1. Which of the following taxonomic categories contains organisms with the least number of similar characters in common?
Correct Answer: D (Kingdom)
As we go higher from species to kingdom in the taxonomic hierarchy, the number of common characteristics decreases, making Kingdom the category with the least shared characters.
As we go higher from species to kingdom in the taxonomic hierarchy, the number of common characteristics decreases, making Kingdom the category with the least shared characters.
2. Methanogens responsible for biogas production from cattle dung belong to:
Correct Answer: B (Archaebacteria)
Methanogens are obligate anaerobic archaebacteria found in the gut of several ruminant animals and in marshy habitats.
Methanogens are obligate anaerobic archaebacteria found in the gut of several ruminant animals and in marshy habitats.
3. Naked protoplasts lacking a cell wall and multinucleated amoeboid vegetative bodies called plasmodium are typical of:
Correct Answer: C (Slime moulds)
Under suitable conditions, saprophytic protists called slime moulds form an aggregation called plasmodium which lacks cell walls during the vegetative phase.
Under suitable conditions, saprophytic protists called slime moulds form an aggregation called plasmodium which lacks cell walls during the vegetative phase.
4. Which fungal class is commonly known as “fungi imperfecti” because sexual reproduction has not been observed?
Correct Answer: D (Deuteromycetes)
Deuteromycetes (e.g., Alternaria, Colletotrichum, Trichoderma) reproduce only by asexual spores called conidia; their sexual stages remain undiscovered or place them into Ascomycetes/Basidiomycetes when found.
Deuteromycetes (e.g., Alternaria, Colletotrichum, Trichoderma) reproduce only by asexual spores called conidia; their sexual stages remain undiscovered or place them into Ascomycetes/Basidiomycetes when found.
5. Peat, widely used as fuel and packing material for trans-shipment of living material due to its water-holding capacity, is obtained from:
Correct Answer: C (Sphagnum)
Sphagnum (peat moss) provides peat used as fuel and possesses significant water retention capacity, making it suitable for transporting living specimens.
Sphagnum (peat moss) provides peat used as fuel and possesses significant water retention capacity, making it suitable for transporting living specimens.
6. Coralloid roots associated with nitrogen-fixing cyanobacteria (Nostoc/Anabaena) are found in:
Correct Answer: B (Cycas)
Cycas possesses specialized coralloid roots housing symbiotic nitrogen-fixing cyanobacteria. Pinus roots associate with fungal mycorrhizae.
Cycas possesses specialized coralloid roots housing symbiotic nitrogen-fixing cyanobacteria. Pinus roots associate with fungal mycorrhizae.
7. Water vascular system (ambulacral system) used for locomotion, food capture, and respiration is a unique diagnostic feature of:
Correct Answer: D (Echinodermata)
Echinoderms (e.g., Asterias, Echinus) uniquely possess a water vascular system operating tube feet for locomotion, food capture, and respiration. Porifera have a water canal system.
Echinoderms (e.g., Asterias, Echinus) uniquely possess a water vascular system operating tube feet for locomotion, food capture, and respiration. Porifera have a water canal system.
8. Which of the following animals is an oviparous (egg-laying) mammal?
Correct Answer: A (Ornithorhynchus)
Ornithorhynchus (duck-billed platypus) is a primitive, egg-laying (oviparous) prototherian mammal. Most other mammals are viviparous.
Ornithorhynchus (duck-billed platypus) is a primitive, egg-laying (oviparous) prototherian mammal. Most other mammals are viviparous.
9. Flame cells (solenocytes) serve as specialized excretory and osmoregulatory structures in:
Correct Answer: B (Platyhelminthes)
Flatworms like Planaria, Taenia, and Fasciola rely on flame cells for excretion and osmoregulation.
Flatworms like Planaria, Taenia, and Fasciola rely on flame cells for excretion and osmoregulation.
10. Presence of pneumatic (air-filled hollow) bones and presence of air sacs connected to lungs for supplemental respiration are adaptations of:
Correct Answer: C (Aves)
Birds have pneumatic long bones to minimize body weight during flight and air sacs attached to lungs to maintain unidirectional airflow during flight.
Birds have pneumatic long bones to minimize body weight during flight and air sacs attached to lungs to maintain unidirectional airflow during flight.
11. Pneumatophores (negatively geotropic respiratory roots) are found in halophytes like:
Correct Answer: A (Rhizophora)
In mangrove plants like Rhizophora growing in swampy, oxygen-depleted areas, vertical roots emerge upward into the air with lenticels for oxygen uptake.
In mangrove plants like Rhizophora growing in swampy, oxygen-depleted areas, vertical roots emerge upward into the air with lenticels for oxygen uptake.
12. Monadelphous stamens, where all filaments are fused into a single continuous staminal tube surrounding the style, occur in:
Correct Answer: C (China rose)
China rose (Hibiscus, family Malvaceae) possesses monadelphous stamens. Pea is diadelphous (9 + 1), and Citrus is polyadelphous.
China rose (Hibiscus, family Malvaceae) possesses monadelphous stamens. Pea is diadelphous (9 + 1), and Citrus is polyadelphous.
13. Marginal placentation, where the placenta forms a ridge along the ventral suture of a monocarpellary ovary, is found in:
Correct Answer: B (Pea)
In marginal placentation (typical of Fabaceae/Pea), ovules are borne in two rows along the ventral suture of the unilocular ovary.
In marginal placentation (typical of Fabaceae/Pea), ovules are borne in two rows along the ventral suture of the unilocular ovary.
14. Which tissue is characterized by cells thickened at corners due to localized deposition of cellulose, hemicellulose, and pectin, providing mechanical support to growing petiole and stems?
