NEET 2021 Biology Solved Paper

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Q1. Erythropoietin hormone which stimulates R.B.C. formation is produced by:
Correct Answer: (c)
JG cells of kidney produce Erythropoietin.
Q2. Match List-I with List-II.

List-IList-II
(a) Vaults(i) Entry of sperm through Cervix is blocked
(b) IUDs(ii) Removal of Vas deferens
(c) Vasectomy(iii) Phagocytosis of sperms within the Uterus
(d) Tubectomy(iv) Removal of fallopian tube
Correct Answer: (a)
Vaults (Block cervix), IUDs (Phagocytosis), Vasectomy (Vas deferens), Tubectomy (Fallopian tube).
Q3. DNA strands on a gel stained with ethidium bromide when viewed under UV radiation, appear as
Correct Answer: (a)
Ethidium bromide stains DNA and fluoresces bright orange under UV light.
Q4. Which one of the following is an example of Hormone releasing IUD?
Correct Answer: (a)
LNG 20 is a hormone releasing IUD.
Q5. Persons with 'AB' blood group are called as "Universal recipients". This is due to :
Correct Answer: (c)
AB blood group has no antibodies (Anti-A or Anti-B) in plasma.
Q6. The factor that leads to Founder effect in a population is :
Correct Answer: (c)
Genetic drift (change in allele frequency by chance) causes Founder effect.
Q7. Assertion (A): A person goes to high altitude and experiences 'altitude sickness' with symptoms like breathing difficulty and heart palpitations.
Reason (R): Due to low atmospheric pressure at high altitude, the body does not get sufficient oxygen.
In the light of the above statements, choose the correct answer from the options given below
Correct Answer: (d)
Both are true and R explains A.
Q8. Match List-I with List-II

List -IList -II
(a) Filariasis(i) Haemophilus influenzae
(b) Amoebiasis(ii) Trichophyton
(c) Pneumonia(iii) Wuchereria bancrofti
(d) Ringworm(iv) Entamoeba histolytica
Correct Answer: (a)
Filariasis (Wuchereria), Amoebiasis (Entamoeba), Pneumonia (Haemophilus), Ringworm (Trichophyton).
Q9. The partial pressures (in mm Hg) of oxygen (O₂) and carbon dioxide (CO₂) at alveoli (the site of diffusion) are:
Correct Answer: (d)
Alveoli: pO2=104, pCO2=40.
Q10. In some members of which of the following pairs of families, pollen grains retain their viability for months after release?
Correct Answer: (c)
Solanaceae, Rosaceae, Leguminosae have long pollen viability.
Q11. The site of perception of light in plants during photoperiodism is
Correct Answer: (c)
The leaves are the site of perception of light/dark duration (photoperiodism).
Q12. DNA fingerprinting involves identifying differences in some specific regions in DNA sequence, called as
Correct Answer: (a)
DNA fingerprinting identifies differences in Repetitive DNA.
Q13. Mutations in plant cells can be induced by:
Correct Answer: (b)
Gamma rays are ionizing radiations used to induce mutations.
Q14. The production of gametes by the parents, formation of zygotes, the F₁ and F₂ plants, can be understood from a diagram called :
Correct Answer: (b)
A Punnett square is a graphical representation to calculate the probability of all possible genotypes of offspring in a genetic cross.
Q15. Dobson units are used to measure thickness of:
Correct Answer: (b)
Dobson units measure Ozone.
Q16. Which of the following secretes the hormone, relaxin, during the later phase of pregnancy?
Correct Answer: (a)
Corpus luteum secretes Relaxin.
Q17. Identify the types of cell junctions that help to stop the leakage of the substances across a tissue and facilitation of communication with neighbouring cells via rapid transfer of ions and molecules.
Correct Answer: (a)
Tight (Stop leakage), Gap (Communication).
Q18. Which of the following is an incorrect statement?
Correct Answer: (d)
A mature sieve tube element possesses a peripheral cytoplasm and a large central vacuole but lacks a nucleus.
Q19. Inspite of interspecific competition in nature, which mechanism the competing species might have evolved for their survival?
Correct Answer: (d)
Resource partitioning allows competing species to survive by using different resources or feeding times.
Q20. Which of the following are not secondary metabolites in plants?
Correct Answer: (a)
Amino acids and glucose are primary metabolites as they have identifiable functions and play known roles in normal physiological processes.
Q21. During the process of gene amplification using PCR, if very high temperature is not maintained in the beginning, then which of the following steps of PCR will be affected first?
Correct Answer: (b)
Denaturation requires high temperature.
Q22. Match the following:

