If you're preparing for the MH SET Life Science examination, solving previous year question papers is the smartest move you can make. In this article, we provide the MH SET life science previous year question paper with solutions 2020, completely solved with detailed explanations. This is your one-stop resource to understand the exam pattern, difficulty level, and types of questions asked.
📘 Why Practice MH SET Life Science Previous Year Question Paper?
Solving the MH SET Life Science previous year question paper helps you:
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Understand the pattern and weightage of topics.
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Familiarize yourself with repeated question trends.
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Improve accuracy and speed.
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Analyze your strengths and weaknesses.
Especially for 2020, this paper gives you insight into how the post-COVID exam pattern might have shifted slightly in tone and structure.
Read:
- MH SET Life Science 2024- Solved Paper
- MH SET Life Science 2023- Solved Paper
- MH SET Life Science 2021- Solved Paper
MH SET Life Science Previous Year Question Paper with Solutions 2020
1. You are looking at a specimen with a compound microscope. The ocular lens has a magnification of 8X and the objective lens has a magnification of 2X. What is the total magnification?
A) 2X
B) 8X
C) 10X
D) 16X
Answer: D) 16X
Explanation: Total magnification = Ocular magnification × Objective magnification = 8 × 2 = 16X
2. Which of the following is true for enzyme catalyzed reactions?
A) Km is affinity constant
B) Vmax can never be achieved
C) Km = ½Vmax
D) Km = Vmax
Answer: A) Km is affinity constant
Explanation: Km (Michaelis constant) reflects the enzyme’s affinity for substrate: lower Km = higher affinity.
3. Which of the following statements about monosaccharides is correct?
P—Epimers of monosaccharides differ in chemical properties.
Q—In aldoses, C1 is the anomeric carbon.
R—Anomers differ in configuration at the glycosidic carbon.
S—Epimers differ in configuration at any carbon other than glycosidic carbon.
A) R and S
B) P and Q
C) Q, R and S
D) P, Q, R and S
Answer: C) Q, R and S
Explanation:
-
Q: True, anomeric carbon is C1 in aldoses.
-
R: Anomers differ at the anomeric (glycosidic) carbon.
-
S: Epimers differ at any single carbon except the anomeric carbon.
-
P: False—epimers have similar chemical properties.
4. If a naive T cell recognizes an antigen-MHC complex on an appropriate APC or target cell, it will be activated, initiating:
A) a primary response
B) a secondary response
C) a prophylactic response
D) degranulation of mast cells
Answer: A) a primary response
Explanation: The first time a T-cell encounters an antigen, it initiates the primary immune response.
5. A Ramachandran plot describes, for a particular amino acid in a polypeptide chain, sterically allowed angles for:
A) Cα–C and Cα–CB bonds
B) Cα–C and Cα–N bonds
C) Cα–C and Cα–H bonds
D) Cα–N and Cα–H bonds
Answer: B) Cα–C and Cα–N bonds
Explanation: Ramachandran plot shows permissible values of phi (Ï•) and psi (ψ) angles around N–Cα and Cα–C bonds.
6. What are (A), (B), (C) & (D) in the given metabolic diagram?
A) Glycolysis, TCA cycle, homolactic fermentation and alcoholic fermentation
B) Glycolysis, TCA cycle, alcoholic fermentation and homolactic fermentation
C) Glycolysis, homolactic fermentation, TCA cycle and alcoholic fermentation
D) Glycolysis, alcoholic fermentation, homolactic fermentation and TCA cycle
Answer: B) Glycolysis, TCA cycle, alcoholic fermentation and homolactic fermentation
Explanation: Pyruvate from glycolysis enters:
-
TCA (aerobic),
-
or fermentation pathways (alcoholic or lactic) under anaerobic conditions.
7. Various atoms of pyrimidine ring are derived from:
A) N1, C4, C5, C6–Aspartate; C2–Bicarbonate; N3–Glutamine
B) N1, C4, C5, C6–Glutamine; C2–Bicarbonate; N3–Aspartate
C) N1, C4, C5, C6–Aspartate; C2–Bicarbonate; N3–Glutamate
D) N1, C4, C5, C6–Asparagine; C2–Bicarbonate; N3–Glutamine
Answer: A
Explanation: Pyrimidine ring formation:
-
N1, C4–C6 from aspartate,
-
C2 from CO₂ (bicarbonate),
-
N3 from glutamine.
