 375 million years back) or slightly earlier, all the present-day continents formed a single large irregular-level mass called Pangaea.
3. Realms Of Life. Sclater ( 1858) divided the earth into six realms for the distribution of birds while Wallace (1923) divided the earth into six realms for the distribution of both plants and animals.
   1. Nearctic
   2. Palaearctic
   3. Neotropical
   4. Oriental
   5. Ethiopian
   6. Australian
4. Discontinuous Distribution. Descendants of a common ancestor in some cases inhabit different continents and also differ from each other.
   1. Even with the same climate and topography, different realms have different types of flora and fauna. Central Africa has lions, elephants, antelope, and giraffes while Brazil has tapir, sloths, opossums, and llamas. The deserts of the two realms also differ with cacti in America and euphorbias in Africa. It is believed that at one time the whole land mass was one piece of Pangaea.
   2. About 200 million years back, it broke up into northern Laurasia and southern Gondwanaland. Laurasia further split up to form Eurasia, Greenland, and North America. Gondwanaland formed South America, South Africa, Australia, New Zealand and India.
   3. Another reorientation occurred 135 million years back when India was pushed upwardly to rest against Eurasia, South Africa joined North Africa and South America came close to North America.
      • The degree and period of separation of an area from another correspond to species diversity.
   4. Double coconut occurs only on Seychelles Island. Egg-laying mammals are restricted to Australia, Tasmania, and New Guinea. Kangaroo and Koala are marsupials found in Australia while Opossum is found in S. America.
   5. The two sides of the isthmus of Panama separated only a few million years back. They possess different but related species of invertebrates.
   6. Galapagos Islands is a group of 14 islands situated 800-960 km off the west coast of South America. Darwin visited the islands and called them living laboratories of evolution. The islands have 23 different species of birds and 11 types of tortoises.
   7. Amongst the birds are 14 species of finches (named Darwin’s finches by David Lach, 1947), a group of small birds which resemble the mainland seed-eating ground finches in general body pattern but differ in food habits, types of beaks, and several other physical features to appear distinct species.
   8. The finches must have come from the mainland but different islands of the Galapagos provided different types of environmental conditions so that the common stock became diversified due to genetic drift and adaptation to different food habits. It is an example of adaptive radiation/divergent evolution. Example,
      1. Alligators – occur only in the S.E. U.S.A. and Eastern China.
      2. Restricted Distribution. The parts separated from the rest of the world long have unique fauna and flora example, Australia.

NEET Biology Evolution Notes

NEET Biology Evidence Of Evolution Biochemical Evidences

1. Enzymes
2. Hormones
3. Blood proteins– of various mammals are similar to a large extent but are sharply distinguishable from those of other vertebrates. Man is nearest to the great apes (Chimpanzees and gorillas) and next in order are the old-world monkeys, the new-world monkeys and the tarsiers.
4. Molecular Homology. Similarity among animals at the molecular level is called Molecular Homology.

NEET Biology Evidence Of Evolution Cytological Evidence

All the living organisms are similar in being:

1. Cellular in nature and are formed of one (protozoans) or more cells (metazoans).
2. Presence of similar organelles having similar ultrastructure and functions.
3. All, the cells are formed of similar material called protoplasm having similar physical, chemical, and biological properties.
4. Basic metabolic cellular functions are performed similarly.

This supports that all the organisms are interrelated and have a common ancestry.

NEET Biology Evidence Of Evolution Comparative Physiology

All living organisms exhibit similarities in their chemical structure and function i. e., the biochemical composition and physiological activities, for example, the blood as regards cell and plasma, is markedly similar in different groups.

NEET Biology Evidence Of Evolution Genetics

The selection and interbreeding of domestic animals by man has led to the establishment of new races. This has been possible because of the changes occurring in genes producing mutations and variations in changed environments.

The natural forces of isolation and natural selection operate on these variations and some of them become heritable, leading to the formation of new races. The same process of gene mutation, variations, selection and interbreeding might have occurred on a large scale in nature leading to the establishment of new species.

Great Chain Of Being Or Aristotle’s Ladder Of Nature:

To express ideas about evolution various naturalists explained their different views. About 2000 years before Darwin explained his theory others expressed their views. According to Plato (428-348 BC), each species was an unchanging ideal form. All earthly representatives are imperfect imitations of such true essence of an ideal unseen world.

• As God is perfect, everything that existed on earth was His ideas. Later on, Aristotle (384-322 B.C.) further explained Plato’s idealistic concept to chain like a series of forms, each form representing a link in the progression from most imperfect to perfect. He called this chain as Ladder of Nature or Scala Naturae. It is also known as the “Great Chain of Being”
• Plate Tectonics: The concept of plate tectonics supposes that the surface layers of the Earth fit together like a spherical zig-zaw puzzle, and the individual pieces are on the move about one another.
• Continental Drift is the process in which it is supposed (from recent geological and other evidence) that the continental land masses have not always occupied their present position on the globe and that, powered by processes within the Earth itself, they are slowly and continuously on the move.
• In this way new land masses are created and destroyed, split apart and joined, over geological time. This hypothesis was first proposed by Snider in 1858 but developed by Taylor in America and Wagner in Germany in the late 1800s.
  • Significance. Continental Drift is one of the processes that can lead to geographical isolation.
• K-T Boundary. The boundary between rocks of the cretaceous and tertiary periods, about 65 million years, often having iridium and marketing the extinction of dinosaurs.
• Magma. It is the molten rock material present in the earth’s interior from which igneous rocks have been formed. Lava is also magma that has reached the surface of the crater of a volcano.
• Aeon Or Eon. It is the geological age consisting of one or more eras, viz., archaean, Proterozoic, and phanerozoic. Phanerozoic eon has three eras-palaeozoic, Mesozoic, and economic.

Evidence of Evolution NEET Notes

Evolution Of Horse:

The primary tendencies observed in equine evolution pertained to movement and alimentation.

They signify adaptations to fluctuating environmental conditions and can be summarized as follows:

• Augmentation in dimensions
• Elongation of extremities and feet
• Reduction of lateral digits.
• Augmentation in length and girth of the third digit
• Alignment and rigidity of the spine
• Enhanced sensory organs
• Expansion in size and intricacy of the brain correlated with the evolution of sensory organs.
• Broadening of incisors, substitution of premolars with molars, elongation of teeth, elevation of molar crown height, augmented lateral support of teeth through cement, and expanded cusp surface areas due to enamel ridge exposure.

