1. Which taxonomic document contains comprehensive information on any one single taxon (such as a single family or genus)?
Correct Answer: C (Monograph)
A monograph deals exclusively with a single taxonomic group (taxon) at any level, providing its exhaustive morphological, anatomical, and phylogenetic details.
A monograph deals exclusively with a single taxonomic group (taxon) at any level, providing its exhaustive morphological, anatomical, and phylogenetic details.
2. Chemosynthetic autotrophic bacteria (such as Nitrosomonas and Nitrobacter) derive energy for cellular ATP synthesis by:
Correct Answer: B (Oxidizing inorganic substances like nitrates, nitrites, and ammonia)
Chemosynthetic autotrophs oxidize inorganic compounds (ammonia to nitrite, nitrite to nitrate, H2S, etc.) and couple the released chemical energy to ATP synthesis while recycling nitrogen, phosphorus, and sulfur.
Chemosynthetic autotrophs oxidize inorganic compounds (ammonia to nitrite, nitrite to nitrate, H2S, etc.) and couple the released chemical energy to ATP synthesis while recycling nitrogen, phosphorus, and sulfur.
3. Ciliated protozoans (e.g., Paramecium) are unique in possessing:
Correct Answer: C (Thousands of coordinated cilia, a gullet, and nuclear dimorphism)
Paramecium exhibits thousands of coordinated cilia, an oral groove opening into a gullet, and two distinct nuclei (a large macronucleus for vegetative functions and a small micronucleus for sexual reproduction).
Paramecium exhibits thousands of coordinated cilia, an oral groove opening into a gullet, and two distinct nuclei (a large macronucleus for vegetative functions and a small micronucleus for sexual reproduction).
4. Which of the following fungal species reproduces asexually by non-motile conidia borne exogenously on conidiophores and produces penicillin?
Correct Answer: B (Penicillium)
Penicillium (an Ascomycete) produces branched conidiophores bearing chains of exogenous conidia (brush-like appearance) and synthesizes the antibiotic penicillin.
Penicillium (an Ascomycete) produces branched conidiophores bearing chains of exogenous conidia (brush-like appearance) and synthesizes the antibiotic penicillin.
5. Flagellated pear-shaped (pyriform) zoospores with two unequal laterally attached flagella are characteristic of:
Correct Answer: B (Phaeophyceae)
Brown algae produce pear-shaped zoospores and gametes with two laterally inserted, unequal heterokont flagella. Green algae have 2–8 equal apical flagella, and red algae produce non-motile spores.
Brown algae produce pear-shaped zoospores and gametes with two laterally inserted, unequal heterokont flagella. Green algae have 2–8 equal apical flagella, and red algae produce non-motile spores.
6. Bryophytes are commonly called the “Amphibians of the plant kingdom” because they:
Correct Answer: B (Live in soil but depend on water for flagellated antherozoids)
Bryophytes occupy terrestrial soil habitats but require a film of water for their biflagellated male antherozoids to swim to the archegonium to achieve syngamy.
Bryophytes occupy terrestrial soil habitats but require a film of water for their biflagellated male antherozoids to swim to the archegonium to achieve syngamy.
7. In gymnosperms, pollen grains are carried directly to the ovule by:
Correct Answer: B (Wind currents entering directly through the micropyle)
Gymnosperms are anemophilous; airborne pollen grains land directly in a pollination drop at the micropylar opening of the naked ovule.
Gymnosperms are anemophilous; airborne pollen grains land directly in a pollination drop at the micropylar opening of the naked ovule.
8. A fresh-water colonial or solitary cnidarian that exists strictly in the polyp form and completely lacks a medusa stage is:
Correct Answer: A (Hydra)
Hydra is a freshwater sessile or creeping solitary hydrozoan that exists exclusively as a polyp, reproducing asexually by budding and sexually without a medusa stage.
Hydra is a freshwater sessile or creeping solitary hydrozoan that exists exclusively as a polyp, reproducing asexually by budding and sexually without a medusa stage.
9. Which of the following arthropods is a “living fossil” possessing blue hemocyanin blood and book gills for respiration?
Correct Answer: C (Limulus)
Limulus (horseshoe crab) is an ancient marine chelicerate arthropod that has survived virtually unchanged for hundreds of millions of years, acting as a living fossil.
Limulus (horseshoe crab) is an ancient marine chelicerate arthropod that has survived virtually unchanged for hundreds of millions of years, acting as a living fossil.
10. Amphioxus (Branchiostoma) belongs to which chordate subphylum?
Correct Answer: B (Cephalochordata)
Branchiostoma (Amphioxus or lancelet) belongs to Cephalochordata, where the persistent notochord extends from the tip of the head to the tail throughout its entire life.
Branchiostoma (Amphioxus or lancelet) belongs to Cephalochordata, where the persistent notochord extends from the tip of the head to the tail throughout its entire life.
11. Edible underground fleshy storage structures in Garlic and Onion where stems are highly reduced into discs surrounded by concentrated scale leaves are:
Correct Answer: C (Bulbs)
In bulbs (onion, garlic), the stem is reduced to a small flat disc bearing adventitious roots below and concentric, overlapping fleshy scale leaves storing food above.
In bulbs (onion, garlic), the stem is reduced to a small flat disc bearing adventitious roots below and concentric, overlapping fleshy scale leaves storing food above.
12. In a perigynous flower (e.g., Plum, Rose, Peach), the ovary is:
Correct Answer: C (Half-inferior)
In perigynous flowers, the margin of the thalamus grows upward to form a cup around the central ovary, bearing sepals, petals, and stamens at the rim (ovary is half-inferior).
In perigynous flowers, the margin of the thalamus grows upward to form a cup around the central ovary, bearing sepals, petals, and stamens at the rim (ovary is half-inferior).
13. A dry dehiscent fruit developing from a monocarpellary, superior ovary with marginal placentation that splits along both dorsal and ventral sutures is a:
Correct Answer: A (Legume)
A legume (pod) is characteristic of family Fabaceae (pea, bean); it develops from a superior unilocular ovary with marginal placentation and dehisces along both sutures.