8. Lac repressor is an example of:
A) Helix-loop-helix
B) Helix-turn-helix
C) C2C2 zinc finger
D) C2H2 zinc finger
Answer: B
Explanation: The lac repressor uses a helix-turn-helix DNA-binding motif to bind the operator.
9. Which of the following is not involved in steady-state regulation of hematopoiesis?
A) Control of cytokines by stromal cells
B) Cytokines from T cells and macrophages
C) Apoptosis of some cells
D) Mesangial cells
Answer: D
Explanation: Mesangial cells are kidney-related, not involved in hematopoiesis.
10. The evolution of tetrapods marks their origin from:
A) Actinopterygians
B) Chondropterygians
C) Sarcopterygians
D) Holocephalians
Answer: C
Explanation: Tetrapods evolved from lobe-finned fishes (Sarcopterygii).
11. The only non-protein component(s) of the electron transport system is/are:
A) Cytochromes
B) NAD and FAD
C) Fe-S center
D) Coenzyme-Q
Answer: D
Explanation: Coenzyme Q (ubiquinone) is a lipid component, unlike the proteinaceous cytochromes and Fe–S clusters.
12. During evolution, the first formed cells were:
A) Photoautotrophs
B) Saprotrophs
C) Chemoautotrophs
D) Chemoheterotrophs
Answer: D
Explanation: The earliest cells were likely chemoheterotrophs—they obtained energy and carbon from organic molecules.
13. In every cycle of its activity, one Na-K ATPase:
A) extrudes 1 Na⁺ and takes in 3 K⁺
B) extrudes 3 Na⁺ and takes in 2 K⁺
C) extrudes 3 K⁺ and takes in 3 Na⁺
D) extrudes 1 Na⁺ and takes in 1 K⁺
Answer: B
Explanation: The Na⁺/K⁺ pump extrudes 3 Na⁺ and takes in 2 K⁺, consuming 1 ATP.
14. The first photosynthetic organisms were:
A) Algae
B) Cyanobacteria
C) Mycoplasmas
D) Bryophytes
Answer: B
Explanation: Cyanobacteria were the first oxygenic photosynthetic organisms, releasing O₂ into early Earth’s atmosphere.
15. Animals adapted to temperate regions have shorter ears, eyes, hair etc. This follows:
A) Bergmann’s law
B) Cope’s law
C) Allen’s law
D) Dollo’s law
Answer: C
Explanation: Allen’s law: animals in colder climates have shorter appendages to minimize heat loss.
16. To determine variation in frog body size from four populations, which test should be used?
A) Student t-test
B) Chi-square
C) Regression analysis
D) F-test
Answer: D
Explanation: F-test/ANOVA is used when comparing means across more than two groups (here, four populations).
17. Which of the following is not a characteristic of competitive inhibition?
A) It increases Km
B) No change in Km
C) Inhibitor binds to active site
D) It can be relieved by increasing substrate
Answer: B
Explanation: Competitive inhibition increases Km, but Vmax remains constant.
18. Gene pool sampling occurs in sexual reproduction because:
A) Not all gametes form zygotes
B) Not all alleles enter gametes
C) Meiosis doesn’t produce identical copies
D) Recombination shuffles genes
Answer: D
Explanation: Recombination during meiosis reshuffles alleles, contributing to gene pool sampling and variation.
19. Evaluate the following two statements:
(I) A reaction is spontaneous when it can proceed in either direction.
(II) A spontaneous process can occur with a large decrease in entropy.
A) I=False, II=False
B) I=True, II=False
C) I=False, II=True
D) I=True, II=True
Answer: B
Explanation:
-
Statement I: True (spontaneity depends on Gibbs free energy, not direction)
-
Statement II: False—spontaneous reactions typically increase entropy or are exergonic.
