1. A repository where dried, pressed, and preserved plant specimens mounted on sheets are systematically arranged according to an accepted classification system is a:
Correct Answer: A (Herbarium)
A herbarium is a storehouse of collected plant specimens that are dried, pressed, preserved on sheets, and organized with labels providing date, place of collection, local/scientific names, and collector’s name.
A herbarium is a storehouse of collected plant specimens that are dried, pressed, preserved on sheets, and organized with labels providing date, place of collection, local/scientific names, and collector’s name.
2. Which cyanobacteria possess chlorophyll a similar to green plants and are capable of oxygenic photosynthesis?
Correct Answer: B (Blue-green algae)
Cyanobacteria (blue-green algae) are photosynthetic autotrophic eubacteria that contain chlorophyll a and perform oxygenic photosynthesis, often forming blooms in polluted water bodies.
Cyanobacteria (blue-green algae) are photosynthetic autotrophic eubacteria that contain chlorophyll a and perform oxygenic photosynthesis, often forming blooms in polluted water bodies.
3. Sleeping sickness in humans is caused by which flagellated protozoan parasite transmitted by the tsetse fly?
Correct Answer: C (Trypanosoma gambiense)
Trypanosoma is a flagellated protozoan parasite that lives in the human bloodstream and cerebrospinal fluid, transmitted by Glossina (tsetse fly) to cause African sleeping sickness.
Trypanosoma is a flagellated protozoan parasite that lives in the human bloodstream and cerebrospinal fluid, transmitted by Glossina (tsetse fly) to cause African sleeping sickness.
4. Ergot of rye, a disease caused by the parasitic ascomycete Claviceps purpurea, produces toxic alkaloids called:
Correct Answer: A (Ergotamine)
Claviceps purpurea (an ascomycete) infects rye and cereal grains, forming sclerotia containing toxic ergot alkaloids (ergotamine) that cause ergotism when consumed.
Claviceps purpurea (an ascomycete) infects rye and cereal grains, forming sclerotia containing toxic ergot alkaloids (ergotamine) that cause ergotism when consumed.
5. Giant marine brown algae that form extensive underwater kelp forests reaching up to 100 meters in height include:
Correct Answer: C (Macrocystis and Laminaria)
Kelps are massive brown algae (Phaeophyceae) characterized by large branched thalli with air bladders that can grow to lengths of up to 100 meters in cold marine environments.
Kelps are massive brown algae (Phaeophyceae) characterized by large branched thalli with air bladders that can grow to lengths of up to 100 meters in cold marine environments.
6. The flask-shaped female sex organ in bryophytes and pteridophytes that produces a single non-motile egg is the:
Correct Answer: B (Archegonium)
The archegonium is the multicellular, flask-shaped female gametangium found in bryophytes, pteridophytes, and gymnosperms, consisting of a neck and a swollen basal venter enclosing an egg.
The archegonium is the multicellular, flask-shaped female gametangium found in bryophytes, pteridophytes, and gymnosperms, consisting of a neck and a swollen basal venter enclosing an egg.
7. Gymnosperms are called “naked seed” plants because their ovules are:
Correct Answer: B (Not enclosed by any ovary wall and remain exposed)
In gymnosperms (gymnos = naked, sperma = seed), ovules are borne naked on megasporophyll surfaces without an enclosing ovary, developing directly into exposed seeds without true fruits.
In gymnosperms (gymnos = naked, sperma = seed), ovules are borne naked on megasporophyll surfaces without an enclosing ovary, developing directly into exposed seeds without true fruits.
8. Choanocytes (flagellated collar cells) that line the spongocoel and radial canals to maintain water flow are unique to:
Correct Answer: A (Phylum Porifera)
Choanocytes line the internal spongocoel and canal system in sponges, beating their flagella to drive water currents that bring food particles, oxygen, and carry away wastes.
Choanocytes line the internal spongocoel and canal system in sponges, beating their flagella to drive water currents that bring food particles, oxygen, and carry away wastes.
9. Hookworms that latch onto the human intestinal mucosa and cause chronic iron-deficiency anemia belong to the genus:
Correct Answer: B (Ancylostoma duodenale)
Ancylostoma duodenale (human hookworm) belongs to Aschelminthes; it attaches to the small intestinal wall with cutting oral plates and sucks blood, leading to microcytic hypochromic anemia.
Ancylostoma duodenale (human hookworm) belongs to Aschelminthes; it attaches to the small intestinal wall with cutting oral plates and sucks blood, leading to microcytic hypochromic anemia.
10. Which class of Chordata features a 4-chambered heart, warm-blooded homeothermy, pneumatic bones, and epidermal scales on hindlimbs?
Correct Answer: C (Aves)
Birds (Aves) are warm-blooded (homeothermic) with a 4-chambered heart, air-filled hollow (pneumatic) flight bones, feather plumage, and epidermal scales retained on their legs.
Birds (Aves) are warm-blooded (homeothermic) with a 4-chambered heart, air-filled hollow (pneumatic) flight bones, feather plumage, and epidermal scales retained on their legs.
11. A short, condensed, subterranean vertical stem with a fleshy solid base and circular nodes bearing scale leaves (e.g., Colocasia, Amorphophallus, Crocus) is a:
Correct Answer: B (Corm)
A corm is a vertically oriented, swollen underground storage stem axis covered with thin scale leaves (e.g., Amorphophallus, Colocasia, Crocus). A rhizome grows horizontally (ginger).
A corm is a vertically oriented, swollen underground storage stem axis covered with thin scale leaves (e.g., Amorphophallus, Colocasia, Crocus). A rhizome grows horizontally (ginger).
12. In a cymose inflorescence, the growth of the main peduncle is:
Correct Answer: B (Limited because the main axis terminates in a flower)
In cymose inflorescences (e.g., Solanum, Jasmine), the apical meristem terminates in a flower, checking main axis elongation while lateral branches produce flowers in basipetal order.
In cymose inflorescences (e.g., Solanum, Jasmine), the apical meristem terminates in a flower, checking main axis elongation while lateral branches produce flowers in basipetal order.
13. In family Liliaceae (e.g., Allium cepa, Aloe, Tulip), the perianth consists of:
Correct Answer: B (6 tepals arranged in two trimerous whorls of (3 + 3))
Liliaceae flowers show undifferentiated calyx and corolla (perianth) composed of 6 tepals arranged as (3 + 3) with trimerous stamens (3 + 3) and a tricarpellary syncarpous ovary.
