Q1. Coitus interruptus involves the male partner withdrawing the penis from the vagina just before:
Correct Answer: (b)
Withdrawal or coitus interruptus is another method in which the male partner withdraws his penis from the vagina just before ejaculation.
Withdrawal or coitus interruptus is another method in which the male partner withdraws his penis from the vagina just before ejaculation.
Q2. Which of the following is responsible for peat formation?
Correct Answer: (d)
Sphagnum, a moss, provides peat that has long been used as fuel and packing material.
Sphagnum, a moss, provides peat that has long been used as fuel and packing material.
Q3. Refer the figure and identify X, Y and Z.
Correct Answer: (b)
X represents FADH2 (produced from succinate). Y is NADH2 (produced from malate). Z is GTP/ATP produced via substrate-level phosphorylation.
X represents FADH2 (produced from succinate). Y is NADH2 (produced from malate). Z is GTP/ATP produced via substrate-level phosphorylation.
Q4. Cutaneous respiration requires
Correct Answer: (a)
For gas exchange to occur through the skin, the surface must remain moist to allow gases to dissolve and diffuse. Furthermore, the skin must be highly vascularized (dense with blood vessels) to efficiently transport oxygen from the surface to the rest of the body.
For gas exchange to occur through the skin, the surface must remain moist to allow gases to dissolve and diffuse. Furthermore, the skin must be highly vascularized (dense with blood vessels) to efficiently transport oxygen from the surface to the rest of the body.
Q5. In plants a common symptom caused by deficiencies of Cu, K, Ca and Mg is the
Correct Answer: (d)
Necrosis, or the death of tissue (particularly leaf tissue), is caused by the deficiency of Ca, Mg, Cu, and K.
Necrosis, or the death of tissue (particularly leaf tissue), is caused by the deficiency of Ca, Mg, Cu, and K.
Q6. Which one of the following process help the water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts?
Correct Answer: (b)
By the process of leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
By the process of leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
Q7. Swimming underwater using forelimbs for propulsion is similar to flying through the air because
Correct Answer: (d)
Both swimming and flying rely on generating lift by pushing against a fluid medium (water or air). By exerting a downward force on the surrounding fluid, an upward lift force is generated, allowing the organism to remain suspended or move efficiently against gravity.
Both swimming and flying rely on generating lift by pushing against a fluid medium (water or air). By exerting a downward force on the surrounding fluid, an upward lift force is generated, allowing the organism to remain suspended or move efficiently against gravity.
Q8. Which of the below mentioned regions exhibit less seasonal variations ?
Correct Answer: (a)
The tropics have a relatively constant and predictable environment with minimal seasonal changes, contributing to higher biodiversity.
The tropics have a relatively constant and predictable environment with minimal seasonal changes, contributing to higher biodiversity.
Q9. A forensic scientist cuts DNA from a crime scene and DNA from a suspect with the same enzyme. Which tool should the scientist use to separate the DNA fragments according to their size?
Correct Answer: (c)
Gel electrophoresis separates fragments of DNA according to their size. Bacterial transformation involves the uptake and expression of foreign DNA by bacteria, so choice (A) is incorrect. CRISPR-Cas9 is used for gene editing, so choice (B) is incorrect. PCR amplifies specific sequences of DNA, so choice (D) is also incorrect.
Gel electrophoresis separates fragments of DNA according to their size. Bacterial transformation involves the uptake and expression of foreign DNA by bacteria, so choice (A) is incorrect. CRISPR-Cas9 is used for gene editing, so choice (B) is incorrect. PCR amplifies specific sequences of DNA, so choice (D) is also incorrect.
Q10. Select the option which arranges the following steps in a correct sequence as per Gram's staining technique:
Treatment with 0.5% iodine solution (1), washing with water (2), treatment with absolute alcohol/ acetate (3), staining with weak alkaline solution of crystal violet (4).
Treatment with 0.5% iodine solution (1), washing with water (2), treatment with absolute alcohol/ acetate (3), staining with weak alkaline solution of crystal violet (4).
Correct Answer: (a)
The correct sequence is: Crystal Violet (4) -> Iodine (1) -> Water wash (2) -> Alcohol/Decolorizer (3).
The correct sequence is: Crystal Violet (4) -> Iodine (1) -> Water wash (2) -> Alcohol/Decolorizer (3).
Q11. Energy pyramids are used to represent energy transfer in an ecosystem because energy is ______ between each trophic level.
Correct Answer: (b)
Energy is lost as heat during transfer and through respiration at each level, which is why energy pyramids are always upright and never inverted.
Energy is lost as heat during transfer and through respiration at each level, which is why energy pyramids are always upright and never inverted.
Q12. Correct statements for 'Mycorrhiza' include:
(i) Many members of genus Glomus form it.
(ii) Fungus provides phosphorus to the plant.
(iii) Plant provides resistance to root-borne pathogens.
(i) Many members of genus Glomus form it.
(ii) Fungus provides phosphorus to the plant.
(iii) Plant provides resistance to root-borne pathogens.
Correct Answer: (a)
Mutualistic benefits listed on page 10.
Mutualistic benefits listed on page 10.
Q13. Monoecious plants such as corn have either staminate or carpelate flowers. Knowing what you do about the molecular mechanisms of floral development, which of the following might explain the development of single-sex flowers?
Correct Answer: (a)
In the ABC model of flower development, stamens are produced by the combination of B and C genes. If B-type genes are expressed in the innermost whorl (normally just C, which makes carpels), it would result in stamens being formed instead of carpels.
In the ABC model of flower development, stamens are produced by the combination of B and C genes. If B-type genes are expressed in the innermost whorl (normally just C, which makes carpels), it would result in stamens being formed instead of carpels.
Q14. Which one of the following is not a function of an ecosystem?