A legume (pod) is characteristic of family Fabaceae (pea, bean); it develops from a superior unilocular ovary with marginal placentation and dehisces along both sutures.
14. Tracheids differ from xylem vessels in that tracheids:
Correct Answer: B (Single elongated dead cells with tapering imperforate ends)
Tracheids are individual elongated cells with closed, tapering ends communicating via bordered pits. Vessels are long syncytial pipes formed by fused cells with perforated end walls.
Tracheids are individual elongated cells with closed, tapering ends communicating via bordered pits. Vessels are long syncytial pipes formed by fused cells with perforated end walls.
15. The presence of sunken stomata situated in deep grooved furrows on leaves and a thick cuticle are xerophytic adaptations found in:
Correct Answer: C (Nerium and Pinus)
Sunken stomata located in hair-lined epidermal crypts combined with a heavily suberized/cutinized cuticle minimize transpiration water loss in xerophytes like Nerium and Pinus needles.
Sunken stomata located in hair-lined epidermal crypts combined with a heavily suberized/cutinized cuticle minimize transpiration water loss in xerophytes like Nerium and Pinus needles.
16. The connective tissue cells that synthesize and secrete heparin, histamine, and serotonin are:
Correct Answer: B (Mast cells)
Mast cells in areolar tissue are granule-filled cells that release histamine (mediates inflammation), serotonin (vasoconstrictor), and heparin (anticoagulant).
Mast cells in areolar tissue are granule-filled cells that release histamine (mediates inflammation), serotonin (vasoconstrictor), and heparin (anticoagulant).
17. In the digestive tract of frogs, partially digested acidic food passing from the stomach into the duodenum is called:
Correct Answer: B (Chyme)
Food masticated and chemically acted on by gastric HCl and pepsin in the stomach forms a semi-liquid acidic mass called chyme before entering the duodenum.
Food masticated and chemically acted on by gastric HCl and pepsin in the stomach forms a semi-liquid acidic mass called chyme before entering the duodenum.
18. The functional junction between the hindbrain medulla oblongata and the spinal cord in frogs passes out of the cranium through the:
Correct Answer: A (Foramen magnum)
The medulla oblongata tapers posteriorly and exits the cartilaginous/bony cranium through the large opening called the foramen magnum to continue as the spinal cord.
The medulla oblongata tapers posteriorly and exits the cartilaginous/bony cranium through the large opening called the foramen magnum to continue as the spinal cord.
19. In female frogs, the paired ovaries:
Correct Answer: B (Are situated near the kidneys but have NO functional connection with them)
Unlike male frogs whose testes connect through vasa efferentia into kidneys, the ovaries in female frogs are anatomically separate from the kidneys and discharge ova through separate oviducts.
Unlike male frogs whose testes connect through vasa efferentia into kidneys, the ovaries in female frogs are anatomically separate from the kidneys and discharge ova through separate oviducts.
20. The transformation of an aquatic, fish-like, gill-breathing tadpole into a terrestrial carnivorous adult frog is called:
Correct Answer: C (Metamorphosis)
Metamorphosis in frogs involves gill regression, tail resorption, limb growth, and pulmonary system development, regulated by thyroid hormone (thyroxine).
Metamorphosis in frogs involves gill regression, tail resorption, limb growth, and pulmonary system development, regulated by thyroid hormone (thyroxine).
21. In Gram-negative bacteria, the cell envelope contains an outer lipopolysaccharide (LPS) layer that:
Correct Answer: B (Acts as an endotoxin and provides resistance against certain antibiotics)
Gram-negative bacteria possess a thin peptidoglycan layer enclosed by an outer membrane containing lipopolysaccharides (endotoxins) that block alcohol de-staining and impede antibiotic entry.
Gram-negative bacteria possess a thin peptidoglycan layer enclosed by an outer membrane containing lipopolysaccharides (endotoxins) that block alcohol de-staining and impede antibiotic entry.
22. The Golgi apparatus packages cellular secretions into vesicles that bud off from its:
Correct Answer: B (Trans / maturing face)
Proteins enter the convex cis face from the ER, undergo post-translational processing as they transit the cisternae, and emerge as secretory vesicles from the concave trans face.
Proteins enter the convex cis face from the ER, undergo post-translational processing as they transit the cisternae, and emerge as secretory vesicles from the concave trans face.
23. Water-soluble anthocyanin pigments that impart red, purple, and blue colors to flower petals and fruits are located in the:
Correct Answer: C (Plant cell Vacuolar sap)
Anthocyanins are water-soluble flavonoid pigments dissolved inside the central vacuole sap. Carotenoids and xanthophylls are fat-soluble pigments located in chromoplasts.
Anthocyanins are water-soluble flavonoid pigments dissolved inside the central vacuole sap. Carotenoids and xanthophylls are fat-soluble pigments located in chromoplasts.
24. The primary proteinaceous filament component of eukaryotic cilia and flagella axonemes that possesses ATPase enzymatic activity for movement is:
Correct Answer: B (Dynein)
Axonemal dynein arms project from doublet microtubules, hydrolyzing ATP to generate sliding forces that bend eukaryotic cilia and flagella.
Axonemal dynein arms project from doublet microtubules, hydrolyzing ATP to generate sliding forces that bend eukaryotic cilia and flagella.
25. Which of the following nitrogenous bases are bicyclic Purines with a double-ring structure?
Correct Answer: A (Adenine and Guanine)
Adenine and Guanine are 9-membered, double-ringed Purines. Cytosine, Thymine, and Uracil are 6-membered, single-ringed Pyrimidines.
Adenine and Guanine are 9-membered, double-ringed Purines. Cytosine, Thymine, and Uracil are 6-membered, single-ringed Pyrimidines.
26. In an enzyme-catalyzed reaction, the Michaelis-Menten constant (Km) represents the substrate concentration at which the reaction velocity reaches:
Correct Answer: B (Half of the maximum velocity)
Km is the substrate concentration at which the enzyme achieves half its maximal catalytic velocity (Vmax / 2). A lower Km indicates higher substrate affinity.
