1. Which of the following defines a biological taxon composed of related genera sharing common floral and vegetative characteristics?
Correct Answer: B (Family)
A Family is a taxonomic category containing one or more related genera (e.g., Solanaceae includes Solanum, Petunia, and Datura) characterized by vegetative and reproductive features.
A Family is a taxonomic category containing one or more related genera (e.g., Solanaceae includes Solanum, Petunia, and Datura) characterized by vegetative and reproductive features.
2. Which of the following archaebacteria inhabit hyper-saline coastal lagoons and salt pans?
Correct Answer: A (Halophiles)
Halophiles are archaebacteria adapted to extreme salt concentrations (e.g., Halobacterium) through specialized cellular membranes and osmoprotectant synthesis.
Halophiles are archaebacteria adapted to extreme salt concentrations (e.g., Halobacterium) through specialized cellular membranes and osmoprotectant synthesis.
3. Golden algae belonging to Chrysophytes are commonly designated as:
Correct Answer: B (Desmids)
Chrysophytes include diatoms and golden-brown algae (desmids), which are microscopic, photosynthetic plankton found in freshwater and marine environments.
Chrysophytes include diatoms and golden-brown algae (desmids), which are microscopic, photosynthetic plankton found in freshwater and marine environments.
4. The hallucinogenic drug LSD (Lysergic acid diethylamide) is derived from the parasitic fungus:
Correct Answer: A (Claviceps purpurea)
LSD is semisynthetically derived from ergot alkaloids extracted from the sclerotia of Claviceps purpurea, an ascomycetous parasite of rye crops.
LSD is semisynthetically derived from ergot alkaloids extracted from the sclerotia of Claviceps purpurea, an ascomycetous parasite of rye crops.
5. Mannitol and laminarin serve as complex carbohydrate food storage reserves in which algal class?
Correct Answer: B (Phaeophyceae)
Brown algae store photosynthetic reserves as complex carbohydrates, primarily the alcohol mannitol and the polysaccharide laminarin.
Brown algae store photosynthetic reserves as complex carbohydrates, primarily the alcohol mannitol and the polysaccharide laminarin.
6. The sporophyte of a moss (e.g., Funaria, Polytrichum) consists anatomically of which three parts?
Correct Answer: A (Foot, Seta, and Capsule)
The moss sporophyte is differentiated into a basal foot (anchorage and absorption), an elongated seta (stalk), and a terminal capsule (where spores form by meiosis).
The moss sporophyte is differentiated into a basal foot (anchorage and absorption), an elongated seta (stalk), and a terminal capsule (where spores form by meiosis).
7. In gymnosperms like Pinus and Cycas, the microspores develop into highly reduced, limited-cell male gametophytes called:
Correct Answer: B (Pollen grains)
The male gametophyte in gymnosperms is reduced to a few cells and enclosed within the protective pollen grain wall.
The male gametophyte in gymnosperms is reduced to a few cells and enclosed within the protective pollen grain wall.
8. Which of the following marine coelenterates is commonly known as the “Sea pen”?
Correct Answer: C (Pennatula)
Pennatula is the Sea pen, Gorgonia is the Sea fan, Adamsia is the Sea anemone, and Physalia is the Portuguese man-of-war.
Pennatula is the Sea pen, Gorgonia is the Sea fan, Adamsia is the Sea anemone, and Physalia is the Portuguese man-of-war.
9. The excretory organs of crustaceans (e.g., Prawns) are:
Correct Answer: B (Antennal glands)
Crustaceans excrete nitrogenous wastes and osmoregulate via paired antennal glands (green glands) located at the base of the antennae.
Crustaceans excrete nitrogenous wastes and osmoregulate via paired antennal glands (green glands) located at the base of the antennae.
10. Presence of a single dorsal hollow nerve cord, notochord, pharyngeal gill slits, and a post-anal tail are diagnostic features of phylum:
Correct Answer: C (Chordata)
The four defining morphological characteristics of Chordata are: a supportive notochord, a dorsal tubular nerve cord, paired pharyngeal gill slits, and a post-anal tail.
The four defining morphological characteristics of Chordata are: a supportive notochord, a dorsal tubular nerve cord, paired pharyngeal gill slits, and a post-anal tail.
11. In ginger (Zingiber officinale) and turmeric (Curcuma longa), vegetative propagation and food storage occur via:
Correct Answer: A (Underground horizontal Rhizomes)
Rhizomes are dorsiventrally flattened, horizontally growing underground perennial stems bearing nodes, scale leaves, and axillary buds that produce leafy aerial shoots.
Rhizomes are dorsiventrally flattened, horizontally growing underground perennial stems bearing nodes, scale leaves, and axillary buds that produce leafy aerial shoots.
12. An hypogynous flower (e.g., Mustard, China rose, Brinjal) features:
Correct Answer: A (Superior ovary with floral parts inserted below it)
In hypogynous flowers, the gynoecium occupies the highest position on the convex/conical thalamus, while calyx, corolla, and androecium are inserted below it.
In hypogynous flowers, the gynoecium occupies the highest position on the convex/conical thalamus, while calyx, corolla, and androecium are inserted below it.
13. In family Poaceae (Gramineae, e.g., Grasses, Wheat, Maize), the perianth is reduced to small membranous scales called:
Correct Answer: C (Lodicules)
In grass flowers, the perianth is represented by 2 (rarely 3) minute hygroscopic scales called lodicules that swell to force open the lemma and palea during anthesis.
In grass flowers, the perianth is represented by 2 (rarely 3) minute hygroscopic scales called lodicules that swell to force open the lemma and palea during anthesis.
14. Phloem fibers (bast fibers) obtained from which plants are commercially utilized for making ropes, twines, and burlap bags?
Correct Answer: A (Jute, Flax, and Hemp)
Phloem fibers (bast fibers) are elongated, unbranched, dead sclerenchymatous cells harvested from secondary phloem of Jute (Corchorus), Flax (Linum), and Hemp (Cannabis).