Correct Answer: (d)
Productivity, decomposition, energy flow, and nutrient cycling are the four basic functional components. Stratification is a structural feature.
Productivity, decomposition, energy flow, and nutrient cycling are the four basic functional components. Stratification is a structural feature.
Q15. Which of the following is not a cause for loss of biodiversity?
Correct Answer: (c)
Keeping animals in zoological parks is a method of ex-situ conservation, which helps protect species, not cause their loss.
Keeping animals in zoological parks is a method of ex-situ conservation, which helps protect species, not cause their loss.
Q16. Which of the following pieces of evidence best supports the hypothesis that birds are more closely related to reptiles than to other animals?
Correct Answer: (d)
(D) DNA evidence strongly supports a degree of ancestry of organisms. The location of fossils in rock layers can change due to geological events, so choice (A) is not the best answer. Choice (B) is incorrect because habitats and trophic levels do not necessarily indicate common ancestry. Mammals also have amniotic eggs, so choice (C) is incorrect.
(D) DNA evidence strongly supports a degree of ancestry of organisms. The location of fossils in rock layers can change due to geological events, so choice (A) is not the best answer. Choice (B) is incorrect because habitats and trophic levels do not necessarily indicate common ancestry. Mammals also have amniotic eggs, so choice (C) is incorrect.
Q17. Suppose that you stick your finger with a sharp pin. The area affected is very small and only one pain receptor fires. However, it fires repeatedly at a rapid rate (it hurts!). This is an example of
Correct Answer: (a)
Temporal summation occurs when a single presynaptic neuron (or receptor) fires multiple action potentials in rapid succession, resulting in the additive effect of postsynaptic potentials at the same location over time.
Temporal summation occurs when a single presynaptic neuron (or receptor) fires multiple action potentials in rapid succession, resulting in the additive effect of postsynaptic potentials at the same location over time.
Q18. Which of the following is used to cut DNA at specific base pair sequences?
Correct Answer: (d)
Restriction enzymes (also known as restriction endonucleases) cut DNA at specific base pair sequences. DNA ligase connects pieces of DNA, so choice (A) is incorrect. Choice (B) is incorrect because gel electrophoresis is used to separate DNA fragments according to their size. Polymerase chain reaction (PCR) is used to amplify specific sequences of DNA, so choice (C) is incorrect.
Restriction enzymes (also known as restriction endonucleases) cut DNA at specific base pair sequences. DNA ligase connects pieces of DNA, so choice (A) is incorrect. Choice (B) is incorrect because gel electrophoresis is used to separate DNA fragments according to their size. Polymerase chain reaction (PCR) is used to amplify specific sequences of DNA, so choice (C) is incorrect.
Q19. Concanavalin A is:
Correct Answer: (c)
Concanavalin A is a well-known lectin derived from the jack bean plant.
Concanavalin A is a well-known lectin derived from the jack bean plant.
Q20. A typical fat molecule is made up of
Correct Answer: (b)
A fat molecule (triglyceride) consists of one glycerol molecule esterified with three fatty acid chains.
A fat molecule (triglyceride) consists of one glycerol molecule esterified with three fatty acid chains.
Q21. For a genetic disease that appears in homozygous recessive (aa) individuals, individuals who are heterozygous (Aa) for the disease are resistant to infections by certain parasites.
If 19% of the individuals in a population have the genetic disease, what is the frequency of individuals who are resistant to the parasites? Assume the population is in Hardy-Weinberg equilibrium.
If 19% of the individuals in a population have the genetic disease, what is the frequency of individuals who are resistant to the parasites? Assume the population is in Hardy-Weinberg equilibrium.
Correct Answer: (b)
(B) If 19% of the individuals have the recessive genetic disease, q2 = 0.19 and q = 0.436. Then since p + q = 1, p = 0.564. The heterozygous individuals are resistant to the parasites and have a frequency of 2pq = 2 × 0.564 × 0.436 = 0.492. Choice (A) is the frequency of the recessive allele and is incorrect. Choice (C) is the frequency of the dominant allele and is incorrect. The frequency of individuals who do not have the recessive disease (some of whom may be heterozygous and others who may be homozygous dominant) is 81%, so choice (D) is incorrect.
(B) If 19% of the individuals have the recessive genetic disease, q2 = 0.19 and q = 0.436. Then since p + q = 1, p = 0.564. The heterozygous individuals are resistant to the parasites and have a frequency of 2pq = 2 × 0.564 × 0.436 = 0.492. Choice (A) is the frequency of the recessive allele and is incorrect. Choice (C) is the frequency of the dominant allele and is incorrect. The frequency of individuals who do not have the recessive disease (some of whom may be heterozygous and others who may be homozygous dominant) is 81%, so choice (D) is incorrect.
Q22. A bivalent meiosis-I consists of
Correct Answer: (c)
A bivalent is a pair of homologous chromosomes. Since each chromosome has 2 chromatids and 1 centromere, the pair has 4 chromatids and 2 centromeres.
A bivalent is a pair of homologous chromosomes. Since each chromosome has 2 chromatids and 1 centromere, the pair has 4 chromatids and 2 centromeres.
Q23. Refer the figures A, B, C and D given below. Which of the following options shows the correct name of the animals shown by the figures A, B, C and D ?
Correct Answer: (a)
A: Locust, B: Scorpion, C: Prawn, D: Pila.
A: Locust, B: Scorpion, C: Prawn, D: Pila.
Q24. You study a gene known to be important in the early stages of heart development. Loss of the gene is also suspected to play a role in triggering lung cancer. What kind of transgenic mouse would you use to study your gene in vivo?
Correct Answer: (c)
A traditional knockout mouse lacks the gene from conception, which would likely result in embryonic lethality if the gene is essential for heart development. A conditional knockout allows the researcher to delete the gene at a specific time or in a specific tissue (such as the lungs of an adult mouse), allowing the study of its role in cancer without stopping development.