The Basic Timeline Of A 4.6 Billion-Year-Old Earth, With Approximate Dates:

• 2 billion years of complex cells (eukaryotes),
• 1 billion years of multicellular life,
• 1000 million years of simple animals,
• 570 million years of arthropods (ancestors of insects, arachnids and crustaceans),
• 550 million years of complex animals,
• 500 million years of fish and proto-amphibians,
• 475 million years of land plants,
• 400 million years of insects and seeds,
• 360 million years of amphibians,
• 300 million years of reptiles,
• 200 million years of mammals,
• 150 million years of birds,
• 130 million years of flowers,
• 65 million years since the dinosaurs died out,
• 2.5 million years since the appearance of the genus Homo,
• 200,000 years of anatomically modern humans,
• 25,000 years since the disappearance of Neanderthal traits from the fossil record.
• 13,000 years since the disappearance of Homo floresiensis from the fossil record.

NEET Biology Evidence Of Evolution Synopsis

Mammals among animals and angiosperms among plants are the most advanced forms. The earliest era in the geologic record is Precambrian.

Phylogenetics = Cladistics. Some workers in cladistics equate homology with synapomorphy. In molecular biology, the term indicates a significant degree of sequence similarity between D.N.A. or protein sequences.

• Evolved from common ancestor = Monophyletic origin
• Dundee. It is the famous city of fossils in Italy
• Unaltered fossils of 25, 000 yrs old elephant woolly mammoths were found in ice of Siberia (Russia)
• Evolution Is Irreversible. Also called Dollo’s law (Dollo, 1893).
• Cope’s Law. In the course of evolution, there is a tendency for animals to increase in size.
• Bergman’s Law. Warm-blooded animals are larger in size in the colder regions as compared to hotter parts.
• Allen’s Law. Extremities like tails and ears become smaller in colder areas.
• Gloger’s Rule. Warm-blooded animals have more melanin in hot wet areas but develop yellow-red pigment in hot dry areas.

Paleontological Evidence Of Evolution NEET Preparation

Ontogeny Repeats Phylogeny

Recapitulation theory – Karl Von Baer

Biogenetic Law – Ernst Haeckel

• Biogenetic Law can be illustrated even with an example amongst plants. Seedlings of Acacia tree initially develop simple leaves which later transform into compound leaves. Another example is that modern-day oaks of the southern U.S.A. retain their foliage throughout the year whereas the oaks of the northern United States are deciduous and shed their leaves during winter.
• Dinosaurs. Extinct reptiles were of two types, lizard-hipped (order Saurischia) and bird-hipped (order ornithischian), originated about 230 million years back, both carnivorous and herbivorous, using four or two legs, brain small as compared to body, often with a long tail, smallest, with size of chicken (Compsogncithus) and the largest Brachiosaurus reaching 12.6 m and weighing 80 tonnes (some workers believe that the largest dinosaur was Apatosaurus = Brontosaurus that reached a length of 21 m having a weight of 30 tonnes). The teeth of carnivorous Tyrannosaurus were 16 cm long. Plesiosaur and Pilosaur are marine reptiles of the Jurassic and Cretaceous period.

The main factor responsible for the mass extinction of dinosaurs is suggested to be the hitting of the earth by a comet or a meteorite with rich amounts of metal- iridium. Another hypothesis, suggested for this mass extinction, is ‘global cooling’

• Pterosaurs are extinct flying reptiles of the Mesozoic age. Some of them had a wing span of 12 m.
• Synapsids/Synapsida. Mammal-like reptiles of carboniferous to Triassic (315-195 million years). Some of them gave rise to mammals (for example, Pelycosaurs and Therapsids). Synapsids were eliminated by dinosaurs.
• Convergence. Development of similarities between animals or plants of different groups resulting from evolution to similar habitats
• Latimeria (Coelocanth) is a lobe-finned (Cross- opterygian) fish in which fins arise from limb-like stalks and not directly from the body. It is the oldest living fish and once was believed to have become extinct about 70,000,000 years ago.

It is regarded as a “living fossil” as it has lived till today without undergoing any change in it. Other living fossils are Antedon (Feather star – echinoderm); Limulus (king crab -an arachnid); Cycas, etc.

• George Cuvier (1769 – 1832). Proposed the theory of catastrophism. Founder/father of modern palaeontology.
• Leonardo de Vinci ( 1452-1519). Father of palaeontology.
• The fossil-like impressions formed on certain rocks due to the deposition of minerals in rock crevices are called pseudofossils.
• The large-scale extinction of plants and animals within a short period is called mass extinction.
• Triassic. An epoch between 181 -225 million years ago with dry climate. Sandstone rocks are common. First mammals appeared.
• Palaccology. It deals with the study of ancient organisms and their environment.
• Hoofed animals like horses originated in the Eocene epoch in North America.
• Igneous rocks are devoid of fossils.
• A thorn of Bougainvillea and tendril in Cucurbita: Homologous

NEET Biology Evidence Of Evolution Multiple Choice Questions And Answers

Question 1. Homologous organs are:

1. Constructed on a similar plan of organization and embryonic development
2. Morphologically similar
3. Functionally identical
4. None of the above.

Answer: 1. Constructed on a similar plan of organization and embryonic development

Question 2. Analogous organs are those which are:

1. Structurally identical
2. Functionally similar
3. Both structurally and functionally resemble each other
4. Normally not functional.

Answer: 2. Functionally similar

Question 3. One of the following is not a vestigial organ:

1. Vermiform appendix
2. Wisdom tooth
3. Epiglottis
4. Scalp hair.

Answer: 3. Epiglottis

NEET Biology Chapter-Wise MCQs

Question 4. Biogenetic law was given by:

1. Hooke
2. Hymen
3. Haeckel
4. Darwin.

Answer: 3. Haeckel

Question 5. Vestigial organs are those:

1. Which were functional long ago but became non-functional now
2. Rudimentary in development
3. Degenerated now
4. Functional at present but reduced.

Answer: 1. Which were functional long ago but became non-functional now

Question 6. The earliest age in the geological record is:

1. Cenozoic
2. Precambrian
3. Palaeozoic
4. Mesozoic.

Answer: 2. Precambrian

Question 7. The Carboniferous period during which amphibians flourished occurred approximately:

1. 25 million years ago
2. 135 million years ago
3. 345 million years ago
4. 500 million years ago.

Answer: 3. 345 million years ago

Read and Learn More NEET Biology Multiple Choice Question and Answers

Question 8. The Permian period, during which most modem orders of insects appeared, occurred approximately:

1. 80 million years ago
2. 135 million years ago
3. 280 million years ago
4. 550 million years ago.