20. Exo-erythrocytic schizogony in Plasmodium occurs in:
A) RBCs
B) Liver
C) Blood
D) Mosquito stomach
Answer: B
Explanation: The liver stage (exo-erythrocytic) is where Plasmodium multiplies before entering RBCs.
21. Genomic DNA library is prepared by using:
A) Only exon sequences
B) mRNA from cells
C) DNA with both coding and non-coding sequences
D) DNA sequences with promoter only
Answer: C) DNA with both coding and non-coding sequences
Explanation: A genomic library contains DNA fragments from entire genome, including introns, promoters, and intergenic regions.
22. Homeotic genes are those:
A) Required for formation of cytoskeleton
B) Required for organ identity and pattern formation
C) That code for enzymes for metabolism
D) That are restricted to immune cells
Answer: B) Required for organ identity and pattern formation
Explanation: Homeotic genes (e.g., Hox genes) specify body part identity along the anterior-posterior axis during development.
23. How many ATP molecules are required to fix one molecule of CO₂ during the Calvin cycle?
A) 1
B) 2
C) 3
D) 4
Answer: C) 3
Explanation: The fixation of 1 CO₂ via the Calvin cycle requires 3 ATP and 2 NADPH.
24. Which plant hormone is commonly used to promote root formation in cuttings?
A) Cytokinin
B) Gibberellin
C) Auxin
D) Abscisic acid
Answer: C) Auxin
Explanation: Auxins (e.g., IAA, IBA) stimulate adventitious root formation, widely used in plant propagation.
25. The ABO blood group system in humans is an example of:
A) Incomplete dominance
B) Co-dominance
C) Epistasis
D) Polygenic inheritance
Answer: B) Co-dominance
Explanation: In AB blood group, both IA and IB alleles are expressed simultaneously, making it a co-dominant trait.
26. Which protein forms a contractile ring during cytokinesis in animal cells?
A) Myosin
B) Actin
C) Tubulin
D) Kinesin
Answer: B) Actin
Explanation: Actin filaments, along with myosin, form the contractile ring during cytokinesis in animal cells.
27. Which of the following vitamin deficiencies causes bleeding disorder?
A) Vitamin A
B) Vitamin B₁₂
C) Vitamin K
D) Vitamin D
Answer: C) Vitamin K
Explanation: Vitamin K is essential for synthesis of clotting factors; its deficiency leads to prolonged bleeding.
28. Which method is used to separate DNA fragments based on size?
A) Chromatography
B) Electrophoresis
C) Spectroscopy
D) Centrifugation
Answer: B) Electrophoresis
Explanation: Agarose gel electrophoresis separates DNA fragments based on length/size.
29. Which of the following is a coenzyme involved in redox reactions?
A) CoA
B) NAD⁺
C) FADH₂
D) Biotin
Answer: B) NAD⁺
Explanation: NAD⁺ is a common redox coenzyme that accepts electrons to form NADH.
30. Which of the following structures is present only in prokaryotic cells?
A) Nucleus
B) Ribosomes
C) Mitochondria
D) Nucleoid
Answer: D) Nucleoid
Explanation: Prokaryotes lack a membrane-bound nucleus; DNA resides in an irregular region called the nucleoid.
31. Which molecule carries amino acids to the ribosome during protein synthesis?
A) mRNA
B) tRNA
C) rRNA
D) DNA
Answer: B) tRNA
Explanation: Transfer RNA (tRNA) delivers specific amino acids to the ribosome during translation.
32. The first amino acid incorporated during translation in prokaryotes is:
A) Glycine
B) Methionine
C) Formyl-methionine (fMet)
D) Serine
Answer: C) Formyl-methionine (fMet)
Explanation: In prokaryotes, the first amino acid is fMet, recognized by the initiator tRNA.
33. DNA polymerase reads the template strand in which direction?
A) 3′ to 5′
B) 5′ to 3′
C) 2′ to 5′
D) Randomly
Answer: A) 3′ to 5′
Explanation: DNA polymerase reads the template 3′ to 5′ and synthesizes the new strand 5′ to 3′.
34. In which organelle does photorespiration occur?
A) Chloroplast
B) Mitochondria
C) Peroxisome
D) All of the above
Answer: D) All of the above
Explanation: Photorespiration involves chloroplasts, mitochondria, and peroxisomes working together to recycle 2-phosphoglycolate.