Km is the substrate concentration at which the enzyme achieves half its maximal catalytic velocity (Vmax / 2). A lower Km indicates higher substrate affinity.
27. Enzymes that join two chemical molecules together with the coupled hydrolysis of ATP (e.g., DNA Ligase, Glutamine synthetase) belong to class:
Correct Answer: D (Ligases)
Ligases (Class 6) catalyze the covalent joining of two distinct molecules (forming C-O, C-S, C-N, or C-C bonds) coupled to the cleavage of high-energy pyrophosphate bonds in ATP.
Ligases (Class 6) catalyze the covalent joining of two distinct molecules (forming C-O, C-S, C-N, or C-C bonds) coupled to the cleavage of high-energy pyrophosphate bonds in ATP.
28. During which sub-stage of Prophase I does the nucleolus completely disappear and homologous chromosomes detach from the nuclear envelope as diakinesis concludes?
Correct Answer: C (Diakinesis)
Diakinesis marks the end of meiotic prophase: chiasmata terminalize, chromosomes fully condense, the nucleolus vanishes, and the nuclear envelope disintegrates.
Diakinesis marks the end of meiotic prophase: chiasmata terminalize, chromosomes fully condense, the nucleolus vanishes, and the nuclear envelope disintegrates.
29. The morphology, size, and shape of eukaryotic chromosomes are most clearly studied during which stage of mitosis?
Correct Answer: C (Metaphase)
Chromosomes reach maximal condensation and align along the equatorial plate during metaphase, making this stage ideal for karyotyping and analyzing chromosome structure.
Chromosomes reach maximal condensation and align along the equatorial plate during metaphase, making this stage ideal for karyotyping and analyzing chromosome structure.
30. Meiosis occurs in specialized diploid germ cells called:
Correct Answer: B (Meiocytes)
Meiocytes are specialized diploid precursor cells (such as pollen mother cells, megaspore mother cells, or primary spermatocytes/oocytes) that undergo meiosis to yield haploid gametes or spores.
Meiocytes are specialized diploid precursor cells (such as pollen mother cells, megaspore mother cells, or primary spermatocytes/oocytes) that undergo meiosis to yield haploid gametes or spores.
31. The light absorption curve of Chlorophyll a matches closely with the rate of photosynthesis across different wavelengths, forming the:
Correct Answer: A (Action spectrum of photosynthesis)
The action spectrum of photosynthesis mirrors the absorption spectrum of chlorophyll a, exhibiting maximal efficiency in the blue (~430 nm) and red (~660 nm) regions of the spectrum.
The action spectrum of photosynthesis mirrors the absorption spectrum of chlorophyll a, exhibiting maximal efficiency in the blue (~430 nm) and red (~660 nm) regions of the spectrum.
32. How many total cycles of the Calvin pathway (carbon fixation) are required to generate ONE molecule of 6-carbon Glucose (C6H12O6)?
Correct Answer: C (6 turns)
Each turn of the Calvin cycle fixes 1 CO2 molecule. Synthesizing one 6-carbon glucose molecule requires 6 complete turns, consuming 18 ATP and 12 NADPH.
Each turn of the Calvin cycle fixes 1 CO2 molecule. Synthesizing one 6-carbon glucose molecule requires 6 complete turns, consuming 18 ATP and 12 NADPH.
33. In the C4 photosynthetic pathway, the primary carboxylation reaction occurs in the ______ using enzyme ______:
Correct Answer: B (Mesophyll cells; PEP carboxylase)
In C4 plants, initial CO2 capture takes place in mesophyll cytosol where PEPcase carboxylates 3-carbon phosphoenolpyruvate (PEP) into 4-carbon oxaloacetic acid (OAA).
In C4 plants, initial CO2 capture takes place in mesophyll cytosol where PEPcase carboxylates 3-carbon phosphoenolpyruvate (PEP) into 4-carbon oxaloacetic acid (OAA).
34. Photosynthesis is limited by light intensity at low irradiance, but at high irradiance it saturates at what percentage of full midday sunlight?
Correct Answer: A (~10% of full sunlight)
Except for shade plants and dense lower forest canopies, light saturation occurs at ~10% of full sunlight, making light rarely a limiting factor in open nature.
Except for shade plants and dense lower forest canopies, light saturation occurs at ~10% of full sunlight, making light rarely a limiting factor in open nature.
35. In glycolysis, the enzyme that catalyzes the phosphorylation of Glucose to Glucose-6-phosphate by consuming 1 ATP molecule is:
Correct Answer: A (Hexokinase)
Hexokinase (in the presence of Mg2+) carries out the first irreversible step of glycolysis, phosphorylating free intracellular glucose into glucose-6-phosphate.
Hexokinase (in the presence of Mg2+) carries out the first irreversible step of glycolysis, phosphorylating free intracellular glucose into glucose-6-phosphate.
36. In skeletal muscle cells during intense anaerobic exercise, pyruvate is reduced to lactic acid by the enzyme:
Correct Answer: B (Lactate dehydrogenase)
Under anaerobic conditions, lactate dehydrogenase reduces pyruvate to lactic acid, regenerating NAD+ to maintain glycolytic ATP synthesis.
Under anaerobic conditions, lactate dehydrogenase reduces pyruvate to lactic acid, regenerating NAD+ to maintain glycolytic ATP synthesis.
37. In the Krebs cycle, the conversion of alpha-ketoglutarate (5C) to Succinyl-CoA (4C) involves:
Correct Answer: A (Oxidative decarboxylation with release of CO2 and reduction of NAD+)
Alpha-ketoglutarate dehydrogenase oxidatively decarboxylates alpha-ketoglutarate (5C) into Succinyl-CoA (4C), generating 1 NADH and releasing 1 molecule of CO2.
Alpha-ketoglutarate dehydrogenase oxidatively decarboxylates alpha-ketoglutarate (5C) into Succinyl-CoA (4C), generating 1 NADH and releasing 1 molecule of CO2.
38. In the mitochondrial electron transport chain, how many protons (H+) must pass back through Complex V (F0-F1 ATP synthase) from the intermembrane space to generate 1 ATP molecule?
