1. Organisms belonging to the same Order must also belong to the same:
Correct Answer: C (Class)
In the taxonomic hierarchy, Order is nested within Class. Therefore, all organisms in a specific Order automatically share the same Class, Phylum/Division, and Kingdom.
In the taxonomic hierarchy, Order is nested within Class. Therefore, all organisms in a specific Order automatically share the same Class, Phylum/Division, and Kingdom.
2. Which group of photosynthetic protists possess two flagella (one longitudinal and one transverse in a furrow) and cause toxic “red tides”?
Correct Answer: B (Dinoflagellates)
Red dinoflagellates like Gonyaulax undergo rapid population blooms that turn the sea red (red tides) and secrete saxitoxins that kill marine life.
Red dinoflagellates like Gonyaulax undergo rapid population blooms that turn the sea red (red tides) and secrete saxitoxins that kill marine life.
3. “Diatomaceous earth” is indestructible and used in polishing, filtration of oils, and syrups because the cell walls of diatoms are embedded with:
Correct Answer: B (Silica)
Diatom walls form two overlapping shells embedded with silica (frustule), which remain indestructible and accumulate over billions of years as diatomaceous earth.
Diatom walls form two overlapping shells embedded with silica (frustule), which remain indestructible and accumulate over billions of years as diatomaceous earth.
4. Neurospora crassa, extensively used as a model organism in biochemical and genetic research, belongs to the fungal class:
Correct Answer: B (Ascomycetes)
Neurospora (along with Claviceps and Aspergillus) is an ascomycete (sac fungus) widely utilized in biochemical genetics and gene mapping.
Neurospora (along with Claviceps and Aspergillus) is an ascomycete (sac fungus) widely utilized in biochemical genetics and gene mapping.
5. Hydrocolloids such as Algin and Carrageen are commercially extracted from:
Correct Answer: B (Brown algae and Red algae respectively)
Algin is produced by marine brown algae (e.g., Laminaria, Fucus), while carrageen is harvested from red algae (e.g., Chondrus crispus).
Algin is produced by marine brown algae (e.g., Laminaria, Fucus), while carrageen is harvested from red algae (e.g., Chondrus crispus).
6. The predominant, free-living, photosynthetic phase in the life cycle of a bryophyte (moss/liverwort) is the:
Correct Answer: B (Haploid gametophyte)
The dominant independent generation in bryophytes is the haploid gametophyte (thalloid or leafy). The sporophyte is physically attached to and nutritionally dependent on the gametophyte.
The dominant independent generation in bryophytes is the haploid gametophyte (thalloid or leafy). The sporophyte is physically attached to and nutritionally dependent on the gametophyte.
7. Which gymnosperm is commonly called a “living fossil” and produces motile, multiflagellated male gametes?
Correct Answer: C (Ginkgo biloba)
Ginkgo biloba is an ancient surviving gymnosperm with unsegmented fan-shaped leaves and swimming male gametes, earning its classification as a living fossil.
Ginkgo biloba is an ancient surviving gymnosperm with unsegmented fan-shaped leaves and swimming male gametes, earning its classification as a living fossil.
8. Comb plates (eight external rows of ciliated comb plates) for locomotion and distinct bioluminescence are characteristic of:
Correct Answer: B (Ctenophora)
Ctenophores (e.g., Pleurobrachia, Ctenoplana) uniquely possess 8 ciliated comb plates for swimming, emit bioluminescent light, and reproduce exclusively sexually.
Ctenophores (e.g., Pleurobrachia, Ctenoplana) uniquely possess 8 ciliated comb plates for swimming, emit bioluminescent light, and reproduce exclusively sexually.
9. A rasping tongue-like feeding organ called a “radula” is found in the mouth of animals belonging to phylum:
Correct Answer: C (Mollusca)
Molluscs (e.g., Pila, Aplysia, Octopus) possess a chitinous ribbon-like radula bearing transverse rows of teeth used for scraping food.
Molluscs (e.g., Pila, Aplysia, Octopus) possess a chitinous ribbon-like radula bearing transverse rows of teeth used for scraping food.
10. Operculum (gill cover on each side) and an air bladder regulating buoyancy are present in:
Correct Answer: B (Osteichthyes)
Bony fishes have four pairs of gills covered by an operculum and a swim/air bladder that provides hydrostatic balance, unlike cartilaginous sharks that must swim constantly.
Bony fishes have four pairs of gills covered by an operculum and a swim/air bladder that provides hydrostatic balance, unlike cartilaginous sharks that must swim constantly.
11. Stem thorns of Bougainvillea and tendrils of Cucurbita represent:
Correct Answer: A (Homologous organs from axillary bud modifications)
Both thorns of Bougainvillea and tendrils of Passiflora/Cucurbita originate as modified axillary buds, serving different functions (defense vs. climbing) as homologous organs.
Both thorns of Bougainvillea and tendrils of Passiflora/Cucurbita originate as modified axillary buds, serving different functions (defense vs. climbing) as homologous organs.
12. In family Solanaceae, the gynoecium is typically characterized by:
Correct Answer: B (Bicarpellary syncarpous, superior with obliquely placed swollen placenta)
Solanaceae (potato/tomato family) is identified by an obliquely placed bicarpellary syncarpous superior ovary with a swollen axile placenta bearing many ovules.
Solanaceae (potato/tomato family) is identified by an obliquely placed bicarpellary syncarpous superior ovary with a swollen axile placenta bearing many ovules.