Phloem fibers (bast fibers) are elongated, unbranched, dead sclerenchymatous cells harvested from secondary phloem of Jute (Corchorus), Flax (Linum), and Hemp (Cannabis).
15. In a dicotyledonous stem, the ring of vascular bundles is:
Correct Answer: B (Conjoint, collateral, open, and endarch)
Dicot stems have vascular bundles arranged in a ring; each bundle is conjoint, collateral, open (cambium present between xylem and phloem), and features endarch protoxylem (directed inward).
Dicot stems have vascular bundles arranged in a ring; each bundle is conjoint, collateral, open (cambium present between xylem and phloem), and features endarch protoxylem (directed inward).
16. The involuntary, non-striated, spindle-shaped muscle fibers found in the walls of blood vessels, stomach, and intestine are:
Correct Answer: B (Smooth muscle fibers)
Smooth muscle cells are fusiform (spindle-shaped), uninucleated, lack sarcomeric cross-striations, and are innervated by the autonomic nervous system.
Smooth muscle cells are fusiform (spindle-shaped), uninucleated, lack sarcomeric cross-striations, and are innervated by the autonomic nervous system.
17. In frogs, the digestive organ that receives bile from the liver and pancreatic juice from the pancreas to complete chemical digestion is the:
Correct Answer: B (Duodenum)
The duodenum is the initial C-shaped loop of the small intestine that receives bile (which emulsifies fats) and pancreatic juice (which digests carbohydrates and proteins) via the common hepatopancreatic duct.
The duodenum is the initial C-shaped loop of the small intestine that receives bile (which emulsifies fats) and pancreatic juice (which digests carbohydrates and proteins) via the common hepatopancreatic duct.
18. The functional sound-transmitting chain in a frog’s auditory apparatus comprises:
Correct Answer: A (External Tympanum -> Columella auris -> Fenestra ovalis)
Acoustic vibrations hit the exposed external tympanic membrane and travel via the single middle ear ossicle (columella auris) to the inner ear labyrinth across the fenestra ovalis.
Acoustic vibrations hit the exposed external tympanic membrane and travel via the single middle ear ossicle (columella auris) to the inner ear labyrinth across the fenestra ovalis.
19. In male frogs, the paired ureters:
Correct Answer: B (Act as urinogenital ducts conveying both urine and spermatozoa)
In male frogs, ureters exit the kidneys carrying both urine and sperm from Bidder’s canal, functioning as urinogenital ducts that discharge into the cloaca.
In male frogs, ureters exit the kidneys carrying both urine and sperm from Bidder’s canal, functioning as urinogenital ducts that discharge into the cloaca.
20. The microvilli lining the small intestine of frogs that expand the surface area for nutrient absorption form mucosal folds called:
Correct Answer: B (Villi)
The internal mucosal epithelium of the frog small intestine is folded into finger-like projections called villi and microvilli, expanding the absorptive area for digested nutrients.
The internal mucosal epithelium of the frog small intestine is folded into finger-like projections called villi and microvilli, expanding the absorptive area for digested nutrients.
21. The non-pathogenic, small, circular, self-replicating extrachromosomal DNA molecules found in bacterial cells are:
Correct Answer: B (Plasmids)
Plasmids are autonomous, double-stranded, circular extrachromosomal DNA molecules in bacteria that confer non-essential survival traits (e.g., antibiotic resistance) and serve as recombinant cloning vectors.
Plasmids are autonomous, double-stranded, circular extrachromosomal DNA molecules in bacteria that confer non-essential survival traits (e.g., antibiotic resistance) and serve as recombinant cloning vectors.
22. The Golgi apparatus was first observed in silver-stained nerve cells by:
Correct Answer: B (Camillo Golgi)
Camillo Golgi first described the reticular Golgi apparatus in owl Purkinje neurons in 1898 using his silver nitrate impregnation technique.
Camillo Golgi first described the reticular Golgi apparatus in owl Purkinje neurons in 1898 using his silver nitrate impregnation technique.
23. In plant cells, chloroplasts and chromoplasts contain fat-soluble pigments like:
Correct Answer: A (Carotenoids)
Carotenoids (carotenes and xanthophylls) are lipid-soluble pigments embedded in the thylakoid membranes of chloroplasts and plastoglobules of chromoplasts, imparting yellow, orange, and red hues.
Carotenoids (carotenes and xanthophylls) are lipid-soluble pigments embedded in the thylakoid membranes of chloroplasts and plastoglobules of chromoplasts, imparting yellow, orange, and red hues.
24. The central protein hub of a centriole is connected to the peripheral triplet microtubules by radial spokes made of:
Correct Answer: A (Protein)
The cartwheel pattern of a centriole (9 + 0 array) features a central proteinaceous hub connected to nine peripheral tubulin triplets via nine proteinaceous radial spokes.
The cartwheel pattern of a centriole (9 + 0 array) features a central proteinaceous hub connected to nine peripheral tubulin triplets via nine proteinaceous radial spokes.
25. A nucleoside differs from a nucleotide in that a nucleoside LACKS a:
Correct Answer: C (Phosphate group)
A nucleoside consists of a nitrogenous base covalently linked to a pentose sugar (e.g., adenosine). Adding one or more phosphate groups via phosphoester bonds forms a nucleotide.
A nucleoside consists of a nitrogenous base covalently linked to a pentose sugar (e.g., adenosine). Adding one or more phosphate groups via phosphoester bonds forms a nucleotide.
26. In the presence of a competitive inhibitor, what happens to the maximal velocity (Vmax) and Michaelis constant (Km) of the enzymatic reaction?
Correct Answer: B (Vmax remains unchanged while apparent Km increases)
Competitive inhibitors bind reversibly to the catalytic active site: higher substrate concentrations outcompete the inhibitor to reach full Vmax, which increases the apparent Km.
Competitive inhibitors bind reversibly to the catalytic active site: higher substrate concentrations outcompete the inhibitor to reach full Vmax, which increases the apparent Km.