35. β-oxidation of fatty acids occurs in:
A) Cytosol
B) Mitochondria
C) Endoplasmic reticulum
D) Ribosome
Answer: B) Mitochondria
Explanation: Fatty acid β-oxidation takes place in the mitochondrial matrix, generating acetyl-CoA.
36. Hemoglobin is a:
A) Monomer
B) Dimer
C) Tetramer
D) Pentamer
Answer: C) Tetramer
Explanation: Hemoglobin consists of 4 subunits—2 α and 2 β chains—making it a tetrameric protein.
37. A cofactor required for blood clotting is:
A) Magnesium
B) Potassium
C) Calcium
D) Zinc
Answer: C) Calcium
Explanation: Calcium ions (Ca²⁺) are essential for the activation of clotting cascade proteins.
38. Which is a non-reducing sugar?
A) Maltose
B) Glucose
C) Sucrose
D) Lactose
Answer: C) Sucrose
Explanation: Sucrose has a glycosidic bond between both anomeric carbons, making it non-reducing.
39. The TCA cycle occurs in:
A) Cytoplasm
B) Ribosome
C) Nucleus
D) Mitochondrial matrix
Answer: D) Mitochondrial matrix
Explanation: The TCA/Krebs cycle takes place in the mitochondrial matrix, where acetyl-CoA is oxidized.
40. The cell wall of fungi is composed of:
A) Cellulose
B) Pectin
C) Chitin
D) Hemicellulose
Answer: C) Chitin
Explanation: Fungal cell walls contain chitin, a polysaccharide made of N-acetylglucosamine units.
41. Which protein binds oxygen in muscles?
A) Hemoglobin
B) Myosin
C) Myoglobin
D) Actin
Answer: C) Myoglobin
Explanation: Myoglobin stores oxygen in muscle tissues, especially for rapid energy use.
42. In human beings, sex is determined by:
A) Number of X chromosomes
B) Presence of Y chromosome
C) Absence of X chromosome
D) Number of autosomes
Answer: B) Presence of Y chromosome
Explanation: The Y chromosome contains the SRY gene, which determines maleness.
43. In plants, which hormone promotes senescence?
A) Cytokinin
B) Auxin
C) Gibberellin
D) Ethylene
Answer: D) Ethylene
Explanation: Ethylene is known for promoting fruit ripening and leaf/organ senescence.
44. The process of programmed cell death is called:
A) Necrosis
B) Apoptosis
C) Autolysis
D) Inflammation
Answer: B) Apoptosis
Explanation: Apoptosis is a tightly regulated process of cell death important in development and homeostasis.
45. Which nitrogenous base is not found in RNA?
A) Uracil
B) Guanine
C) Cytosine
D) Thymine
Answer: D) Thymine
Explanation: RNA uses uracil instead of thymine, which is found only in DNA.
46. In photosynthesis, oxygen is produced from:
A) CO₂
B) Water
C) Glucose
D) Chlorophyll
Answer: B) Water
Explanation: Photolysis of water releases O₂, electrons, and protons during light reactions.
47. The technique used to separate proteins based on size is:
A) Ion exchange chromatography
B) Gel filtration chromatography
C) Affinity chromatography
D) Isoelectric focusing
Answer: B) Gel filtration chromatography
Explanation: Also called size exclusion chromatography, it separates proteins by molecular size.
48. Which process occurs during Prophase I of meiosis?
A) Chromosome decondensation
B) Cytokinesis
C) Crossing over
D) Chromosome alignment
Answer: C) Crossing over
Explanation: Crossing over between homologous chromosomes occurs in Prophase I, specifically pachytene stage.
49. Which of the following is a macroelement required for plant growth?
A) Boron
B) Zinc
C) Iron
D) Magnesium
Answer: D) Magnesium
Explanation: Magnesium is a macronutrient, vital for chlorophyll synthesis and enzyme activation.