Correct Answer: B (2 H+)
According to the NCERT biology syllabus, passage of 2 H+ ions through the F0 transmembrane channel down the electrochemical gradient drives the F1 headpiece to synthesize 1 ATP.
According to the NCERT biology syllabus, passage of 2 H+ ions through the F0 transmembrane channel down the electrochemical gradient drives the F1 headpiece to synthesize 1 ATP.
39. The synthetic auxin commonly used in tissue culture to induce root differentiation from callus tissue is:
Correct Answer: A (NAA and IBA)
High auxin-to-cytokinin ratios (using NAA or IBA) induce rhizogenesis (root formation) in plant tissue culture callus.
High auxin-to-cytokinin ratios (using NAA or IBA) induce rhizogenesis (root formation) in plant tissue culture callus.
40. The phenomenon where plants follow different developmental pathways in response to environment or life phases to form different kinds of structures (e.g., heterophylly in Cotton, Coriander, Larkspur) is:
Correct Answer: B (Plasticity)
Plasticity is the capacity of plants to alter their morphology in response to environmental cues or developmental stages (e.g., juvenile vs. adult leaves in cotton, aerial vs. submerged leaves in buttercup).
Plasticity is the capacity of plants to alter their morphology in response to environmental cues or developmental stages (e.g., juvenile vs. adult leaves in cotton, aerial vs. submerged leaves in buttercup).
41. The total lung capacity (TLC) of an adult human represents the total volume of air in the lungs after maximal inspiration, equal to:
Correct Answer: C (Vital Capacity + Residual Volume)
Total Lung Capacity (TLC = TV + IRV + ERV + RV = VC + RV) averages 5000 to 6000 mL in a healthy adult male.
Total Lung Capacity (TLC = TV + IRV + ERV + RV = VC + RV) averages 5000 to 6000 mL in a healthy adult male.
42. Every 100 mL of oxygenated blood delivers approximately how much oxygen (O2) to active tissues under normal resting physiological conditions?
Correct Answer: B (5 mL)
Every 100 mL of oxygenated arterial blood carries ~20 mL of O2, delivering ~5 mL of O2 to tissues at rest. Every 100 mL of deoxygenated blood returns ~4 mL of CO2 to the alveoli.
Every 100 mL of oxygenated arterial blood carries ~20 mL of O2, delivering ~5 mL of O2 to tissues at rest. Every 100 mL of deoxygenated blood returns ~4 mL of CO2 to the alveoli.
43. Platelets (thrombocytes) that participate in blood coagulation cascades are cell fragments derived from giant bone marrow cells called:
Correct Answer: B (Megakaryocytes)
Blood platelets (thrombocytes, 150,000–350,000/mm3) are enucleated cell fragments shed from polyploid megakaryocytes in the bone marrow.
Blood platelets (thrombocytes, 150,000–350,000/mm3) are enucleated cell fragments shed from polyploid megakaryocytes in the bone marrow.
44. The Purkinje fibers along with the right and left bundle branches in the ventricular myocardium ensure that:
Correct Answer: B (Ventricular contraction begins at the heart apex and sweeps upward)
Purkinje fibers rapidly conduct electrical waves to the apex and papillary muscles, squeezing blood upward toward the pulmonary trunk and aorta.
Purkinje fibers rapidly conduct electrical waves to the apex and papillary muscles, squeezing blood upward toward the pulmonary trunk and aorta.
45. In the human kidney, the high hydrostatic capillary blood pressure that drives glomerular ultrafiltration is created because the:
Correct Answer: A (Afferent arteriole has a wider diameter than the Efferent arteriole)
The afferent arteriole is wider than the outflowing efferent arteriole, creating vascular resistance and high capillary hydrostatic pressure (~55 mm Hg) to drive ultrafiltration.
The afferent arteriole is wider than the outflowing efferent arteriole, creating vascular resistance and high capillary hydrostatic pressure (~55 mm Hg) to drive ultrafiltration.
46. The structural contractile protein of skeletal muscle that possesses an ATPase enzyme head, an actin-binding site, and a light meromyosin tail is:
Correct Answer: C (Myosin)
Each thick myosin filament is a polymer of meromyosins: Heavy Meromyosin (HMM) forms the globular head with ATPase activity, and Light Meromyosin (LMM) forms the tail.
Each thick myosin filament is a polymer of meromyosins: Heavy Meromyosin (HMM) forms the globular head with ATPase activity, and Light Meromyosin (LMM) forms the tail.
47. The joint between the atlas (1st cervical vertebra) and the occipital condyles of the skull that allows nodding (“Yes”) movements of the head is a:
Correct Answer: A (Condyloid / Ellipsoid synovial joint)
The atlanto-occipital joint (between occipital condyles and atlas) is an ellipsoid condyloid joint permitting flexion and extension (head nodding). The atlanto-axial joint is a pivot joint for rotation.
The atlanto-occipital joint (between occipital condyles and atlas) is an ellipsoid condyloid joint permitting flexion and extension (head nodding). The atlanto-axial joint is a pivot joint for rotation.
48. Age-related skeletal disorder characterized by decreased bone mass and increased fracture risk due to deficient estrogen levels in postmenopausal women is:
Correct Answer: C (Osteoporosis)
Osteoporosis is an age-related loss of bone mineral density where osteoclastic resorption outpaces osteoblastic deposition, commonly exacerbated by postmenopausal estrogen decline.
Osteoporosis is an age-related loss of bone mineral density where osteoclastic resorption outpaces osteoblastic deposition, commonly exacerbated by postmenopausal estrogen decline.
49. The fovea centralis in the human retina is a thinned-out yellow spot (macula lutea) where:
Correct Answer: B (Only cone cells are densely packed, providing maximal visual acuity)
The fovea is the central pit of the macula lutea where rods are displaced and cone density is highest, delivering peak daylight visual resolution.
The fovea is the central pit of the macula lutea where rods are displaced and cone density is highest, delivering peak daylight visual resolution.