Liliaceae flowers show undifferentiated calyx and corolla (perianth) composed of 6 tepals arranged as (3 + 3) with trimerous stamens (3 + 3) and a tricarpellary syncarpous ovary.
14. Phellogen, Phellem, and Phelloderm are collectively designated as the:
Correct Answer: B (Periderm)
During secondary growth in woody dicots, phellogen (cork cambium) cuts off phellem (cork) toward the outside and phelloderm (secondary cortex) toward the inside; these three layers form the periderm.
During secondary growth in woody dicots, phellogen (cork cambium) cuts off phellem (cork) toward the outside and phelloderm (secondary cortex) toward the inside; these three layers form the periderm.
15. In monocotyledonous roots:
Correct Answer: B (Polyarch vascular bundles and large pith)
Monocot roots have more than six radial vascular bundles (polyarch condition), a well-developed central parenchymatous pith, and no secondary cambial growth.
Monocot roots have more than six radial vascular bundles (polyarch condition), a well-developed central parenchymatous pith, and no secondary cambial growth.
16. The type of epithelium composed of a single layer of cube-like cells with surface microvilli found in the Proximal Convoluted Tubule (PCT) of nephrons is:
Correct Answer: B (Simple cuboidal brush-border epithelium)
The luminal surface of the PCT is lined by simple cuboidal cells with densely packed microvilli (brush border), which increases surface area for reabsorption of electrolytes and nutrients.
The luminal surface of the PCT is lined by simple cuboidal cells with densely packed microvilli (brush border), which increases surface area for reabsorption of electrolytes and nutrients.
17. In the circulatory system of the frog, oxygenated blood returning from the lungs is carried by the pulmonary veins into the:
Correct Answer: B (Left atrium)
In frogs, the left atrium receives oxygenated blood from the lungs via pulmonary veins, while the right atrium receives deoxygenated blood from the sinus venosus.
In frogs, the left atrium receives oxygenated blood from the lungs via pulmonary veins, while the right atrium receives deoxygenated blood from the sinus venosus.
18. The forebrain of a frog includes paired olfactory lobes, paired cerebral hemispheres, and an unpaired:
Correct Answer: C (Diencephalon)
The frog forebrain consists of anterior olfactory lobes, paired cerebral hemispheres, and a posterior diencephalon. The midbrain consists of two optic lobes, and the hindbrain includes the cerebellum and medulla.
The frog forebrain consists of anterior olfactory lobes, paired cerebral hemispheres, and a posterior diencephalon. The midbrain consists of two optic lobes, and the hindbrain includes the cerebellum and medulla.
19. Mature female frogs produce approximately how many ova during a single breeding spawn?
Correct Answer: C (2500 to 3000 ova)
A gravid female frog lays 2,500 to 3,000 pigmented eggs at a time in water, which are fertilized externally by the male during amplexus.
A gravid female frog lays 2,500 to 3,000 pigmented eggs at a time in water, which are fertilized externally by the male during amplexus.
20. The larval stage of a frog (tadpole) respires through ______ and excretes nitrogenous waste predominantly as ______:
Correct Answer: A (Gills; Ammonia)
Tadpole larvae are fully aquatic, breathing through external/internal branchial gills and excreting toxic ammonia (ammonotelism). Adult terrestrial frogs breathe via lungs/skin and excrete urea (ureotelism).
Tadpole larvae are fully aquatic, breathing through external/internal branchial gills and excreting toxic ammonia (ammonotelism). Adult terrestrial frogs breathe via lungs/skin and excrete urea (ureotelism).
21. In prokaryotes, bacterial flagella consist of three morphological regions:
Correct Answer: A (Filament, Hook, and Basal Body)
A bacterial flagellum is made of the protein flagellin and comprises an anchor basal body embedded in the cell envelope, a curved flexible hook, and a long extracellular filament.
A bacterial flagellum is made of the protein flagellin and comprises an anchor basal body embedded in the cell envelope, a curved flexible hook, and a long extracellular filament.
22. The Golgi cisternae are curved, membrane-bound flattened discs with a diameter ranging from:
Correct Answer: B (0.5 to 1.0 micrometer)
Described by Camillo Golgi in 1898, Golgi cisternae are stacked flat membranous sacs with diameters of 0.5 to 1.0 micrometer.
Described by Camillo Golgi in 1898, Golgi cisternae are stacked flat membranous sacs with diameters of 0.5 to 1.0 micrometer.
23. In mitochondria, ATP-synthesizing F0-F1 particles (oxysomes) are embedded in the:
Correct Answer: B (Inner mitochondrial membrane facing the matrix)
Oxysomes (Complex V / ATP synthase) are anchored within the inner mitochondrial membrane; the hydrophobic F0 base spans the lipid bilayer and the catalytic F1 headpiece projects into the matrix.
Oxysomes (Complex V / ATP synthase) are anchored within the inner mitochondrial membrane; the hydrophobic F0 base spans the lipid bilayer and the catalytic F1 headpiece projects into the matrix.
24. The nucleolus, chromatin, and nuclear matrix are enclosed by a nuclear envelope perforated by nuclear pores formed by the:
Correct Answer: A (Fusion of outer and inner nuclear membranes)
Nuclear pore complexes are circular apertures created by the fusion of the inner and outer nuclear membranes, regulating bidirectional macromolecule transport (RNA and proteins).
Nuclear pore complexes are circular apertures created by the fusion of the inner and outer nuclear membranes, regulating bidirectional macromolecule transport (RNA and proteins).
25. Which heterocyclic nitrogenous base is present exclusively in RNA and replaces Thymine found in DNA?
Correct Answer: D (Uracil)
RNA contains the pyrimidine base Uracil instead of Thymine (5-methyluracil). Adenine, Guanine, and Cytosine are common to both DNA and RNA.
RNA contains the pyrimidine base Uracil instead of Thymine (5-methyluracil). Adenine, Guanine, and Cytosine are common to both DNA and RNA.
26. In feedback allosteric inhibition, the end-product of a multi-step metabolic pathway inhibits:
Correct Answer: A (The first allosteric committed-step enzyme of the pathway)
In feedback inhibition (e.g., isoleucine inhibiting threonine deaminase), high concentrations of the pathway end-product bind to an allosteric regulatory site on the initial enzyme to halt production.