50. The oxygen-binding pigment in vertebrate red blood cells is:
A) Chlorophyll
B) Myoglobin
C) Hemoglobin
D) Albumin
Answer: C) Hemoglobin
Explanation: Hemoglobin in RBCs binds oxygen via heme groups, transporting it to tissues.
51. Which of the following is a sex-linked recessive disorder?
A) Thalassemia
B) Sickle cell anemia
C) Hemophilia
D) Down’s syndrome
Answer: C) Hemophilia
Explanation: Hemophilia is an X-linked recessive disorder affecting blood clotting, mostly seen in males.
52. The process by which DNA is copied into RNA is called:
A) Replication
B) Translation
C) Transcription
D) Mutation
Answer: C) Transcription
Explanation: Transcription is the synthesis of RNA from a DNA template using RNA polymerase.
53. Which hormone regulates sugar metabolism?
A) Glucagon
B) Thyroxine
C) Insulin
D) Cortisol
Answer: C) Insulin
Explanation: Insulin lowers blood glucose by promoting uptake of glucose into cells and storage as glycogen.
54. Which is not a component of the nucleotide?
A) Sugar
B) Nitrogenous base
C) Phosphate
D) Amino acid
Answer: D) Amino acid
Explanation: A nucleotide consists of a pentose sugar, a nitrogenous base, and a phosphate group—no amino acid.
55. The structural carbohydrate in plant cell walls is:
A) Starch
B) Pectin
C) Cellulose
D) Glycogen
Answer: C) Cellulose
Explanation: Cellulose is made of β-1,4-linked glucose units and forms the plant cell wall framework.
56. The disease tuberculosis is caused by:
A) Mycobacterium leprae
B) Bacillus anthracis
C) Mycobacterium tuberculosis
D) Staphylococcus aureus
Answer: C) Mycobacterium tuberculosis
Explanation: TB is caused by M. tuberculosis, an acid-fast, slow-growing bacterium.
57. What is the role of ligase in DNA replication?
A) Opens the DNA strands
B) Synthesizes new DNA strand
C) Seals nicks between Okazaki fragments
D) Unwinds the DNA helix
Answer: C
Explanation: DNA ligase forms phosphodiester bonds, sealing gaps between Okazaki fragments on the lagging strand.
58. The number of chromosomes in a human zygote is:
A) 23
B) 46
C) 92
D) 44
Answer: B) 46
Explanation: A zygote has 46 chromosomes (23 from sperm + 23 from egg).
59. A protein is said to be denatured when:
A) It is hydrolyzed
B) It is digested
C) It loses its tertiary structure
D) Its amino acid sequence is changed
Answer: C
Explanation: Denaturation involves loss of secondary, tertiary, or quaternary structure, not primary structure.
60. Which structure is involved in photosynthesis in cyanobacteria?
A) Thylakoid membranes
B) Chloroplast
C) Mitochondria
D) Nucleoid
Answer: A
Explanation: Cyanobacteria lack chloroplasts, but have thylakoid-like membranes for photosynthesis.
61. Which organelle is known as the suicidal bag of the cell?
A) Golgi body
B) Mitochondria
C) Lysosome
D) Peroxisome
Answer: C
Explanation: Lysosomes contain hydrolytic enzymes that digest cellular components during autolysis.
62. Which of the following is not a greenhouse gas?
A) CO₂
B) CH₄
C) N₂
D) N₂O
Answer: C
Explanation: Nitrogen gas (N₂) is not a greenhouse gas; it’s inert and doesn’t trap heat.
63. The human forelimb and bat wing are examples of:
A) Analogous organs
B) Vestigial organs
C) Homologous organs
D) Atavistic organs
Answer: C
Explanation: Homologous structures have a common ancestry but may serve different functions.
64. The enzyme responsible for RNA synthesis is:
A) DNA polymerase
B) RNA polymerase
C) Helicase
D) Ligase
Answer: B
Explanation: RNA polymerase catalyzes the synthesis of RNA from a DNA template.
65. Which element is present in chlorophyll?
A) Iron
B) Calcium
C) Magnesium
D) Zinc
Answer: C
Explanation: The central atom in chlorophyll is magnesium (Mg²⁺), essential for light absorption.