A traditional knockout mouse lacks the gene from conception, which would likely result in embryonic lethality if the gene is essential for heart development. A conditional knockout allows the researcher to delete the gene at a specific time or in a specific tissue (such as the lungs of an adult mouse), allowing the study of its role in cancer without stopping development.
Q25. The given figure shows T.S. of monocot stem. Identify the correct labelling of A to F marked in the given figure.
Correct Answer: (a)
A: Epidermis, B: Sclerenchymatous hypodermis, C: Scattered vascular bundles, D/E: vascular tissue, F: Massive parenchymatous ground tissue.
A: Epidermis, B: Sclerenchymatous hypodermis, C: Scattered vascular bundles, D/E: vascular tissue, F: Massive parenchymatous ground tissue.
Q26. The ____ cannot be controlled by conscious thought.
Correct Answer: (c)
The autonomic nervous system regulates involuntary physiological processes such as heart rate, blood pressure, respiration, and digestion. In contrast, the somatic nervous system is associated with the voluntary control of body movements via skeletal muscles.
The autonomic nervous system regulates involuntary physiological processes such as heart rate, blood pressure, respiration, and digestion. In contrast, the somatic nervous system is associated with the voluntary control of body movements via skeletal muscles.
Q27. Assertion: Bottled juices are clearer than home-made ones.
Reason: Bottled juices are clarified using lipases.
Correct Answer: (a)
Bottled juices are clarified using pectinases and proteases, not lipases.
Bottled juices are clarified using pectinases and proteases, not lipases.
Q28. Dicondylic skull with 10-pairs of cranial nerves occur in
Correct Answer: (b)
Amphibians possess a dicondylic skull and 10 pairs of cranial nerves.
Amphibians possess a dicondylic skull and 10 pairs of cranial nerves.
Q29. Root differs from stem in having
Correct Answer: (d)
Roots generally possess unicellular hairs (root hairs), whereas stems may have multicellular hairs (trichomes). Roots also lack nodes and internodes.
Roots generally possess unicellular hairs (root hairs), whereas stems may have multicellular hairs (trichomes). Roots also lack nodes and internodes.
Q30. After the first mitotic division of the zygote, the larger of the two cells becomes the
Correct Answer: (c)
The zygote divides asymmetrically to form a smaller apical cell and a larger basal cell. The apical cell gives rise to the embryo, while the larger basal cell divides to form the suspensor.
The zygote divides asymmetrically to form a smaller apical cell and a larger basal cell. The apical cell gives rise to the embryo, while the larger basal cell divides to form the suspensor.
Q31. Arrange the following events into the correct order after a paper cut occurs.
Correct Answer: (b)
The correct sequence is: bacteria enter the cut, injured cells release histamine to initiate inflammation, macrophages engulf invading bacteria, and finally helper T cells are activated to initiate adaptive immunity.
The correct sequence is: bacteria enter the cut, injured cells release histamine to initiate inflammation, macrophages engulf invading bacteria, and finally helper T cells are activated to initiate adaptive immunity.
Q32. Consider the following statements comparing fermentation and aerobic respiration:
(1) Fermentation accounts for only a partial breakdown of glucose whereas in aerobic respiration it is completely degraded to CO2 and H2O.
(2) In fermentation there is a net gain of only one molecules of ATP for each molecule of glucose, whereas many molecules of ATP are generated under aerobic conditions.
(3) NADH is oxidised to NAD+ rather quickly in fermentation, however the reaction is very slow in case of aerobic respiration.
(1) Fermentation accounts for only a partial breakdown of glucose whereas in aerobic respiration it is completely degraded to CO2 and H2O.
(2) In fermentation there is a net gain of only one molecules of ATP for each molecule of glucose, whereas many molecules of ATP are generated under aerobic conditions.
(3) NADH is oxidised to NAD+ rather quickly in fermentation, however the reaction is very slow in case of aerobic respiration.
Correct Answer: (a)
Statement (1) is correct. (2) is wrong (2 ATP, not 1). (3) is wrong (NADH oxidation is slow in fermentation but fast/vigorous in aerobic respiration).
Statement (1) is correct. (2) is wrong (2 ATP, not 1). (3) is wrong (NADH oxidation is slow in fermentation but fast/vigorous in aerobic respiration).
Q33. Photoperiod is perceived by
Correct Answer: (a)
Plants detect changes in day/night length (photoperiodism) using photoreceptors. Phytochromes primarily detect red and far-red light, while cryptochromes detect blue light. Chlorophyll is used for energy conversion, not primary signaling for photoperiod.
Plants detect changes in day/night length (photoperiodism) using photoreceptors. Phytochromes primarily detect red and far-red light, while cryptochromes detect blue light. Chlorophyll is used for energy conversion, not primary signaling for photoperiod.
Q34. Fick’s Law of Diffusion states that the rate of diffusion is directly proportional to
Correct Answer: (b)
According to Fick's Law (R = DAΔp/d), the rate of diffusion (R) is directly proportional to the surface area (A) available for exchange and the difference in partial pressure (Δp) of the gas across the membrane.
According to Fick's Law (R = DAΔp/d), the rate of diffusion (R) is directly proportional to the surface area (A) available for exchange and the difference in partial pressure (Δp) of the gas across the membrane.
Q35. Match column I (function) with column II (Types of enzymes) and select the correct option.
| Column I (Function) | Column II (Types of enzymes) |
|---|---|
| A. Enzymes catalysing breakdown without addition of water. | I. Isomerases |
| B. Enzyme catalyzes the conversion of an aldose sugar to a ketose sugar. | II. Oxidoreductase |
| C. Enzyme where catalysis involves transfer of electrons. | III. Ligases |
| D. Enzyme catalysing bonding of two components with the help of ATP. | IV. Lyases |
Correct Answer: (c)
Lyases break bonds without water. Isomerases catalyze structural rearrangements (aldose to ketose). Oxidoreductases involve electron transfer. Ligases join molecules using ATP energy.