13. The ray florets of sunflower (family Asteraceae/Compositae) possess an ovary that is:
Correct Answer: B (Inferior)
In epigynous flowers (e.g., ray florets of sunflower, guava, cucumber), the thalamus encloses the ovary completely and fuses with it, situating the ovary below other floral whorls.
In epigynous flowers (e.g., ray florets of sunflower, guava, cucumber), the thalamus encloses the ovary completely and fuses with it, situating the ovary below other floral whorls.
14. Bulliform (motor) cells present in the upper epidermis of monocot (grass) leaves help in:
Correct Answer: B (Inward rolling of leaves to minimize transpiration)
Bulliform cells are large, empty, flaccid cells in grass leaves. During drought stress, they lose turgor and cause leaf margins to curl inward to reduce exposed surface area.
Bulliform cells are large, empty, flaccid cells in grass leaves. During drought stress, they lose turgor and cause leaf margins to curl inward to reduce exposed surface area.
15. Lenticels are lens-shaped aerating openings in the periderm of woody stems formed due to the activity of:
Correct Answer: B (Phellogen)
Phellogen cuts off loosely arranged, non-suberized parenchymatous complementary cells that rupture the epidermis to form lenticels for gaseous exchange.
Phellogen cuts off loosely arranged, non-suberized parenchymatous complementary cells that rupture the epidermis to form lenticels for gaseous exchange.
16. The supportive structural skeletal tissue found in the external ear pinna and tip of the nose is:
Correct Answer: B (Elastic cartilage)
Elastic cartilage containing a dense network of yellow elastin fibers provides flexibility and recoil to the pinna, external auditory meatus, and epiglottis.
Elastic cartilage containing a dense network of yellow elastin fibers provides flexibility and recoil to the pinna, external auditory meatus, and epiglottis.
17. In the digestive system of the frog, bile juice produced by the liver and pancreatic secretions enter the duodenum through a common:
Correct Answer: B (Common bile-pancreatic duct)
The gallbladder and pancreas release their digestive enzymes into the duodenum via a shared common hepatopancreatic duct.
The gallbladder and pancreas release their digestive enzymes into the duodenum via a shared common hepatopancreatic duct.
18. The triangular venous chamber on the dorsal surface of a frog’s heart that receives deoxygenated blood from the venae cavae is the:
Correct Answer: A (Sinus venosus)
Sinus venosus is a thin-walled triangular chamber on the dorsal side of the frog heart that collects systemic venous blood from three venae cavae and opens into the right atrium.
Sinus venosus is a thin-walled triangular chamber on the dorsal side of the frog heart that collects systemic venous blood from three venae cavae and opens into the right atrium.
19. In female frogs, mature ova from both ovaries are discharged into the cloaca separately via:
Correct Answer: B (Oviducts opening independently)
Unlike male frogs whose ureters convey both urine and sperm, female frogs possess independent paired oviducts that open separately into the cloaca.
Unlike male frogs whose ureters convey both urine and sperm, female frogs possess independent paired oviducts that open separately into the cloaca.
20. The transparent third eyelid in frogs that protects the eyes while submerged underwater is the:
Correct Answer: B (Nictitating membrane)
The nictitating membrane is a transparent fold of skin drawn over the frog’s eyeball to protect it underwater while maintaining vision.
The nictitating membrane is a transparent fold of skin drawn over the frog’s eyeball to protect it underwater while maintaining vision.
21. Inclusion bodies in prokaryotic cells (e.g., cyanophycean granules, glycogen granules, and phosphate granules) are:
Correct Answer: B (Non-membrane-bound reserve materials lying freely)
Prokaryotic inclusion bodies store nutrient reserves and float freely in the cytoplasm without enclosing phospholipid membranes.
Prokaryotic inclusion bodies store nutrient reserves and float freely in the cytoplasm without enclosing phospholipid membranes.
22. The “cis” (forming) and “trans” (maturing) faces of the Golgi apparatus are:
Correct Answer: B (Convex cis and Concave trans, biochemically distinct)
Transport vesicles from the ER fuse with the convex cis face, traverse the cisternae, and leave as secretory vesicles from the concave trans face.
Transport vesicles from the ER fuse with the convex cis face, traverse the cisternae, and leave as secretory vesicles from the concave trans face.
23. Hydrolytic enzymes found in lysosomes (acid hydrolases like lipases, proteases, carbohydrases) operate optimally at:
Correct Answer: B (Acidic pH ~5.0)
Lysosomes maintain an internal acidic pH (~5) via active proton pumps (H+ ATPases) on their membrane, providing the optimal environment for acid hydrolases.
Lysosomes maintain an internal acidic pH (~5) via active proton pumps (H+ ATPases) on their membrane, providing the optimal environment for acid hydrolases.
24. The core microtubular structure of eukaryotic centrioles and basal bodies displays an organization of:
Correct Answer: B (9 + 0 triplets of tubulin)
Centrioles exhibit a cartwheel architecture comprising 9 evenly spaced peripheral triplets of tubulin without central microtubules (9 + 0 array).
Centrioles exhibit a cartwheel architecture comprising 9 evenly spaced peripheral triplets of tubulin without central microtubules (9 + 0 array).
25. Lecithin, an important component of biological cell membranes, is chemically classified as a:
Correct Answer: B (Phospholipid)
Lecithin (phosphatidylcholine) is a major structural phospholipid composed of glycerol, two fatty acids, a phosphate group, and a choline molecule.
Lecithin (phosphatidylcholine) is a major structural phospholipid composed of glycerol, two fatty acids, a phosphate group, and a choline molecule.