Answer: 3. 280 million years ago

Question 9. Macroevolution is the evolution of:

1. Macromolecules
2. Phylogenetic gaps
3. Major events occurring over geologic time
4. Large organisms.

Answer: 3. Major events occurring over geologic time

NEET Biology MCQs

Question 10. A structure, such as a feather that evolved in one context and was then used for a completely new function is a:

1. Mystery to macro evolutionists
2. Pre-adaptation
3. Macrostructure
4. Paedomorphs.

Answer: 2. Pre-adaptation

Question 11. Retention in an adult organism of juvenile features of its ancestor is known as:

1. Allometiy
2. Preadaptation
3. Macro-development
4. Paedomorphosis.

Answer: 4. Paedomorphosis.

Question 12. The wings of a bird and the forelegs of the horse are:

1. Analogous organs
2. Homologues
3. Vestigial structure
4. Phylogenetic structure.

Answer: 2. Homologues

Question 13. The pelvis and the leg bones of a snake are:

1. Analogous organs
2. Homologous structures
3. Vestigial structure
4. Phylogenetic structure.

Answer: 3. Vestigial structure

Question 14. The best test of the relatedness of the species is in the similarity of their:

1. Anatomy
2. DNA and proteins
3. Development
4. Courtship behaviour.

Answer: 2. DNA and proteins

Question 15. George Cuvier realized that the history of life is recorded in fossils and believed that replace of one species by another is caused by:

1. Massive number of mutations
2. The wrath of God
3. Extinctions due to catastrophes such as floods
4. Genetic inbreeding.

Answer: 3. Extinctions due to catastrophes such as floods

Question 16. Most fossils are found in:

1. Granite
2. Sedimentary rocks
3. Lava flows
4. Black soil.

Answer: 2. Sedimentary rocks

Question 17. Of all the living species that ever lived approximately how many have gone extinct?

1. Less than 1%
2. 20%
3. 60%
4. More than 99%.

Answer: 4. More than 99%.

Evidence Of Evolution MCQs

Question 18. For the origin of life, most important condition is:

1. H₂O
2. Carbon
3. Nitrogen
4. Free oxygen.

Answer: 1. H₂O

Question 19. The richest source of fossils is:

1. Basalt
2. Granite
3. Lava
4. Sedimentary rocks.

Answer: 4. Sedimentary rocks.

Question 20. The fossil animals which show characters of two different groups of animals are called as:

1. Extinct animals
2. Missing links
3. Vestigial animals
4. None of these.

Answer: 2. Missing links

Question 21. The Haeckel’s theory of recapitulation (Biogenetic Law) means that:

1. All organisms start as an egg
2. Life history of an animal reflects its evolutionary history
3. The progeny of an organism resembles its parents
4. Body parts once lost are regenerated.

Answer: 2. Life history of an animal reflects its evolutionary history

Question 22. Who established the precipitation method of blood tests for finding out the inter-relationship among different animals:

1. Haeckel
2. Foxon
3. L. De Vinci
4. H.F. Nuttal.

Answer: 4. H.F. Nuttal.

Evidence Of Evolution MCQs

Question 23. The connecting link between chordates and non- chordates is:

1. Peripatus
2. Balanoglossus
3. Sphenodon
4. Tachyglossus.

Answer: 2. Balanoglossus

Question 24. Which of the following would be easily fossilized?

1. External ear
2. Heart
3. Skin
4. Tooth.

Answer: 4. Tooth.

Question 25. Which of the following is a living fossil?

1. Euglena
2. Balanoglossus
3. Sycon
4. Limulus.

Answer: 4. Limulus.

Question 26. The archaeozoic era is considered as the age of:

1. Protista
2. Marine life
3. Amphibians
4. Fishes.

Answer: 1. Protista

NEET Evolution Mcqs With Answers

Question 27. Geologically one of the following eras is known as the ‘Age of Reptiles’ or the ‘Golden Age of Dinosaurs.’

1. Palaeozoic
2. Cenozoic
3. Mesozoic
4. Psychozoic.

Answer: 3. Mesozoic

Question 28. Appearance of teeth in the embryos of birds is an example of:

1. Vestigial organs
2. Ontogeny repeats phylogeny
3. Atavism
4. Speciation.

Answer: 2. Ontogeny repeats phylogeny

Question 29. Archaeopteryx is a missing link between:

1. Reptiles and birds
2. Reptiles and mammals
3. Birds and mammals
4. None of these.

Answer: 1. Reptiles and birds

Question 30. Dinosaurs are extinct:

1. Reptiles
2. Mammals
3. Birds
4. Amphibians.

Answer: 1. Reptiles

Question 31. Some of the important evidences of organic evolution are:

1. Occurrence of homologous and vestigial organs
2. Occurrence of analogous and vestigial organs
3. Occurrence of homologous and analogous organs
4. Occurrence of analogous organs only.

Answer: 1. Occurrence of homologous and vestigial organs

Question 32. Which of the following is not a vestigial organ in man?

1. Vermiform appendix
2. Plica semilunaris
3. Ear muscles
4. Epiglottis.

Answer: 4. Vermiform appendix

Question 33. Which of the following are the examples of analogous structures?

1. Leaves of a plant and cladodes of Ruscus
2. Wings of an insect and wings of bird
3. Hands of man, monkey and kangaroo
4. Both (1) and (2).

Answer: 4. Both (1) and (2).

Question 34. Blood groups A, B, AB and O occur in humans. The blood groups A and B are found in apes but not in monkeys. This suggests that:

1. Humans, monkeys and apes are related
2. Human beings are more closely related to apes
3. Human beings are more closely related to monkeys
4. Human beings are more closely related to apes than to monkeys.

Answer: 4. Human beings are more closely related to apes than to monkeys.

Question 35. Which one of the following is homologous?

1. Tails of scorpion, bird and monkey
2. Stings of bees, scorpions and fangs of monkey
3. Wings of butterflies, flying fish and bird
4. Paddles of whale, antis of man and wings of bat.

Answer: 4. Paddles of whale, antis of man and wings of bat.

Question 36. Which of the following illustrates palaeontological evidence in favour of organic evolution?

1. Archaeopteryx
2. Peppered moth
3. Duck-billed platypus
4. Darwin’s finches.

Answer: 1. Archaeopteryx

NEET Evolution Mcqs With Answers

Question 37. Evolutionary changes occurring in distantly related organisms are classified as:

1. Parallel evolution
2. Divergent evolution
3. Convergent evolution
4. Macro-evolution.

Answer: 3. Convergent evolution

Evolution MCQ For NEET Biology With Answers Question 38. Which of the following are homologous?