Lyases break bonds without water. Isomerases catalyze structural rearrangements (aldose to ketose). Oxidoreductases involve electron transfer. Ligases join molecules using ATP energy.
Q36. Acetyl CoA is formed by the breakdown of:
Correct Answer: (b)
Fatty acids are broken down through beta-oxidation into 2-carbon Acetyl CoA units that enter the TCA cycle.
Fatty acids are broken down through beta-oxidation into 2-carbon Acetyl CoA units that enter the TCA cycle.
Q37. Read the following statements (i-iv) regarding “ethephon” and answer the question which follows them.
(i) Ethephon is sprayed in aqueous solution and is readily absorbed and transported within the plant.
(ii) It hastens fruit ripening in tomatoes and apples.
(iii) It can be used to induce fruit thinning in cotton, cherry and walnut.
(iv) It is used to promote female sex expression in cucumber and increase yield.
How many of the above statement(s) is/ are correct?
(i) Ethephon is sprayed in aqueous solution and is readily absorbed and transported within the plant.
(ii) It hastens fruit ripening in tomatoes and apples.
(iii) It can be used to induce fruit thinning in cotton, cherry and walnut.
(iv) It is used to promote female sex expression in cucumber and increase yield.
How many of the above statement(s) is/ are correct?
Correct Answer: (d)
All four statements accurately describe the commercial applications of Ethephon as an ethylene-releasing agent.
All four statements accurately describe the commercial applications of Ethephon as an ethylene-releasing agent.
Q38. White matter is ________, and gray matter is ________.
Correct Answer: (d)
White matter consists primarily of myelinated axons, giving it a white appearance. Gray matter consists of neuronal cell bodies, dendrites, and unmyelinated axons. Both are essential components of the central nervous system (CNS).
White matter consists primarily of myelinated axons, giving it a white appearance. Gray matter consists of neuronal cell bodies, dendrites, and unmyelinated axons. Both are essential components of the central nervous system (CNS).
Q39. Deficiency symptoms of nitrogen and potassium are visible first in
Correct Answer: (a)
Elements like N and K are highly mobile and are translocated from old (senescent) leaves to young leaves during deficiency.
Elements like N and K are highly mobile and are translocated from old (senescent) leaves to young leaves during deficiency.
Q40. Which of the following is true about lipophilic hormones?
Correct Answer: (b)
Lipophilic hormones do not dissolve well in the aqueous environment of the blood plasma. Therefore, they must travel through the circulatory system bound to specialized transport proteins to remain in solution until they reach their target cells.
Lipophilic hormones do not dissolve well in the aqueous environment of the blood plasma. Therefore, they must travel through the circulatory system bound to specialized transport proteins to remain in solution until they reach their target cells.
Q41. Which of the following statements are correct?
Correct Answer: (a)
The Na+/K+ pump requires energy to move ions against gradients. Steroid synthesis in SER is an animal cell feature. Plant vacuoles can occupy up to 90% of cell volume.
The Na+/K+ pump requires energy to move ions against gradients. Steroid synthesis in SER is an animal cell feature. Plant vacuoles can occupy up to 90% of cell volume.
Q42. Trimerous flower, superior ovary and axile placentation is characteristics of
Correct Answer: (a)
Liliaceae is defined by trimerous flowers (parts in threes) and a tricarpellary, syncarpous superior ovary with axile placentation.
Liliaceae is defined by trimerous flowers (parts in threes) and a tricarpellary, syncarpous superior ovary with axile placentation.
Q43. The A and B genes are 10 cM apart on a chromosome. If an A B/a b heterozygote is testcrossed to a b/a b, how many of each progeny class would you expect out of 100 total progeny?
Correct Answer: (d)
A 10 cM distance indicates a 10% recombination frequency. For 100 progeny, 10 will be recombinants (5 A b and 5 a B). The remaining 90 will be parentals, split equally between the non-recombinant types (45 A B and 45 a b).
A 10 cM distance indicates a 10% recombination frequency. For 100 progeny, 10 will be recombinants (5 A b and 5 a B). The remaining 90 will be parentals, split equally between the non-recombinant types (45 A B and 45 a b).
Q44. FISH analysis of a breast tumor biopsy for HER2 gene reveals two spots of fluorescence in cells. What conclusion do these data support about the tumor?
Correct Answer: (d)
Fluorescence In Situ Hybridization (FISH) is used to visualize specific DNA sequences. Normal diploid cells have two copies of every gene. Since the analysis shows only two spots of fluorescence, the HER2 gene has not been duplicated or amplified. Because targeted therapies like Herceptin are only effective in tumors where the gene is amplified and overexpressing protein, these treatments would not be suitable for this patient.
Fluorescence In Situ Hybridization (FISH) is used to visualize specific DNA sequences. Normal diploid cells have two copies of every gene. Since the analysis shows only two spots of fluorescence, the HER2 gene has not been duplicated or amplified. Because targeted therapies like Herceptin are only effective in tumors where the gene is amplified and overexpressing protein, these treatments would not be suitable for this patient.
Q45. Match the plant hormones given in column I with their function/other name given in column II and choose the correct combination.
| Column-I (Plant hormone) | Column-II (Function/other name) |
|---|---|
| A. Zeatin | I. Flowering hormone |
| B. Florigen | II. Synthetic auxin |
| C. IBA | III. Cytokinin |
| D. NAA | IV. Natural auxin |
Correct Answer: (d)
Zeatin is a cytokinin. Florigen is the hypothetical flowering hormone. IBA is a natural auxin. NAA is a synthetic auxin.
Zeatin is a cytokinin. Florigen is the hypothetical flowering hormone. IBA is a natural auxin. NAA is a synthetic auxin.