27. Enzymes that catalyze the non-hydrolytic removal of groups from substrates, leaving double bonds behind (or adding groups to double bonds), belong to:
Correct Answer: C (Class 4: Lyases)
Lyases (Class 4) cleave C-C, C-O, or C-N bonds by elimination mechanisms without hydrolysis or oxidation, forming double bonds or rings.
Lyases (Class 4) cleave C-C, C-O, or C-N bonds by elimination mechanisms without hydrolysis or oxidation, forming double bonds or rings.
28. The synaptonemal complex formed between paired homologous chromosomes during zygotene is composed of:
Correct Answer: B (Proteinaceous zipper-like filament framework)
The synaptonemal complex is a tripartite protein structure that aligns paired homologous chromatids point-for-point to facilitate meiotic recombination.
The synaptonemal complex is a tripartite protein structure that aligns paired homologous chromatids point-for-point to facilitate meiotic recombination.
29. The phase of mitosis during which sister chromatids reach their respective poles, decondense back into diffuse chromatin, and reform nuclear envelopes is:
Correct Answer: D (Telophase)
Telophase reverses prophase events: segregated chromatids uncoil into diffuse chromatin, nuclear envelopes reassemble around each daughter nucleus, and nucleoli reform.
Telophase reverses prophase events: segregated chromatids uncoil into diffuse chromatin, nuclear envelopes reassemble around each daughter nucleus, and nucleoli reform.
30. Recombination between homologous maternal and paternal chromosomes during meiosis leads to:
Correct Answer: B (New non-parental genetic allele combinations)
Reciprocal crossing over between non-sister chromatids breaks linked parental alleles, generating novel recombinant genotypes that drive evolutionary adaptation.
Reciprocal crossing over between non-sister chromatids breaks linked parental alleles, generating novel recombinant genotypes that drive evolutionary adaptation.
31. In photosynthetic light reactions, plastocyanin is a small copper-containing mobile peripheral protein that transfers electrons directly from:
Correct Answer: B (Cytochrome b6f complex to Photosystem I)
Plastocyanin is a water-soluble copper protein located in the thylakoid lumen that shuttles electrons from the cytochrome b6f complex to the oxidized P700 reaction center of PS I.
Plastocyanin is a water-soluble copper protein located in the thylakoid lumen that shuttles electrons from the cytochrome b6f complex to the oxidized P700 reaction center of PS I.
32. The enzyme RuBisCO represents approximately what percentage of the total soluble protein in green plant leaves?
Correct Answer: C (16% to 50%)
RuBisCO accounts for 16% to 50% of the total soluble chloroplast protein in leaf tissue, functioning as the primary carbon-fixing catalyst on the planet.
RuBisCO accounts for 16% to 50% of the total soluble chloroplast protein in leaf tissue, functioning as the primary carbon-fixing catalyst on the planet.
33. In C4 photosynthesis, how many total ATP molecules are consumed to synthesize one single molecule of Glucose (C6H12O6)?
Correct Answer: B (30 ATP)
Fixing 1 CO2 in C4 plants requires 5 ATP (3 for Calvin cycle + 2 to regenerate PEP from pyruvate). For 6 CO2 (1 glucose), total consumption is: 6 × 5 = 30 ATP (and 12 NADPH).
Fixing 1 CO2 in C4 plants requires 5 ATP (3 for Calvin cycle + 2 to regenerate PEP from pyruvate). For 6 CO2 (1 glucose), total consumption is: 6 × 5 = 30 ATP (and 12 NADPH).
34. Photosynthesis is inhibited at high temperatures primarily because:
Correct Answer: B (Photosynthetic enzymes undergo thermal denaturation and photorespiration increases)
High temperatures denature dark-reaction stromal enzymes, damage thylakoid membranes, and favor RuBisCO oxygenase activity over carboxylation.
High temperatures denature dark-reaction stromal enzymes, damage thylakoid membranes, and favor RuBisCO oxygenase activity over carboxylation.
35. The single reaction in glycolysis where a high-energy phosphate bond is generated without direct ATP consumption via inorganic phosphate (H3PO4) is:
Correct Answer: C (PGAL to 1,3-Bisphosphoglycerate)
Glyceraldehyde-3-phosphate dehydrogenase uses inorganic phosphate (Pi) and NAD+ to oxidize and phosphorylate PGAL into 1,3-BPGA without consuming ATP.
Glyceraldehyde-3-phosphate dehydrogenase uses inorganic phosphate (Pi) and NAD+ to oxidize and phosphorylate PGAL into 1,3-BPGA without consuming ATP.
36. In facultative and obligate anaerobes, fermentation of pyruvate is essential because it:
Correct Answer: B (Re-oxidizes NADH back to NAD+)
Without oxygen to accept electrons via mitochondrial ETS, fermentation reduces pyruvate into lactate or ethanol to recycle NAD+, keeping glycolysis operational.
Without oxygen to accept electrons via mitochondrial ETS, fermentation reduces pyruvate into lactate or ethanol to recycle NAD+, keeping glycolysis operational.
37. In the Krebs cycle, the enzyme Succinate dehydrogenase catalyzes the oxidation of Succinate to Fumarate with the reduction of:
Correct Answer: B (FAD to FADH2)
Succinate dehydrogenase (inner membrane Complex II) oxidizes succinate into fumarate, transferring reducing equivalents directly to its prosthetic group to form FADH2.
Succinate dehydrogenase (inner membrane Complex II) oxidizes succinate into fumarate, transferring reducing equivalents directly to its prosthetic group to form FADH2.
38. In the mitochondrial ETS, Complex IV (Cytochrome c oxidase) contains which metal cofactors and cytochromes?
Correct Answer: A (Cytochromes a and a3, and two copper centers)
Complex IV contains Cytochromes a and a3 alongside two catalytic copper centers (CuA and CuB) that transfer electrons to terminal molecular oxygen (O2).