50. Acromegaly, a condition marked by severe disfigurement of facial bones and disproportionate hands and feet in adults, results from:
Correct Answer: B (Hypersecretion of Growth Hormone in adults)
Excess GH secretion in adults (after epiphyseal plates have fused) cannot increase height but stimulates periosteal bone thickening, causing acromegaly.
Excess GH secretion in adults (after epiphyseal plates have fused) cannot increase height but stimulates periosteal bone thickening, causing acromegaly.
51. The filiform apparatus located at the micropylar tip of synergid cells in the embryo sac functions to:
Correct Answer: B (Chemically guide the entry of the pollen tube)
The filiform apparatus consists of finger-like cell-wall invaginations in synergids that secrete chemotropic signals to guide the incoming pollen tube into the embryo sac.
The filiform apparatus consists of finger-like cell-wall invaginations in synergids that secrete chemotropic signals to guide the incoming pollen tube into the embryo sac.
52. A single shield-shaped cotyledon situated laterally on the embryonal axis in a monocot seed (e.g., Grass / Maize) is the:
Correct Answer: C (Scutellum)
In monocot seeds (grasses), the solitary large cotyledon is modified into an absorptive shield-like organ called the scutellum, positioned adjacent to the endosperm.
In monocot seeds (grasses), the solitary large cotyledon is modified into an absorptive shield-like organ called the scutellum, positioned adjacent to the endosperm.
53. Polyembryony (occurrence of more than one embryo in a seed) commonly observed in Citrus and Mango arises when:
Correct Answer: A (Maternal nucellar cells divide, push into the embryo sac, and develop into embryos)
In Citrus and mango, maternal diploid nucellar cells surrounding the embryo sac divide adventitiously and project into the cavity to form multiple asexual embryos.
In Citrus and mango, maternal diploid nucellar cells surrounding the embryo sac divide adventitiously and project into the cavity to form multiple asexual embryos.
54. In human males, the primary source of fructose, prostaglandins, and clotting proteins present in seminal plasma is the:
Correct Answer: B (Seminal vesicles)
Seminal vesicles secrete an alkaline fluid rich in fructose (energy source for sperm motility), prostaglandins (stimulate uterine contractions), and clotting proteins.
Seminal vesicles secrete an alkaline fluid rich in fructose (energy source for sperm motility), prostaglandins (stimulate uterine contractions), and clotting proteins.
55. In human females, the cyclic shedding of the endometrial lining (menstruation) is prevented if:
Correct Answer: B (Fertilization occurs and blastocyst secretes hCG)
Trophoblast cells of the implanted blastocyst secrete human chorionic gonadotropin (hCG), preventing luteal breakdown and maintaining progesterone secretion to sustain the endometrium.
Trophoblast cells of the implanted blastocyst secrete human chorionic gonadotropin (hCG), preventing luteal breakdown and maintaining progesterone secretion to sustain the endometrium.
56. The acrosome reaction during fertilization is triggered when the sperm head binds to which glycoprotein receptor on the zona pellucida?
Correct Answer: C (ZP3)
Binding of sperm surface ligands to ZP3 receptors on the zona pellucida triggers Ca2+ influx and acrosomal exocytosis, releasing hyaluronidase and acrosin to digest the egg coat.
Binding of sperm surface ligands to ZP3 receptors on the zona pellucida triggers Ca2+ influx and acrosomal exocytosis, releasing hyaluronidase and acrosin to digest the egg coat.
57. The solid group of cells within the blastocyst that gives rise to all three embryonic germ layers (ectoderm, mesoderm, endoderm) is the:
Correct Answer: B (Inner Cell Mass)
The inner cell mass (embryoblast) consists of pluripotent stem cells that differentiate into the embryonic germ layers, while the outer trophoblast forms extra-embryonic placental membranes.
The inner cell mass (embryoblast) consists of pluripotent stem cells that differentiate into the embryonic germ layers, while the outer trophoblast forms extra-embryonic placental membranes.
58. The first movements of the human fetus and appearance of hair on the fetal head are usually observed by the mother during which month of pregnancy?
Correct Answer: C (5th month)
According to human embryology, initial fetal movements (quickening) and fine head hair development occur during the 5th month (20 weeks) of gestation.
According to human embryology, initial fetal movements (quickening) and fine head hair development occur during the 5th month (20 weeks) of gestation.
59. Emergency contraceptive pills (e.g., high-dose levonorgestrel) are effective in preventing potential pregnancy if administered within:
Correct Answer: A (72 hours of unprotected coitus)
Emergency morning-after pills (progestogen or progestogen-estrogen combinations) must be taken within 72 hours of unprotected intercourse to delay ovulation or block implantation.
Emergency morning-after pills (progestogen or progestogen-estrogen combinations) must be taken within 72 hours of unprotected intercourse to delay ovulation or block implantation.
60. Amniocentesis is a prenatal diagnostic test performed by sampling amniotic fluid to analyze:
Correct Answer: B (Fetal karyotype and chromosomal/genetic metabolic disorders)
Amniocentesis harvests cultured fetal cells from amniotic fluid for karyotyping to diagnose chromosomal aneuploidies and inborn metabolic errors.
Amniocentesis harvests cultured fetal cells from amniotic fluid for karyotyping to diagnose chromosomal aneuploidies and inborn metabolic errors.
61. In sweet peas, the inheritance of flower color and pollen shape failed to show independent assortment in Bateson and Punnett’s experiments due to:
Correct Answer: B (Physical genetic linkage of genes on the same chromosome)
Bateson and Punnett observed coupling and repulsion in Lathyrus odoratus because the alleles for purple flowers and long pollen reside on the same chromosome (linkage).
Bateson and Punnett observed coupling and repulsion in Lathyrus odoratus because the alleles for purple flowers and long pollen reside on the same chromosome (linkage).
62. The chromosomal sex-determination mechanism in grasshoppers and certain insects where females possess two X chromosomes and males possess only a single X is:
Correct Answer: B (XX female – XO male)
In grasshoppers (discovered by Henking’s X-body research), females have an XX genotype while males have a single X chromosome (XO), producing gametes with an X or without an X.