Correct Answer: B (Collenchyma)
Collenchyma is living mechanical tissue with uneven corner pectin/cellulose thickenings, found in dicot stems and leaf petioles below the epidermis.
Collenchyma is living mechanical tissue with uneven corner pectin/cellulose thickenings, found in dicot stems and leaf petioles below the epidermis.
15. The Casparian strip present in root endodermis cells is made of an impermeable, suberized matrix that blocks:
Correct Answer: A (Apoplastic water flow)
The Casparian strip of the endodermis contains suberin, which prevents apoplastic flow through cell walls and forces water and ions across the selectively permeable plasma membrane into the symplast.
The Casparian strip of the endodermis contains suberin, which prevents apoplastic flow through cell walls and forces water and ions across the selectively permeable plasma membrane into the symplast.
16. The spring wood (early wood) differs from autumn wood (late wood) in having:
Correct Answer: A (Larger, wider xylem vessels with lower density)
Spring wood forms during high cambial activity with wide vessels and lower density, while autumn wood forms narrower vessels with higher density and darker color.
Spring wood forms during high cambial activity with wide vessels and lower density, while autumn wood forms narrower vessels with higher density and darker color.
17. Which of the following junctions facilitates rapid direct ion and small molecule communication between adjacent animal cells?
Correct Answer: C (Gap junctions)
Gap junctions connect the cytoplasm of adjacent cells through channels (connexons), enabling fast passage of ions, metabolites, and electrical impulses.
Gap junctions connect the cytoplasm of adjacent cells through channels (connexons), enabling fast passage of ions, metabolites, and electrical impulses.
18. In male frogs, sperm leaves the testes via 10–12 vasa efferentia and enters which renal structure before discharging into the cloaca?
Correct Answer: B (Bidder’s canal)
In male frogs, vasa efferentia traverse the kidney to open into Bidder’s canal, communicating with the urinogenital duct entering the cloaca.
In male frogs, vasa efferentia traverse the kidney to open into Bidder’s canal, communicating with the urinogenital duct entering the cloaca.
19. How many chambers are present in a frog’s heart, and what is its systemic arrangement?
Correct Answer: B (Three chambers with sinus venosus and conus arteriosus)
A frog’s heart is a muscular 3-chambered pump (right atrium, left atrium, and a single undivided ventricle) accompanied by accessory sinus venosus and truncus/conus arteriosus.
A frog’s heart is a muscular 3-chambered pump (right atrium, left atrium, and a single undivided ventricle) accompanied by accessory sinus venosus and truncus/conus arteriosus.
20. The midbrain of a frog is characterized anatomically by a pair of prominent:
Correct Answer: B (Optic lobes)
Frogs possess a pair of well-developed dorsolateral optic lobes forming the midbrain. Mammals have four rounded lobes (corpora quadrigemina).
Frogs possess a pair of well-developed dorsolateral optic lobes forming the midbrain. Mammals have four rounded lobes (corpora quadrigemina).
21. According to the Fluid Mosaic Model of Singer and Nicolson (1972), the quasi-fluid nature of membrane lipids enables:
Correct Answer: B (Lateral movement of proteins within the bilayer)
The quasi-fluid lipid bilayer allows lateral diffusion of embedded membrane proteins, defining the membrane’s functional fluidity.
The quasi-fluid lipid bilayer allows lateral diffusion of embedded membrane proteins, defining the membrane’s functional fluidity.
22. The major site for the synthesis of lipids, phospholipids, and steroid hormones in eukaryotic cells is the:
Correct Answer: B (Smooth Endoplasmic Reticulum)
SER is the site for lipid synthesis, phospholipid metabolism, and steroid hormone production (in animal cells). RER functions in protein synthesis and processing.
SER is the site for lipid synthesis, phospholipid metabolism, and steroid hormone production (in animal cells). RER functions in protein synthesis and processing.
23. Which non-membrane-bound organelle is found in both eukaryotic and prokaryotic cells?
Correct Answer: B (Ribosome)
Ribosomes (70S in prokaryotes, 80S in eukaryotic cytoplasm) lack a surrounding phospholipid membrane and occur across all cell types.
Ribosomes (70S in prokaryotes, 80S in eukaryotic cytoplasm) lack a surrounding phospholipid membrane and occur across all cell types.
24. What is the sedimentation coefficient of the large and small subunits of prokaryotic 70S ribosomes?
Correct Answer: B (50S and 30S)
Prokaryotic 70S ribosomes consist of a 50S large subunit and a 30S small subunit. Eukaryotic 80S ribosomes comprise 60S and 40S subunits.
Prokaryotic 70S ribosomes consist of a 50S large subunit and a 30S small subunit. Eukaryotic 80S ribosomes comprise 60S and 40S subunits.
25. In a polysaccharide chain (e.g., glycogen), the right end is called the ______ end, and the left end is the ______ end:
Correct Answer: A (Reducing; Non-reducing)
In glycogen and starch chains, the terminal glucose at the right end has an open hemiacetal ring and is reducing, while the left end is non-reducing.
In glycogen and starch chains, the terminal glucose at the right end has an open hemiacetal ring and is reducing, while the left end is non-reducing.
26. An essential amino acid that must be supplied in human dietary intake is:
Correct Answer: C (Tryptophan)
Essential amino acids (Valine, Leucine, Isoleucine, Phenylalanine, Tryptophan, Methionine, Threonine, Lysine, Histidine) cannot be synthesized by the human body and must be acquired through food.
Essential amino acids (Valine, Leucine, Isoleucine, Phenylalanine, Tryptophan, Methionine, Threonine, Lysine, Histidine) cannot be synthesized by the human body and must be acquired through food.