Q46. The human TAS2R38 gene encodes a cell membrane protein that influences the ability to taste bitter compounds. Individuals who possess at least one TAS2R38 allele have the “taster” phenotype and can taste certain types of bitter compounds. It is estimated that about 70% of humans have the taster phenotype. Which of the following best explains the frequency of the taster phenotype?
Correct Answer: (a)
(A) Since TAS2R38 is present in the population at a higher frequency, it probably did provide a survival advantage and allowed individuals who possessed this allele to survive and reproduce at a greater rate than individuals who did not possess the allele. Choice (B) is incorrect because TAS2R38 does not cause individuals to consume bitter foods; it just influences their ability to taste bitter foods. Bitter foods do not necessarily have a higher nutrient content than other foods, so choice (C) is incorrect. There is no evidence in the question that the TAS2R38 allele lowered an individual’s chance of survival, so choice (D) is incorrect.
(A) Since TAS2R38 is present in the population at a higher frequency, it probably did provide a survival advantage and allowed individuals who possessed this allele to survive and reproduce at a greater rate than individuals who did not possess the allele. Choice (B) is incorrect because TAS2R38 does not cause individuals to consume bitter foods; it just influences their ability to taste bitter foods. Bitter foods do not necessarily have a higher nutrient content than other foods, so choice (C) is incorrect. There is no evidence in the question that the TAS2R38 allele lowered an individual’s chance of survival, so choice (D) is incorrect.
Q47. In dicot root
Correct Answer: (c)
Dicot roots exhibit a radial arrangement where xylem and phloem are located on separate radii.
Dicot roots exhibit a radial arrangement where xylem and phloem are located on separate radii.
Q48. Which is the important site of formation of glycoproteins and glycolipids in eukaryotic cells?
Correct Answer: (b)
The Golgi apparatus is the primary site for glycosylation in the cell.
The Golgi apparatus is the primary site for glycosylation in the cell.
Q49. In terms of studying gene function, what is the main benefit that genome editing has over RNAi?
Correct Answer: (a)
RNA interference (RNAi) is a 'knockdown' technology that degrades mRNA or blocks translation, resulting in reduced protein levels but often leaving some function intact. Genome editing (like CRISPR/Cas9) creates permanent changes in the DNA sequence, allowing for a complete 'knockout' or total elimination of the gene's function.
RNA interference (RNAi) is a 'knockdown' technology that degrades mRNA or blocks translation, resulting in reduced protein levels but often leaving some function intact. Genome editing (like CRISPR/Cas9) creates permanent changes in the DNA sequence, allowing for a complete 'knockout' or total elimination of the gene's function.
Q50. The evolution of modern horses (Equus) is best described as
Correct Answer: (b)
The fossil record of horses shows a bushy, branching evolutionary tree rather than a straight line. Many different lineages coexisted, evolved different adaptations (e.g., for size or diet), and eventually went extinct, leaving only the genus Equus today.
The fossil record of horses shows a bushy, branching evolutionary tree rather than a straight line. Many different lineages coexisted, evolved different adaptations (e.g., for size or diet), and eventually went extinct, leaving only the genus Equus today.
Q51. A molecule of CO₂ that is generated in the cardiac muscle of the left ventricle would not pass through which of the following structures before leaving the body?
Correct Answer: (b)
CO₂ produced in the left ventricle enters the coronary circulation, returns to the right atrium, then passes through the right ventricle and lungs before being exhaled. It does not re-enter the left atrium before leaving the body.
CO₂ produced in the left ventricle enters the coronary circulation, returns to the right atrium, then passes through the right ventricle and lungs before being exhaled. It does not re-enter the left atrium before leaving the body.
Q52. As population size (N) approaches the carrying capacity (K) in the logistic growth model, dN/dt =
Correct Answer: (b)
When N approaches K, resources become limiting and population growth slows. At carrying capacity, births and deaths balance, so the growth rate (dN/dt) approaches zero.
When N approaches K, resources become limiting and population growth slows. At carrying capacity, births and deaths balance, so the growth rate (dN/dt) approaches zero.
Q53. In the cell cycle, cyclin proteins are produced in concert with the cycle. This likely involves
Correct Answer: (a)
Cyclin levels must change rapidly. This is achieved by timing the transcription of cyclin genes at specific checkpoints and, once their task is complete, marking the proteins with ubiquitin for rapid destruction by the proteasome.
Cyclin levels must change rapidly. This is achieved by timing the transcription of cyclin genes at specific checkpoints and, once their task is complete, marking the proteins with ubiquitin for rapid destruction by the proteasome.
Q54. A dikaryon is formed when
Correct Answer: (b)
A dikaryon (n+n) stage results when plasmogamy occurs but karyogamy is delayed.
A dikaryon (n+n) stage results when plasmogamy occurs but karyogamy is delayed.
Q55. G protein–coupled receptors are involved in the nervous system by
Correct Answer: (d)
G protein–coupled receptors (metabotropic receptors) act as postsynaptic receptors that, upon binding neurotransmitters, initiate complex intracellular signaling cascades. These are distinct from ionotropic receptors, which are ligand-gated ion channels themselves.
G protein–coupled receptors (metabotropic receptors) act as postsynaptic receptors that, upon binding neurotransmitters, initiate complex intracellular signaling cascades. These are distinct from ionotropic receptors, which are ligand-gated ion channels themselves.
Q56. Which one of the following is a non-reducing carbohydrate?
Correct Answer: (b)
Sucrose is a non-reducing sugar because the functional groups of both glucose and fructose are involved in the glycosidic linkage.
Sucrose is a non-reducing sugar because the functional groups of both glucose and fructose are involved in the glycosidic linkage.
Q57. In the tropical rainforest, the majority of trees have showy animal-pollinated flowers. In temperate forests the majority of trees are wind pollinated. Which of the following explains these contrasting patterns?