Complex IV contains Cytochromes a and a3 alongside two catalytic copper centers (CuA and CuB) that transfer electrons to terminal molecular oxygen (O2).
39. The bioassay used to test the biological activity of Ethylene based on radial horizontal swelling of seedling stems is the:
Correct Answer: B (Triple response bioassay)
The ethylene triple-response bioassay in etiolated dicot seedlings consists of: inhibition of stem elongation, radial stem thickening/swelling, and horizontal diageotropic growth with exaggerated apical hook formation.
The ethylene triple-response bioassay in etiolated dicot seedlings consists of: inhibition of stem elongation, radial stem thickening/swelling, and horizontal diageotropic growth with exaggerated apical hook formation.
40. The plant hormone that promotes female flower production in cucumbers, induces uniform flowering in pineapples, and accelerates tomato ripening is:
Correct Answer: C (Ethylene)
Ethylene (applied commercially as aqueous Ethephon) synchronizes flowering and fruit set in pineapples, accelerates ripening in tomatoes and apples, and increases female flowers in cucurbits to boost crop yields.
Ethylene (applied commercially as aqueous Ethephon) synchronizes flowering and fruit set in pineapples, accelerates ripening in tomatoes and apples, and increases female flowers in cucurbits to boost crop yields.
41. The respiratory membrane (diffusion boundary) through which gaseous exchange occurs between alveolar air and capillary blood has a total thickness of:
Correct Answer: B (Much less than a millimeter)
The diffusion barrier is less than a millimeter thick (~0.2–0.5 μm), comprising alveolar squamous epithelium, capillary endothelium, and their fused basement membrane.
The diffusion barrier is less than a millimeter thick (~0.2–0.5 μm), comprising alveolar squamous epithelium, capillary endothelium, and their fused basement membrane.
42. About what percentage of carbon dioxide is transported bound to the amino groups of hemoglobin as carbamino-hemoglobin (Hb-CO2)?
Correct Answer: B (20 to 25%)
Carbon dioxide is transported as: 70% as bicarbonate ions (HCO3–), 20–25% as carbamino-hemoglobin (Hb-CO2), and 7% dissolved in plasma water.
Carbon dioxide is transported as: 70% as bicarbonate ions (HCO3–), 20–25% as carbamino-hemoglobin (Hb-CO2), and 7% dissolved in plasma water.
43. Which blood group represents the universal donor whose packed RBCs can be transfused safely into any ABO blood group recipient?
Correct Answer: D (O negative)
Group O-negative red blood cells lack A, B, and Rh surface agglutinogens, preventing immune destruction by recipient plasma antibodies during emergency transfusions.
Group O-negative red blood cells lack A, B, and Rh surface agglutinogens, preventing immune destruction by recipient plasma antibodies during emergency transfusions.
44. A condition in which the heart is unable to pump blood effectively enough to meet the metabolic requirements of peripheral tissues is:
Correct Answer: C (Heart Failure)
Heart failure is the state where cardiac output is insufficient for metabolic demands, frequently accompanied by pulmonary vascular congestion.
Heart failure is the state where cardiac output is insufficient for metabolic demands, frequently accompanied by pulmonary vascular congestion.
45. In human kidneys, the Glomerular Filtration Rate (GFR) in a healthy adult is approximately:
Correct Answer: B (125 mL/minute or 180 Liters per day)
Both kidneys filter ~125 mL of plasma filtrate per minute (180 L/day); ~99% is reabsorbed along the nephron tubules, leaving 1.5 L excreted as urine daily.
Both kidneys filter ~125 mL of plasma filtrate per minute (180 L/day); ~99% is reabsorbed along the nephron tubules, leaving 1.5 L excreted as urine daily.
46. The structural regulatory protein of skeletal muscle thin filaments that masks the myosin-binding sites on actin molecules in the resting state is:
Correct Answer: B (Tropomyosin along with the Troponin complex)
In resting muscle, two fibrous strands of tropomyosin lie in the grooves of F-actin filaments, holding troponin over actin active sites to block cross-bridge formation.
In resting muscle, two fibrous strands of tropomyosin lie in the grooves of F-actin filaments, holding troponin over actin active sites to block cross-bridge formation.
47. The total number of cranial and facial bones constituting the human skull (excluding hyoid and ear ossicles) is:
Correct Answer: A (22 bones: 8 Cranial and 14 Facial)
The human skull comprises 22 bones: 8 cranial bones that enclose the brain and 14 facial bones that form the anterior facial framework.
The human skull comprises 22 bones: 8 cranial bones that enclose the brain and 14 facial bones that form the anterior facial framework.
48. The autoimmune neuromuscular disease that causes fatigue, weakness, and eventual paralysis of skeletal muscles by destroying nicotinic acetylcholine receptors is:
Correct Answer: C (Myasthenia gravis)
Myasthenia gravis is an autoimmune disorder where autoantibodies block and destroy nicotinic ACh receptors at the motor end plate, impairing neuromuscular transmission.
Myasthenia gravis is an autoimmune disorder where autoantibodies block and destroy nicotinic ACh receptors at the motor end plate, impairing neuromuscular transmission.
49. In the human ear, dynamic equilibrium and spatial balance during rotational head movement are maintained by the sensory crista ampullaris located in the:
Correct Answer: B (Ampulla of the three Semicircular canals)
The swollen ampulla of each semicircular canal houses a crista ampullaris with hair cells embedded in a cupula, sensing rotational/angular acceleration. Maculae sense linear acceleration.
The swollen ampulla of each semicircular canal houses a crista ampullaris with hair cells embedded in a cupula, sensing rotational/angular acceleration. Maculae sense linear acceleration.
50. Dwarfism caused by deficiency of growth hormone (GH) in childhood produces a proportionate body with:
Correct Answer: B (Normal intelligence and proportionate stature)
Pituitary dwarfism results from childhood GH deficiency and features normal cognitive development with proportionate dwarfism. Thyroid cretinism causes stunted growth with severe mental retardation.