List-IList-II
(a) Physalia(i) Pearl oyster
(b) Limulus(ii) Portuguese Man of War
(c) Ancylostoma(iii) Living fossil
(d) Pinctada(iv) Hookworm
Correct Answer: (b)
Physalia (Man of War), Limulus (Living fossil), Ancylostoma (Hookworm), Pinctada (Pearl oyster).
Q23. Match List-I with List-II.

List-IList-II
(a) Cristae(i) Primary constriction in chromosome
(b) Thylakoids(ii) Disc-shaped sacs in Golgi apparatus
(c) Centromere(iii) Infoldings in mitochondria
(d) Cisternae(iv) Flattened membranous sacs in stroma of plastids
Correct Answer: (b)
Cristae (Mitochondria), Thylakoids (Plastids), Centromere (Chromosome), Cisternae (Golgi).
Q24. Match List-I with List-II.

List - IList - II
(a) Cells with active cell division capacity(i) Vascular tissues
(b) Tissue having all cells similar in structure and function(ii) Meristematic tissue
(c) Tissue having different types of cells(iii) Sclereids
(d) Dead cells with highly thickened walls and narrow lumen(iv) Simple tissue
Correct Answer: (d)
Active division (Meristematic), Similar cells (Simple), Different cells (Vascular), Dead cells (Sclereids).
Q25. The fruit fly has 8 chromosomes (2n) in each cell. During interphase of Mitosis if the number of chromosomes at G₁ phase is 8, what would be the number of chromosomes after S phase?
Correct Answer: (d)
Chromosome number remains 8 (DNA content doubles).
Q26. Which of the following stages of meiosis involves division of centromere?
Correct Answer: (b)
Division of centromere occurs during Anaphase II.
Q27. Match List-I with List-II.

List-IList-II
(a) S Phase(i) Proteins are synthesized
(b) G2 Phase(ii) Inactive phase
(c) Quiescent stage(iii) Interval between mitosis and initiation of DNA replication
(d) G1 Phase(iv) DNA replication
Correct Answer: (b)
S Phase (DNA replication), G2 (Proteins), Quiescent (Inactive), G1 (Interval).
Q28. Statement I: The codon 'AUG' codes for methionine and phenylalanine.
Statement II: 'AAA' and 'AAG' both codons code for the amino acid lysine.
In the light of the above statements, choose the correct answer from the options given below.
Correct Answer: (c)
AUG codes only for Methionine. AAA/AAG code for Lysine.
Q29. What is the role of RNA polymerase III in the process of transcription in eukaryotes?
Correct Answer: (a)
RNA Pol III transcribes tRNA, 5S rRNA and snRNAs.
Q30. If Adenine makes 30% of the DNA molecule, what will be the percentage of Thymine, Guanine and Cytosine in it?
Correct Answer: (b)
T=A=30%, G=C=20%.
Q31. Which stage of meiotic prophase shows terminalisation of chiasmata as its distinctive feature?
Correct Answer: (b)
Terminalisation occurs in Diakinesis.
Q32. During muscular contraction which of the following events occur?
(a) 'H' zone disappears
(b) 'A' band widens
(c) 'I' band reduces
(d) Myosine hydrolyzes ATP, releasing the ADP and Pi
(e) Z-lines attached to actins are pulled inwards.
Choose the correct answer from the options given below.
Correct Answer: (a)
A-band width remains constant. Other events (H zone disappears, I band reduces, ATP hydrolysis, Z-line pulled) occur.
Q33. Which of the following is not a step in Multiple Ovulation Embryo Transfer Technology (MOET)?
Correct Answer: (d)
MOET uses FSH-like hormone, not LH.
Q34. Which of the following plants is monoecious?
Correct Answer: (a)
Chara is monoecious.
Q35. Match List-I with List-II.