1. Passijlora tendril and Bougainvillea thorn
2. Insect wing and bird wing
3. Tortoiseshell and mollusc shell
4. Sweet potato and Ginger.

Answer: 1. Passijlora tendril and Bougainvillea thorn

Question 39. Which of the following is an extinct animal?

1. Protopterus
2. Columba
3. Archaeopteryx
4. Equus.

Answer: 3. Archaeopteryx

Question 40. A fossil is a:

1. Laboratory preserved animal
2. Dead animals of the past
3. Organic relic of the past
4. Stuffed animal of the past.

Answer: 3. Organic relic of the past

Question 41. Which of the following is the vestigial organ in man?

1. Vermiform appendix
2. Cervical vertebrae
3. Atlas vertebra
4. None of the above.

Answer: 1. Vermiform appendix

Question 42. Successful adaptation simply means:

1. An increase in fitness
2. Producing viable offspring
3. Evolving new characters
4. Moving to a new place.

Answer: 2. Producing viable offspring

Question 43. The law of superposition is associated with:

1. Vision in arthropods
2. Study of fossils
3. Inheritance
4. All of the above.

Answer: 1. Vision in arthropods

Evidence Of Evolution MCQs

Question 44. How many million years is the age of the oldest rock on earth

1. 3500
2. 20
3. 5000
4. 4500.

Answer: 1. 3500

MCQ Evidences for Evolution Question 45. Fossil of Archaeopteryx is placed in:

1. Moscow
2. New York
3. London
4. Vienna.

Answer: 3. London

Question 46. Which of the following is the most primitive mammal?

1. Spiny anteater
2. Scaly anteater
3. ArmadiWo
4. Seal.

Answer: 1. Spiny anteater

Question 47. Birds of Galapagos island were named as Darwin’s finches by:

1. Wallace
2. Darwin
3. Dr David Lach
4. Empedocles.

Answer: 3. Dr David Lach

Question 48. Which one of the following groups are not analogous organs?

1. Wings of birds and wings of butterflies
2. The eye of octopus and eye of mammals
3. Flippers of penguins and flippers of dolphin
4. Thoms of Bougainvillea and tendril of Cucurhila
5. Tuberous roots of sweet potato and stem tuber of potato

Answer: 2. The Eye of octopus and the eye of mammal

Question 49. Haeckel’s recapitulation theory was based on:

1. Germ layers
2. Germplasm
3. Genetic variation
4. None of the above.

Answer: 1. Germ layers

Question 50. The dating of rocks is done by calculating the ratio between which of the following pairs in the igneous rocks associated with sedimentary rocks:

1. Uranium—Lead
2. Potassium-Argon
3. Rubidium —Strontium
4. All the above.

Answer: 4. All the above.

NEET Biology Origin Of Life

Life– The inherent capacity of organisms to utilise outside materials for energy, growth and reproduction through chemical reactions. Life is regarded as a power that an organism possesses to maintain and produce itself.

Big Bang Theory – A single huge explosion

• The universe expanded → Temperature came down – Hydrogen and Helium formed later on.
• Gases condensed under gravitation and formed galaxies of the present-day universe.
• Earth formed almost 4.5 billion years ago.
• No atmosphere on early Earth.
• Water vapours, methane, CO₂, NH₃ released from molten mass covered the surface.

UV rays of the sun broke up.

Read and Learn More NEET Biology Notes

Oxygen is combined with ammonia, and methane to form water CO₂ and other simple molecules.  An ozone layer was formed.

Biopoiesis – the process by which life originated.

According to the Cosmozoic theory developed by Richter and supported by Thomson, Helmholtz and Arrhenius states that life (protoplasm) reached the earth in the form of spores or germs from outer space.

NEET Biology Origin Of Life

Theory of special creation—By Father Suarez.According, to it life was created by super supernatural power in 6 days.

• 1st day — he made heaven and earth
• 2nd day—separated sky from water
• 3rd day—dry land of plants
• 4th day—Sun, moon and stars
• 5th day—Birds and fishes
• 6th day—Land animals and human beings.

Theory of eternity of Life—By Richter (1865), Preyer (1880), Helmholtz (1884), Arrhenius (1908), Moyle (1950), Bonds (1952).

According to it, “Life is immortal”. Living matter has occurred in association with non-living matter from the beginning. Thus according to this theory, Life changes its form and it was never created.

• According to spontaneous generation theory, life originated from non-living things. It is estimated that life originated approximately 3,600 million years ago.
• Scientists supporting this theory— Aristotle, Van Helmont, William Harvey, Haeckel, Plato, Xanophanes, Thales, Anaximander, Empedocles
• Experimental support was provided by the Van Helmont experiment (1642).
• Abiogenesis was challenged on the basis of experiments by—Francisco Redi and Spallanzani. Finally disapproved by – Louis Pasteur.

Biogenesis. The fact that new life (nowadays) comes from any pre-existing life (Omne vivutn exvivo).

Theory Of Catastrophism. It states that there have been several creations each preceded by a catastrophe due to some geological disturbance. Each catastrophe completely destroyed life and each creation consisted of life quite different from that of the previous one. (George Cuvier and Orbigney)

NEET Biology Origin Of Life

Oparin-Haldane Theory (Naturalistic, Chemical or Heterotroph Theory)

A.I. Oparin and J.B.S. Haldane’s (1936)

The theory of the “Origin of Life” is widely acknowledged.

• Life emerged by chemical evolution, as the primordial Earth’s atmosphere was decreasing, characterized by elevated temperatures and the presence of gases like as nitrogen, hydrogen, methane, ammonia, and water vapor.
• As the temperature decreased, certain gasses condensed into liquids, while some liquids solidified. Free oxygen was nonexistent.
• Extensive polymers, including proteins, nucleic acids, and other molecules, were methodically synthesized by the influence of high-energy solar radiation, energy from alternative sources (likely isotopes on primordial Earth), and energy from electrical discharges.

The main steps of the theory are as follows:

• The first organisms were heterotrophs and anaerobic containing nucleoproteins which gave rise to autotrophs.
• Universe – 15-20 bya (Billion years ago.)
• Earth – 4.5/4.6 bya
• Life 4.0 bya (life appeared 500 mya after the formation of the earth)
• Non-cellular form of life may have originated 3 by (RNA + Protein + Polysaccharides)
• Cellular form of life 2000 mya(million years ago)
• Life was present on earth about 3.9 bya.
• Microfossils of cyanobacteria appeared 3.3 to 3.5 bya.
• Origin of Eukaryotic cell – 1.5 bya.