(i) Wind is rare in tropical forests
(ii) Because of high species diversity in the tropics, individuals of tree species are often widely separated making wind an inefficient means of pollen dispersal.
(iii) More opportunities for coevolved mutualisms exist in tropical forests because of the high diversity of animal species.
(iv) Trees in tropical forests are mostly evergreen and year round leaf canopies impede pollen dispersal by wind.
(v) Flowering in tropical forests occurs over a short period of time when wind is absent.
(i) Wind is rare in tropical forests
(ii) Because of high species diversity in the tropics, individuals of tree species are often widely separated making wind an inefficient means of pollen dispersal.
(iii) More opportunities for coevolved mutualisms exist in tropical forests because of the high diversity of animal species.
(iv) Trees in tropical forests are mostly evergreen and year round leaf canopies impede pollen dispersal by wind.
(v) Flowering in tropical forests occurs over a short period of time when wind is absent.
Correct Answer: (c)
High diversity means individuals of the same species are far apart (ii), leading to co-evolution with animal pollinators (iii), while dense evergreen canopies block wind (iv).
High diversity means individuals of the same species are far apart (ii), leading to co-evolution with animal pollinators (iii), while dense evergreen canopies block wind (iv).
Q58. Cells that target and kill body cells infected by viruses are
Correct Answer: (b)
Natural killer (NK) cells are part of the innate immune system and specialize in detecting and destroying virus-infected and cancerous cells without prior sensitization. They recognize altered or missing MHC-I molecules on infected cells and induce apoptosis.
Natural killer (NK) cells are part of the innate immune system and specialize in detecting and destroying virus-infected and cancerous cells without prior sensitization. They recognize altered or missing MHC-I molecules on infected cells and induce apoptosis.
Q59. Dikaryon formation is the characteristic feature of
Correct Answer: (a)
In Ascomycetes and Basidiomycetes, an intervening dikaryotic stage (n+n) occurs before the nuclei fuse.
In Ascomycetes and Basidiomycetes, an intervening dikaryotic stage (n+n) occurs before the nuclei fuse.
Q60. In vertebrate hearts, atria contract from the top, and ventricles contract from the bottom. How is this accomplished?
Correct Answer: (a)
Electrical conduction begins at the SA node in the atria, spreads across atrial tissue, then passes to the AV node. From there, the impulse travels through the bundle of His and Purkinje fibers to the apex of the ventricles, ensuring contraction from the bottom upward for efficient blood ejection.
Electrical conduction begins at the SA node in the atria, spreads across atrial tissue, then passes to the AV node. From there, the impulse travels through the bundle of His and Purkinje fibers to the apex of the ventricles, ensuring contraction from the bottom upward for efficient blood ejection.
Q61. Energy flow in an ecosystem is
Correct Answer: (a)
Energy flows through the food chain in one direction only, from producers to various levels of consumers.
Energy flows through the food chain in one direction only, from producers to various levels of consumers.
Q62. Which of the following statements about Rhizobium legume nodule formation is not correct?
Correct Answer: (d)
Statement (d) is incorrect; the infection thread carries the bacteria specifically to the inner cortex cells, not just any root cell.
Statement (d) is incorrect; the infection thread carries the bacteria specifically to the inner cortex cells, not just any root cell.
Q63. Legume’s roots have swellings called nodules that
Correct Answer: (d)
Root nodules are specialized structures that house symbiotic Rhizobium bacteria which convert atmospheric nitrogen into a form the plant can use.
Root nodules are specialized structures that house symbiotic Rhizobium bacteria which convert atmospheric nitrogen into a form the plant can use.
Q64. Match the terms given in column I with their features given in column II and choose the correct option.
| Column-I (Terms) | Column-II (Features) |
|---|---|
| A. Fibres | I. Cells are living and thin walled with cellulosic cell wall, store food materials in the form of starch or fat |
| B. Sclereids | II. Main water conductive cells of the pteridophytes and the gymnosperms |
| C. Tracheids | III. Thick walled, elongated and pointed cells, generally occurring in groups |
| D. Vessels | IV. Long cylindrical tube like structure and cells are devoid of protoplasm. Characteristic feature of angiosperms |
| E. Xylem parenchyma | V. Reduced form of sclerenchyma cells with highly thickened lignified cellular walls that form small bundles of durable layers of tissue in most plants. |
Correct Answer: (b)
Fibres are pointed and grouped; Sclereids are highly thickened; Tracheids conduct in gymnosperms; Vessels are characteristic of angiosperms; Parenchyma is living and stores food.
Fibres are pointed and grouped; Sclereids are highly thickened; Tracheids conduct in gymnosperms; Vessels are characteristic of angiosperms; Parenchyma is living and stores food.
Q65. Which of the following is NOT part of the Watson–Crick model of the structure of DNA?
Correct Answer: (b)
A fundamental aspect of the Watson-Crick model is that the two strands of the double helix are antiparallel, meaning they run in opposite directions (one 5′-to-3′ and the other 3′-to-5′).
A fundamental aspect of the Watson-Crick model is that the two strands of the double helix are antiparallel, meaning they run in opposite directions (one 5′-to-3′ and the other 3′-to-5′).
Q66. Blood clots are made of
Correct Answer: (a)
Blood clots consist primarily of fibrin, an insoluble protein formed from fibrinogen during the clotting cascade. Prothrombin is a clotting factor but is not a structural component of the clot itself.
Blood clots consist primarily of fibrin, an insoluble protein formed from fibrinogen during the clotting cascade. Prothrombin is a clotting factor but is not a structural component of the clot itself.
Q67. Which of the following component enables archaebacteria to survive in extreme conditions?
Correct Answer: (a)
Archaebacteria differ from other bacteria in having a different cell wall structure, which is responsible for their survival in extreme conditions.