26. In the secondary structure of proteins, the alpha-helix conformation is stabilized by:
Correct Answer: B (Intramolecular hydrogen bonds)
Alpha-helical protein spirals are stabilized by regular intramolecular hydrogen bonding between the C=O of each amino acid and the N-H of the fourth residue ahead.
Alpha-helical protein spirals are stabilized by regular intramolecular hydrogen bonding between the C=O of each amino acid and the N-H of the fourth residue ahead.
27. A non-protein organic group that is tightly and permanently bound to the apoenzyme (such as heme in peroxidase and catalase) is a:
Correct Answer: B (Prosthetic group)
Prosthetic groups are organic cofactors bound tightly and continuously to the catalytic apoenzyme subunit (e.g., heme in catalase/peroxidase).
Prosthetic groups are organic cofactors bound tightly and continuously to the catalytic apoenzyme subunit (e.g., heme in catalase/peroxidase).
28. Terminalization of chiasmata and breakdown of the nuclear envelope mark the completion of:
Correct Answer: D (Diakinesis)
Diakinesis is the final stage of meiotic Prophase I, recognized by full chiasmata terminalization, nucleolus disappearance, and nuclear envelope breakdown.
Diakinesis is the final stage of meiotic Prophase I, recognized by full chiasmata terminalization, nucleolus disappearance, and nuclear envelope breakdown.
29. Cells that exit the active mitotic cycle and enter a quiescent, metabolically active non-dividing state are in:
Correct Answer: A (G0 phase)
Cells that suspend division (e.g., adult neurons, heart muscle cells) exit G1 into a quiescent G0 stage where they remain metabolically functional without replicating DNA.
Cells that suspend division (e.g., adult neurons, heart muscle cells) exit G1 into a quiescent G0 stage where they remain metabolically functional without replicating DNA.
30. The disc-shaped protein complexes located on the centromere to which spindle fibers attach during cell division are:
Correct Answer: B (Kinetochores)
Kinetochores are trilaminar protein plates on either side of the primary centromeric constriction where microtubules anchor during metaphase.
Kinetochores are trilaminar protein plates on either side of the primary centromeric constriction where microtubules anchor during metaphase.
31. In photosynthetic light reactions, Photosystem I (PS I) and Photosystem II (PS II) have reaction center absorption maxima at:
Correct Answer: A (700 nm and 680 nm respectively)
PS I features a reaction center chlorophyll a absorbing at 700 nm (P700), while PS II absorbs maximally at 680 nm (P680).
PS I features a reaction center chlorophyll a absorbing at 700 nm (P700), while PS II absorbs maximally at 680 nm (P680).
32. Cyclic photophosphorylation involves only Photosystem I and results in the production of:
Correct Answer: B (ATP only)
Cyclic electron transport operates in stroma lamellae (lacking PS II and NADP reductase), cycling electrons back to P700 and generating ATP without producing NADPH or evolving oxygen.
Cyclic electron transport operates in stroma lamellae (lacking PS II and NADP reductase), cycling electrons back to P700 and generating ATP without producing NADPH or evolving oxygen.
33. According to Mitchell’s chemiosmotic hypothesis, ATP synthesis in chloroplast thylakoids is driven by a proton gradient with high H+ concentration accumulating in the:
Correct Answer: B (Thylakoid lumen)
Water photolysis and plastoquinone proton pumping drive H+ ions into the thylakoid lumen, creating an electrochemical proton motive force across the thylakoid membrane.
Water photolysis and plastoquinone proton pumping drive H+ ions into the thylakoid lumen, creating an electrochemical proton motive force across the thylakoid membrane.
34. The primary 3-carbon stable fixation product formed when CO2 is accepted by RuBP in the C3 pathway is:
Correct Answer: A (3-Phosphoglyceric acid)
In C3 photosynthesis (discovered by Melvin Calvin), RuBisCO carboxylation of 5-carbon RuBP yields two molecules of 3-carbon 3-PGA.
In C3 photosynthesis (discovered by Melvin Calvin), RuBisCO carboxylation of 5-carbon RuBP yields two molecules of 3-carbon 3-PGA.
35. In C4 plants (e.g., maize, sorghum), the decarboxylation of 4-carbon malate to release CO2 for the Calvin cycle takes place in the:
Correct Answer: B (Bundle sheath cell chloroplasts)
Malic acid formed in mesophyll cells is transported into bundle sheath cells, where it is decarboxylated into pyruvate and CO2, saturating RuBisCO with CO2.
Malic acid formed in mesophyll cells is transported into bundle sheath cells, where it is decarboxylated into pyruvate and CO2, saturating RuBisCO with CO2.
36. In glycolysis, the irreversible conversion of Fructose-6-phosphate to Fructose-1,6-bisphosphate is catalyzed by the key regulatory pacemaker enzyme:
Correct Answer: B (Phosphofructokinase)
Phosphofructokinase is the rate-limiting, committed-step enzyme of glycolysis, converting F-6-P to F-1,6-BP using 1 ATP.
Phosphofructokinase is the rate-limiting, committed-step enzyme of glycolysis, converting F-6-P to F-1,6-BP using 1 ATP.
37. During anaerobic lactic acid and alcoholic fermentation, approximately what percentage of the total energy in a glucose molecule is released?
Correct Answer: A (Less than 7%)
Fermentation achieves incomplete oxidation of glucose, recovering less than 7% of its total bond enthalpy as 2 net ATP molecules.