List-IList-II
(a) Protein(i) C = C double bonds
(b) Unsaturated fatty acid(ii) Phosphodiester bonds
(c) Nucleic acid(iii) Glycosidic bonds
(d) Polysaccharide(iv) Peptide bonds
Correct Answer: (d)
Protein (Peptide), Unsaturated fat (C=C), Nucleic acid (Phosphodiester), Polysaccharide (Glycosidic).
Q36. Which enzyme is responsible for the conversion of inactive fibrinogens to fibrins?
Correct Answer: (d)
Thrombin converts fibrinogen to fibrin.
Q37. The centriole undergoes duplication during:
Correct Answer: (d)
Centriole duplicates in S-phase.
Q38. Which of the following algae contains mannitol as reserve food material?
Correct Answer: (d)
Ectocarpus is a brown alga (Phaeophyceae) which stores mannitol.
Q39. The amount of nutrients, such as carbon, nitrogen, phosphorus and calcium present in the soil at any given time, is referred as :
Correct Answer: (b)
Standing state refers to the amount of inorganic nutrients in the soil.
Q40. Match Column-I with Column-II.

Column-IColumn-II
(a) Nitrococcus(i) Denitrification
(b) Rhizobium(ii) Conversion of ammonia to nitrite
(c) Thiobacillus(iii) Conversion of nitrite to nitrate
(d) Nitrobacter(iv) Conversion of atmospheric nitrogen to ammonia
Correct Answer: (d)
Nitrococcus (Ammonia to Nitrite), Rhizobium (N2 Fixation), Thiobacillus (Denitrification), Nitrobacter (Nitrite to Nitrate).
Q41. Following are the statements with reference to 'lipids'.
(a) Lipids having only single bonds are called unsaturated fatty acids
(b) Lecithin is a phospholipid.
(c) Trihydroxy propane is glycerol.
(d) Palmitic acid has 20 carbon atoms including carboxyl carbon.
(e) Arachidonic acid has 16 carbon atoms.
Choose the correct answer from the options given below.
Correct Answer: (b)
(b) and (c) are correct. (a) is Saturated. (d) is 16C. (e) is 20C.
Q42. Sphincter of oddi is present at:
Correct Answer: (a)
Sphincter of Oddi is at the hepato-pancreatic duct junction.
Q43. Which of the following algae produce Carrageen?
Correct Answer: (b)
Carrageen is produced by Red algae.
Q44. Plants follow different pathways in response to environment or phases of life to form different kinds of structures. This ability is called
Correct Answer: (b)
This phenomenon is called Plasticity (e.g., heterophylly).
Q45. The first stable product of CO₂ fixation in Sorghum is
Correct Answer: (a)
Sorghum is a C4 plant. The first stable product of CO2 fixation is Oxaloacetic acid (OAA).
Q46. Which of the following statements is correct ?
Correct Answer: (a)
Fusion of protoplasms is Plasmogamy.
Q47. Complete the flow chart on central dogma.
(a) DNA ⟶ (b) ⟶ mRNA ⟶ (c) ⟶ (d)
Correct Answer: (b)
DNA replicates (a), transcribes to mRNA (b), translates to Protein (c, d).
Q48. In the equation GPP – R = NPP
R represents :
Correct Answer: (c)
In the equation GPP – R = NPP, R refers to respiratory loss. GPP is gross primary productivity and NPP is net primary productivity.
Q49. With regard to insulin choose correct options.
(a) C-peptide is not present in mature insulin.
(b) The insulin produced by rDNA technology has C-peptide.
(c) The pro-insulin has C-peptide
(d) A-peptide and B-peptide of insulin are interconnected by disulphide bridges.
Choose the correct answer from the options given below
Correct Answer: (c)
(a), (c), (d) are correct. (b) is incorrect.
Q50. Match List-I with List-II