27. An organic cofactor that is transiently and loosely bound to the apoenzyme protein during catalysis is a:
Correct Answer: B (Co-enzyme)
Coenzymes are non-protein organic compounds that associate transiently with apoenzymes during catalysis, often derived from vitamins (like niacin in NAD). Prosthetic groups (like heme in peroxidase) are tightly and permanently bound.
Coenzymes are non-protein organic compounds that associate transiently with apoenzymes during catalysis, often derived from vitamins (like niacin in NAD). Prosthetic groups (like heme in peroxidase) are tightly and permanently bound.
28. The enzyme recombinase catalyzes the exchange of genetic material between non-sister chromatids during which stage of meiosis?
Correct Answer: C (Pachytene)
Recombinase facilitates crossing over and genetic recombination between non-sister chromatids of homologous chromosomes during the pachytene stage of Prophase I.
Recombinase facilitates crossing over and genetic recombination between non-sister chromatids of homologous chromosomes during the pachytene stage of Prophase I.
29. Colchicine, an antimitotic alkaloid chemical, arrests cell division at which phase by preventing spindle fiber formation?
Correct Answer: B (Metaphase)
Colchicine binds to tubulin dimers, preventing microtubule assembly into mitotic spindle fibers and arresting dividing cells at metaphase, often inducing polyploidy.
Colchicine binds to tubulin dimers, preventing microtubule assembly into mitotic spindle fibers and arresting dividing cells at metaphase, often inducing polyploidy.
30. Splitting of the centromere and separation of sister chromatids to opposite poles occurs during:
Correct Answer: C (Anaphase of mitosis and Anaphase II of meiosis)
In Anaphase I, homologous chromosomes separate while centromeres remain intact. Centromeres split during mitotic anaphase and meiotic Anaphase II.
In Anaphase I, homologous chromosomes separate while centromeres remain intact. Centromeres split during mitotic anaphase and meiotic Anaphase II.
31. What is the chief photosynthetic pigment responsible for trapping light and forming the reaction center core in photosynthetic systems?
Correct Answer: A (Chlorophyll a)
Chlorophyll a is the essential reaction center pigment in photosystems (P680 in PS II, P700 in PS I). Chlorophyll b, xanthophylls, and carotenoids are accessory antenna pigments.
Chlorophyll a is the essential reaction center pigment in photosystems (P680 in PS II, P700 in PS I). Chlorophyll b, xanthophylls, and carotenoids are accessory antenna pigments.
32. In C3 plants, how many molecules of ATP and NADPH are required to synthesize one net molecule of Glucose via the Calvin cycle?
Correct Answer: B (18 ATP and 12 NADPH)
Fixing 1 molecule of CO2 takes 3 ATP and 2 NADPH. Synthesizing 1 hexose glucose molecule (fixing 6 CO2) requires: 6 x 3 = 18 ATP and 6 x 2 = 12 NADPH.
Fixing 1 molecule of CO2 takes 3 ATP and 2 NADPH. Synthesizing 1 hexose glucose molecule (fixing 6 CO2) requires: 6 x 3 = 18 ATP and 6 x 2 = 12 NADPH.
33. “Kranz anatomy”, characterized by large bundle sheath cells containing agranal chloroplasts without intercellular spaces, is an adaptation of:
Correct Answer: A (C4 plants)
Kranz anatomy allows C4 plants to concentrate CO2 around bundle sheath RuBisCO enzymes, preventing photorespiratory oxygenase activity and maximizing photosynthetic yield.
Kranz anatomy allows C4 plants to concentrate CO2 around bundle sheath RuBisCO enzymes, preventing photorespiratory oxygenase activity and maximizing photosynthetic yield.
34. Photorespiration (C2 cycle) involves a cooperative biochemical sequence across which three cell organelles?
Correct Answer: B (Chloroplast, Peroxisome, and Mitochondria)
When RuBisCO binds oxygen, phosphoglycolate is formed, entering the glycolate cycle across the chloroplast, peroxisome, and mitochondrion, consuming ATP without generating sugars.
When RuBisCO binds oxygen, phosphoglycolate is formed, entering the glycolate cycle across the chloroplast, peroxisome, and mitochondrion, consuming ATP without generating sugars.
35. The EMP pathway (Glycolysis) occurs in the:
Correct Answer: C (Cytoplasm of all living cells)
Glycolysis (EMP pathway) breaks down 1 glucose into 2 pyruvates in the cytoplasm, functioning in both aerobic and anaerobic cellular respiration.
Glycolysis (EMP pathway) breaks down 1 glucose into 2 pyruvates in the cytoplasm, functioning in both aerobic and anaerobic cellular respiration.
36. The catalytic linking step converting Pyruvate into Acetyl-CoA in the mitochondrial matrix is catalyzed by:
Correct Answer: B (Pyruvate dehydrogenase)
Pyruvate undergoes oxidative decarboxylation into Acetyl-CoA via the pyruvate dehydrogenase complex, requiring Mg2+, TPP, lipoic acid, CoA, and NAD+.
Pyruvate undergoes oxidative decarboxylation into Acetyl-CoA via the pyruvate dehydrogenase complex, requiring Mg2+, TPP, lipoic acid, CoA, and NAD+.
37. In the Krebs cycle, substrate-level phosphorylation (synthesis of GTP/ATP) occurs during the conversion of:
Correct Answer: C (Succinyl-CoA to Succinic acid)
Converting high-energy Succinyl-CoA to Succinate by succinyl-CoA synthetase is coupled with GDP phosphorylation to GTP (substrate-level phosphorylation).