In feedback inhibition (e.g., isoleucine inhibiting threonine deaminase), high concentrations of the pathway end-product bind to an allosteric regulatory site on the initial enzyme to halt production.
27. An enzyme that catalyzes geometric, structural, or positional changes within a single substrate molecule belongs to class:
Correct Answer: C (Isomerases)
Isomerases (Class 5) catalyze intramolecular rearrangements, converting substrates into structural, positional, or geometric isomers (e.g., phosphoglucoisomerase).
Isomerases (Class 5) catalyze intramolecular rearrangements, converting substrates into structural, positional, or geometric isomers (e.g., phosphoglucoisomerase).
28. The proteinaceous kinetochore structures on chromosomes begin interacting with and capturing mitotic spindle microtubules during:
Correct Answer: C (Prometaphase / Metaphase)
Spindle fibers attach to kinetochores located on centromeres during late prophase/prometaphase and align chromosomes along the equatorial plate in metaphase.
Spindle fibers attach to kinetochores located on centromeres during late prophase/prometaphase and align chromosomes along the equatorial plate in metaphase.
29. An animal cell undergoing cytokinesis forms a cleavage furrow through the contractile activity of an equatorial ring composed of:
Correct Answer: B (Actin microfilaments and Myosin II motors)
In animal cells, cytokinesis occurs centripetally as a contractile ring of actin microfilaments and myosin motor proteins constricts the plasma membrane into a cleavage furrow.
In animal cells, cytokinesis occurs centripetally as a contractile ring of actin microfilaments and myosin motor proteins constricts the plasma membrane into a cleavage furrow.
30. Meiotic non-disjunction of homologous chromosomes during Anaphase I or sister chromatids during Anaphase II results in:
Correct Answer: B (Aneuploidy)
Failure of chromosomes or chromatids to disjoin properly during meiotic anaphase produces gametes with extra or missing chromosomes, causing aneuploidy (e.g., Down syndrome, Turner syndrome).
Failure of chromosomes or chromatids to disjoin properly during meiotic anaphase produces gametes with extra or missing chromosomes, causing aneuploidy (e.g., Down syndrome, Turner syndrome).
31. The accessory pigments Chlorophyll b, Carotenoids, and Xanthophylls protect the reaction center Chlorophyll a from:
Correct Answer: A (Photo-oxidation and widen the absorption spectrum)
Accessory antenna pigments absorb various light wavelengths and transfer excitation energy to Chlorophyll a while shielding it from photo-oxidative degradation under excess light.
Accessory antenna pigments absorb various light wavelengths and transfer excitation energy to Chlorophyll a while shielding it from photo-oxidative degradation under excess light.
32. The final stage of the Calvin cycle (Regeneration of RuBP) requires how many ATP molecules for every CO2 molecule fixed?
Correct Answer: C (1 ATP per CO2 fixed)
Regenerating the primary CO2 acceptor RuBP from triose phosphate molecules requires phosphorylation by ribulose-5-phosphate kinase, using 1 ATP per CO2 fixed (6 ATP per glucose).
Regenerating the primary CO2 acceptor RuBP from triose phosphate molecules requires phosphorylation by ribulose-5-phosphate kinase, using 1 ATP per CO2 fixed (6 ATP per glucose).
33. In C4 leaves, the thick-walled bundle sheath cells that form wreaths around vascular bundles:
Correct Answer: A (Thick suberized walls impermeable to gas, large agranal chloroplasts, no intercellular spaces)
Kranz bundle sheath cells have gas-impermeable suberized walls and agranal chloroplasts with abundant RuBisCO, preventing oxygen infiltration and photorespiration.
Kranz bundle sheath cells have gas-impermeable suberized walls and agranal chloroplasts with abundant RuBisCO, preventing oxygen infiltration and photorespiration.
34. During photorespiration in C3 plants, what percentage of photosynthetic carbon is lost as CO2?
Correct Answer: B (Approximately 25% of fixed carbon)
In the photorespiratory C2 pathway, out of every 4 carbons entering as two 2-carbon phosphoglycolate molecules, 1 carbon is lost as mitochondrial CO2 (25% carbon loss) without ATP generation.
In the photorespiratory C2 pathway, out of every 4 carbons entering as two 2-carbon phosphoglycolate molecules, 1 carbon is lost as mitochondrial CO2 (25% carbon loss) without ATP generation.
35. The cleavage of Fructose-1,6-bisphosphate into two interconvertible 3-carbon triose phosphates (DHAP and PGAL) in glycolysis is catalyzed by:
Correct Answer: C (Aldolase)
Aldolase cleaves 6-carbon Fructose-1,6-bisphosphate into two 3-carbon triose isomers: Dihydroxyacetone phosphate (DHAP) and 3-Phosphoglyceraldehyde (PGAL).
Aldolase cleaves 6-carbon Fructose-1,6-bisphosphate into two 3-carbon triose isomers: Dihydroxyacetone phosphate (DHAP) and 3-Phosphoglyceraldehyde (PGAL).
36. What is the theoretical maximum yield of ATP generated per glucose molecule oxidized through aerobic cellular respiration in eukaryotic cells?
Correct Answer: C (36 to 38 ATP)
Complete aerobic oxidation of 1 glucose yields 36–38 ATP (depending on whether the glycerol-phosphate or malate-aspartate shuttle transfers cytosolic NADH into mitochondria).
Complete aerobic oxidation of 1 glucose yields 36–38 ATP (depending on whether the glycerol-phosphate or malate-aspartate shuttle transfers cytosolic NADH into mitochondria).
37. In the mitochondrial electron transport system, Ubiquinone (Coenzyme Q) receives reducing equivalents from:
Correct Answer: A (Both Complex I and Complex II)
Ubiquinone is a mobile lipid electron carrier within the inner membrane that collects electrons from Complex I (NADH oxidation) and Complex II (succinate/FADH2 oxidation) and transfers them to Complex III.
Ubiquinone is a mobile lipid electron carrier within the inner membrane that collects electrons from Complex I (NADH oxidation) and Complex II (succinate/FADH2 oxidation) and transfers them to Complex III.
38. The Respiratory Quotient (RQ) for germinating fatty seeds (e.g., castor, sunflower) during active lipid mobilization is:
Correct Answer: B (Less than 1.0, approx. 0.7)
Fats contain less oxygen in their molecular structure than carbohydrates, requiring more consumed O2 relative to released CO2 ($RQ < 1.0$, typically ~0.7).