List-IList-II
(a) Protoplast fusion(i) Totipotency
(b) Plant tissue culture(ii) Pomato
(c) Meristem culture(iii) Somaclones
(d) Micropropagation(iv) Virus free plants
Correct Answer: (a)
Protoplast fusion (Pomato), PTC (Totipotency), Meristem (Virus free), Micropropagation (Somaclones).
Q51. Receptors for sperm binding in mammals are present on :
Correct Answer: (c)
Zona pellucida contains sperm receptors.
Q52. Read the following statements
(a) Metagenesis is observed in Helminths.
(b) Echinoderms are triploblastic and coelomate animals.
(c) Round worms have organ-system level of body organization.
(d) Comb plates present in ctenophores help in digestion.
(e) Water vascular system is characteristic of Echinoderms.
Choose the correct answer from the options given below.
Correct Answer: (c)
(b), (c) and (e) are correct statements.
Q53. Which of the following statements is incorrect?
Correct Answer: (c)
Cyclic photophosphorylation involves only PS I.
Q54. Which one of the following statements about Histones is wrong?
Correct Answer: (a)
Histones are basic proteins, not acidic.
Q55. Which of the following statements is not correct?
Correct Answer: (a)
The pyramid of biomass in sea is generally inverted because the biomass of fishes exceeds that of phytoplankton.
Q56. Amensalism can be represented as:
Correct Answer: (d)
Amensalism is an interaction between two organisms of different species in which one species inhibits the growth of other species by secreting certain chemicals. The first species is neither get benefited nor harmed (- 0).
Q57. Identify the incorrect pair
Correct Answer: (c)
Ricin is a toxin, not a drug.
Q58. Match List-I with List-II.

List-IList-II
(a) Cohesion(i) More attraction in liquid phase
(b) Adhesion(ii) Mutual attraction among water molecules
(c) Surface tension(iii) Water loss in liquid phase
(d) Guttation(iv) Attraction towards polar surfaces
Correct Answer: (d)
Cohesion (Mutual attraction), Adhesion (Polar surfaces), Surface tension (Liquid phase), Guttation (Water loss).
Q59. The term used for transfer of pollen grains from anthers of one plant to stigma of a different plant which, during pollination, brings genetically different types of pollen grains to stigma, is :
Correct Answer: (d)
Xenogamy involves the transfer of pollen grains to a genetically different plant.
Q60. Which one of the following belongs to the family Muscidae?
Correct Answer: (c)
House fly belongs to Muscidae.
Q61. Now a days it is possible to detect the mutated gene causing cancer by allowing radioactive probe to hybridise its complimentary DNA in a clone of cells, followed by its detection using autoradiography because :
Correct Answer: (b)
The probe will not bind to the mutated gene due to mismatch, hence it won't appear on film.
Q62. Gemmae are present in
Correct Answer: (c)
Gemmae are asexual buds found in Liverworts (e.g. Marchantia).
Q63. Which of the following is not an application of PCR (Polymerase Chain Reaction)?
Correct Answer: (b)
PCR is used for gene amplification, detection of mutations, and diagnosis. Protein purification is not an application of PCR.
Q64. During the purification process for recombinant DNA technology, addition of chilled ethanol precipitates out :
Correct Answer: (a)
Chilled ethanol is used to precipitate DNA.
Q65. Which of the following is a correct sequence of steps in a PCR (Polymerase Chain Reaction)?
Correct Answer: (d)
Correct sequence: Denaturation -> Annealing -> Extension.
Q66. Plasmid pBR322 has PstI restriction enzyme site within gene ampR that confers ampicillin resistance. If this enzyme is used for inserting a gene for β-galactoside production and the recombinant plasmid is inserted in an E.coli strain
Correct Answer: (d)
Insertional inactivation of the ampR gene results in the loss of ampicillin resistance.
Q67. Which of these is not an important component of initiation of parturition in humans ?
Correct Answer: (c)
Prolactin is for lactation, not parturition initiation.
Q68. Which is the "Only enzyme" that has "Capability" to catalyse Initiation, Elongation and Termination in the process of transcription in prokaryotes?
Correct Answer: (a)
DNA dependent RNA polymerase catalyses all steps in prokaryotes.
Q69. In a cross between a male and female, both heterozygous for sickle cell anaemia gene, what percentage of the progeny will be diseased?
Correct Answer: (b)
Heterozygous cross yields 25% diseased (homozygous recessive).
Q70. Match List-I with List-II.