Pituitary dwarfism results from childhood GH deficiency and features normal cognitive development with proportionate dwarfism. Thyroid cretinism causes stunted growth with severe mental retardation.
51. In over 60% of angiosperms, shedding of pollen grains occurs at the:
Correct Answer: A (2-celled stage)
In >60% of angiosperms, pollen is shed at the 2-celled stage. In the remaining species, the generative cell divides mitotically to yield two male gametes prior to anther dehiscence (3-celled stage).
In >60% of angiosperms, pollen is shed at the 2-celled stage. In the remaining species, the generative cell divides mitotically to yield two male gametes prior to anther dehiscence (3-celled stage).
52. The hard outer protective seed coat of a mature angiosperm seed develops from the:
Correct Answer: B (Outer integument of the ovule)
During seed development, the ovule’s outer integument hardens into the protective testa, and the inner integument forms the tegmen.
During seed development, the ovule’s outer integument hardens into the protective testa, and the inner integument forms the tegmen.
53. The genetic phenomenon of producing seeds without fertilization, mimicking sexual reproduction while bypassing meiosis and syngamy, is:
Correct Answer: B (Apomixis)
Apomixis is a form of asexual reproduction that produces clonal maternal seeds without syngamy or meiosis, preventing trait segregation in hybrid agricultural lines.
Apomixis is a form of asexual reproduction that produces clonal maternal seeds without syngamy or meiosis, preventing trait segregation in hybrid agricultural lines.
54. Interstitial Leydig cells located between seminiferous tubules synthesize and secrete testosterone under the direct stimulation of:
Correct Answer: B (LH)
Luteinizing Hormone (LH/ICSH) released from the anterior pituitary binds to Leydig cell surface receptors, activating androgen (testosterone) biosynthesis.
Luteinizing Hormone (LH/ICSH) released from the anterior pituitary binds to Leydig cell surface receptors, activating androgen (testosterone) biosynthesis.
55. During human oogenesis, primary oocytes remain arrested from fetal life until puberty at which meiotic stage?
Correct Answer: A (Prophase I: Diplotene stage)
Oogonia begin Meiosis I during fetal development and arrest at the diplotene stage of Prophase I, resuming division only after puberty under cyclical gonadotropin surges.
Oogonia begin Meiosis I during fetal development and arrest at the diplotene stage of Prophase I, resuming division only after puberty under cyclical gonadotropin surges.
56. The LH surge that triggers rupture of the mature Graafian follicle and releases the secondary oocyte into the pelvic cavity occurs at approximately:
Correct Answer: B (Day 14)
Peak estrogen levels exert positive feedback on the pituitary, inducing a mid-cycle LH surge (~day 14) that triggers Graafian follicle rupture and ovulation.
Peak estrogen levels exert positive feedback on the pituitary, inducing a mid-cycle LH surge (~day 14) that triggers Graafian follicle rupture and ovulation.
57. The finger-like projections that develop on the trophoblast layer after implantation and interdigitate with maternal uterine tissue are:
Correct Answer: B (Chorionic villi)
Trophoblast cells produce invasive chorionic villi that interdigitate with the vascularized endometrium to form the placenta for fetal gas, nutrient, and waste exchange.
Trophoblast cells produce invasive chorionic villi that interdigitate with the vascularized endometrium to form the placenta for fetal gas, nutrient, and waste exchange.
58. The yellowish fluid “Colostrum” secreted during initial lactation is rich in which protective antibody class that confers passive immunity to the newborn?
Correct Answer: B (IgA)
Colostrum contains high concentrations of secretory dimeric IgA antibodies that coat the neonatal gastrointestinal tract to protect against enteric pathogens.
Colostrum contains high concentrations of secretory dimeric IgA antibodies that coat the neonatal gastrointestinal tract to protect against enteric pathogens.
59. CuT and Multiload 375 are contraceptive Intrauterine Devices (IUDs) that prevent fertilization by:
Correct Answer: B (Releasing copper ions that suppress sperm motility and fertilizing capacity)
Copper ions (Cu2+) released into the uterine cavity increase macrophage phagocytosis of sperm and suppress sperm motility and acrosomal reaction efficiency.
Copper ions (Cu2+) released into the uterine cavity increase macrophage phagocytosis of sperm and suppress sperm motility and acrosomal reaction efficiency.
60. In an Assisted Reproductive Technology (ART) procedure, Gamete Intra-Fallopian Transfer (GIFT) is recommended for a woman who:
Correct Answer: B (Cannot produce viable ova but has patent fallopian tubes)
GIFT transfers donor ova along with sperm into the ampullary region of a recipient who cannot ovulate but possesses healthy fallopian tubes for natural in vivo fertilization.
GIFT transfers donor ova along with sperm into the ampullary region of a recipient who cannot ovulate but possesses healthy fallopian tubes for natural in vivo fertilization.
61. Human ABO blood groups are determined by the ‘I’ gene with three alleles (IA, IB, i). How many possible genotypes and phenotypes can occur in the human population?
Correct Answer: B (6 genotypes and 4 phenotypes)
Three alleles produce 6 genotypes (IAIA, IAi, IBIB, IBi, IAIB, ii) that yield 4 distinct phenotypic blood groups: A, B, AB, and O.
Three alleles produce 6 genotypes (IAIA, IAi, IBIB, IBi, IAIB, ii) that yield 4 distinct phenotypic blood groups: A, B, AB, and O.
62. The Chromosomal Theory of Inheritance uniting Mendelian genetics with chromosome behavior during meiosis was proposed in 1902 by:
Correct Answer: A (Walter Sutton and Theodor Boveri)
Sutton and Boveri noted that chromosome segregation during meiosis parallels Mendelian gene behavior, formulating the Chromosomal Theory of Inheritance.
Sutton and Boveri noted that chromosome segregation during meiosis parallels Mendelian gene behavior, formulating the Chromosomal Theory of Inheritance.