Converting high-energy Succinyl-CoA to Succinate by succinyl-CoA synthetase is coupled with GDP phosphorylation to GTP (substrate-level phosphorylation).
38. In the mitochondrial Electron Transport Chain, Complex V is:
Correct Answer: D (ATP Synthase)
Complex V is ATP synthase. Protons pass through the F0 transmembrane channel into the matrix, driving the F1 headpiece to synthesize ATP from ADP and inorganic phosphate.
Complex V is ATP synthase. Protons pass through the F0 transmembrane channel into the matrix, driving the F1 headpiece to synthesize ATP from ADP and inorganic phosphate.
39. The “Bakanae” (foolish seedling) disease of rice seedlings led to the discovery of which plant hormone?
Correct Answer: B (Gibberellin)
E. Kurosawa identified that foolish seedling disease in rice was caused by active substances secreted by the fungal pathogen Gibberella fujikuroi, leading to the isolation of gibberellins.
E. Kurosawa identified that foolish seedling disease in rice was caused by active substances secreted by the fungal pathogen Gibberella fujikuroi, leading to the isolation of gibberellins.
40. The gaseous phytohormone that promotes horizontal growth of seedlings, swelling of the axis, apical hook formation in dicots, and rapid fruit ripening is:
Correct Answer: B (Ethylene)
Ethylene is a gaseous plant growth regulator that triggers the triple response in seedlings, accelerates climacteric fruit ripening, and promotes senescence and abscission.
Ethylene is a gaseous plant growth regulator that triggers the triple response in seedlings, accelerates climacteric fruit ripening, and promotes senescence and abscission.
41. The total volume of air inspired or expired during a normal respiration cycle in a healthy human is:
Correct Answer: A (Tidal Volume)
Tidal Volume (TV) is ~500 mL per breath, translating to 6,000–8,000 mL of air inhaled or exhaled per minute.
Tidal Volume (TV) is ~500 mL per breath, translating to 6,000–8,000 mL of air inhaled or exhaled per minute.
42. Carbonic anhydrase enzyme, which facilitates the reversible conversion of CO2 and water into carbonic acid, is found in highest concentrations in:
Correct Answer: B (Red Blood Cells)
RBCs contain high concentrations of carbonic anhydrase (and trace amounts in plasma), catalyzing the conversion of CO2 + H2O into H2CO3, which dissociates into HCO3- and H+.
RBCs contain high concentrations of carbonic anhydrase (and trace amounts in plasma), catalyzing the conversion of CO2 + H2O into H2CO3, which dissociates into HCO3- and H+.
43. The QRS complex on a standard Electrocardiogram (ECG) trace represents:
Correct Answer: B (Ventricular depolarization)
The QRS complex marks ventricular depolarization, which initiates ventricular systole. Counting QRS complexes over time determines heart rate.
The QRS complex marks ventricular depolarization, which initiates ventricular systole. Counting QRS complexes over time determines heart rate.
44. The Hepatic Portal Vein drains nutrient-rich venous blood directly from the:
Correct Answer: B (Digestive gut to the Liver)
The hepatic portal system carries deoxygenated, nutrient-rich blood from the digestive tract to the liver before it enters systemic circulation.
The hepatic portal system carries deoxygenated, nutrient-rich blood from the digestive tract to the liver before it enters systemic circulation.
45. Angiotensin II elevates blood pressure and increases Glomerular Filtration Rate (GFR) by:
Correct Answer: B (Vasoconstrictor and stimulates Aldosterone release)
Angiotensin II constricts arterioles and stimulates aldosterone secretion from the adrenal cortex, promoting Na+ and water reabsorption to elevate blood pressure and GFR.
Angiotensin II constricts arterioles and stimulates aldosterone secretion from the adrenal cortex, promoting Na+ and water reabsorption to elevate blood pressure and GFR.
46. The structural and functional units of the human liver are hepatic lobules, which are surrounded by a thin connective tissue sheath called:
Correct Answer: B (Glisson’s capsule)
Each hepatic lobule is covered by a thin fibro-elastic connective tissue sheath called Glisson’s capsule, a diagnostic feature of mammalian liver histology.
Each hepatic lobule is covered by a thin fibro-elastic connective tissue sheath called Glisson’s capsule, a diagnostic feature of mammalian liver histology.
47. The structural joint between the cranial bones of the skull is an example of a:
Correct Answer: A (Fibrous joint)
Cranial bones are held tightly edge-to-edge by dense fibrous connective tissue forming immovable suture joints to protect the brain.
Cranial bones are held tightly edge-to-edge by dense fibrous connective tissue forming immovable suture joints to protect the brain.
48. Unmyelinated nerve fibers are enclosed by Schwann cells without forming a myelin sheath and are commonly found in the:
Correct Answer: B (Autonomous and somatic neural systems)
Unmyelinated axons are enclosed by Schwann cells without myelin wrapping, typically found in autonomous and somatic nerves. Myelinated fibers occur in spinal and cranial nerves and central white matter.
Unmyelinated axons are enclosed by Schwann cells without myelin wrapping, typically found in autonomous and somatic nerves. Myelinated fibers occur in spinal and cranial nerves and central white matter.
49. Which cerebral region serves as the principal center for controlling body temperature, hunger, thirst, and neurohormone synthesis?
Correct Answer: B (Hypothalamus)
The hypothalamus contains neurosecretory nuclei regulating thermoregulation, hunger, thirst, circadian rhythms, and endocrine release via the pituitary gland.
The hypothalamus contains neurosecretory nuclei regulating thermoregulation, hunger, thirst, circadian rhythms, and endocrine release via the pituitary gland.