Fats contain less oxygen in their molecular structure than carbohydrates, requiring more consumed O2 relative to released CO2 ($RQ < 1.0$, typically ~0.7).
39. The bioassay used to determine the biological potency of Cytokinins based on cell division in cultured plant tissue is the:
Correct Answer: B (Tobacco pith callus growth bioassay)
Skoog and Miller identified cytokinins (kinetin) by measuring callus proliferation in cultured tobacco stem pith tissue in the presence of auxin.
Skoog and Miller identified cytokinins (kinetin) by measuring callus proliferation in cultured tobacco stem pith tissue in the presence of auxin.
40. The plant growth inhibitor hormone that promotes bud dormancy, stomatal closure under water stress, and acts antagonistically to Gibberellins is:
Correct Answer: A (Abscisic acid)
ABA induces stomatal closure during drought, enforces seed dormancy, and suppresses seed germination, acting as a functional antagonist to gibberellic acid.
ABA induces stomatal closure during drought, enforces seed dormancy, and suppresses seed germination, acting as a functional antagonist to gibberellic acid.
41. The chemosensitive area adjacent to the medullary respiratory rhythm center is highly sensitive to changes in:
Correct Answer: B (Arterial pCO2 and Hydrogen ion concentration)
The central chemoreceptors in the medulla oblongata monitor cerebrospinal fluid and arterial blood for elevated pCO2 and H+ ions (acidosis) to stimulate ventilation; arterial pO2 plays an insignificant direct role in central regulation.
The central chemoreceptors in the medulla oblongata monitor cerebrospinal fluid and arterial blood for elevated pCO2 and H+ ions (acidosis) to stimulate ventilation; arterial pO2 plays an insignificant direct role in central regulation.
42. Cigarette smoking causes chronic respiratory disease Emphysema, pathologically characterized by:
Correct Answer: B (Breakdown of alveolar septal walls with enlarged air spaces and loss of elastic recoil)
Proteases released by cigarette smoke inflammation destroy alveolar elastic fibers and inter-alveolar septa in emphysema, reducing the surface area available for gas exchange.
Proteases released by cigarette smoke inflammation destroy alveolar elastic fibers and inter-alveolar septa in emphysema, reducing the surface area available for gas exchange.
43. Which granulocytes secrete histamine, serotonin, and heparin and participate in systemic inflammatory and hypersensitivity reactions?
Correct Answer: C (Basophils)
Basophils are the least abundant leukocytes (0.5–1%); their coarse cytoplasmic granules release histamine (vasodilator), serotonin, and heparin (anticoagulant) during inflammation.
Basophils are the least abundant leukocytes (0.5–1%); their coarse cytoplasmic granules release histamine (vasodilator), serotonin, and heparin (anticoagulant) during inflammation.
44. In the cardiac cycle, the Atrioventricular Node (AVN) introduces a physiological delay of about 0.1 second before sending impulses down the Bundle of His in order to:
Correct Answer: B (Allow atria to complete contraction and empty blood into ventricles)
The AV nodal delay (~0.1 s) ensures atrial systole finishes pumping blood into the ventricles before ventricular systole begins.
The AV nodal delay (~0.1 s) ensures atrial systole finishes pumping blood into the ventricles before ventricular systole begins.
45. The Juxtaglomerular Apparatus (JGA) is a specialized cellular structure formed by the modification of the:
Correct Answer: B (Distal Convoluted Tubule and Afferent arteriole)
The JGA comprises renin-secreting juxtaglomerular cells in the afferent arteriole and chemosensitive macula densa cells in the adjacent DCT wall.
The JGA comprises renin-secreting juxtaglomerular cells in the afferent arteriole and chemosensitive macula densa cells in the adjacent DCT wall.
46. The structural unit of compact human bone featuring concentric lamellae surrounding a central neurovascular channel is the:
Correct Answer: A (Haversian system / Osteon)
Mammalian compact bone is organized into cylindrical osteons (Haversian systems) containing concentric lamellae of calcified matrix around a central neurovascular Haversian canal.
Mammalian compact bone is organized into cylindrical osteons (Haversian systems) containing concentric lamellae of calcified matrix around a central neurovascular Haversian canal.
47. The synovial joint between the carpal and metacarpal of the human thumb that allows circumduction and opposition is a:
Correct Answer: C (Saddle joint)
The first carpometacarpal joint (between the trapezium and the first metacarpal of the thumb) is a saddle joint, enabling biaxial movement and opposable thumb grip.
The first carpometacarpal joint (between the trapezium and the first metacarpal of the thumb) is a saddle joint, enabling biaxial movement and opposable thumb grip.
48. The progressive hereditary muscular disorder characterized by degenerative wasting of skeletal muscles due to a defective dystrophin gene is:
Correct Answer: C (Muscular Dystrophy)
Duchenne muscular dystrophy is an X-linked recessive genetic disease where mutations in the dystrophin gene cause structural membrane fragility and progressive muscle wasting. Myasthenia gravis is autoimmune.
Duchenne muscular dystrophy is an X-linked recessive genetic disease where mutations in the dystrophin gene cause structural membrane fragility and progressive muscle wasting. Myasthenia gravis is autoimmune.
49. The sensory organ of Corti containing auditory hair cells that rest on the basilar membrane is located inside the:
Correct Answer: C (Cochlea / Scala media)
The organ of Corti is the auditory receptor structure situated on the basilar membrane of the cochlear duct (scala media), converting sound vibrations into neural action potentials.
The organ of Corti is the auditory receptor structure situated on the basilar membrane of the cochlear duct (scala media), converting sound vibrations into neural action potentials.
50. Cretinism, a congenital disorder marked by stunted physical growth, mental retardation, and deaf-mutism in infants, is caused by:
Correct Answer: A (Maternal Hypothyroidism during pregnancy)
Maternal iodine deficiency and resultant hypothyroidism during gestation impair fetal neurodevelopment, causing cretinism (mental retardation, low IQ, deaf-mutism, stunted growth).
Maternal iodine deficiency and resultant hypothyroidism during gestation impair fetal neurodevelopment, causing cretinism (mental retardation, low IQ, deaf-mutism, stunted growth).