In grasshoppers (discovered by Henking’s X-body research), females have an XX genotype while males have a single X chromosome (XO), producing gametes with an X or without an X.
63. Thalassemia is distinguished from Sickle-cell anemia because Thalassemia is a:
Correct Answer: A (Quantitative defect in synthesizing fewer globin chains vs. qualitative defect in Sickle-cell)
Thalassemia is a quantitative defect (reduced synthesis rate of normal alpha or beta chains), whereas Sickle-cell anemia is a qualitative defect (amino acid substitution producing mutant HbS).
Thalassemia is a quantitative defect (reduced synthesis rate of normal alpha or beta chains), whereas Sickle-cell anemia is a qualitative defect (amino acid substitution producing mutant HbS).
64. In a double-stranded DNA duplex, if the total molar percentage of Guanine is 30%, what is the percentage of Thymine according to Chargaff’s rules?
Correct Answer: B (20%)
According to Chargaff’s rule (A = T and G = C): if G = 30%, then C = 30% (Total G + C = 60%). The remaining A + T = 40%, so T = 40% / 2 = 20%.
According to Chargaff’s rule (A = T and G = C): if G = 30%, then C = 30% (Total G + C = 60%). The remaining A + T = 40%, so T = 40% / 2 = 20%.
65. Which of the following RNA molecules acts as a dynamic structural and catalytic adaptor component of ribosomes during translation?
Correct Answer: C (rRNA)
Ribosomal RNA (rRNA) is the most abundant cellular RNA, forming the structural scaffolding of ribosomes and catalyzing peptide bond formation (peptidyl transferase).
Ribosomal RNA (rRNA) is the most abundant cellular RNA, forming the structural scaffolding of ribosomes and catalyzing peptide bond formation (peptidyl transferase).
66. In prokaryotes, translation can begin even before the mRNA transcript is fully transcribed because:
Correct Answer: B (Transcription and translation occur in the same compartment)
Because bacteria lack a nuclear membrane, ribosomes bind to the nascent 5′-end of mRNA while RNA polymerase is still elongating the 3′-end (coupled transcription-translation).
Because bacteria lack a nuclear membrane, ribosomes bind to the nascent 5′-end of mRNA while RNA polymerase is still elongating the 3′-end (coupled transcription-translation).
67. The sequence of structural genes in the Lac Operon of E. coli from the operator side is:
Correct Answer: A (lac Z -> lac Y -> lac A)
The polycistronic structural genes of the lac operon are arranged in order: lacZ (beta-galactosidase), lacY (permease), and lacA (transacetylase).
The polycistronic structural genes of the lac operon are arranged in order: lacZ (beta-galactosidase), lacY (permease), and lacA (transacetylase).
68. Analogous organs that evolve through convergent evolution to perform similar functions despite different anatomical origins include:
Correct Answer: B (Sweet potato and Potato)
Sweet potato (root tuber) and Irish potato (underground stem tuber) share different developmental origins but both function in underground starch storage, demonstrating analogy.
Sweet potato (root tuber) and Irish potato (underground stem tuber) share different developmental origins but both function in underground starch storage, demonstrating analogy.
69. When natural selection shifts the mean phenotype of a population toward one extreme direction over time (e.g., DDT resistance in mosquitoes), it is called:
Correct Answer: B (Directional selection)
Directional selection favors individuals at one extreme of the phenotypic range, shifting the population distribution curve toward the favored trait (e.g., industrial melanism, antibiotic resistance).
Directional selection favors individuals at one extreme of the phenotypic range, shifting the population distribution curve toward the favored trait (e.g., industrial melanism, antibiotic resistance).
70. The hominid ancestor “Homo habilis” is termed the “handy man” because fossils show they were the first to:
Correct Answer: B (Manufacture stone tools intentionally)
Homo habilis (cranial capacity 650–800 cc) was the earliest hominid toolmaker, crafting chipped stone implements to process forage.
Homo habilis (cranial capacity 650–800 cc) was the earliest hominid toolmaker, crafting chipped stone implements to process forage.
71. Ascariasis is caused by the giant intestinal roundworm Ascaris lumbricoides. Patients typically develop:
Correct Answer: B (Internal abdominal bleeding, muscular pain, anemia, fever, and intestinal blockage)
Heavy Ascaris infestations lead to intestinal lumen obstruction, mucosal ulceration, anemia from nutritional diversion, and pulmonary larval migration symptoms.
Heavy Ascaris infestations lead to intestinal lumen obstruction, mucosal ulceration, anemia from nutritional diversion, and pulmonary larval migration symptoms.
72. An exaggerated inflammatory response of the immune system to environmental antigens (allergens like pollen, mites, animal dander) is mediated by:
Correct Answer: B (IgE antibodies and histamine release from tissue mast cells)
Allergens cross-link allergen-specific IgE bound to mast cell surfaces, stimulating rapid degranulation and release of histamine and serotonin.
Allergens cross-link allergen-specific IgE bound to mast cell surfaces, stimulating rapid degranulation and release of histamine and serotonin.
73. Which secondary lymphoid organ acts as a major blood filter by trapping blood-borne microorganisms and recycling old worn-out erythrocytes?
Correct Answer: B (Spleen)
The spleen is a large bean-shaped secondary lymphoid organ containing red pulp (which phagocytoses old RBCs) and white pulp (which mounts immune responses against blood-borne antigens).
The spleen is a large bean-shaped secondary lymphoid organ containing red pulp (which phagocytoses old RBCs) and white pulp (which mounts immune responses against blood-borne antigens).
74. Alpha-interferons administered in biological cancer immunotherapy act by:
Correct Answer: B (Activating the patient’s immune system to destroy tumor cells)
Tumor cells evade host immunity; administering biological response modifiers like alpha-interferon stimulates cytotoxic T-cells and NK cells to recognize and destroy neoplasms.
Tumor cells evade host immunity; administering biological response modifiers like alpha-interferon stimulates cytotoxic T-cells and NK cells to recognize and destroy neoplasms.