50. A decrease in blood calcium levels (hypocalcemia) triggers the release of:
Correct Answer: B (Parathyroid hormone)
Hypocalcemia stimulates parathyroid glands to release PTH, which mobilizes calcium from bones into the blood and increases renal tubular calcium reabsorption.
Hypocalcemia stimulates parathyroid glands to release PTH, which mobilizes calcium from bones into the blood and increases renal tubular calcium reabsorption.
51. Transfer of pollen grains from the anther to the stigma of another flower on the SAME plant is called:
Correct Answer: B (Geitonogamy)
Geitonogamy is functionally cross-pollination involving a pollinator, but genetically equivalent to autogamy since pollens come from the same parent plant.
Geitonogamy is functionally cross-pollination involving a pollinator, but genetically equivalent to autogamy since pollens come from the same parent plant.
52. The protective sheath enclosing the embryonic shoot apex and leaf primordia in a monocot seed is the:
Correct Answer: A (Coleoptile)
In grass embryos, the epicotyl with shoot apex is enclosed in a foliar sheath called the coleoptile. The radicle and root cap are enclosed by the coleorhiza.
In grass embryos, the epicotyl with shoot apex is enclosed in a foliar sheath called the coleoptile. The radicle and root cap are enclosed by the coleorhiza.
53. Parthenocarpic fruits (such as seedless bananas) develop:
Correct Answer: A (Without fertilization of the ovary)
Parthenocarpy is fruit development without prior ovule fertilization, resulting in seedless fruits (e.g., banana, or induced with auxins).
Parthenocarpy is fruit development without prior ovule fertilization, resulting in seedless fruits (e.g., banana, or induced with auxins).
54. Sertoli cells present in the seminiferous tubules are regulated by which pituitary hormone and perform what function?
Correct Answer: B (FSH; nourish developing spermatogenic cells)
FSH acts on Sertoli (nurse) cells to stimulate spermiogenesis and secretes androgen-binding protein (ABP) and inhibin.
FSH acts on Sertoli (nurse) cells to stimulate spermiogenesis and secretes androgen-binding protein (ABP) and inhibin.
55. During human oogenesis, the first polar body is formed during:
Correct Answer: B (Completion of Meiosis I)
The primary oocyte completes its unequal first meiotic division inside the mature tertiary follicle just prior to ovulation, yielding a large haploid secondary oocyte and a tiny first polar body.
The primary oocyte completes its unequal first meiotic division inside the mature tertiary follicle just prior to ovulation, yielding a large haploid secondary oocyte and a tiny first polar body.
56. Which hormone maintains the secretory integrity of the uterine endometrium required for blastocyst implantation and pregnancy?
Correct Answer: B (Progesterone)
Progesterone secreted by the corpus luteum maintains the vascular, glandular endometrial layer. Its withdrawal triggers menstruation.
Progesterone secreted by the corpus luteum maintains the vascular, glandular endometrial layer. Its withdrawal triggers menstruation.
57. The non-cellular glycoprotein coat surrounding the plasma membrane of a mammalian secondary oocyte is the:
Correct Answer: B (Zona pellucida)
The zona pellucida is an acellular glycoprotein matrix secreted by the primary/secondary oocyte. Sperm interaction with ZP3 receptors triggers the acrosome reaction.
The zona pellucida is an acellular glycoprotein matrix secreted by the primary/secondary oocyte. Sperm interaction with ZP3 receptors triggers the acrosome reaction.
58. The milk ejection reflex (let-down reflex) during lactation is triggered by the neuroendocrine release of:
Correct Answer: B (Oxytocin)
Prolactin stimulates milk synthesis in alveoli, whereas oxytocin stimulates contraction of myoepithelial cells surrounding mammary alveoli to eject milk.
Prolactin stimulates milk synthesis in alveoli, whereas oxytocin stimulates contraction of myoepithelial cells surrounding mammary alveoli to eject milk.
59. Medical Termination of Pregnancy (MTP) Amendment Act of India permits legal abortion up to 20 weeks with the opinion of one registered medical practitioner, and up to how many weeks for special categories of women?
Correct Answer: B (24 weeks)
Under the MTP Amendment Act, gestation limits extend up to 24 weeks for vulnerable categories (survivors of rape, minors, fetal abnormalities) with approval from two medical practitioners.
Under the MTP Amendment Act, gestation limits extend up to 24 weeks for vulnerable categories (survivors of rape, minors, fetal abnormalities) with approval from two medical practitioners.
60. In an Assisted Reproductive Technology (ART) clinic, transferring an in vitro fertilized embryo with MORE than 8 blastomeres into the uterus is termed:
Correct Answer: C (IUT)
Embryos up to 8 blastomeres are transferred into the fallopian tube (ZIFT), whereas embryos beyond 8 blastomeres are transferred directly into the uterine cavity (IUT).
Embryos up to 8 blastomeres are transferred into the fallopian tube (ZIFT), whereas embryos beyond 8 blastomeres are transferred directly into the uterine cavity (IUT).
61. In snapdragon (Antirrhinum majus), crossing a pure red-flowered plant (RR) with a pure white-flowered plant (rr) yields all pink-flowered F1 plants (Rr). Selfing these F1 plants gives an F2 genotypic ratio of:
Correct Answer: B (1 : 2 : 1)
Incomplete dominance results in identical phenotypic and genotypic ratios in the F2 generation: 1 Red (RR) : 2 Pink (Rr) : 1 White (rr).
Incomplete dominance results in identical phenotypic and genotypic ratios in the F2 generation: 1 Red (RR) : 2 Pink (Rr) : 1 White (rr).