List-IList-II
(a) Lenticels(i) Phellogen
(b) Cork cambium(ii) Suberin deposition
(c) Secondary cortex(iii) Exchange of gases
(d) Cork(iv) Phelloderm
Correct Answer: (a)
Lenticels (Exchange), Cork cambium (Phellogen), Sec. cortex (Phelloderm), Cork (Suberin).
Q71. For effective treatment of the disease, early diagnosis and understanding its pathophysiology is very important. Which of the following molecular diagnostic techniques is very useful for early detection?
Correct Answer: (b)
ELISA is used for early diagnosis.
Q72. Select the correct pair.
Correct Answer: (b)
Cells of medullary rays form Interfascicular cambium.
Q73. Match List - I with List - II

List - IList - II
(a) Adaptive radiation(i) Selection of resistant varieties due to excessive use of herbicides and pesticides
(b) Convergent evolution(ii) Bones of forelimbs in Man and Whale
(c) Divergent evolution(iii) Wings of Butterfly and Bird
(d) Evolution by anthropogenic action(iv) Darwin Finches
Correct Answer: (a)
Adaptive radiation (Finches), Convergent (Wings), Divergent (Forelimbs), Anthropogenic (Resistance).
Q74. Chronic auto immune disorder affecting neuro muscular junction leading to fatigue, weakening and paralysis of skeletal muscle is called as:
Correct Answer: (b)
Myasthenia gravis is the autoimmune disorder affecting NMJ.
Q75. The organelles that are included in the endomembrane system are
Correct Answer: (a)
Endomembrane system includes ER, Golgi, Lysosomes, Vacuoles.
Q76. Which of the following is not an objective of Biofortification in crops?
Correct Answer: (a)
Biofortification targets nutrient quality, not disease resistance.
Q77. Match List-I with List-II

List -IList -II
(a) Scapula(i) Cartilaginous joints
(b) Cranium(ii) Flat bone
(c) Sternum(iii) Fibrous joints
(d) Vertebral column(iv) Triangular flat bone
Correct Answer: (c)
Scapula (Triangular), Cranium (Fibrous joints), Sternum (Flat bone), Vertebral (Cartilaginous).
Q78. Genera like Selaginella and Salvinia produce two kinds of spores. Such plants are known as:
Correct Answer: (c)
They produce macro and micro spores, hence called Heterosporous.
Q79. Which of the following statements is incorrect?
Correct Answer: (a)
NADH gives 3 ATP, FADH2 gives 2 ATP. The statement reverses this.
Q80. Diadelphous stamens are found in
Correct Answer: (b)
Pea (Fabaceae) has diadelphous stamens.
Q81. Which of the following RNAs is not required for the synthesis of protein?
Correct Answer: (c)
siRNA is not directly involved in translation mechanism.
Q82. Which of the following characteristics is incorrect with respect to cockroach?
Correct Answer: (d)
Gastric caeca are at junction of foregut and midgut.
Q83. Identify the correct statement.
Correct Answer: (a)
Rho factor is required for termination of transcription.
Q84. A typical angiosperm embryo sac at maturity is:
Correct Answer: (d)
A typical angiosperm embryo sac is 8-nucleate and 7-celled.
Q85. In the exponential growth equation Nₜ = N₀eʳᵗ, e represents
Correct Answer: (b)
e is the base of natural logarithms.
Q86. A specific recognition sequence identified by endonucleases to make cuts at specific positions within the DNA is:
Correct Answer: (b)
Restriction enzymes cut at Palindromic sequences.
Q87. When gene targetting involving gene amplification is attempted in an individual's tissue to treat disease, it is known as :
Correct Answer: (a)
This process is called Gene therapy.
Q88. Which one of the following organisms bears hollow and pneumatic long bones?
Correct Answer: (d)
Neophron (Bird) has pneumatic bones.
Q89. Match List-I with List - II