NEET Biology Origin Of Life Some Early Contributors To The Knowledge Of Evolution And Related Topics

Thales (624-548 B.C.): A Greek who proposed a theory that water (ocean) was the mother of all life.

Anaximander (611—547 B.C.): A Greek who thought that life arose from a mixture of water and earth and that landforms arose from aquatic types, particularly under the influence of the sun’s heat.

Heraclitus (510—450 B.C.): A Greek natural philosopher who stated that “struggle is life” and “all is flux”— thoughts that are basic to modem ideas in evolution.

Empedocles (495-435 B.C.): A Greek who theorized that living organisms were generated spontaneously from scattered materials, being attracted by love and hate.

“Founder of the concept of organic evolution”

Aristotle (384-322 B.C.): A Greek who theorized that in the living world, there was a gradual change from the simple and imperfect to the more complex and perfect, thus suggesting the idea of evolution.

Saint Augustine (353-439 A.D.): Saint Augustine interpreted the first chapter of Genesis, stating that in the beginning matter was created with the properties and potentialities to evolve into living and non-living worlds as we know them today.

Origin Of Life NEET Notes

Leonard de Vinci (1412-1529) “Father of Palaeontology”

Francisco Redi (1621-1697): An Italian who overthrew the theory of spontaneous generation, which stated that life arose from non-living materials spontaneously, by discovering that eggs and larvae of insects originated from previous living insects, rather than from non-living substances.

Carl Linnaeus: Father of taxonomy

Giovanni Avadeuna (1760) proposed Geological time scale

Thomas’ Robert Malthus (1766-1834): An English economist whose “Essay on Population,” published in 1798, inspired both Darwin and Wallace in their theories of evolution.

Charles Lyell (1797-1875): A Scottish geologist who laid the foundations for the science of earth structure in his Principles of Geology (1830-1832). He is considered an important contributor to the theory of organic evolution because of his influence on Charles Darwin and Alfred Russel Wallace.

Georges Cuvier (1769-1832): A Frenchman who supported the “Cataclysmic Theory,” in which he stated that there had been numerous creations, each of which was followed by a cataclysm (catastrophe) that destroyed it, and its place was taken by new forms. He is regarded as the founder/father of modern palaeontology

Georges de Buffon (1707-1788): A French naturalist who excluded the possibility that species have the ability to evolve (change). He probably was influenced by the ancient ideas revived during the Renaissance that discredited such a possibility.

Charles Bonnet (1720-1793): A Swiss naturalist and philosopher who first used the term “evolution” but not quite as we do today, and conceived that organisms could be arranged in a ladder-like, linear series.

Erasmus Darwin (1731-1802): An English evolutionist who was the grandfather of Charles Darwin. He believed that acquired traits could be transmitted to future generations and he may have influenced Lamarck, who had similar views.

Jean Baptiste Lamarck (1744-1829): A French biologist who was a student of organic evolution. He believed that environmental influences, and the effects of the use and disuse of body parts, were causes of evolutionary changes—a theory that laid the foundation for the “Theory of the Inheritance of Acquired Traits.”

Charles Darwin (1809-1882): Darwin, on a voyage around the world in the sailing ship HMS Beagle, indicated the descent of species by the development of varieties from common stocks. This process entailed a “struggle for existence,” which resulted in a “natural selection of species” and a “survival of the fittest.” He wrote The Origin of Species by Means of Natural Selection (1859).

Evolution And Origin Of Life NEET

Thomas Henry Huxley (1825-1895): An English surgeon who actively supported the views of Charles Darwin and assisted in promoting them extensively.

Alfred Russel Wallace (1823-1913): An Englishman who studied animal geography in the East Indies and concluded that the life of wild animals is a struggle for existence. He worked on the problem of the origin of species and arrived at conclusions concerning evolution that resembled those of Charles Darwin.

Louis Pasteur (1822-1895): A French microbiologist and chemist who proved that only living organisms such as bacteria and yeasts could cause fermentation. He proposed a method of preventing this process by heating to a temperature high enough to kill the germs. This method is known as pasteurization. Pasteur’s work ended the controversy regarding the possibility of the spontaneous generation of living organisms from non-living materials.

August Weismann (1834-1914): A German who distinguished between body cells and germ cells and proposed the “Theory of the Continuity of Germplasm from Generation to Generation” (1885). He opposed the idea that acquired traits might be transmitted.

Mendel’s work published (1866)—(Unknown to Darwin)

Henry Walter Bates (1825—1913). Proposed the concept of Batesian mimicry in 1862.

J Fritz Muller (1821—1897). Described in 1879 the Mullarian mimicry.

Scaler (1858) divided the earth into six realms for the distribution of birds,

Richard Leaky (1930). Modem Palaeontologist

Lewis and Leaky (1955) excavated fossil forms of Ramapithecus and Kenyapithecus

Evolution And Origin Of Life NEET

Lucy, C. Johanson (1981) American anthropologist discovered the complete skeleton of a 30-35 lakhs years female fossil hominid resembling Australopithecus

Eugene Dubois (1891) excavated a fossil of Homo erectus erectus

Laplace (1749—1827) proposed a nebular hypothesis to explain the origin of the solar system

Horowitz suggested that the earliest form of life was in the form of naked gene

Solar System. Sun along with orbiting planets and their satellites, the comets and asteroids constitute the solar system.

Origin Of The Solar System. The solar system originated from the gravitational contraction (condensation) of a solid cosmic cloud and dust called a nebula.

• During condensation, this cloud began to rotate due to the initial velocities of particles brought together. The condensation and spin continued. Thus most of the mass is concentrated near the centre. The flattened discs broke into a number of whirling masses of smaller clouds. The sun was formed from the central dense part.
• The sun started radiating energy. The other planets including the Earth were formed from the cooler, less dense outer regions almost in the same plane.

Cosmology. The study of heavenly bodies and the cosmos is called cosmology. The major theories of the origin of the universe are chemical origin and the Big Bang is the most accepted theory about the origin of the universe.

According to the Big Bang theory universe came into existence some 19 billion years ago by a thermonuclear explosion, called the Big Bang, or a dense entity will eventually contract again. Sun and its planets including Earth came into existence at the same time from a common source.