62. How many genetically distinct types of gametes can be produced by an individual with genotype AaBbCc?
Correct Answer: C (8)
Number of gametic types = 2^n, where n is the number of heterozygous gene loci. Here n = 3 (Aa, Bb, Cc), so 2^3 = 8 gamete combinations.
Number of gametic types = 2^n, where n is the number of heterozygous gene loci. Here n = 3 (Aa, Bb, Cc), so 2^3 = 8 gamete combinations.
63. A human female with Turner’s syndrome exhibits which karyotypic profile and clinical features?
Correct Answer: B (45, XO; sterile female with rudimentary ovaries)
Turner’s syndrome results from monosomy of the X chromosome (44 autosomes + XO = 45), producing sterile females with short stature, webbed neck, and underdeveloped secondary sexual traits.
Turner’s syndrome results from monosomy of the X chromosome (44 autosomes + XO = 45), producing sterile females with short stature, webbed neck, and underdeveloped secondary sexual traits.
64. In a classic experiment by Avery, MacLeod, and McCarty, transformation of live R-strain pneumococci into virulent S-strain was inhibited only by adding:
Correct Answer: C (DNase enzyme)
Proteases and RNases did not affect transformation, whereas deoxyribonuclease (DNase) abolished transforming activity, establishing DNA as the chemical basis of heredity.
Proteases and RNases did not affect transformation, whereas deoxyribonuclease (DNase) abolished transforming activity, establishing DNA as the chemical basis of heredity.
65. The pitch of a standard B-DNA double helix and the distance between adjacent base pairs are:
Correct Answer: A (3.4 nm and 0.34 nm)
In B-DNA, each helical turn spans 3.4 nm and accommodates ~10 base pairs, spacing adjacent stacked base pairs 0.34 nm apart.
In B-DNA, each helical turn spans 3.4 nm and accommodates ~10 base pairs, spacing adjacent stacked base pairs 0.34 nm apart.
66. Splicing of eukaryotic hnRNA involves removing non-coding sequences called ______ and joining coding sequences called ______:
Correct Answer: B (Introns; Exons)
Spliceosomes excise non-coding intervening sequences (introns) from hnRNA and ligate expressed coding sequences (exons) to yield mature mRNA.
Spliceosomes excise non-coding intervening sequences (introns) from hnRNA and ligate expressed coding sequences (exons) to yield mature mRNA.
67. The presence of non-sense (termination) codons in an mRNA stops translation. Which of the following is a STOP codon?
Correct Answer: C (UAA)
UAA (ochre), UAG (amber), and UGA (opal) do not bind aminoacyl-tRNAs; they bind release factors that terminate polypeptide chain elongation.
UAA (ochre), UAG (amber), and UGA (opal) do not bind aminoacyl-tRNAs; they bind release factors that terminate polypeptide chain elongation.
68. Flippers of penguins and dolphins performing similar swimming functions despite differing anatomical origins exemplify:
Correct Answer: B (Analogy arising from convergent evolution)
Penguin flippers (modified avian wings) and dolphin flippers (modified mammalian forelimbs) share different anatomical ancestries but adapted convergently for swimming.
Penguin flippers (modified avian wings) and dolphin flippers (modified mammalian forelimbs) share different anatomical ancestries but adapted convergently for swimming.
69. Evolution of multiple Australian marsupials (e.g., Tasmanian wolf, sugar glider, wombat) from an ancestral stock within an isolated island continent is a classic demonstration of:
Correct Answer: A (Adaptive radiation)
Adaptive radiation is the diversification of a founder species into diverse ecological niches within an isolated geographical region.
Adaptive radiation is the diversification of a founder species into diverse ecological niches within an isolated geographical region.
70. Which extinct human ancestor lived in East and Central Africa ~2 million years ago, hunted with stone weapons, but primarily ate fruits?
Correct Answer: C (Australopithecus)
Australopithecines lived in African grasslands ~2 million years ago, made primitive stone weapons, walked erect, and had a fruit-based diet.
Australopithecines lived in African grasslands ~2 million years ago, made primitive stone weapons, walked erect, and had a fruit-based diet.
71. The common cold differs from pneumonia in that the common cold virus (Rhinovirus):
Correct Answer: B (Infects nose and passage but spares lungs)
Rhinoviruses infect upper respiratory mucosal membranes without compromising the pulmonary alveoli, distinguishing common colds from pneumonia.
Rhinoviruses infect upper respiratory mucosal membranes without compromising the pulmonary alveoli, distinguishing common colds from pneumonia.
72. Which primary cell type acts as an “HIV factory” by continuously generating new viral progeny via reverse transcription?
Correct Answer: B (Macrophages)
HIV enters host macrophages where its RNA genome replicates into viral DNA via reverse transcriptase. Macrophages survive and release viral progeny continuously, acting as HIV factories.
HIV enters host macrophages where its RNA genome replicates into viral DNA via reverse transcriptase. Macrophages survive and release viral progeny continuously, acting as HIV factories.
73. Morphine, a potent narcotic analgesic given to surgical patients, is chemically extracted from the latex of:
Correct Answer: A (Papaver somniferum)
Morphine is an opiate alkaloid obtained from the dried latex of unripened capsules of Papaver somniferum (opium poppy) and acts as an effective sedative and painkiller.
Morphine is an opiate alkaloid obtained from the dried latex of unripened capsules of Papaver somniferum (opium poppy) and acts as an effective sedative and painkiller.
74. The graft rejection response in patients following allogeneic organ transplantation is mediated primarily by:
Correct Answer: B (Cell-Mediated Immunity)
T-lymphocytes recognize foreign major histocompatibility complex (MHC/HLA) surface antigens on donor tissue, mounting cell-mediated immune graft rejection.