51. In an unfertilized 7-celled, 8-nucleate Polygonum-type embryo sac, the central cell contains:
Correct Answer: B (Two polar nuclei)
The large central cell contains two free polar nuclei that sit beneath the egg apparatus and fuse prior to or during triple fusion to form the diploid secondary nucleus.
The large central cell contains two free polar nuclei that sit beneath the egg apparatus and fuse prior to or during triple fusion to form the diploid secondary nucleus.
52. Cleistogamous flowers (e.g., Viola, Oxalis, Commelina) are characterized by:
Correct Answer: B (Remaining permanently closed, ensuring autogamous seed-set)
Cleistogamous flowers never open; anthers dehisce directly onto the stigma inside the closed bud, guaranteeing autogamy and seed development without relying on external pollinators.
Cleistogamous flowers never open; anthers dehisce directly onto the stigma inside the closed bud, guaranteeing autogamy and seed development without relying on external pollinators.
53. The tender liquid water of green coconut represents ______ and the white surrounding kernel represents ______:
Correct Answer: B (Free-nuclear endosperm; Cellular endosperm)
Coconut water is free-nuclear endosperm consisting of thousands of coenocytic nuclei floating in liquid; as the fruit matures, cytokinesis deposits the surrounding solid cellular endosperm (kernel).
Coconut water is free-nuclear endosperm consisting of thousands of coenocytic nuclei floating in liquid; as the fruit matures, cytokinesis deposits the surrounding solid cellular endosperm (kernel).
54. In the human male testis, the rete testis opens into the head of the epididymis through the:
Correct Answer: C (Vasa efferentia)
Spermatozoa pass from seminiferous tubules into the rete testis, exit via 10–20 fine vasa efferentia tubules, and enter the epididymis for functional maturation and storage.
Spermatozoa pass from seminiferous tubules into the rete testis, exit via 10–20 fine vasa efferentia tubules, and enter the epididymis for functional maturation and storage.
55. Granulosa cells in ovarian follicles secrete which non-steroidal peptide hormone that selectively suppresses anterior pituitary FSH secretion via negative feedback?
Correct Answer: C (Inhibin)
Inhibin (secreted by granulosa cells in females and Sertoli cells in males) feeds back on the anterior pituitary to selectively downregulate FSH secretion.
Inhibin (secreted by granulosa cells in females and Sertoli cells in males) feeds back on the anterior pituitary to selectively downregulate FSH secretion.
56. Human fertilization in the female reproductive tract occurs in which specific anatomical region of the fallopian tube?
Correct Answer: B (Ampullary region)
Fertilization takes place in the ampulla of the fallopian tube when the ovulated secondary oocyte and viable spermatozoa arrive simultaneously.
Fertilization takes place in the ampulla of the fallopian tube when the ovulated secondary oocyte and viable spermatozoa arrive simultaneously.
57. The cortical reaction triggered upon initial sperm penetration prevents polyspermy by:
Correct Answer: B (Hardening the zona pellucida and destroying ZP3 receptors)
Cortical granule exocytosis releases enzymes that hydrolyze ZP3 receptors and cross-link glycoproteins (zona reaction), creating a permanent block to additional sperm entry.
Cortical granule exocytosis releases enzymes that hydrolyze ZP3 receptors and cross-link glycoproteins (zona reaction), creating a permanent block to additional sperm entry.
58. The umbilical cord that connects the fetus to the maternal placenta contains:
Correct Answer: B (Two Umbilical Arteries and One Umbilical Vein)
The umbilical cord contains two umbilical arteries carrying deoxygenated blood and wastes from fetus to placenta, and one umbilical vein delivering oxygenated blood from placenta to fetus, embedded in Wharton’s jelly.
The umbilical cord contains two umbilical arteries carrying deoxygenated blood and wastes from fetus to placenta, and one umbilical vein delivering oxygenated blood from placenta to fetus, embedded in Wharton’s jelly.
59. Medical Termination of Pregnancy (MTP) is considered safest and least risky when performed during the:
Correct Answer: A (First trimester up to 12 weeks)
MTP carries minimal risk to maternal health when performed within the first trimester (first 12 weeks of gestation). Second-trimester abortions are substantially more hazardous.
MTP carries minimal risk to maternal health when performed within the first trimester (first 12 weeks of gestation). Second-trimester abortions are substantially more hazardous.
60. Which sexually transmitted infection (STI) caused by a spirochete bacterium (Treponema pallidum) produces painless chancres in its primary stage?
Correct Answer: B (Syphilis)
Syphilis is caused by Treponema pallidum; its primary stage manifests as an indurated, painless genital ulcer (chancre), followed by systemic secondary rashes and tertiary cardiovascular/neurosyphilis if untreated.
Syphilis is caused by Treponema pallidum; its primary stage manifests as an indurated, painless genital ulcer (chancre), followed by systemic secondary rashes and tertiary cardiovascular/neurosyphilis if untreated.
61. In pea plants, yellow seed color (Y) is dominant over green (y) and round seed shape (R) is dominant over wrinkled (r). In a dihybrid cross ($YyRr \times YyRr$), the proportion of yellow-wrinkled seeds in the F2 generation is:
Correct Answer: B (3/16)
In Mendel’s classical dihybrid F2 phenotypic ratio of 9:3:3:1: 9/16 are Yellow Round, 3/16 are Yellow Wrinkled, 3/16 are Green Round, and 1/16 are Green Wrinkled.
In Mendel’s classical dihybrid F2 phenotypic ratio of 9:3:3:1: 9/16 are Yellow Round, 3/16 are Yellow Wrinkled, 3/16 are Green Round, and 1/16 are Green Wrinkled.
62. Which genetic term describes the failure of homologous chromosomes or sister chromatids to separate properly during meiotic cell division?
Correct Answer: C (Non-disjunction)
Non-disjunction is the failure of chromosome pairs or sister chromatids to segregate during anaphase, producing aneuploid gametes with $(n+1)$ or $(n-1)$ chromosomes.
Non-disjunction is the failure of chromosome pairs or sister chromatids to segregate during anaphase, producing aneuploid gametes with $(n+1)$ or $(n-1)$ chromosomes.
63. A pedigree symbol displaying a completely shaded square shape represents a/an:
Correct Answer: B (Affected diseased male)
In standard pedigree charting: Squares represent males, Circles represent females, Shaded symbols indicate affected individuals, and Double lines between symbols indicate consanguineous marriage.