List - IList - II
(a) Allen's Rule(i) Kangaroo rat
(b) Physiological adaptation(ii) Desert lizard
(c) Behavioural adaptation(iii) Marine fish at depth
(d) Biochemical adaptation(iv) Polar seal
Correct Answer: (c)
Allen's (Polar seal), Physiological (Kangaroo rat), Behavioural (Desert lizard), Biochemical (Marine fish).
Q90. When the centromere is situated in the middle of two equal arms of chromosomes, the chromosome is referred as :
Correct Answer: (d)
Middle centromere refers to Metacentric chromosome.
Q91. Match List - I with List - II

List -IList -II
(a) Metamerism(i) Coelenterata
(b) Canal system(ii) Ctenophora
(c) Comb plates(iii) Annelida
(d) Cnidoblasts(iv) Porifera
Correct Answer: (c)
Metamerism (Annelida), Canal system (Porifera), Comb plates (Ctenophora), Cnidoblasts (Coelenterata).
Q92. The Adenosine deaminase deficiency results into
Correct Answer: (d)
ADA deficiency leads to Severe Combined Immunodeficiency (SCID).
Q93. Match Column-I with Column-II

Column-IColumn-II
(a) % K(5) C1+2+(2) A(9)+1 G1(i) Brassicaceae
(b) ⊕ K(5) C(5) A5 G(2)(ii) Liliaceae
(c) ⊕ P(3+3) A3+3 G(3)(iii) Fabaceae
(d) ⊕ K2+2 C4 A2+4 G(2)(iv) Solanaceae
Correct Answer: (c)
(a) Fabaceae, (b) Solanaceae, (c) Liliaceae, (d) Brassicaceae.
Q94. Following are the statements about prostomium of earthworm.
(a) It serves as a covering for mouth.
(b) It helps to open cracks in the soil into which it can crawl.
(c) It is one of the sensory structures.
(d) It is the first body segment.
Choose the correct answer from the options given below.
Correct Answer: (d)
Prostomium is a covering, sensory, helps open cracks. Peristomium is the first segment.
Q95. Veneral diseases can spread through :
(a) Using sterile needles
(b) Transfusion of blood from infected person
(c) Infected mother to foetus
(d) Kissing
(e) Inheritance
Choose the correct answer from the option given below
Correct Answer: (b)
Blood transfusion and mother to fetus allow spread.
Q96. Which of the following statements wrongly represents the nature of smooth muscle?
Correct Answer: (b)
Intercalated discs are found in cardiac muscles.
Q97. Succus entericus is referred to as:
Correct Answer: (a)
Succus entericus is Intestinal juice.
Q98. Match List-I with List-II

List-IList-II
(a) Aspergillus niger(i) Acetic Acid
(b) Acetobacter aceti(ii) Lactic Acid
(c) Clostridium butylicum(iii) Citric Acid
(d) Lactobacillus(iv) Butyric Acid
Correct Answer: (c)
Aspergillus (Citric), Acetobacter (Acetic), Clostridium (Butyric), Lactobacillus (Lactic).
Q99. The favourable conditions required for the formation of oxyhaemoglobin at the alveoli are:
Correct Answer: (d)
Oxyhaemoglobin forms at high pO2, low pCO2, low H+, low temp.
Q100. The plant hormone used to destroy weeds in a field
Correct Answer: (b)
2,4-D is a synthetic auxin widely used to remove broad leaved weeds or dicotyledonous weeds in cereal crops.

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