Theories Of Origin of Life NEET

Two Major Events Of The History Of Life Are:

1. Origin of life (biopoiesis).
2. Evolution of life.

The Major Theories Of the Origin Of Life Are:

1. Special Creation (Proposed by Father Saurez). This theory of special creation attributes the origin of life to a supernatural or vitalistic event at a particular time in the past. In other words, this theory believes in the creation of life by God.
2. Spontaneous Generation. (Concept held by Thales, Anaximander, Empedocles, plants). This theory discards abiogenesis and believes in the biogenetic origin of life i.e. life originates from pre-existing life-biogenesis.
3. Extraterrestrial or Cosmic Origin (Richter). This theory believes that life on Earth came from some other planet.
4. Terrestrial Origin or Abiogenic Origin (Oparin and Haldane). This theory states that life originates on Earth from collections of organic molecules that were produced early in the history of Earth.

This theory of terrestrial origin has a scientific base.

Role Of Catalytic Rna In Origin Of Life

1. The precursor of RNA of ciliate protozoan, Tetralymena was found to contain a self-splicing intron-containing 413 nucleotides which act as enzymes,
2. The very first living molecule might have been an RNA replicase that catalysed its own replication without the help of a protein.
3. Catalytic RNA are now considered to be molecular fossils.

• Biogeny. Origin of first life.
• Chemogeny. Origin and evolution of organic chemicals.
• Cognogeny Is The Evolution of different forms of living species.
• Biopoiesis. Origin of life.
• Biogenesis. Origin of life from life.
• Continental Drift Theory. Proposed by Wagener (1912) that about 250-200 million years there was a single land mass or continent which subsequently got split into continents as are known today.

Plate Tectonics:

John Tujo Wilson (1965) posited that the Earth’s outer surface comprises a mosaic of thick plates, both large and small, with a thickness of 70-100 km, which move in relation to one another, perhaps due to convection currents in the semi-molten mantle underneath.

• This movement is thought to have commenced approximately 2000 million years ago at a velocity of 6 centimeters per year. As a result, the continents are gradually rotating around the Earth. They have previously accomplished this four times.
• Francisco Redi denied the spontaneous creation of flies from decaying flesh in 1668.
• The energy radiated by the sun originates from nuclear fusion events.
• The initial kind consists of seas created from atmospheric water.
• Clay is optimal for the concentration of monomers. cs Cells with extended metabolic pathways were favored as primitive cells depleted the directly usable organic compounds.
• The most ancient fossilized cells resemble heterotrophic bacteria.
• The primordial autotrophs were likely anaerobic chemoautotrophs.
• The initial creatures to emit oxygen were likely cyanobacteria.

NEET Biology Origin Of Life Synopsis

The study of the universe or cosmos is called cosmology.

• Exobiology. Investigation of life on heavenly bodies other than the earth.
• The first organisms were — Heterotrophs. (Chemo- heterotrophs).
• Age of the earth – 4600 million yrs.
• Earliest prokaryotes – 3600 million yrs.
• The first formed compounds were probably – proteins and nucleic acids.
• Aristotle – The first proponent of the theory of abiogenesis.
• Origin of life – somewhere between 4.5 x 10⁸ to 3.6 x 10⁸ years ago.
• Origin of life – in water (probably sea).
• Gas is absent in the primitive atmosphere – free oxygen.

Gases present in the primitive atmosphere – N₂, CH₄, H₂, NH₃, H₂O_(g)

• Spontaneous generation (Abiogenesis) theory was proposed by Van Helmont (1577—1644) and the concept was supported by – Thales, Xanophanes, Empedocles, Plato, and Anaximander.
• Empedocles is regarded as the father of evolutionary concepts.
• Spontaneous generation theory challenged by – Fran-cisco Redi, Spallanzani and Pasteur Tyndall
• No life on the moon as there is no atmosphere on the moon because of the low escape velocity on the moon in which gas molecules easily cross.
• A.I. Oparin wrote a book “Genesis and Evolutionary Development of Life” and “Origin of Life” on Earth.
• “Evolution from Space” was written by Fred Hoyle.
• F.H.C. Crick (1982) published a book with the title ‘Life itself’.
• Cosmozoic theory of the origin of life was proposed by Richter and supported by Arrhenius.

Sydney W. Fox. discovered aqueous suspension of polymers’ spherical aggregates. He called the coacervates a microsphere.

• S.W Fox demonstrated that if a nearly dry mixture of amino acids is heated, polypeptide molecules are formed.
• Melwin Calvin (1951) strongly irradiated CO₂ and H₂ in a cyclotron to form formic acid, succinic acid and oxalic acid.
• J.B.C. Haldane bom on 5 Dec. 1897 in England. He shifted to India in July 1957 and settled in Bhubnashwer. He died on 1st Dec. 1964. He was a biologist, biochemist and geneticist.
• Louis Pasteur gave “Germ Theory of Disease and Immunology.”
• Progenote is regarded as early single-celled common ancestors of archaebacteria, eubacteria and eukaryotes. Thus, no present-day bacterial type can be regarded as an ancestor of eukaryotes.

NEET Biology Origin Of Life Of Earth

The genesis of life is associated with the inception of Earth, the Cosmos, and the Universe, which emerged 10 to 20 billion years ago due to the Big Bang (a thermonuclear explosion). A galaxy, such as the Milky Way, consists of billions of stars, including our Sun, together with its respective planets and satellites.

• The solar system comprises the sun, its planets, and their satellites.
• Earth is the third planet, characterized by its rocks, water, and atmosphere. It commenced as gaseous clouds of metallic and non-metallic atoms, subsequently condensing to create surface rocks, a boiling fluid core, and a gaseous atmosphere.
• Cosmology. Investigation of the cosmos.
• The oldest extant rock is 4.3 billion years old and contains no evidence of life.
• 3.9 billion-year-old rocks contained carbonates indicative of biological activities.
• The most ancient microfossils of Cyanobacteria date back 3.3 to 3.5 billion years.
• Francis Crick and Leslie Orgel suggested the notion of guided panspermia, which was substantiated by genetic code and the function of the metal molybdenum.

NEET Biology Origin Of Life Multiple Choice Questions And Answers

Question 1. Life has originated due to:

1. Creation by god
2. Effects of sunshine on mud
3. Spontaneous generation
4. None of the above.

Answer: 4. None of the above.

Question 2. On one of the planets life has originated approximately some:

1. Half billion years ago
2. One billion years ago
3. Two billion years ago
4. Four billion years ago.

Answer: 4. Four billion years ago.