Fermentation achieves incomplete oxidation of glucose, recovering less than 7% of its total bond enthalpy as 2 net ATP molecules.
38. In the mitochondrial Krebs cycle, which single enzyme complex is embedded directly in the inner mitochondrial membrane rather than dissolved in the matrix?
Correct Answer: C (Succinic dehydrogenase)
Succinate dehydrogenase is an integral membrane protein of the inner mitochondrial membrane (functioning directly as Complex II in the electron transport chain).
Succinate dehydrogenase is an integral membrane protein of the inner mitochondrial membrane (functioning directly as Complex II in the electron transport chain).
39. The bioassay widely employed for testing the physiological activity of Auxin hormones is the:
Correct Answer: A (Avena coleoptile curvature test)
F.W. Went demonstrated that decapitated oat (Avena sativa) coleoptiles curve proportionally in response to unilateral auxin diffusion from agar blocks.
F.W. Went demonstrated that decapitated oat (Avena sativa) coleoptiles curve proportionally in response to unilateral auxin diffusion from agar blocks.
40. Formation of interfascicular cambium and cork cambium (phellogen) from fully differentiated living parenchyma cells is an example of:
Correct Answer: B (Dedifferentiation)
Dedifferentiation occurs when mature, non-dividing parenchyma cells regain active mitotic capacity to form secondary meristems like cork cambium and interfascicular cambium.
Dedifferentiation occurs when mature, non-dividing parenchyma cells regain active mitotic capacity to form secondary meristems like cork cambium and interfascicular cambium.
41. The pneumotaxic center, which moderates respiratory rhythm by reducing the duration of inspiration, is located in the:
Correct Answer: A (Pons region)
The pneumotaxic center in the dorsal pons sends inhibitory impulses to the medullary respiratory rhythm generator, limiting inspiration and altering respiratory rates.
The pneumotaxic center in the dorsal pons sends inhibitory impulses to the medullary respiratory rhythm generator, limiting inspiration and altering respiratory rates.
42. Occupational lung disorders like Silicosis are pathologically marked by:
Correct Answer: B (Chronic inflammation leading to fibrosis)
Inhaled silica particles trigger long-term alveolar macrophage inflammation, causing widespread fibrotic nodule formation and loss of lung elasticity.
Inhaled silica particles trigger long-term alveolar macrophage inflammation, causing widespread fibrotic nodule formation and loss of lung elasticity.
43. Normal human systemic arterial blood pressure is recorded as 120/80 mm Hg, where 120 mm Hg and 80 mm Hg represent:
Correct Answer: A (Ventricular systolic and diastolic pressure)
120 mm Hg represents peak arterial pressure during ventricular systole (contraction), while 80 mm Hg reflects baseline arterial pressure during ventricular diastole (relaxation).
120 mm Hg represents peak arterial pressure during ventricular systole (contraction), while 80 mm Hg reflects baseline arterial pressure during ventricular diastole (relaxation).
44. A sudden acute chest pain radiating down the arm due to inadequate oxygen supply to myocardial tissue is known clinically as:
Correct Answer: C (Angina pectoris)
Angina pectoris manifests as acute retrosternal chest pain caused by transient myocardial ischemia due to narrowed coronary arteries.
Angina pectoris manifests as acute retrosternal chest pain caused by transient myocardial ischemia due to narrowed coronary arteries.
45. In hemodialysis, the dialyzing fluid has the exact same composition as normal plasma EXCEPT that it lacks:
Correct Answer: B (Nitrogenous wastes)
The dialysate lacks urea, creatinine, and uric acid, creating a concentration gradient that draws nitrogenous wastes out of patient blood across cellophane membranes.
The dialysate lacks urea, creatinine, and uric acid, creating a concentration gradient that draws nitrogenous wastes out of patient blood across cellophane membranes.
46. The functional unit of a skeletal muscle myofibril between two successive Z-lines is called a:
Correct Answer: B (Sarcomere)
A sarcomere spans between two adjacent Z-lines, comprising a complete central A-band and two flanking half I-bands.
A sarcomere spans between two adjacent Z-lines, comprising a complete central A-band and two flanking half I-bands.
47. Myasthenia gravis is an autoimmune disease characterized by antibodies directed against:
Correct Answer: B (Nicotinic Acetylcholine receptors)
Autoantibodies block and destroy post-synaptic acetylcholine receptors at the motor end plate, causing progressive skeletal muscle weakness and fatigue.
Autoantibodies block and destroy post-synaptic acetylcholine receptors at the motor end plate, causing progressive skeletal muscle weakness and fatigue.
48. The refractory period during nerve impulse propagation occurs when voltage-gated Na+ channels are inactivated and repolarization is driven by:
Correct Answer: B (Efflux of K+ ions out of the axon)
Following the action potential spike, voltage-gated K+ channels open, allowing rapid K+ efflux to restore negative resting membrane potential.
Following the action potential spike, voltage-gated K+ channels open, allowing rapid K+ efflux to restore negative resting membrane potential.
49. Which human endocrine gland is called the “Master Gland” because its tropic hormones regulate other peripheral endocrine glands?
Correct Answer: B (Anterior Pituitary)
The anterior pituitary produces trophic hormones (TSH, ACTH, FSH, LH) regulating the thyroid, adrenal cortex, and gonads under hypothalamic control.
The anterior pituitary produces trophic hormones (TSH, ACTH, FSH, LH) regulating the thyroid, adrenal cortex, and gonads under hypothalamic control.