75. “Smack” (Heroin / Diacetylmorphine) is chemically prepared by the:
Correct Answer: A (Acetylation of morphine)
Heroin (diacetylmorphine) is synthesized by acetylating morphine extracted from the latex of Papaver somniferum; it acts as a white, bitter crystalline central depressant.
Heroin (diacetylmorphine) is synthesized by acetylating morphine extracted from the latex of Papaver somniferum; it acts as a white, bitter crystalline central depressant.
76. Lactic Acid Bacteria (LAB) improve the nutritional value of curd over milk by significantly increasing the content of:
Correct Answer: B (Vitamin B12)
During milk fermentation into curd, Lactobacillus coagulates milk proteins and enriches the product with synthesized Vitamin B12 while suppressing harmful gut microbes.
During milk fermentation into curd, Lactobacillus coagulates milk proteins and enriches the product with synthesized Vitamin B12 while suppressing harmful gut microbes.
77. The red-pigmented yeast Monascus purpureus is used for the commercial fermentation of:
Correct Answer: B (Statins)
Monascus purpureus produces statins (e.g., lovastatin), which competitively inhibit HMG-CoA reductase to reduce hepatic cholesterol synthesis.
Monascus purpureus produces statins (e.g., lovastatin), which competitively inhibit HMG-CoA reductase to reduce hepatic cholesterol synthesis.
78. In a municipal sewage treatment plant, the sediment collected in the secondary settling tank is called:
Correct Answer: B (Activated sludge)
Settling the aerated effluent deposits activated sludge rich in aerobic microbial flocs; part is recycled as inoculum, and the rest is digested in anaerobic sludge digesters.
Settling the aerated effluent deposits activated sludge rich in aerobic microbial flocs; part is recycled as inoculum, and the rest is digested in anaerobic sludge digesters.
79. Baculoviruses belonging to the genus Nucleopolyhedrovirus are desirable biocontrol agents because they:
Correct Answer: B (Species-specific, narrow-spectrum insecticidal activity)
Baculoviruses selectively infect target arthropod pests without harming non-target organisms, making them ideal biological agents for Integrated Pest Management (IPM).
Baculoviruses selectively infect target arthropod pests without harming non-target organisms, making them ideal biological agents for Integrated Pest Management (IPM).
80. Free-living anaerobic nitrogen-fixing bacteria commonly present in soil include:
Correct Answer: B (Rhodospirillum)
Azotobacter and Beijerinckia are free-living aerobic nitrogen-fixing bacteria, whereas Rhodospirillum is a free-living anaerobic nitrogen fixer.
Azotobacter and Beijerinckia are free-living aerobic nitrogen-fixing bacteria, whereas Rhodospirillum is a free-living anaerobic nitrogen fixer.
81. In agarose gel electrophoresis, smaller DNA fragments move:
Correct Answer: B (Farther toward the positive anode due to the sieving effect)
DNA fragments carry a constant negative charge-to-mass ratio; the agarose meshwork retards larger fragments, allowing smaller fragments to travel farther toward the positive anode.
DNA fragments carry a constant negative charge-to-mass ratio; the agarose meshwork retards larger fragments, allowing smaller fragments to travel farther toward the positive anode.
82. In plasmid pBR322, the ‘rop’ gene codes for proteins involved in:
Correct Answer: B (Regulating plasmid replication and copy number control)
In pBR322, ‘rop’ (Repressor of Primer) encodes a regulatory protein involved in plasmid DNA replication and copy-number maintenance.
In pBR322, ‘rop’ (Repressor of Primer) encodes a regulatory protein involved in plasmid DNA replication and copy-number maintenance.
83. The direct physical delivery of recombinant DNA into plant cells using high-velocity gold or tungsten micro-projectiles is called:
Correct Answer: B (Biolistics / Gene Gun method)
The biolistic/gene-gun technique bombards target plant tissues with microscopic gold or tungsten micro-carriers coated with recombinant DNA.
The biolistic/gene-gun technique bombards target plant tissues with microscopic gold or tungsten micro-carriers coated with recombinant DNA.
84. The thermostable enzyme Taq polymerase isolated from Thermus aquaticus is essential for PCR because it:
Correct Answer: B (Remains active through high-temperature denaturation cycles)
Taq polymerase is isolated from a thermophilic bacterium; it maintains structural stability during the 94°C denaturation phase, eliminating the need to add fresh enzyme in each PCR cycle.
Taq polymerase is isolated from a thermophilic bacterium; it maintains structural stability during the 94°C denaturation phase, eliminating the need to add fresh enzyme in each PCR cycle.
85. The alkaline pH of the caterpillar midgut solubilizes Bt protein crystals, activating the toxin that kills the pest by:
Correct Answer: B (Binding to midgut epithelial cells and creating lytic pores)
Active Cry toxins bind to cadherin receptors on insect midgut microvilli, oligomerizing into lytic pores that cause osmotic swelling, lysis, and fatal septicemia.
Active Cry toxins bind to cadherin receptors on insect midgut microvilli, oligomerizing into lytic pores that cause osmotic swelling, lysis, and fatal septicemia.
86. RNA interference (RNAi) is a natural gene-silencing mechanism that operates in all eukaryotic organisms as a cellular defense against:
Correct Answer: B (Viral infections and mobile genetic elements)
Eukaryotes use RNAi as an evolutionary defense to target and degrade foreign double-stranded RNA originating from viral replication or parasitic transposon activity.
Eukaryotes use RNAi as an evolutionary defense to target and degrade foreign double-stranded RNA originating from viral replication or parasitic transposon activity.
87. Mature human insulin differs structurally from proinsulin in that proinsulin possesses:
Correct Answer: B (A connecting C-peptide of 31 amino acids that is cleaved out)
Proinsulin contains A, B, and connecting C-peptides. Endopeptidases excise the C-peptide, leaving the A (21 aa) and B (30 aa) chains joined by disulfide bonds in mature insulin.
Proinsulin contains A, B, and connecting C-peptides. Endopeptidases excise the C-peptide, leaving the A (21 aa) and B (30 aa) chains joined by disulfide bonds in mature insulin.