66. An organism that feeds on dead organic matter is called:
A) Autotroph
B) Parasite
C) Saprophyte
D) Predator
Answer: C
Explanation: Saprophytes feed on decaying organic matter, playing a key role in decomposition.
67. The phenomenon of self-pollination is common in:
A) Maize
B) Wheat
C) Coconut
D) Pea
Answer: D
Explanation: Pea plants have bisexual flowers and frequently undergo self-pollination.
68. Which tissue is responsible for transport of water in plants?
A) Phloem
B) Xylem
C) Parenchyma
D) Collenchyma
Answer: B
Explanation: Xylem conducts water and minerals from roots to shoots.
69. The end product of anaerobic respiration in yeast is:
A) Lactic acid
B) Ethanol and CO₂
C) Pyruvic acid
D) Acetyl-CoA
Answer: B
Explanation: In yeast, anaerobic respiration (fermentation) yields ethanol and carbon dioxide.
70. The nitrogenous base present only in RNA is:
A) Thymine
B) Uracil
C) Cytosine
D) Guanine
Answer: B
Explanation: Uracil replaces thymine in RNA.
71. Which type of immunity is provided by vaccination?
A) Natural active immunity
B) Natural passive immunity
C) Artificial passive immunity
D) Artificial active immunity
Answer: D
Explanation: Vaccination introduces antigens, inducing the body to generate its own immune response = artificial active immunity.
72. The powerhouse of the cell is:
A) Ribosome
B) Lysosome
C) Mitochondria
D) Nucleus
Answer: C
Explanation: Mitochondria produce ATP via oxidative phosphorylation—thus called the powerhouse.
73. In mitosis, chromosomes are aligned at the cell equator during:
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
Answer: B
Explanation: In metaphase, chromosomes line up at the metaphase plate before being pulled apart.
74. Which structure controls movement of substances in and out of the cell?
A) Cell wall
B) Nucleus
C) Plasma membrane
D) Cytoplasm
Answer: C
Explanation: The plasma membrane is selectively permeable, controlling entry and exit of substances.
75. Which pigment is found in red algae?
A) Chlorophyll b
B) Xanthophyll
C) Phycoerythrin
D) Fucoxanthin
Answer: C
Explanation: Red algae (Rhodophyta) contain phycoerythrin, which gives them their characteristic red color.
76. Which part of the brain controls voluntary muscular movements?
A) Cerebellum
B) Cerebrum
C) Medulla oblongata
D) Hypothalamus
Answer: B) Cerebrum
Explanation: The motor cortex in the cerebrum controls voluntary muscle movements.
77. Pancreatic juice contains enzymes that help digest:
A) Proteins
B) Carbohydrates
C) Fats
D) All of the above
Answer: D
Explanation: Pancreatic juice contains trypsin (proteins), amylase (carbohydrates), and lipase (fats).
78. Which type of connective tissue connects muscle to bone?
A) Ligament
B) Tendon
C) Cartilage
D) Areolar tissue
Answer: B
Explanation: Tendons connect muscles to bones, while ligaments connect bone to bone.
79. Which pigment is found in chloroplasts?
A) Melanin
B) Haemoglobin
C) Chlorophyll
D) Phycocyanin
Answer: C
Explanation: Chlorophyll is the green pigment in chloroplasts responsible for photosynthesis.
80. Which disease is caused by a protozoan parasite?
A) AIDS
B) Malaria
C) Tuberculosis
D) Influenza
Answer: B
Explanation: Malaria is caused by Plasmodium spp., a protozoan parasite transmitted by Anopheles mosquito.
81. Which part of the nephron is responsible for filtration of blood?
A) Loop of Henle
B) Proximal convoluted tubule
C) Bowman’s capsule
D) Collecting duct
Answer: C
Explanation: Bowman’s capsule, with the glomerulus, forms the renal corpuscle where filtration occurs.
82. The male gamete in plants is produced in:
A) Anther
B) Ovary
C) Style
D) Stigma
Answer: A
Explanation: Anthers produce pollen grains, which contain the male gametes (sperm nuclei) in plants.