50. Destruction or hypofunction of the adrenal cortex causing severe mineralocorticoid/glucocorticoid deficiency, bronze skin, and hypoglycemia leads to:
Correct Answer: B (Addison’s Disease)
Addison’s disease is caused by adrenal cortical hyposecretion, manifesting as low blood pressure, dehydration, electrolyte imbalance, weakness, and skin bronzing.
Addison’s disease is caused by adrenal cortical hyposecretion, manifesting as low blood pressure, dehydration, electrolyte imbalance, weakness, and skin bronzing.
51. In a typical flowering plant embryo sac, the antipodal cells are located at the:
Correct Answer: B (Chalazal end)
The three antipodal cells occupy the chalazal end of the embryo sac, while the egg apparatus (one egg cell and two synergids) is located at the micropylar end.
The three antipodal cells occupy the chalazal end of the embryo sac, while the egg apparatus (one egg cell and two synergids) is located at the micropylar end.
52. Water pollinated (hydrophilous) species like Vallisneria exhibit:
Correct Answer: A (Female flowers reaching water surface on long stalks)
In Vallisneria (epi-hydrophily), female flowers rise to the surface on long pedicels to receive pollen grains released by floating male flowers.
In Vallisneria (epi-hydrophily), female flowers rise to the surface on long pedicels to receive pollen grains released by floating male flowers.
53. Development of apomictic seeds directly from unreduced diploid nucellar cells surrounding the embryo sac is seen in:
Correct Answer: B (Citrus and Mango)
In Citrus and mango, maternal diploid nucellar cells proliferate and project into the embryo sac, forming multiple apomictic embryos (polyembryony).
In Citrus and mango, maternal diploid nucellar cells proliferate and project into the embryo sac, forming multiple apomictic embryos (polyembryony).
54. Leydig cells located in the testicular intertubular spaces synthesize testosterone when stimulated by:
Correct Answer: B (LH)
Luteinizing Hormone (LH/ICSH) from the anterior pituitary stimulates Leydig cells to produce testosterone, while FSH acts on Sertoli cells.
Luteinizing Hormone (LH/ICSH) from the anterior pituitary stimulates Leydig cells to produce testosterone, while FSH acts on Sertoli cells.
55. The structural cap covering the anterior half of the sperm nucleus containing hydrolytic enzymes is the:
Correct Answer: A (Acrosome)
The acrosome is a Golgi-derived vesicle containing sperm lysins (hyaluronidase and acrosin) that dissolve the zona pellucida during fertilization.
The acrosome is a Golgi-derived vesicle containing sperm lysins (hyaluronidase and acrosin) that dissolve the zona pellucida during fertilization.
56. The LH surge that induces ovulation and converts the ruptured Graafian follicle into the corpus luteum occurs around day:
Correct Answer: B (Day 14)
Rising estrogen levels trigger a mid-cycle surge of LH at ~day 14, causing the Graafian follicle to rupture and release the secondary oocyte.
Rising estrogen levels trigger a mid-cycle surge of LH at ~day 14, causing the Graafian follicle to rupture and release the secondary oocyte.
57. The hollow ball of cells with an outer trophoblast layer and an inner cell mass that implants into the endometrium is the:
Correct Answer: B (Blastocyst)
The blastocyst consists of an outer trophoblast layer (which adheres to the endometrium) and an inner cell mass that develops into the embryo.
The blastocyst consists of an outer trophoblast layer (which adheres to the endometrium) and an inner cell mass that develops into the embryo.
58. The hormone detected in qualitative home urine pregnancy tests is:
Correct Answer: B (hCG)
hCG is secreted by syncytiotrophoblast cells following implantation to rescue the corpus luteum, and its excretion in maternal urine forms the basis of pregnancy test kits.
hCG is secreted by syncytiotrophoblast cells following implantation to rescue the corpus luteum, and its excretion in maternal urine forms the basis of pregnancy test kits.
59. “Saheli”, a non-steroidal once-a-week oral contraceptive pill, was developed in India by:
Correct Answer: B (CDRI, Lucknow)
CDRI Lucknow developed Saheli (centchroman), a selective estrogen receptor modulator taken weekly with minimal side effects.
CDRI Lucknow developed Saheli (centchroman), a selective estrogen receptor modulator taken weekly with minimal side effects.
60. Which Assisted Reproductive Technique involves collecting an ovum from a donor and transferring it into the fallopian tube of a recipient female?
Correct Answer: C (GIFT)
GIFT is designed for women who cannot produce eggs but have patent fallopian tubes and a suitable uterus to support fertilization and pregnancy.
GIFT is designed for women who cannot produce eggs but have patent fallopian tubes and a suitable uterus to support fertilization and pregnancy.
61. In human blood groups, codominance is exhibited when an individual has the genotype:
Correct Answer: C (IA IB)
In IA IB heterozygotes, both alleles express their respective sugar polymers equally on erythrocyte membranes, creating the AB blood phenotype.
In IA IB heterozygotes, both alleles express their respective sugar polymers equally on erythrocyte membranes, creating the AB blood phenotype.
62. Experimental proof for the Chromosomal Theory of Inheritance was provided by T.H. Morgan using Drosophila melanogaster because:
Correct Answer: B (Two-week life cycle with large progeny numbers)
Drosophila is an ideal genetic model because it breeds easily in simple synthetic media, has a ~2-week life cycle, shows clear sexual dimorphism, and has only 4 chromosome pairs.
Drosophila is an ideal genetic model because it breeds easily in simple synthetic media, has a ~2-week life cycle, shows clear sexual dimorphism, and has only 4 chromosome pairs.