Archaebacteria differ from other bacteria in having a different cell wall structure, which is responsible for their survival in extreme conditions.
Q68. Which is correct link reaction:
Correct Answer: (a)
Option (a) correctly shows Pyruvate + NAD+ + CoA $\xrightarrow[Mg^{2+}]{PDH}$ Acetyl CoA + NADH + H+ + CO2.
Option (a) correctly shows Pyruvate + NAD+ + CoA $\xrightarrow[Mg^{2+}]{PDH}$ Acetyl CoA + NADH + H+ + CO2.
Q69. You think one of your teammates is using anabolic steroids to build muscle. Continued use of steroids can cause profound changes in cell function because these hormones act
Correct Answer: (a)
Anabolic steroids are synthetic variants of testosterone, a lipophilic steroid hormone. They pass into the cell and bind to intracellular androgen receptors, which then enter the nucleus to upregulate the transcription of genes responsible for muscle protein synthesis.
Anabolic steroids are synthetic variants of testosterone, a lipophilic steroid hormone. They pass into the cell and bind to intracellular androgen receptors, which then enter the nucleus to upregulate the transcription of genes responsible for muscle protein synthesis.
Q70. Which of the following animals has well developed nervous tissue but no brain :
Correct Answer: (c)
Hydra has a nerve net but lacks a centralized brain.
Hydra has a nerve net but lacks a centralized brain.
Q71. Which of the following phase follows S and G2 phases of interphase?
Correct Answer: (a)
The M-phase starts with nuclear division, and its first stage is Prophase, which follows the interphase.
The M-phase starts with nuclear division, and its first stage is Prophase, which follows the interphase.
Q72. Huntington’s disease is caused by a short tandem CAG repeat in the HTT gene. Individuals with fewer than 35 CAG repeats in the HTT gene do not develop Huntington’s disease. Individuals with 40 or more CAG repeats will develop Huntington’s disease.
Which of the following tools would be most useful in amplifying the number of copies of the HTT gene so that more DNA would be available for analysis?
Which of the following tools would be most useful in amplifying the number of copies of the HTT gene so that more DNA would be available for analysis?
Correct Answer: (c)
Polymerase chain reaction makes multiple copies of a specific DNA sequence and would be the best choice for amplifying the number of copies of the HTT gene. Choice (A) is incorrect because CRISPR-Cas9 is used for gene editing. Gel electrophoresis separates fragments of DNA by size, so choice (B) is incorrect. Restriction enzymes cut DNA at specific sequences, so choice (D) is incorrect.
Polymerase chain reaction makes multiple copies of a specific DNA sequence and would be the best choice for amplifying the number of copies of the HTT gene. Choice (A) is incorrect because CRISPR-Cas9 is used for gene editing. Gel electrophoresis separates fragments of DNA by size, so choice (B) is incorrect. Restriction enzymes cut DNA at specific sequences, so choice (D) is incorrect.
Q73. Which of the following statements is not true?
Correct Answer: (a)
Not all arteries carry oxygenated blood (e.g., pulmonary arteries carry deoxygenated blood), and not all veins carry deoxygenated blood (pulmonary veins carry oxygenated blood). The other statements correctly describe vascular structure and regulation.
Not all arteries carry oxygenated blood (e.g., pulmonary arteries carry deoxygenated blood), and not all veins carry deoxygenated blood (pulmonary veins carry oxygenated blood). The other statements correctly describe vascular structure and regulation.
Q74. Artificial insemination (AI) is used primarily when the male partner has:
Correct Answer: (b)
Infertility cases either due to inability... or due to very low sperm counts... could be corrected by artificial insemination.
Infertility cases either due to inability... or due to very low sperm counts... could be corrected by artificial insemination.
Q75. What potential problems must be considered in creating a transgenic bacterium with the human insulin gene isolated from genomic DNA to produce insulin?
Correct Answer: (b)
Human insulin is synthesized as a precursor (proinsulin) that requires eukaryotic-specific post-translational modifications, including the formation of disulfide bonds and the enzymatic cleavage of the C-peptide in the Golgi apparatus. Bacteria lack these organelles and specialized processing enzymes, so they cannot produce active insulin from a simple genomic gene sequence without additional engineering.
Human insulin is synthesized as a precursor (proinsulin) that requires eukaryotic-specific post-translational modifications, including the formation of disulfide bonds and the enzymatic cleavage of the C-peptide in the Golgi apparatus. Bacteria lack these organelles and specialized processing enzymes, so they cannot produce active insulin from a simple genomic gene sequence without additional engineering.
Q76. Receptors that trigger innate immune responses
Correct Answer: (c)
Innate immune receptors, such as Toll-like receptors, recognize conserved pathogen-associated molecular patterns (PAMPs) that are common to many pathogens, allowing a rapid, non-specific immune response.
Innate immune receptors, such as Toll-like receptors, recognize conserved pathogen-associated molecular patterns (PAMPs) that are common to many pathogens, allowing a rapid, non-specific immune response.
Q77. One of the most notable differences between gamete formation in most animals and gamete formation in plants is that
Correct Answer: (b)
In animals, meiosis directly produces gametes. In plants, meiosis produces haploid spores; these spores grow into a haploid gametophyte, which then produces gametes through mitosis.
In animals, meiosis directly produces gametes. In plants, meiosis produces haploid spores; these spores grow into a haploid gametophyte, which then produces gametes through mitosis.
Q78. Second messengers are activated in response to
Correct Answer: (c)
Hydrophilic (water-soluble) hormones cannot cross the phospholipid bilayer of the cell membrane. To exert their effects, they bind to cell-surface receptors, which then trigger the production of intracellular second messengers (like cAMP) to relay the signal.