In standard pedigree charting: Squares represent males, Circles represent females, Shaded symbols indicate affected individuals, and Double lines between symbols indicate consanguineous marriage.
64. Hershey and Chase proved that DNA (and not protein) enters bacterial host cells during bacteriophage T2 infection by labeling viral DNA and protein respectively with:
Correct Answer: B (Radioactive Phosphorus-32 and Sulfur-35)
Hershey and Chase labeled DNA with $^{32}\text{P}$ (phosphates present in DNA, absent in proteins) and viral capsids with $^{35}\text{S}$ (sulfur present in methionine/cysteine, absent in DNA), demonstrating that only $^{32}\text{P}$ entered host bacteria.
Hershey and Chase labeled DNA with $^{32}\text{P}$ (phosphates present in DNA, absent in proteins) and viral capsids with $^{35}\text{S}$ (sulfur present in methionine/cysteine, absent in DNA), demonstrating that only $^{32}\text{P}$ entered host bacteria.
65. The Central Dogma of Molecular Biology proposed by Francis Crick states that genetic information flows directionally from:
Correct Answer: A (DNA -> mRNA -> Protein)
The Central Dogma describes directional genetic flow: DNA replicates itself, transcribes into messenger RNA, and mRNA translates into functional proteins.
The Central Dogma describes directional genetic flow: DNA replicates itself, transcribes into messenger RNA, and mRNA translates into functional proteins.
66. In eukaryotic transcription, which RNA polymerase enzyme synthesizes precursor messenger RNA (heterogeneous nuclear RNA / hnRNA)?
Correct Answer: B (RNA Polymerase II)
Eukaryotes use three RNA polymerases: Pol I transcribes rRNAs (28S, 18S, 5.8S); Pol II transcribes mRNA precursor (hnRNA); Pol III transcribes tRNA, 5S rRNA, and snRNAs.
Eukaryotes use three RNA polymerases: Pol I transcribes rRNAs (28S, 18S, 5.8S); Pol II transcribes mRNA precursor (hnRNA); Pol III transcribes tRNA, 5S rRNA, and snRNAs.
67. The “Clover-leaf” secondary structure and “Inverted-L” tertiary structure are characteristic conformations of:
Correct Answer: B (Transfer RNA)
tRNA folds into a 2D clover-leaf structure with an anticodon loop and 3′-CCA acceptor stem, which packs into a compact 3D inverted-L shape.
tRNA folds into a 2D clover-leaf structure with an anticodon loop and 3′-CCA acceptor stem, which packs into a compact 3D inverted-L shape.
68. The Russian biochemist A.I. Oparin and British scientist J.B.S. Haldane proposed that the first primitive forms of life originated from:
Correct Answer: B (Pre-existing non-living organic molecules via chemical evolution)
The Oparin-Haldane hypothesis stated that abiogenesis on primitive Earth proceeded through chemical evolution—organic monomers condensed into polymers within a warm reducing ocean (“primordial soup”).
The Oparin-Haldane hypothesis stated that abiogenesis on primitive Earth proceeded through chemical evolution—organic monomers condensed into polymers within a warm reducing ocean (“primordial soup”).
69. Hugo de Vries argued that speciation is driven by large, single-step, discontinuous mutations that occur abruptly, a process he termed:
Correct Answer: A (Saltation)
De Vries formulated his Mutation Theory studying evening primrose (Oenothera lamarckiana), proposing that large single-step mutations (saltations) drive speciation rather than slow continuous micro-variations.
De Vries formulated his Mutation Theory studying evening primrose (Oenothera lamarckiana), proposing that large single-step mutations (saltations) drive speciation rather than slow continuous micro-variations.
70. The hominid ancestor with a brain capacity of 1400 cc that lived in cold Eurasian environments, wore animal skins, and buried its dead with rituals was:
Correct Answer: D (Homo neanderthalensis)
Neanderthals had a 1400 cc brain volume, inhabited near East and Central Asia ~100,000 to 40,000 years ago, made tailored hide clothing, and buried their dead.
Neanderthals had a 1400 cc brain volume, inhabited near East and Central Asia ~100,000 to 40,000 years ago, made tailored hide clothing, and buried their dead.
71. Entamoeba histolytica invades the mucosal lining of which human organ, producing severe amoebic dysentery with blood and mucus in stools?
Correct Answer: C (Large intestine)
Entamoeba histolytica is a protozoan parasite of the human large intestine (colon) that hydrolyzes mucosa with histolysin, causing flask-shaped ulcers and bloody dysentery.
Entamoeba histolytica is a protozoan parasite of the human large intestine (colon) that hydrolyzes mucosa with histolysin, causing flask-shaped ulcers and bloody dysentery.
72. Which antibody isotype forms a pentameric structure linked by a J-chain and represents the first antibody class synthesized during a primary immune response?
Correct Answer: B (IgM)
IgM is a heavy pentamer with 10 antigen-binding sites connected by a joining (J) chain, acting as the primary antibody produced upon initial antigen exposure.
IgM is a heavy pentamer with 10 antigen-binding sites connected by a joining (J) chain, acting as the primary antibody produced upon initial antigen exposure.
73. Autoimmune diseases occur when the immune system loses self-tolerance and attacks its own body tissues. Which of the following is an autoimmune disease?
Correct Answer: C (Rheumatoid arthritis and Myasthenia gravis)
In autoimmunity (e.g., Rheumatoid arthritis, Myasthenia gravis, Hashimoto’s thyroiditis), autoreactive antibodies attack host joint synovial membranes, neuromuscular receptors, or thyroid cells.
In autoimmunity (e.g., Rheumatoid arthritis, Myasthenia gravis, Hashimoto’s thyroiditis), autoreactive antibodies attack host joint synovial membranes, neuromuscular receptors, or thyroid cells.
74. Diagnostic histological biopsy for cancer involves:
Correct Answer: B (Excising a tissue piece, staining, and examining microscopically)
In histopathological biopsy, a suspected tumor sample is fixed, sectioned, stained with hematoxylin and eosin, and examined microscopically to confirm neoplastic architecture.
In histopathological biopsy, a suspected tumor sample is fixed, sectioned, stained with hematoxylin and eosin, and examined microscopically to confirm neoplastic architecture.
75. The powerful central nervous system stimulant and hallucinogenic alkaloid obtained from Atropa belladonna and Datura species is:
Correct Answer: C (Atropine / Scopolamine)
Atropa belladonna (deadly nightshade) and Datura stramonium contain anticholinergic tropane alkaloids (atropine, scopolamine) that cause potent hallucinations and delirium.