63. A classic pedigree chart showing inheritance of an autosomal dominant trait in humans is observed in:
Correct Answer: A (Myotonic dystrophy)
Myotonic dystrophy is an autosomal dominant disorder. Sickle cell anemia, cystic fibrosis, PKU, and thalassemia are autosomal recessive traits.
Myotonic dystrophy is an autosomal dominant disorder. Sickle cell anemia, cystic fibrosis, PKU, and thalassemia are autosomal recessive traits.
64. In eukaryotic DNA packaging, the nucleosome core particle is wrapped by approximately:
Correct Answer: B (200 base pairs of DNA)
A typical nucleosome consists of ~200 bp of negatively charged DNA wrapped around an octamer of basic histone proteins (two each of H2A, H2B, H3, and H4).
A typical nucleosome consists of ~200 bp of negatively charged DNA wrapped around an octamer of basic histone proteins (two each of H2A, H2B, H3, and H4).
65. Taylor and colleagues proved semiconservative replication of DNA in chromosomes using radioactive tritiated thymidine on:
Correct Answer: B (Vicia faba)
Taylor demonstrated semiconservative chromosome replication in plant root tip cells of Vicia faba using autoradiography with tritiated thymidine (3H-thymidine).
Taylor demonstrated semiconservative chromosome replication in plant root tip cells of Vicia faba using autoradiography with tritiated thymidine (3H-thymidine).
66. The enzyme that charges a tRNA molecule by coupling it to its specific amino acid is:
Correct Answer: B (Aminoacyl-tRNA synthetase)
Aminoacyl-tRNA synthetase activates an amino acid using ATP and attaches it to the 3′-CCA end of its cognate tRNA in a process known as tRNA charging.
Aminoacyl-tRNA synthetase activates an amino acid using ATP and attaches it to the 3′-CCA end of its cognate tRNA in a process known as tRNA charging.
67. In the lac operon of E. coli, the repressor protein is synthesized constitutively by the:
Correct Answer: A (‘i’ gene)
The regulatory ‘i’ gene continuously transcribes the repressor protein, which binds the operator to block RNA polymerase unless inactivated by allolactose.
The regulatory ‘i’ gene continuously transcribes the repressor protein, which binds the operator to block RNA polymerase unless inactivated by allolactose.
68. Homology indicating common evolutionary ancestry is exemplified by:
Correct Answer: B (Thorn of Bougainvillea and Tendril of Cucurbita)
Both arise as modified axillary buds (divergent evolution), representing true homology. The others are analogous structures resulting from convergent evolution.
Both arise as modified axillary buds (divergent evolution), representing true homology. The others are analogous structures resulting from convergent evolution.
69. The evolutionary process where different species independently evolve similar functional traits in response to similar ecological pressures is:
Correct Answer: B (Convergent evolution)
Convergent evolution leads to analogous structures in unrelated evolutionary lineages adapting to similar ecological niches (e.g., placental wolf and Tasmanian marsupial wolf).
Convergent evolution leads to analogous structures in unrelated evolutionary lineages adapting to similar ecological niches (e.g., placental wolf and Tasmanian marsupial wolf).
70. The fossil hominid with a cranial capacity of approximately 900 cc and clear evidence of meat-eating was:
Correct Answer: B (Homo erectus)
Homo erectus arose ~1.5 million years ago, had a 900 cc brain volume, and ate meat, distinguishing it from the earlier vegetarian Homo habilis (650–800 cc).
Homo erectus arose ~1.5 million years ago, had a 900 cc brain volume, and ate meat, distinguishing it from the earlier vegetarian Homo habilis (650–800 cc).
71. In malaria, the sexual stage of Plasmodium (fertilization and sporozoite development) occurs in the:
Correct Answer: C (Gut and salivary glands of the mosquito)
Gametocytes taken up during a blood meal undergo syngamy in the mosquito’s gut lumen, forming oocysts that release sporozoites into its salivary glands.
Gametocytes taken up during a blood meal undergo syngamy in the mosquito’s gut lumen, forming oocysts that release sporozoites into its salivary glands.
72. A person stepping on a rusted nail is administered an anti-tetanus serum (ATS) injection, which provides:
Correct Answer: B (Passive artificial immunity)
ATS delivers pre-formed antitoxin antibodies directly into the bloodstream, neutralizing the tetanus toxin immediately without waiting for host antibody synthesis.
ATS delivers pre-formed antitoxin antibodies directly into the bloodstream, neutralizing the tetanus toxin immediately without waiting for host antibody synthesis.
73. Retroviruses like HIV carry which enzyme to synthesize a DNA copy from their single-stranded RNA viral genome?
Correct Answer: B (Reverse Transcriptase)
Reverse transcriptase transcribes the viral ssRNA template into complementary viral cDNA, which integrates into the host cell genome.
Reverse transcriptase transcribes the viral ssRNA template into complementary viral cDNA, which integrates into the host cell genome.
74. Non-ionizing radiation that causes thymine dimers and mutations in human DNA, predisposing to skin cancers, is:
Correct Answer: C (Ultraviolet radiation)
UV radiation is non-ionizing radiation that damages DNA by inducing cyclobutane pyrimidine (thymine) dimers, predisposing skin cells to neoplastic transformation.
UV radiation is non-ionizing radiation that damages DNA by inducing cyclobutane pyrimidine (thymine) dimers, predisposing skin cells to neoplastic transformation.