Hydrophilic (water-soluble) hormones cannot cross the phospholipid bilayer of the cell membrane. To exert their effects, they bind to cell-surface receptors, which then trigger the production of intracellular second messengers (like cAMP) to relay the signal.
Q79. Which of the following is the most serious threat to biodiversity?
Correct Answer: (c)
Habitat loss and fragmentation is considered the most significant threat driving animal and plant species to extinction.
Habitat loss and fragmentation is considered the most significant threat driving animal and plant species to extinction.
Q80. Prezygotic isolation
Correct Answer: (d)
Reinforcement is the process by which natural selection increases reproductive isolation. If two diverging populations come back into contact and produce hybrids with lower fitness, selection will favor individuals that do not mate with the other group, thereby strengthening prezygotic barriers.
Reinforcement is the process by which natural selection increases reproductive isolation. If two diverging populations come back into contact and produce hybrids with lower fitness, selection will favor individuals that do not mate with the other group, thereby strengthening prezygotic barriers.
Q81. De-differentiation is:
Correct Answer: (a)
De-differentiation is the phenomenon where permanent, differentiated cells (like parenchyma) regain the capacity to divide under specific conditions.
De-differentiation is the phenomenon where permanent, differentiated cells (like parenchyma) regain the capacity to divide under specific conditions.
Q82. Which of the following is NOT an ion homeostatically maintained in vertebrates?
Correct Answer: (d)
Vertebrates tightly regulate essential ions such as sodium (Na⁺), chloride (Cl⁻), and calcium (Ca²⁺) because they are critical for nerve conduction, muscle contraction, and cellular functions. Fluoride (Fl⁻) is not an essential ion that is homeostatically regulated by vertebrate excretory systems.
Vertebrates tightly regulate essential ions such as sodium (Na⁺), chloride (Cl⁻), and calcium (Ca²⁺) because they are critical for nerve conduction, muscle contraction, and cellular functions. Fluoride (Fl⁻) is not an essential ion that is homeostatically regulated by vertebrate excretory systems.
Q83. Which one of the following is incorrect about the activities associated with PS-I and PS-II in non-cyclic photophosphorylation?
Correct Answer: (d)
In non-cyclic electron transport, NADPH is produced on the stroma side of the membrane associated with the electrons coming from Photosystem I.
In non-cyclic electron transport, NADPH is produced on the stroma side of the membrane associated with the electrons coming from Photosystem I.
Q84. A species whose effect on the composition of a community is greater than expected based on its abundance can be called a
Correct Answer: (d)
Keystone species exert a disproportionately large influence on community structure relative to their abundance, often shaping species diversity and interactions.
Keystone species exert a disproportionately large influence on community structure relative to their abundance, often shaping species diversity and interactions.
Q85. Place the following events in the correct order:
1. Sarcoplasmic reticulum releases Ca2+.
2. Myosin binds to actin.
3. Action potential arrives from neuron.
4. Ca2+ binds to troponin.
1. Sarcoplasmic reticulum releases Ca2+.
2. Myosin binds to actin.
3. Action potential arrives from neuron.
4. Ca2+ binds to troponin.
Correct Answer: (d)
The correct sequence starts with the stimulus (Action potential arrives, 3), which triggers the release of calcium from storage (SR releases Ca2+, 1). The calcium then binds to the regulatory protein (Ca2+ binds to troponin, 4), which reveals the binding sites, allowing the cross-bridge to form (Myosin binds to actin, 2).
The correct sequence starts with the stimulus (Action potential arrives, 3), which triggers the release of calcium from storage (SR releases Ca2+, 1). The calcium then binds to the regulatory protein (Ca2+ binds to troponin, 4), which reveals the binding sites, allowing the cross-bridge to form (Myosin binds to actin, 2).
Q86. Which one is the correct food chain ?
Correct Answer: (d)
Producer (Grass) → Primary Consumer (Grasshopper) → Secondary Consumer (Frog) → Tertiary Consumer (Snake) → Top Consumer (Eagle).
Producer (Grass) → Primary Consumer (Grasshopper) → Secondary Consumer (Frog) → Tertiary Consumer (Snake) → Top Consumer (Eagle).
Q87. Why is the white-eye phenotype always observed in males carrying the white-eye allele?
Correct Answer: (c)
In species with XY sex determination, such as Drosophila or humans, males are hemizygous for genes located on the X chromosome. Because they possess only one X, any allele present—whether dominant or recessive—will be expressed in the phenotype since there is no second allele to mask it.
In species with XY sex determination, such as Drosophila or humans, males are hemizygous for genes located on the X chromosome. Because they possess only one X, any allele present—whether dominant or recessive—will be expressed in the phenotype since there is no second allele to mask it.
Q88. Match the following for fertilization barriers:
| Layer | Location |
|---|---|
| A. Zona pellucida | (I) Outer layer of cells |
| B. Corona radiata | (II) Membrane directly surrounding ovum |
Correct Answer: (a)
Based on Figure 2.10.
Based on Figure 2.10.
Q89. An osmoregulator would maintain its internal fluids at a concentration that is ____ relative to its surroundings.
Correct Answer: (d)
Osmoregulators actively control their internal osmotic concentration and may maintain body fluids that are hypertonic, hypotonic, or isotonic relative to the external environment, depending on ecological conditions.
Osmoregulators actively control their internal osmotic concentration and may maintain body fluids that are hypertonic, hypotonic, or isotonic relative to the external environment, depending on ecological conditions.
Q90. Which of the following is not the example of recent extinction
Correct Answer: (d)
Dodo (Mauritius), Quagga (Africa), and Steller’s Sea Cow (Russia) are examples of recent extinctions listed by IUCN. Pigeons (specifically common house pigeons) are not extinct.
Dodo (Mauritius), Quagga (Africa), and Steller’s Sea Cow (Russia) are examples of recent extinctions listed by IUCN. Pigeons (specifically common house pigeons) are not extinct.