63. A human female with Turner’s syndrome exhibits which karyotypic profile?
Correct Answer: C (45, XO)
Turner’s syndrome is caused by monosomy of the X chromosome (44 autosomes + XO = 45), producing sterile females with rudimentary streak ovaries and short stature.
Turner’s syndrome is caused by monosomy of the X chromosome (44 autosomes + XO = 45), producing sterile females with rudimentary streak ovaries and short stature.
64. In the nucleosome core of chromatin, the histone octamer consists of two copies each of which four histone proteins?
Correct Answer: B (H2A, H2B, H3, and H4)
The nucleosome core is a spool of 8 basic histone proteins (two each of H2A, H2B, H3, and H4) around which ~200 base pairs of DNA wrap. Histone H1 binds linker DNA.
The nucleosome core is a spool of 8 basic histone proteins (two each of H2A, H2B, H3, and H4) around which ~200 base pairs of DNA wrap. Histone H1 binds linker DNA.
65. The primary enzyme responsible for synthesizing new complementary DNA strands during replication in E. coli is:
Correct Answer: C (DNA Polymerase III)
DNA Polymerase III is the main replicative enzyme in E. coli, polymerizing deoxynucleotides at ~2000 bp/sec with proofreading fidelity.
DNA Polymerase III is the main replicative enzyme in E. coli, polymerizing deoxynucleotides at ~2000 bp/sec with proofreading fidelity.
66. In eukaryotes, the post-transcriptional process of removing non-coding introns and ligating coding exons in a defined order is:
Correct Answer: C (Splicing)
Spliceosomes (snRNPs and proteins) excise intervening non-coding introns from hnRNA and ligate expressed exons together to generate mature translatable mRNA.
Spliceosomes (snRNPs and proteins) excise intervening non-coding introns from hnRNA and ligate expressed exons together to generate mature translatable mRNA.
67. The initiation codon AUG codes for the amino acid:
Correct Answer: A (Methionine)
AUG serves as the universal translation start codon, recognized by initiator tRNA carrying methionine (N-formylmethionine in prokaryotes).
AUG serves as the universal translation start codon, recognized by initiator tRNA carrying methionine (N-formylmethionine in prokaryotes).
68. The Stanley Miller and Harold Urey (1953) spark-discharge experiment produced amino acids (glycine, alanine, aspartic acid) by subjecting which gas mixture to electric sparks?
Correct Answer: A (CH4, NH3, H2, and Water vapor at 800°C)
Miller circulated methane, ammonia, hydrogen (in a 2:1:2 ratio), and water vapor through tungsten electrodes at 800°C, synthesizing simple amino acids and validating abiotic organic synthesis.
Miller circulated methane, ammonia, hydrogen (in a 2:1:2 ratio), and water vapor through tungsten electrodes at 800°C, synthesizing simple amino acids and validating abiotic organic synthesis.
69. The evolution of diverse beak adaptations in Darwin’s Finches across the Galapagos Islands illustrates:
Correct Answer: B (Adaptive radiation from an ancestral seed-eating stock)
Darwin’s finches evolved from an ancestral mainland seed-eating finch into specialized insectivorous, vegetarian, and cactus-feeding forms to occupy distinct island niches.
Darwin’s finches evolved from an ancestral mainland seed-eating finch into specialized insectivorous, vegetarian, and cactus-feeding forms to occupy distinct island niches.
70. The fossil hominid ancestor “Java Ape Man” discovered in 1891 is scientifically classified as:
Correct Answer: B (Homo erectus)
Homo erectus fossils discovered in Java in 1891 date to ~1.5 million years ago, showing an upright bipedal stance, a 900 cc cranial capacity, and meat consumption.
Homo erectus fossils discovered in Java in 1891 date to ~1.5 million years ago, showing an upright bipedal stance, a 900 cc cranial capacity, and meat consumption.
71. The malignant, life-threatening form of human malaria characterized by cerebral complications is caused by:
Correct Answer: C (Plasmodium falciparum)
Plasmodium falciparum causes malignant tertian malaria, where infected erythrocytes clog cerebral microvessels, leading to coma and high mortality.
Plasmodium falciparum causes malignant tertian malaria, where infected erythrocytes clog cerebral microvessels, leading to coma and high mortality.
72. Interferons are cytokine proteins secreted by:
Correct Answer: B (Virus-infected host cells to protect uninfected cells)
Virus-infected cells secrete alpha-, beta-, and gamma-interferons that induce antiviral proteins (such as protein kinase R) in adjacent cells to block viral translation.
Virus-infected cells secrete alpha-, beta-, and gamma-interferons that induce antiviral proteins (such as protein kinase R) in adjacent cells to block viral translation.
73. Mucosa-Associated Lymphoid Tissue (MALT) located in the mucosal linings of respiratory, digestive, and urogenital tracts accounts for what percentage of total human lymphoid tissue?
Correct Answer: C (~50%)
MALT (including Peyer’s patches, appendix, and tonsils) constitutes about 50% of the lymphoid tissue in the human body, providing frontline mucosal immunity.
MALT (including Peyer’s patches, appendix, and tonsils) constitutes about 50% of the lymphoid tissue in the human body, providing frontline mucosal immunity.
74. The definitive confirmatory test used to validate a positive ELISA screening result for HIV infection is:
Correct Answer: B (Western Blotting)
ELISA is a high-sensitivity initial screening test; positive results are confirmed via Western Blotting to resolve specific HIV antigens (gp120, gp41, p24).
ELISA is a high-sensitivity initial screening test; positive results are confirmed via Western Blotting to resolve specific HIV antigens (gp120, gp41, p24).
75. Chronic heavy consumption of ethyl alcohol causes liver cirrhosis primarily by:
Correct Answer: B (Accumulating fat deposits followed by fibrosis and loss of liver parenchyma)
Ethanol metabolism generates excess NADH, driving hepatic steatosis (fatty liver) and chronic inflammation that progresses to irreversible fibrotic scarring (cirrhosis).