Atropa belladonna (deadly nightshade) and Datura stramonium contain anticholinergic tropane alkaloids (atropine, scopolamine) that cause potent hallucinations and delirium.
76. The fermented dough used for baking bread rises and becomes porous due to carbon dioxide (CO2) released during anaerobic fermentation by:
Correct Answer: A (Saccharomyces cerevisiae)
Baker’s yeast ferment sugars in dough, releasing bubbles of carbon dioxide ($CO_2$) gas that get trapped and cause the dough to rise (proofing), making bread soft and spongy.
Baker’s yeast ferment sugars in dough, releasing bubbles of carbon dioxide ($CO_2$) gas that get trapped and cause the dough to rise (proofing), making bread soft and spongy.
77. The bottled fruit juices available commercially in the market are clearer than fresh homemade juices because commercial juices are treated with:
Correct Answer: B (Pectinases and Proteases)
Turbidity in fresh fruit juices is caused by suspended pectin fibers and plant proteins; clarifying juices with microbial pectinases and proteases produces a crystal-clear liquid.
Turbidity in fresh fruit juices is caused by suspended pectin fibers and plant proteins; clarifying juices with microbial pectinases and proteases produces a crystal-clear liquid.
78. What happens to the Biochemical Oxygen Demand (BOD) and dissolved oxygen levels in a river polluted heavily with untreated domestic sewage?
Correct Answer: B (BOD rises sharply while dissolved oxygen plummets)
Decomposer bacteria consume dissolved oxygen to oxidize organic sewage, sharply increasing BOD and depleting dissolved oxygen ($O_2$), causing aquatic asphyxiation.
Decomposer bacteria consume dissolved oxygen to oxidize organic sewage, sharply increasing BOD and depleting dissolved oxygen ($O_2$), causing aquatic asphyxiation.
79. Dragonflies and Ladybird beetles are effective predators in biological pest control against:
Correct Answer: A (Mosquitoes and Aphids respectively)
Ladybird beetles feed on crop-damaging aphids, while adult dragonflies and their aquatic nymphs hunt mosquito larvae and adults.
Ladybird beetles feed on crop-damaging aphids, while adult dragonflies and their aquatic nymphs hunt mosquito larvae and adults.
80. The nitrogen-fixing bacterium Rhizobium forms functional pink root nodules in leguminous plants because the nodules contain:
Correct Answer: B (Leghaemoglobin and Nitrogenase enzyme)
The nitrogenase enzyme is oxygen-sensitive. The pink pigment leghemoglobin acts as an oxygen scavenger, binding free $O_2$ to maintain the microaerophilic environment required for nitrogen fixation.
The nitrogenase enzyme is oxygen-sensitive. The pink pigment leghemoglobin acts as an oxygen scavenger, binding free $O_2$ to maintain the microaerophilic environment required for nitrogen fixation.
81. In gel electrophoresis, DNA bands are resolved by size. The dye used to stain the agarose gel to visualize DNA under UV light is:
Correct Answer: B (Ethidium bromide)
Ethidium bromide intercalates between stacked base pairs; exposure to ultraviolet (UV) radiation fluoresces bright orange bands indicating DNA fragment locations.
Ethidium bromide intercalates between stacked base pairs; exposure to ultraviolet (UV) radiation fluoresces bright orange bands indicating DNA fragment locations.
82. The ‘ori’ (Origin of Replication) sequence in a recombinant plasmid vector controls the:
Correct Answer: B (Initiation of DNA replication and copy number)
The origin of replication (‘ori’) is the nucleotide sequence where host DNA polymerases bind to initiate replication; it determines the plasmid copy number per host cell.
The origin of replication (‘ori’) is the nucleotide sequence where host DNA polymerases bind to initiate replication; it determines the plasmid copy number per host cell.
83. In blue-white colony screening for recombinants using the lacZ gene, non-recombinant bacterial colonies appear blue on X-gal agar because:
Correct Answer: A (Intact lacZ produces active beta-galactosidase that hydrolyzes X-gal)
Non-recombinant plasmids retain an intact lacZ gene that synthesizes functional beta-galactosidase, cleaving the substrate X-gal into a blue precipitate. Recombinant plasmids disrupt lacZ and stay white.
Non-recombinant plasmids retain an intact lacZ gene that synthesizes functional beta-galactosidase, cleaving the substrate X-gal into a blue precipitate. Recombinant plasmids disrupt lacZ and stay white.
84. Stirred-tank bioreactors are preferred over simple shake flasks for large-scale production because bioreactors:
Correct Answer: B (Provide optimal growth conditions with continuous mixing)
Bioreactors provide automated control over temperature, pH, agitation, foam, and dissolved oxygen to maintain cells in exponential growth for industrial biosynthesis.
Bioreactors provide automated control over temperature, pH, agitation, foam, and dissolved oxygen to maintain cells in exponential growth for industrial biosynthesis.
85. The soil bacterium Bacillus thuringiensis produces crystalline endotoxins that are classified as:
Correct Answer: A (Insecticidal proteins active against Lepidopterans, Coleopterans, and Dipterans)
Bt produces delta-endotoxin crystal proteins active against lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes).
Bt produces delta-endotoxin crystal proteins active against lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes).
86. Transgenic tobacco plants resistant to the root-knot nematode Meloidogyne incognita were engineered using:
Correct Answer: B (RNA interference mediated by Agrobacterium vectors)
Nematode-specific genes were introduced into tobacco via Agrobacterium, producing sense and antisense RNA that formed dsRNA to silence target nematode mRNA upon ingestion.
Nematode-specific genes were introduced into tobacco via Agrobacterium, producing sense and antisense RNA that formed dsRNA to silence target nematode mRNA upon ingestion.
87. During natural insulin processing in the human pancreas, conversion of proinsulin to active mature insulin involves:
Correct Answer: B (Proteolytic excision and removal of the connecting C-peptide)
Prohormone proinsulin is converted to mature insulin when endopeptidases cleave out the 31-amino acid C-peptide, leaving the A and B chains linked by disulfide bridges.
Prohormone proinsulin is converted to mature insulin when endopeptidases cleave out the 31-amino acid C-peptide, leaving the A and B chains linked by disulfide bridges.