75. The psychoactive drug “Cocaine” interferes with the neuronal reuptake of which neurotransmitter at synapses?
Correct Answer: B (Dopamine)
Cocaine inhibits the dopamine transporter (DAT), blocking dopamine clearance and overstimulating reward circuits to generate intense euphoria.
Cocaine inhibits the dopamine transporter (DAT), blocking dopamine clearance and overstimulating reward circuits to generate intense euphoria.
76. The bacterium responsible for commercial production of acetic acid (vinegar) via fermentation is:
Correct Answer: C (Acetobacter aceti)
Acetobacter aceti oxidizes ethanol into acetic acid. Clostridium produces butyric acid, and Aspergillus produces citric acid.
Acetobacter aceti oxidizes ethanol into acetic acid. Clostridium produces butyric acid, and Aspergillus produces citric acid.
77. The “clot buster” enzyme used to dissolve intravascular fibrin blood clots in myocardial infarction patients is:
Correct Answer: B (Streptokinase)
Streptokinase (produced by Streptococcus and modified by genetic engineering) converts plasminogen to plasmin, dissolving coronary thrombi in heart attack patients.
Streptokinase (produced by Streptococcus and modified by genetic engineering) converts plasminogen to plasmin, dissolving coronary thrombi in heart attack patients.
78. The primary gas component in Gobar gas (Biogas) produced by methanogens is:
Correct Answer: A (Methane)
Biogas generated by Methanobacterium in anaerobic digesters contains 50–70% methane (CH4), 30–40% carbon dioxide (CO2), and traces of H2 and H2S.
Biogas generated by Methanobacterium in anaerobic digesters contains 50–70% methane (CH4), 30–40% carbon dioxide (CO2), and traces of H2 and H2S.
79. Ladybird beetles and Dragonflies are used as natural biocontrol predators against:
Correct Answer: B (Aphids and Mosquitoes respectively)
Ladybird beetles feed on agricultural aphid pests, while adult dragonflies prey on flying mosquitoes and their aquatic larvae.
Ladybird beetles feed on agricultural aphid pests, while adult dragonflies prey on flying mosquitoes and their aquatic larvae.
80. Nitrogen-fixing cyanobacteria that associate symbiotically with the roots of Cycas and the water fern Azolla include:
Correct Answer: C (Anabaena and Nostoc)
Anabaena and Nostoc are autotrophic, nitrogen-fixing cyanobacteria that form symbioses in Cycas coralloid roots and Azolla fern leaves.
Anabaena and Nostoc are autotrophic, nitrogen-fixing cyanobacteria that form symbioses in Cycas coralloid roots and Azolla fern leaves.
81. The first step in creating a recombinant DNA molecule involves cutting both the foreign source DNA and plasmid vector using:
Correct Answer: B (The same restriction endonuclease)
Using the same restriction enzyme ensures that both vector and insert have identical complementary single-stranded overhangs (sticky ends) for base-pairing and ligation.
Using the same restriction enzyme ensures that both vector and insert have identical complementary single-stranded overhangs (sticky ends) for base-pairing and ligation.
82. In recombinant plasmid selection, the insertional inactivation of the beta-galactosidase gene (lacZ) yields:
Correct Answer: B (White recombinant colonies on X-gal)
Cloning an insert into the lacZ coding region disrupts beta-galactosidase activity, preventing X-gal cleavage so recombinant colonies remain white.
Cloning an insert into the lacZ coding region disrupts beta-galactosidase activity, preventing X-gal cleavage so recombinant colonies remain white.
83. Microscopic gold or tungsten particles coated with DNA are accelerated at high velocities into target plant cells using a:
Correct Answer: B (Gene gun)
Biolistics (gene gun) bombards plant cells with heavy microscopic gold/tungsten beads carrying recombinant DNA to achieve stable nuclear or plastid transformation.
Biolistics (gene gun) bombards plant cells with heavy microscopic gold/tungsten beads carrying recombinant DNA to achieve stable nuclear or plastid transformation.
84. The DNA fragments separated on an agarose gel can be transferred and extracted from the gel matrix via:
Correct Answer: B (Elution)
Elution involves excising the stained DNA band from the agarose gel slice and purifying the DNA fragments from the gel matrix.
Elution involves excising the stained DNA band from the agarose gel slice and purifying the DNA fragments from the gel matrix.
85. Bt cotton plants are genetically engineered to resist pest infestations by expressing insecticidal crystal endotoxin genes from:
Correct Answer: B (Bacillus thuringiensis)
Bt cotton carries Cry protein genes from Bacillus thuringiensis, protecting the crop against lepidopteran pests like cotton bollworms.
Bt cotton carries Cry protein genes from Bacillus thuringiensis, protecting the crop against lepidopteran pests like cotton bollworms.
86. Transgenic “Golden Rice” is biofortified to express beta-carotene in its edible endosperm to alleviate deficiencies in:
Correct Answer: A (Vitamin A)
Golden Rice synthesizes provitamin A (beta-carotene) in the grain endosperm, helping combat dietary Vitamin A deficiency and childhood blindness.
Golden Rice synthesizes provitamin A (beta-carotene) in the grain endosperm, helping combat dietary Vitamin A deficiency and childhood blindness.
87. Recombinant human insulin consists of two polypeptide chains, A and B, linked together by:
Correct Answer: C (Interchain Disulfide bonds)
Mature human insulin consists of an A chain (21 amino acids) and a B chain (30 amino acids) covalently stabilized by two interchain disulfide bonds.