Ethanol metabolism generates excess NADH, driving hepatic steatosis (fatty liver) and chronic inflammation that progresses to irreversible fibrotic scarring (cirrhosis).
76. “Toddy”, a traditional refreshing beverage consumed in parts of South India, is prepared by fermenting:
Correct Answer: B (Sap tapped from palm trees)
Toddy is produced through natural wild yeast fermentation of sugary sap harvested from the inflorescences of palmyra and coconut palms.
Toddy is produced through natural wild yeast fermentation of sugary sap harvested from the inflorescences of palmyra and coconut palms.
77. The “clot buster” enzyme Streptokinase used to clear intravascular blood clots in acute myocardial infarction patients is produced by:
Correct Answer: A (Streptococcus bacteria)
Streptokinase is harvested from hemolytic Streptococcus cultures and engineered as a thrombolytic medication to dissolve fibrin clots in coronary arteries.
Streptokinase is harvested from hemolytic Streptococcus cultures and engineered as a thrombolytic medication to dissolve fibrin clots in coronary arteries.
78. The primary biological stage of sewage treatment aims to drastically reduce the:
Correct Answer: B (Biochemical Oxygen Demand of the effluent)
Secondary biological treatment uses aerobic microbial flocs in aeration basins to metabolize dissolved organic waste, lowering effluent BOD before environmental discharge.
Secondary biological treatment uses aerobic microbial flocs in aeration basins to metabolize dissolved organic waste, lowering effluent BOD before environmental discharge.
79. The free-living fungus Trichoderma polysporum is commercially valuable as the source of:
Correct Answer: B (Cyclosporin A)
The soil fungus Trichoderma polysporum produces Cyclosporin A, an immunosuppressant that inhibits T-cell activation to prevent graft rejection in organ transplant recipients.
The soil fungus Trichoderma polysporum produces Cyclosporin A, an immunosuppressant that inhibits T-cell activation to prevent graft rejection in organ transplant recipients.
80. Which of the following is an endomycorrhizal fungus that forms vesicular-arbuscular mycorrhizae (VAM) to absorb phosphorus for plants?
Correct Answer: A (Glomus)
Fungi belonging to the genus Glomus form endomycorrhizal associations with plant roots, extending hyphal networks to absorb soil phosphorus and confer drought/pathogen resistance.
Fungi belonging to the genus Glomus form endomycorrhizal associations with plant roots, extending hyphal networks to absorb soil phosphorus and confer drought/pathogen resistance.
81. In recombinant DNA technology, the naming of restriction enzyme EcoRI reflects that ‘co’ stands for:
Correct Answer: B (Species coli)
In EcoRI: ‘E’ comes from the genus Escherichia, ‘co’ from the species coli, ‘R’ from strain RY13, and Roman numeral ‘I’ indicates it was the first endonuclease isolated from this strain.
In EcoRI: ‘E’ comes from the genus Escherichia, ‘co’ from the species coli, ‘R’ from strain RY13, and Roman numeral ‘I’ indicates it was the first endonuclease isolated from this strain.
82. In plasmid pBR322, the PvuI restriction endonuclease recognition site is located within the:
Correct Answer: A (Ampicillin resistance gene)
In pBR322, PstI and PvuI recognition sites are located within the ampR gene, whereas BamHI and SalI sites are located within the tetR gene.
In pBR322, PstI and PvuI recognition sites are located within the ampR gene, whereas BamHI and SalI sites are located within the tetR gene.
83. To isolate pure genomic DNA from plant tissue, the cellulose-rich cell walls are digested using:
Correct Answer: C (Cellulase and Pectinase)
Plant cells are lysed using cellulase and pectinase to degrade cellulose and pectin wall polymers. Fungal walls require chitinase, and bacterial walls require lysozyme.
Plant cells are lysed using cellulase and pectinase to degrade cellulose and pectin wall polymers. Fungal walls require chitinase, and bacterial walls require lysozyme.
84. The method of cellular transformation where electric pulses create transient microscopic pores in the plasma membrane for DNA uptake is:
Correct Answer: C (Electroporation)
Electroporation applies brief high-voltage electric pulses to cell suspensions, creating temporary nanometer-sized pores in the plasma membrane through which foreign DNA enters.
Electroporation applies brief high-voltage electric pulses to cell suspensions, creating temporary nanometer-sized pores in the plasma membrane through which foreign DNA enters.
85. The cryIAb gene engineered into transgenic maize crops confers protection against:
Correct Answer: B (Corn borer)
The cryIAb endotoxin gene specifically targets and kills corn borer larvae, whereas cryIAc and cryIIAb control cotton bollworms.
The cryIAb endotoxin gene specifically targets and kills corn borer larvae, whereas cryIAc and cryIIAb control cotton bollworms.
86. In RNA interference (RNAi), the ribonuclease III enzyme that processes long double-stranded RNA into short 21–23 nucleotide siRNAs is:
Correct Answer: B (Dicer)
Dicer is an endoribonuclease that cleaves long precursor dsRNA into small interfering RNA (siRNA) duplexes of ~21–23 base pairs during RNA interference.
Dicer is an endoribonuclease that cleaves long precursor dsRNA into small interfering RNA (siRNA) duplexes of ~21–23 base pairs during RNA interference.
87. Eli Lilly synthesized recombinant human insulin (Humulin) by expressing chains A and B separately in E. coli and combining them chemically by forming:
Correct Answer: C (Disulfide bonds)
Insulin A and B chains were produced separately in E. coli and joined in vitro by generating authentic disulfide bonds between corresponding cysteine residues.
Insulin A and B chains were produced separately in E. coli and joined in vitro by generating authentic disulfide bonds between corresponding cysteine residues.
88. In clinical gene therapy, what is the major limitation of transfusing genetically modified T-lymphocytes into ADA-deficient patients?
Correct Answer: B (Genetically engineered lymphocytes are not immortal)
Because mature circulating T-lymphocytes have a finite lifespan, patients require repeated infusions of engineered cells unless hematopoietic stem cells are transformed in early embryonic development.