88. Severe Combined Immunodeficiency (SCID) caused by ADA gene deficiency was the first disease treated with human gene therapy in:
Correct Answer: B (1990)
The first clinical gene therapy trial was conducted in September 1990 by W. French Anderson on a 4-year-old girl with ADA-deficient SCID using retroviral cDNA transfer.
The first clinical gene therapy trial was conducted in September 1990 by W. French Anderson on a 4-year-old girl with ADA-deficient SCID using retroviral cDNA transfer.
89. Genetically modified “Golden Rice” produces grains enriched with beta-carotene to combat:
Correct Answer: A (Vitamin A deficiency)
Golden Rice expresses beta-carotene (provitamin A) in its endosperm, biofortifying rice to prevent childhood blindness and immune deficiency caused by Vitamin A malnutrition.
Golden Rice expresses beta-carotene (provitamin A) in its endosperm, biofortifying rice to prevent childhood blindness and immune deficiency caused by Vitamin A malnutrition.
90. In 1997, a US company obtained a patent on Indian Basmati rice varieties through the US Patent and Trademark Office by:
Correct Answer: B (Crossing traditional Indian Basmati with semi-dwarf varieties)
The foreign company crossed traditional Indian Basmati with semi-dwarf strains and claimed patent ownership over the germplasm, prompting international legal challenges over biopiracy.
The foreign company crossed traditional Indian Basmati with semi-dwarf strains and claimed patent ownership over the germplasm, prompting international legal challenges over biopiracy.
91. The ecological interaction between cattle egrets feeding on insects flushed out by grazing cattle is an example of:
Correct Answer: B (Commensalism)
The egrets benefit by capturing insects stirred up from vegetation by grazing cattle, while the cattle are unaffected (+, 0 interaction).
The egrets benefit by capturing insects stirred up from vegetation by grazing cattle, while the cattle are unaffected (+, 0 interaction).
92. In a population showing Verhulst-Pearl logistic growth, the population growth rate (dN/dt) slows down and reaches an asymptote when:
Correct Answer: B (Population density ‘N’ equals carrying capacity ‘K’)
Under logistic growth (dN/dt = rN[(K – N)/K]), environmental resistance increases as N approaches K; when N = K, (K – N)/K = 0 and population growth levels off.
Under logistic growth (dN/dt = rN[(K – N)/K]), environmental resistance increases as N approaches K; when N = K, (K – N)/K = 0 and population growth levels off.
93. In primary ecological succession on bare rock (Lithosere), which group follows the pioneer crustose lichens?
Correct Answer: B (Foliose/Fruticose lichens and Mosses)
In a lithosere, crustose lichens weather the rock surface, paving the way for foliose lichens (Dermatocarpon) and mosses (Polytrichum), which trap dust to form a deeper soil substrate.
In a lithosere, crustose lichens weather the rock surface, paving the way for foliose lichens (Dermatocarpon) and mosses (Polytrichum), which trap dust to form a deeper soil substrate.
94. In an ecosystem, the standing crop of a trophic level is measured as the:
Correct Answer: B (Total mass of living organisms or number in a unit area)
Standing crop is the total living biomass (expressed as dry weight or fresh weight) or number of organisms present in a trophic level at a specific moment.
Standing crop is the total living biomass (expressed as dry weight or fresh weight) or number of organisms present in a trophic level at a specific moment.
95. In a grassland ecosystem, the pyramid of numbers is:
Correct Answer: A (Upright)
In grasslands, primary producers (grasses) vastly outnumber primary consumers (grasshoppers), which outnumber secondary consumers (frogs), making the pyramid of numbers upright.
In grasslands, primary producers (grasses) vastly outnumber primary consumers (grasshoppers), which outnumber secondary consumers (frogs), making the pyramid of numbers upright.
96. The latitudinal gradient of biodiversity shows that species diversity:
Correct Answer: B (Decreases progressively from the equator toward the polar regions)
Tropics harbor higher species diversity than temperate or polar zones because tropical environments are older, less seasonal, and receive higher solar irradiance.
Tropics harbor higher species diversity than temperate or polar zones because tropical environments are older, less seasonal, and receive higher solar irradiance.
97. The catastrophic decline in Amazonian biodiversity caused by clearing rainforests for soybean cultivation and cattle pastures is an example of:
Correct Answer: A (Habitat loss and fragmentation)
Converting the Amazon rainforest into agricultural monocultures and pastures fragments habitats, driving populations of forest species toward extinction.
Converting the Amazon rainforest into agricultural monocultures and pastures fragments habitats, driving populations of forest species toward extinction.
98. The recent historical extinction of the marsupial Tasmanian Wolf (Thylacine) in Australia was driven primarily by:
Correct Answer: B (Unregulated human hunting and over-exploitation)
The Tasmanian wolf (Thylacinus cynocephalus) was hunted to extinction in Australia in the 20th century due to bounties offered to protect livestock.
The Tasmanian wolf (Thylacinus cynocephalus) was hunted to extinction in Australia in the 20th century due to bounties offered to protect livestock.
99. Preserving endangered animal gametes in viable fertile form for decades at -196°C in liquid nitrogen is:
Correct Answer: B (Cryopreservation)
Cryopreservation maintains cells, gametes, and tissue samples in liquid nitrogen (-196°C) to arrest metabolism for long-term ex-situ conservation.
Cryopreservation maintains cells, gametes, and tissue samples in liquid nitrogen (-196°C) to arrest metabolism for long-term ex-situ conservation.
100. The total number of Biosphere Reserves, National Parks, and Wildlife Sanctuaries designated in India is approximately:
Correct Answer: A (14 Biosphere Reserves, 90 National Parks, and 448 Wildlife Sanctuaries)
According to the NCERT biology syllabus benchmark, India’s in-situ protected area network encompasses 14 Biosphere Reserves, 90 National Parks, and 448 Wildlife Sanctuaries.
According to the NCERT biology syllabus benchmark, India’s in-situ protected area network encompasses 14 Biosphere Reserves, 90 National Parks, and 448 Wildlife Sanctuaries.