Question 3. The branch of zoology dealing with similarities and differences between individuals related by descent is:

1. Evolution
2. Ecology
3. Eugenics
4. Genetics.

Answer: 1. Evolution

Origin Of Life MCQs For NEET

Question 4. The spontaneous generation theory was first refuted by:

1. S.L. Miller
2. F. Redi
3. L. Spallanzani
4. L. Pasteur.

Answer: 2. F. Redi

Questions  Question 5. According to one of the most widely accepted theories, the earth’s atmosphere before any life had originated on this planet consisted of a mixture of:

1. Hydrogen, carbon dioxide, ammonia, oxygen
2. Ozone, methane, oxygen and water vapour
3. Water vapour, hydrogen, ammonia and methane
4. Oxygen, hydrogen, methane and ammonia.

Answer: 3. Water vapour, hydrogen, ammonia and methane

Question 6. Pasteur is famous for

1. Rejection of spontaneous generation theory
2. Cell theory
3. Vaccination
4. Both (1) and (3).

Answer: 4. Both (1) and (3).

Question 7. There is no life on the moon as there is no:

1. Nitrogen
2. Oxygen
3. Carbon
4. Water.

Answer: 4. Water.

Question 8. In the field of discovery of the origin of life, Miller prepared:

1. Ammonia
2. Protein
3. Amino acids
4. Hydrogen.

Answer: 3. Amino acids

Read and Learn More NEET Biology Multiple Choice Question and Answers

Question 9. Large colloidal particles containing protein with water molecules are:

1. Microsphere
2. Coacervates
3. Spherules
4. All of the above.

Answer: 4. All of the above.

Origin Of Life MCQs For NEET

Question 10. The energy source for the origin of life came from:

1. Ultraviolet light
2. Electric charge
3. High temperature
4. All the above.

Answer: 4. All the above.

Question 11. Which of the following were first formed?

1. Eobionts
2. Coacervates
3. Genes
4. Cells.

Answer: 2. Coacervates

Question 12. The first organisms were:

1. Autotrophs
2. Hctcrotrophs
3. Saprotrophs
4. None of the above.

Answer: 2. Hctcrotrophs

Question 13. Which of the scientists is associated with the naturalistic theory of the origin of life?

1. Pasteur
2. Oparin
3. Miller
4. Redi.

Answer: 2. Oparin

Origin Of Life MCQs For NEET

Question 14. Which is the most accepted theory of the origin of life

1. Theory of special creation
2. Theory of spontaneous generation
3. Oparin-Haldane theory
4. Theory of eternity of life.

Answer: 3. Oparin-Haldane theory

Question 15. Miller synthesized simple amino acids from:

1. H₂, NH₃, HCN and O₂
2. H₂, NH₃, CH₄ and water vapours
3. NH₃, CH₄, HCN
4. H₂, O₂, N₂ and H₂O.

Answer: 2. H₂, NH₃, CH₄ and water vapours

Question 16. The theory of special creation envisages the role of:

1. Chemical evolution
2. Abiogenesis
3. Divine intervention
4. Physical accretion.

Answer: 3. Divine intervention

Question 17. The theory of catastrophism considers one of the following as its mainstay:

1. That the earth was periodically devastated by catastrophes causing drastic changes
2. Catastrophic events eliminate life form
3. Does not support the theory of special creation
4. Elimination is the end of all events.

Answer: 1. That the earth was periodically devastated by catastrophes causing drastic changes

NEET Biology Origin Of Life Questions

Question 18. The branch of Biology dealing with the study of the distribution of organisms in different geographic regions is:

1. Biogeography
2. Ecology
3. Eugenics
4. Genetics.

Answer: 1. Biogeography

Question 19. ‘Origin of Life’ hypothesis was initiated by:

1. Mendel
2. Darwin
3. Oparin
4. Pasteur.

Answer: 3. Oparin

Question 20. The atmosphere of the earth at the time of the origin of life was:

1. Oxidising
2. Reducing
3. Neither oxidising nor reducing
4. Having very low temperature.

Answer: 2. Reducing

Question 21. According to Oparin, the universe was a vast dense cloud of hot gases:

1. 7-10 billion years ago
2. 5-7 billion years ago
3. 6-8 billion years ago
4. 10-15 billion years ago.

Answer: 2. 5-7 billion years ago

Question 22. Which one of the gases was absent at the time of the origin of life?

1. Oxygen
2. Methane
3. Hydrogen
4. Ammonia.

Answer: 1. Oxygen

NEET Biology Origin Of Life Questions

Question 23. The theory of spontaneous generation of life explains that:

1. God created all life
2. Life originated de novo
3. Scientists created life in laboratories
4. Life begets life.

Answer: 2. Life originated de novo

Question 24. Cuvier suggested which of the following theories:

1. Mutation
2. Theory of special creation
3. Theory of catastrophism
4. Natural selection.

Answer: 3. Theory of catastrophism

Question 25. Who is regarded as the father of evolutionary concepts?

1. Linnaeus
2. Darwin
3. Lamarck
4. Empedocles.

Answer: 4. Empedocles.

Question 26. People who believed in the theory of “Spontaneous creation” assumed that:

1. Organisms arise only from other organisms
2. Organisms arise spontaneously
3. Organisms arise from water
4. Organisms arise spontaneously and also from similar organisms.

Answer: 2. Organisms arise spontaneously

Question 27. The principle of sterilization is based upon experiments carried by:

1. I.A. Oparin
2. L.Pasteur
3. F. Redi
4. C. Spallanzani.

Answer: 2. L.Pasteur

NEET Biology Origin Of Life Questions

Question 28. The idea that the egg of Eve or the sperm of Adam contained minute human was part of:

1. Theory of biogenesis
2. Concept of epigenesis
3. Theory of preformation
4. Theory of recapitulation.

Answer: 3. Theory of preformation

Question 29. The first organisms to appear on Earth were more like plants because:

1. Plants are similar
2. Plants are more
3. Plants do photosynthesis
4. None of these.

Answer: 3. Plants do photosynthesis

Question 30. Who of the following proved that life originated from simple amino acids:

1. Muller
2. Miller and Fisher
3. Oparin
4. de Vries.

Answer: 2. Miller and Fisher

Question 31. In Stanley Miller’s classic experiment:

1. Nucleic acids were formed
2. Ultraviolet radiation was used
3. Oxygen was one of the starting ingredients
4. Amino acids were formed.

Answer: 4. Amino acids were formed.

NEET Previous Year Questions On Origin Of Life

Question 32. Mitochondria contain particles made up of about 100 polypeptide molecules of several different types. The particles catalyze the production of acetyl Co A and carbon dioxide from pyruvate. When disassembled into the component polypeptides, no enzymatic activity is seen. These particles are examples of:

1. Spontaneous generation
2. Emergent properties of systems
3. The origin of life
4. Informational macromolecules.

Answer: 2. Emergent properties of systems

Question 33. Which of the following is not true of the microspheres studied by Sydney Fox?