83. Which enzyme is responsible for digestion of proteins in the stomach?
A) Amylase
B) Lipase
C) Pepsin
D) Trypsin
Answer: C
Explanation: Pepsin is secreted in the stomach and breaks down proteins into peptides.
84. In plants, the opening and closing of stomata is controlled by:
A) Guard cells
B) Mesophyll cells
C) Palisade cells
D) Parenchyma
Answer: A
Explanation: Guard cells swell and shrink to open or close the stomatal pore based on turgor pressure.
85. The process by which plants lose water through stomata is:
A) Evaporation
B) Condensation
C) Transpiration
D) Osmosis
Answer: C
Explanation: Transpiration is the loss of water vapor through stomata in leaves.
86. Which one of the following is a vestigial organ in humans?
A) Kidney
B) Spleen
C) Appendix
D) Pancreas
Answer: C
Explanation: The appendix is considered a vestigial organ, once thought to aid in digestion.
87. The bicuspid valve is located between:
A) Right atrium and right ventricle
B) Left atrium and left ventricle
C) Right ventricle and pulmonary artery
D) Left ventricle and aorta
Answer: B
Explanation: The bicuspid (mitral) valve regulates blood flow from the left atrium to left ventricle.
88. Which process produces gametes in sexually reproducing organisms?
A) Mitosis
B) Meiosis
C) Binary fission
D) Budding
Answer: B
Explanation: Meiosis reduces the chromosome number by half and leads to gamete formation.
89. Which of the following is a biological nitrogen fixer?
A) Clostridium
B) Nitrobacter
C) Nitrosomonas
D) Azotobacter
Answer: D
Explanation: Azotobacter is a free-living nitrogen-fixing bacterium in soil.
90. Which of the following is a natural greenhouse gas?
A) O₂
B) N₂
C) CH₄
D) H₂
Answer: C
Explanation: Methane (CH₄) is a potent greenhouse gas produced naturally (e.g., from ruminants, wetlands).
91. The function of ribosomes is:
A) DNA replication
B) Protein synthesis
C) Lipid synthesis
D) Carbohydrate metabolism
Answer: B
Explanation: Ribosomes translate mRNA into proteins, playing a central role in translation.
92. The hormone auxin is primarily involved in:
A) Flowering
B) Leaf fall
C) Cell elongation
D) Seed dormancy
Answer: C
Explanation: Auxins promote cell elongation and are crucial in phototropism and apical dominance.
93. Which vitamin is synthesized in the skin using sunlight?
A) Vitamin A
B) Vitamin C
C) Vitamin D
D) Vitamin K
Answer: C
Explanation: UVB radiation converts 7-dehydrocholesterol to vitamin D₃ in the skin.
94. Which part of the plant transports food?
A) Xylem
B) Phloem
C) Cortex
D) Pericycle
Answer: B
Explanation: Phloem transports organic nutrients (e.g., sucrose) from source to sink tissues.
95. Bile is produced in the:
A) Stomach
B) Pancreas
C) Gall bladder
D) Liver
Answer: D
Explanation: Bile is produced in the liver and stored in the gall bladder.
96. Pulse rate is directly related to:
A) Digestion
B) Respiration
C) Heartbeat
D) Excretion
Answer: C
Explanation: Pulse measures the heartbeat, i.e., contractions of the heart per minute.
97. The total number of cranial nerves in humans is:
A) 10
B) 12
C) 31
D) 33
Answer: B
Explanation: Humans have 12 pairs of cranial nerves arising from the brain.
98. Which organ produces insulin?
A) Liver
B) Kidney
C) Pancreas
D) Spleen
Answer: C
Explanation: The pancreas, specifically β-cells of islets of Langerhans, secretes insulin.
99. The term plasmolysis refers to:
A) Rupturing of a cell
B) Entry of water into cell
C) Shrinking of cytoplasm
D) Cell division
Answer: C
Explanation: Plasmolysis is the shrinkage of cytoplasm away from the cell wall in hypertonic solution.
100. The basic unit of heredity is:
A) Chromosome
B) Nucleus
C) DNA
D) Gene
Answer: D
Explanation: A gene is the fundamental unit of heredity, coding for a specific trait or function.