T-lymphocytes recognize foreign major histocompatibility complex (MHC/HLA) surface antigens on donor tissue, mounting cell-mediated immune graft rejection.
75. The yellowish fluid “Colostrum” secreted by the mother during initial lactation days provides natural passive immunity because it is rich in:
Correct Answer: A (IgA antibodies)
Colostrum is rich in secretory IgA antibodies, providing crucial passive mucosal immunity to the newborn’s gastrointestinal and respiratory tracts.
Colostrum is rich in secretory IgA antibodies, providing crucial passive mucosal immunity to the newborn’s gastrointestinal and respiratory tracts.
76. The fermented beverage “Toddy” is made by fermenting sap from palm trees using:
Correct Answer: B (Wild yeasts)
Toddy is a traditional fermented drink from Southern India produced by wild yeast fermentation of collected sugary palm sap.
Toddy is a traditional fermented drink from Southern India produced by wild yeast fermentation of collected sugary palm sap.
77. The immunosuppressive agent Cyclosporin A and the blood cholesterol lowering Statin are produced respectively by:
Correct Answer: A (Trichoderma polysporum and Monascus purpureus)
Cyclosporin A is produced by the fungus Trichoderma polysporum; Statins are produced by the yeast Monascus purpureus (acting by competitively inhibiting HMG-CoA reductase).
Cyclosporin A is produced by the fungus Trichoderma polysporum; Statins are produced by the yeast Monascus purpureus (acting by competitively inhibiting HMG-CoA reductase).
78. During biological sewage treatment, Biochemical Oxygen Demand (BOD) reflects:
Correct Answer: B (Amount of oxygen consumed during organic oxidation)
BOD measures the organic waste content in wastewater; higher BOD indicates greater organic pollution.
BOD measures the organic waste content in wastewater; higher BOD indicates greater organic pollution.
79. Baculoviruses of the genus Nucleopolyhedrovirus are utilized as biocontrol agents because they:
Correct Answer: B (Species-specific, narrow-spectrum insecticides)
Baculoviruses target specific pest insect complexes and arthropods without harming birds, mammals, plants, or non-target insects, making them ideal for IPM.
Baculoviruses target specific pest insect complexes and arthropods without harming birds, mammals, plants, or non-target insects, making them ideal for IPM.
80. An aquatic fern that serves as an excellent biofertilizer in paddy fields due to its symbiotic nitrogen-fixing cyanobacterium (Anabaena) is:
Correct Answer: B (Azolla)
The floating freshwater fern Azolla harbors Anabaena azollae in its dorsal leaf cavities, fixing atmospheric nitrogen and boosting rice crop yields.
The floating freshwater fern Azolla harbors Anabaena azollae in its dorsal leaf cavities, fixing atmospheric nitrogen and boosting rice crop yields.
81. Restriction endonucleases cleave DNA molecules by hydrolyzing:
Correct Answer: B (Phosphodiester bonds at specific palindromes)
Restriction endonucleases recognize specific palindromic sequences and cut internal phosphodiester bonds on both strands of the DNA duplex.
Restriction endonucleases recognize specific palindromic sequences and cut internal phosphodiester bonds on both strands of the DNA duplex.
82. In recombinant plasmid pBR322, the PstI restriction site is located within which selectable marker gene?
Correct Answer: A (Ampicillin resistance gene)
The ampR gene contains PstI and PvuI restriction sites, while the tetR gene contains BamHI and SalI sites.
The ampR gene contains PstI and PvuI restriction sites, while the tetR gene contains BamHI and SalI sites.
83. The process of forcing recombinant DNA into competent bacterial cells via transient ice-to-42°C thermal shifts is called:
Correct Answer: C (Heat shock treatment)
Competent bacteria incubated with rDNA on ice are subjected to a brief 42°C heat shock and returned to ice, enabling plasmid uptake through membrane pores.
Competent bacteria incubated with rDNA on ice are subjected to a brief 42°C heat shock and returned to ice, enabling plasmid uptake through membrane pores.
84. The thermostable Taq polymerase used in PCR reactions is isolated from:
Correct Answer: B (Thermus aquaticus)
Taq DNA polymerase is extracted from the thermophilic bacterium Thermus aquaticus and withstands high-temperature denaturation steps (~94°C) without denaturing.
Taq DNA polymerase is extracted from the thermophilic bacterium Thermus aquaticus and withstands high-temperature denaturation steps (~94°C) without denaturing.
85. Bt crystal toxin (Cry protein) produced by Bacillus thuringiensis is insecticidal because:
Correct Answer: B (Alkaline pH solubilizes crystals to create pores)
The inactive protoxin dissolves in the alkaline midgut of susceptible insect larvae, binding to midgut epithelial cells and forming lytic pores that cause gut perforation.
The inactive protoxin dissolves in the alkaline midgut of susceptible insect larvae, binding to midgut epithelial cells and forming lytic pores that cause gut perforation.
86. The nematode pest that infects the roots of tobacco plants and was controlled using transgenic RNA interference (RNAi) is:
Correct Answer: A (Meloidogyne incognita)
Meloidogyne incognita infects tobacco roots, causing root knots. Introducing nematode-specific dsRNA via Agrobacterium vectors silences essential parasite mRNAs.
Meloidogyne incognita infects tobacco roots, causing root knots. Introducing nematode-specific dsRNA via Agrobacterium vectors silences essential parasite mRNAs.
87. Mature functional human insulin differs from proinsulin in that mature insulin lacks the:
Correct Answer: C (C-peptide)
Proinsulin contains an extra connecting C-peptide sequence (31 amino acids) that is cleaved during proteolytic maturation, leaving chains A and B joined by disulfide bonds.