Mature human insulin consists of an A chain (21 amino acids) and a B chain (30 amino acids) covalently stabilized by two interchain disulfide bonds.
88. Severe Combined Immunodeficiency (SCID) caused by Adenosine Deaminase (ADA) deficiency leads to the toxic accumulation of deoxyadenosine that destroys:
Correct Answer: B (T and B lymphocytes)
ADA deficiency blocks purine salvage, leading to toxic dATP accumulation that selectively kills developing T and B lymphocytes.
ADA deficiency blocks purine salvage, leading to toxic dATP accumulation that selectively kills developing T and B lymphocytes.
89. A radioactive single-stranded DNA or RNA molecule used in hybridization techniques to identify complementary target genes is a:
Correct Answer: C (Probe)
A probe is a defined single-stranded nucleotide sequence tagged with a radioactive/fluorescent label to locate complementary sequences via Southern or Northern blotting.
A probe is a defined single-stranded nucleotide sequence tagged with a radioactive/fluorescent label to locate complementary sequences via Southern or Northern blotting.
90. Transgenic animal models engineered for safety testing of polio vaccines prior to human release are:
Correct Answer: A (Transgenic mice)
Transgenic mice expressing the human poliovirus receptor are utilized to test the batch-to-batch neurovirulence and safety of polio vaccines.
Transgenic mice expressing the human poliovirus receptor are utilized to test the batch-to-batch neurovirulence and safety of polio vaccines.
91. An ecological interaction in which one partner is harmed while the other remains completely unaffected (-, 0) is:
Correct Answer: C (Amensalism)
Amensalism is a (-, 0) interaction where one species is inhibited or destroyed (e.g., bacteria by Penicillium mold) while the producer remains unaffected.
Amensalism is a (-, 0) interaction where one species is inhibited or destroyed (e.g., bacteria by Penicillium mold) while the producer remains unaffected.
92. In a stable population with an age pyramid that is bell-shaped, the proportion of pre-reproductive individuals is:
Correct Answer: B (Roughly equal to reproductive group)
A stable zero-growth population yields a bell-shaped age pyramid where the pre-reproductive and reproductive age brackets are balanced.
A stable zero-growth population yields a bell-shaped age pyramid where the pre-reproductive and reproductive age brackets are balanced.
93. Primary succession on newly exposed bare rock surfaces (Lithosere) is initiated by pioneer species like:
Correct Answer: B (Crustose lichens)
Crustose lichens secrete organic acids that weather rock minerals, generating the first thin soil layer needed for mosses and higher plants to establish.
Crustose lichens secrete organic acids that weather rock minerals, generating the first thin soil layer needed for mosses and higher plants to establish.
94. Secondary productivity in an ecosystem refers to the rate of:
Correct Answer: B (Formation of new biomass by consumers)
Secondary productivity is the rate of new consumer biomass synthesis as herbivores and carnivores assimilate ingested food energy.
Secondary productivity is the rate of new consumer biomass synthesis as herbivores and carnivores assimilate ingested food energy.
95. In any terrestrial ecosystem, which ecological pyramid is ALWAYS upright and can never be inverted?
Correct Answer: C (Pyramid of Energy)
Because energy is lost as metabolic heat at each progressive trophic transition (~10% transfer efficiency), the pyramid of energy is always upright.
Because energy is lost as metabolic heat at each progressive trophic transition (~10% transfer efficiency), the pyramid of energy is always upright.
96. In the logarithmic species-area curve equation log S = log C + Z log A, the regression coefficient ‘Z’ for a normal small regional area ranges between:
Correct Answer: A (0.1 to 0.2)
Within standard local ecological regions, the slope of the regression line (Z) falls strictly between 0.1 and 0.2 regardless of taxonomic group.
Within standard local ecological regions, the slope of the regression line (Z) falls strictly between 0.1 and 0.2 regardless of taxonomic group.
97. Which of the following is considered the MOST critical driver among the “Evil Quartet” causing species extinctions?
Correct Answer: A (Habitat loss and fragmentation)
Habitat destruction and breaking large ecosystems into small isolated patches is the single greatest cause driving species to extinction.
Habitat destruction and breaking large ecosystems into small isolated patches is the single greatest cause driving species to extinction.
98. Steller’s Sea Cow and the Passenger Pigeon went extinct in the last 500 years primarily due to:
Correct Answer: B (Over-exploitation by humans)
Excessive over-hunting and commercial harvesting by humans drove both Steller’s sea cow and the passenger pigeon to extinction.
Excessive over-hunting and commercial harvesting by humans drove both Steller’s sea cow and the passenger pigeon to extinction.
99. Which of the following is an In-situ (on-site) method of biodiversity conservation?
Correct Answer: D (Biosphere Reserves and National Parks)
In-situ conservation preserves endangered species in their native habitats (National Parks, Sanctuaries, Biosphere Reserves). Zoos, botanical gardens, and seed banks are Ex-situ methods.
In-situ conservation preserves endangered species in their native habitats (National Parks, Sanctuaries, Biosphere Reserves). Zoos, botanical gardens, and seed banks are Ex-situ methods.
100. The historic UN Conference on Environment and Development (The Earth Summit) promoting biodiversity conservation was held in 1992 in:
Correct Answer: A (Rio de Janeiro, Brazil)
The Earth Summit was held in Rio de Janeiro in 1992, where nations signed the Convention on Biological Diversity (CBD) to conserve biological resources.
The Earth Summit was held in Rio de Janeiro in 1992, where nations signed the Convention on Biological Diversity (CBD) to conserve biological resources.