1. They are formed by the addition of water to proteinoids
2. They are of uniform size, about 2μm in diameter.
3. Microspheres grow and bud off new microspheres
4. They are bounded by a layer of lipid
5. The boundary of a microsphere shows selective permeability.

Answer: 4. The boundary of a microsphere shows selective permeability.

Question 34. Coacervates maintained their entity with the help of

1. Lipid membrane
2. Protein membrane
3. Lipoprotein membrane
4. Glycoprotein membrane.

Answer: 1. Lipid membrane

Question 35. Nucleotides, porphyrins, polypeptides and other bio-chemicals developed non-enzymatically in early broth due to:

1. Oxygen free atmosphere
2. High temperature
3. Irradiated environment
4. All the above.

Answer: 4. All the above.

Question 36. Archaespheroides barbertonesis is:

1. Most primitive living prokaryote
2. Cambrian trilobite
3. Precambrian cyanobacterium
4. First eukaryote.

Answer: 3. Precambrian cyanobacterium

Question 37. First eukaryotes evolved through:

1. Mutation in prokaryotes
2. Either mutation in prokaryotes or symbiotic association of different prokaryotes
3. Symbiotic association of different prokaryotes
4. None of the above.

Answer: 2. Either mutation in prokaryotes or symbiotic association of different prokaryotes

Question 38. The modem theory of the origin of life is related to:

1. A.I. Oparin
2. Cuvier
3. Epicurus
4. Lamarck.

Answer: 1. A.I. Oparin

Question 39. The primitive atmosphere of Earth was devoid of:

1. Ammonia
2. Free oxygen
3. Methane
4. Cyanamide.

Answer: 2. Free oxygen

NEET Previous Year Questions On Origin Of Life

Question 40. According to cosmozoic theory, life comes on Earth from other planets in space in the form of:

1. Spores
2. Seeds
3. Gametes
4. All the above.

Answer: 1. Spores

Question 41. The scientists related to the theory of spontaneous generation and experiments with swan-necked flasks are:

1. Van Helmont
2. Louis Pasteur
3. Miller
4. Haeckel.

Answer: 2. Louis Pasteur

Question 42. Under certain conditions scientists have obtained cell-like structures but not the true organisation of a cell. These are referred to as:

1. Microbes
2. Coacervates
3. Eobionts
4. Protists.

Answer: 2. Coacervates

Question 43. The theory of Pangenesis is related to:

1. Darwin
2. de Vries
3. Cuvier
4. Aristotle.

Answer: 1. Darwin

Question 44. Anaximander believed in the origin of life through:

1. Special creation
2. Spontaneous generation
3. Panspermia
4. Biogenesis.

Answer: 2. Spontaneous generation

Question 45. Spallanzani kept boiled nutrition broth indefinitely in:

1. Covered jars
2. Uncovered jars
3. Sealed flasks
4. Swan-necked flasks.

Answer: 3. Sealed flasks

Question 46. The term proto biogenesis is used for the theory of:

1. Special creation
2. Biochemical origin
3. Panspermia
4. Spontaneous generation.

Answer: 2. Biochemical origin

NEET Previous Year Questions On Origin Of Life

Question 47. The correct sequence of origin of life is:

1. Coacervate, biomolecule, autotroph and heterotroph
2. Biomolecule, coacervate, autotroph and heterotroph
3. Coacervate, autotroph, biomolecule and heterotroph
4. None of the above.

Answer: 4. None of the above.

Question 48. One of the following appeared on the earth with the coming of the plants, and was absent in the past:

1. Carbon dioxide
2. Methane
3. Ammonia
4. Oxygen.

Answer: 4. Oxygen.

Question 49. Conditions of primitive earth were recreated in the laboratory and amino acids and bases were synthesized abiotically by:

1. Miller and Urey
2. Oparin A.I. and Haldane, J.B.S.
3. Oparin and Sydney fox
4. Louis Pasteur.

Answer: 1. Miller and Urey

Question 50. The theory that living organisms on the earth came from outer space is based on the study of:

1. Igneous
2. Sedimentary rocks
3. Meteorites
4. Moon soil.

Answer: 3. Meteorites

Theories Of Origin Of Life NEET Questions

Question 51. Life cannot originate from inorganic materials at present because of:

1. High degree of environmental pollution
2. A very high amount of oxygen in the atmosphere
3. Very low atmospheric temperature
4. Absence of raw material.

Answer: 2. A very high amount of oxygen in the atmosphere

Origin and Evolution of Life MCQs Test Question 52. Choose the correct sequence during the formation of chemicals on early Earth:

1. Ammonia, water, nucleic acids and proteins
2. Ammonia, proteins, carbohydrates and nucleic acids
3. Ammonia, nucleic acids, proteins and carbohydrates
4. Proteins, carbohydrates, water and nucleic acids.

Answer: 2. Ammonia, proteins, carbohydrates and nucleic acids

Question 53. “Origin of Life was written by:

1. S.L. Miller
2. A.I. Oparin
3. De Vries
4. Charles Darwin.

Answer: 1. S.L. Miller

Question 54. Origin of life took place in/on:

1. Water
2. Air
3. Mountains
4. Land.

Answer: 2. Air

Question 55. Panspermia are:

1. Yeast
2. Life spores
3. Bacteria
4. Viruses.

Answer: 3. Bacteria

Question 56. Organic compounds first evolved on earth and required for the origin of life were:

1. Urea and amino acids
2. Proteins and nucleic acids
3. Proteins and amino acids
4. Urea and nucleic acids.

Answer: 2. Proteins and nucleic acids

Question 57. “All plants and animals were created and perpetrated themselves without any change”, is the theory of:

1. Genesis
2. Panspermia
3. Abiogenesis
4. Biogenesis.

Answer: 4. Biogenesis.

Question 58. Origin of life occurred in:

1. Air
2. Soil
3. Mountains
4. Water.

Answer: 4. Water.

Question 59. The most important compounds for the origin of life were:

1. Nucleotides
2. Nucleic acids
3. Protein
4. Amino acids.

Answer: 1. Nucleotides

Theories Of Origin Of Life NEET Questions

Question 60. Earth originated in the past:

1. 1.6 billion yrs.
2. 4.6 billion yrs.
3. 8.6 billion yrs.
4. 86 million yrs.

Answer: 3. 8.6 billion yrs.