Proinsulin contains an extra connecting C-peptide sequence (31 amino acids) that is cleaved during proteolytic maturation, leaving chains A and B joined by disulfide bonds.
88. The clinical gene therapy administered in 1990 to treat a 4-year-old girl with severe combined immunodeficiency targeted a deficiency in:
Correct Answer: B (Adenosine Deaminase)
ADA deficiency impairs purine metabolism and cripples T/B-cell immunity. Gene therapy introduced functional ADA cDNA into the patient’s lymphocytes using a retroviral vector.
ADA deficiency impairs purine metabolism and cripples T/B-cell immunity. Gene therapy introduced functional ADA cDNA into the patient’s lymphocytes using a retroviral vector.
89. The transgenic cow ‘Rosie’ (1997) produced humanized milk enriched with 2.4 grams per liter of:
Correct Answer: B (Human alpha-lactalbumin)
Rosie produced milk containing human alpha-lactalbumin (2.4 g/L), making it nutritionally more balanced for human infants than natural cow’s milk.
Rosie produced milk containing human alpha-lactalbumin (2.4 g/L), making it nutritionally more balanced for human infants than natural cow’s milk.
90. In India, the apex statutory body responsible for reviewing genetically modified organism (GMO) research and approving commercial GM crop releases is:
Correct Answer: C (GEAC)
The Genetic Engineering Appraisal Committee (under MoEFCC) evaluates biosafety, environmental impacts, and commercial approvals for GM organisms.
The Genetic Engineering Appraisal Committee (under MoEFCC) evaluates biosafety, environmental impacts, and commercial approvals for GM organisms.
91. In the logistic population growth equation dN/dt = rN((K – N)/K), the letter ‘K’ represents:
Correct Answer: B (Carrying capacity)
K represents carrying capacity—the maximum population size that a habitat’s limiting resources can sustain indefinitely.
K represents carrying capacity—the maximum population size that a habitat’s limiting resources can sustain indefinitely.
92. The interaction between cattle egrets foraging near grazing livestock to feed on flushed insects is an example of:
Correct Answer: B (Commensalism)
The egrets benefit by capturing insects stirred up by grazing cattle, while the livestock are unaffected (+, 0 interaction).
The egrets benefit by capturing insects stirred up by grazing cattle, while the livestock are unaffected (+, 0 interaction).
93. Lichens (mutualistic association between algae and fungi) and Mycorrhizae (fungi with roots of higher plants) are classic examples of:
Correct Answer: B (Mutualism)
Mutualism is an obligate ecological interaction where both participating species derive reciprocal physiological and nutritional benefits (+, +).
Mutualism is an obligate ecological interaction where both participating species derive reciprocal physiological and nutritional benefits (+, +).
94. The rate of biomass formation by heterotrophic consumers per unit area and time is designated as:
Correct Answer: C (Secondary Productivity)
Secondary productivity is the rate of new organic biomass synthesis by consumers (herbivores and carnivores) using assimilated food energy.
Secondary productivity is the rate of new organic biomass synthesis by consumers (herbivores and carnivores) using assimilated food energy.
95. In a grassland ecosystem, a pyramid of numbers showing 5,842,000 primary producers supporting 3 top carnivores is:
Correct Answer: A (Upright)
Grassland pyramids of numbers are upright: millions of grass plants support thousands of herbivores, fewer primary carnivores, and very few apex carnivores.
Grassland pyramids of numbers are upright: millions of grass plants support thousands of herbivores, fewer primary carnivores, and very few apex carnivores.
96. Which ecosystem service did Robert Costanza calculate as accounting for approximately 50% of the total estimated value of planetary ecosystem services?
Correct Answer: C (Soil formation)
Out of the total global ecosystem services value (~US $33 trillion/year), soil formation accounts for roughly 50%, while recreation and nutrient cycling account for <10% each.
Out of the total global ecosystem services value (~US $33 trillion/year), soil formation accounts for roughly 50%, while recreation and nutrient cycling account for <10% each.
97. The tropical Amazon rainforest is known as the “Lungs of the planet” because it produces an estimated:
Correct Answer: B (20% of total planetary oxygen)
The Amazon rainforest spans millions of square kilometers in South America and produces roughly 20% of the Earth’s atmospheric oxygen.
The Amazon rainforest spans millions of square kilometers in South America and produces roughly 20% of the Earth’s atmospheric oxygen.
98. Which invasive alien catfish introduced illegally for aquaculture purposes in India poses a severe threat to indigenous freshwater fishes?
Correct Answer: C (Clarias gariepinus)
The illegal introduction of the aggressive African catfish (Clarias gariepinus) has threatened indigenous riverine catfishes across India.
The illegal introduction of the aggressive African catfish (Clarias gariepinus) has threatened indigenous riverine catfishes across India.
99. Preserving endangered gametes in viable, fertile condition for long durations in liquid nitrogen at -196°C is known as:
Correct Answer: C (Cryopreservation)
Cryopreservation stores seeds, pollen, tissue cultures, and gametes in liquid nitrogen (-196°C) for long-term ex-situ conservation.
Cryopreservation stores seeds, pollen, tissue cultures, and gametes in liquid nitrogen (-196°C) for long-term ex-situ conservation.
100. In India, Sacred Groves in Meghalaya that serve as last refuges for many rare and threatened endemic plants are located in the:
Correct Answer: A (Khasi and Jaintia Hills)
The Khasi and Jaintia Hills in Meghalaya host sacred groves protected by indigenous communities, preserving threatened plant species.
The Khasi and Jaintia Hills in Meghalaya host sacred groves protected by indigenous communities, preserving threatened plant species.