88. In 1990, the first clinical gene therapy was given to a 4-year-old girl with SCID caused by a defect in the gene for:
Correct Answer: A (Adenosine Deaminase)
The inaugural clinical gene therapy treated a 4-year-old patient with ADA-deficient SCID by inserting functional human ADA cDNA into her T-lymphocytes using a retroviral vector.
The inaugural clinical gene therapy treated a 4-year-old patient with ADA-deficient SCID by inserting functional human ADA cDNA into her T-lymphocytes using a retroviral vector.
89. The first transgenic cow ‘Rosie’ (1997) produced milk containing 2.4 g/L of which human protein, making it more nutritionally balanced than natural bovine milk?
Correct Answer: B (Human alpha-lactalbumin)
Rosie was engineered to produce human alpha-lactalbumin ($2.4\text{ g/L}$), making her milk nutritionally equivalent and gentler for human infants compared to standard cow milk.
Rosie was engineered to produce human alpha-lactalbumin ($2.4\text{ g/L}$), making her milk nutritionally equivalent and gentler for human infants compared to standard cow milk.
90. Which statutory organization in India makes decisions regarding the validity of GM research and the safety of introducing GM organisms for public services?
Correct Answer: C (GEAC)
The Genetic Engineering Appraisal Committee (under the Ministry of Environment, Forest and Climate Change) evaluates biosafety, field trials, and commercial approvals for GMOs in India.
The Genetic Engineering Appraisal Committee (under the Ministry of Environment, Forest and Climate Change) evaluates biosafety, field trials, and commercial approvals for GMOs in India.
91. The Mediterranean orchid Ophrys lures male Colpa bees into pseudo-copulation to ensure cross-pollination by:
Correct Answer: B (Floral petal mimics the female bee in size, color, and markings)
Ophrys employs sexual deceit: one petal mimics the female Colpa bee in appearance and pheromone scent, prompting pseudo-copulation that transfers pollinia.
Ophrys employs sexual deceit: one petal mimics the female Colpa bee in appearance and pheromone scent, prompting pseudo-copulation that transfers pollinia.
92. In a logistic population growth model ($dN/dt = rN[(K – N)/K]$), when population density ‘N’ reaches the carrying capacity ‘K’, the rate of population growth ($dN/dt$) becomes:
Correct Answer: A (Zero)
When $N = K$, the term $(K – N)/K$ equals zero, so $dN/dt = 0$, causing the population curve to level off at its carrying capacity asymptote.
When $N = K$, the term $(K – N)/K$ equals zero, so $dN/dt = 0$, causing the population curve to level off at its carrying capacity asymptote.
93. What is the correct chronological sequence of seral stages in a Hydrarch ecological succession in freshwater bodies?
Correct Answer: A (Phytoplankton -> Submerged -> Floating -> Reed-swamp -> Marsh-meadow -> Scrub -> Forest)
Hydrarch succession starts with plankton pioneers, followed by rooted submerged plants (Hydrilla), floating plants, reed-swamp, marsh-meadow, scrub, and finally a mesic forest climax.
Hydrarch succession starts with plankton pioneers, followed by rooted submerged plants (Hydrilla), floating plants, reed-swamp, marsh-meadow, scrub, and finally a mesic forest climax.
94. In a terrestrial forest ecosystem, the largest fraction of energy flows through the:
Correct Answer: B (Detritus Food Chain)
In terrestrial ecosystems, most primary biomass enters the detrital food web via fallen litter, making the DFC the dominant energy conduit compared to GFC.
In terrestrial ecosystems, most primary biomass enters the detrital food web via fallen litter, making the DFC the dominant energy conduit compared to GFC.
95. In an open ocean ecosystem, the pyramid of biomass is inverted because:
Correct Answer: B (Standing crop biomass of phytoplankton is much smaller)
Phytoplankton reproduce rapidly with high turnover rates; their standing biomass at any given moment is smaller than the larger, longer-lived fish they support.
Phytoplankton reproduce rapidly with high turnover rates; their standing biomass at any given moment is smaller than the larger, longer-lived fish they support.
96. The ecologist who demonstrated experimentally that plots with more species showed less year-to-year variation in total biomass and contributed to ecosystem stability was:
Correct Answer: B (David Tilman)
David Tilman’s long-term outdoor prairie plots confirmed that higher species richness reduces year-to-year biomass fluctuations and enhances community stability.
David Tilman’s long-term outdoor prairie plots confirmed that higher species richness reduces year-to-year biomass fluctuations and enhances community stability.
97. In Paul Ehrlich’s ‘Rivet Popper Hypothesis’, removing rivets from an airplane’s wings corresponds to the:
Correct Answer: B (Extinction of a keystone species)
Ehrlich compared ecosystems to airplanes: loss of minor rivets (non-critical species) causes gradual degradation, but popping rivets from wings (keystone species) threatens flight integrity.
Ehrlich compared ecosystems to airplanes: loss of minor rivets (non-critical species) causes gradual degradation, but popping rivets from wings (keystone species) threatens flight integrity.
98. The extinction of the passenger pigeon (Ectopistes migratorius) in North America was primarily driven by:
Correct Answer: B (Human over-exploitation and commercial hunting)
Unregulated commercial hunting and habitat encroachment drove the passenger pigeon from billions of individuals to complete extinction in the early 20th century.
Unregulated commercial hunting and habitat encroachment drove the passenger pigeon from billions of individuals to complete extinction in the early 20th century.
99. Sacred Groves in Meghalaya that provide inviolable protection to rare endemic flora through religious traditions are located in the:
Correct Answer: A (Khasi and Jaintia Hills)
The Khasi and Jaintia Hills in Meghalaya harbor sacred groves protected by tribal custom, preserving relict plant species found nowhere else.
The Khasi and Jaintia Hills in Meghalaya harbor sacred groves protected by tribal custom, preserving relict plant species found nowhere else.
100. In a Biosphere Reserve, the legally protected central undisturbed zone where NO human activity is allowed is the:
Correct Answer: A (Core Zone)
A Biosphere Reserve contains a strictly protected Core Zone (no human interference), a Buffer Zone (limited research and education), and an outer Transition Zone (sustainable human settlements and agriculture).
A Biosphere Reserve contains a strictly protected Core Zone (no human interference), a Buffer Zone (limited research and education), and an outer Transition Zone (sustainable human settlements and agriculture).