Because mature circulating T-lymphocytes have a finite lifespan, patients require repeated infusions of engineered cells unless hematopoietic stem cells are transformed in early embryonic development.
89. A single-stranded DNA or RNA tagged with a radioactive isotope used to detect a complementary gene sequence in a genomic library is a:
Correct Answer: C (Probe)
A molecular probe is a defined single-stranded nucleotide sequence labeled with a radioactive isotope or fluorophore that hybridizes to complementary target DNA for autoradiographic visualization.
A molecular probe is a defined single-stranded nucleotide sequence labeled with a radioactive isotope or fluorophore that hybridizes to complementary target DNA for autoradiographic visualization.
90. Transgenic mice are extensively used in pre-clinical pharmacology as animal models to test:
Correct Answer: B (Vaccine safety and chemical carcinogenicity testing)
Transgenic mice account for >95% of transgenic models, engineered with human genes to assess vaccine neurovirulence (polio) and test drug toxicity/carcinogenicity.
Transgenic mice account for >95% of transgenic models, engineered with human genes to assess vaccine neurovirulence (polio) and test drug toxicity/carcinogenicity.
91. The ecological interaction between Cuscuta (dodder) growing on a hedge plant and absorbing nutrition through haustoria is:
Correct Answer: C (Parasitism)
Cuscuta is a non-green parasitic angiosperm that produces root haustoria to extract water and nutrients from host vascular bundles, harming the host (+, -).
Cuscuta is a non-green parasitic angiosperm that produces root haustoria to extract water and nutrients from host vascular bundles, harming the host (+, -).
92. In a stable population with an age pyramid that is bell-shaped:
Correct Answer: B (Pre-reproductive and reproductive age groups are nearly equal)
A bell-shaped pyramid indicates a stable, stationary population where birth and death rates are balanced, resulting in nearly equal pre-reproductive and reproductive cohorts.
A bell-shaped pyramid indicates a stable, stationary population where birth and death rates are balanced, resulting in nearly equal pre-reproductive and reproductive cohorts.
93. Primary ecological succession differs from secondary succession because primary succession occurs on:
Correct Answer: C (Newly exposed bare rock, cooled lava, or sand dunes devoid of soil)
Primary succession begins on sterile sites lacking previous life and soil (bare rocks, lava flows). Secondary succession occurs where preexisting communities were disrupted but soil remains.
Primary succession begins on sterile sites lacking previous life and soil (bare rocks, lava flows). Secondary succession occurs where preexisting communities were disrupted but soil remains.
94. The annual net primary productivity (NPP) of the entire biosphere is approximately 170 billion tons of dry organic matter. Terrestrial ecosystems contribute:
Correct Answer: B (115 billion tons)
Of the global 170 billion tons of annual NPP, land ecosystems produce 115 billion tons (~68%), while oceans produce only 55 billion tons due to nutrient and light constraints.
Of the global 170 billion tons of annual NPP, land ecosystems produce 115 billion tons (~68%), while oceans produce only 55 billion tons due to nutrient and light constraints.
95. In a grassland ecosystem, the pyramid of biomass is:
Correct Answer: A (Upright)
In terrestrial grasslands, autotrophic grass biomass exceeds herbivore biomass, which in turn exceeds carnivore biomass, maintaining an upright pyramid of biomass.
In terrestrial grasslands, autotrophic grass biomass exceeds herbivore biomass, which in turn exceeds carnivore biomass, maintaining an upright pyramid of biomass.
96. India harbors exceptional biodiversity, containing approximately what percentage of global species diversity across its 2.4% world land area?
Correct Answer: C (8.1%)
India encompasses 2.4% of the world’s land area but accounts for 8.1% of global documented species richness, making it one of the world’s 12 mega-biodiversity countries.
India encompasses 2.4% of the world’s land area but accounts for 8.1% of global documented species richness, making it one of the world’s 12 mega-biodiversity countries.
97. Breaking up large continuous forest tracts into smaller isolated patches due to human activities (roads, urbanization, agriculture) is termed:
Correct Answer: B (Habitat fragmentation)
Habitat fragmentation splits large continuous habitats into small isolated patches, creating edge effects and disrupting species requiring large home ranges or migratory corridors.
Habitat fragmentation splits large continuous habitats into small isolated patches, creating edge effects and disrupting species requiring large home ranges or migratory corridors.
98. The recent historical extinction of the Quagga occurred in:
Correct Answer: B (Africa)
Recent documented extinctions include: Quagga (Africa), Dodo (Mauritius), Thylacine (Australia), Steller’s Sea Cow (Russia), and three tiger subspecies (Bali, Javan, Caspian).
Recent documented extinctions include: Quagga (Africa), Dodo (Mauritius), Thylacine (Australia), Steller’s Sea Cow (Russia), and three tiger subspecies (Bali, Javan, Caspian).
99. Which of the following is an Ex-situ (off-site) biodiversity conservation method where endangered seeds are kept viable at low temperature and humidity?
Correct Answer: C (Seed Bank / Gene Bank)
Seed banks preserve desiccation-tolerant seeds under low moisture and sub-zero temperatures as an ex-situ conservation method. National Parks and Sanctuaries are in-situ methods.
Seed banks preserve desiccation-tolerant seeds under low moisture and sub-zero temperatures as an ex-situ conservation method. National Parks and Sanctuaries are in-situ methods.
100. Biodiversity Hotspots cover less than 2% of Earth’s land surface, but strictly protecting them could reduce ongoing mass extinctions by almost:
Correct Answer: C (30%)
Although the 34 global biodiversity hotspots occupy under 2% of the planet’s land area, their protection could reduce the ongoing rate of mass extinctions by approximately 30%.
Although the 34 global biodiversity hotspots occupy under 2% of the planet’s land area, their protection could reduce the ongoing rate of mass extinctions by approximately 30%.