Q1. Pyrenoids in green algal cells are related to
Correct Answer: (a)
Pyrenoids are proteinaceous bodies found in the chloroplasts of green algae that are surrounded by starch plates and are involved in starch storage.
Pyrenoids are proteinaceous bodies found in the chloroplasts of green algae that are surrounded by starch plates and are involved in starch storage.
Q2. How can osteocytes remain alive within bone?
Correct Answer: (b)
Osteocytes are living bone cells housed in lacunae. They receive nutrients and oxygen through blood vessels present in Haversian canals. These canals form an organized network that maintains the viability of osteocytes deep within bone tissue.
Osteocytes are living bone cells housed in lacunae. They receive nutrients and oxygen through blood vessels present in Haversian canals. These canals form an organized network that maintains the viability of osteocytes deep within bone tissue.
Q3. Character displacement
Correct Answer: (a)
Character displacement occurs when two similar species compete for the same resources in the same area (sympatry). Natural selection favors individuals in each species that use different resources, leading to the divergence of physical traits, which can further enhance reproductive isolation.
Character displacement occurs when two similar species compete for the same resources in the same area (sympatry). Natural selection favors individuals in each species that use different resources, leading to the divergence of physical traits, which can further enhance reproductive isolation.
Q4. Asexual reproduction is likely to be most common in which ecosystem?
Correct Answer: (a)
Asexual reproduction is favored in stable and predictable environments. Tropical rainforests provide such conditions because they have a constant temperature, high and regular rainfall, and very little seasonal variation. This environmental stability allows organisms to survive and reproduce successfully without the need for genetic variation. In contrast, temperate grasslands experience strong seasonal changes, the arctic tundra has extremely cold and harsh conditions, and deciduous forests show marked seasonal variation, all of which favor sexual reproduction rather than asexual reproduction.
Asexual reproduction is favored in stable and predictable environments. Tropical rainforests provide such conditions because they have a constant temperature, high and regular rainfall, and very little seasonal variation. This environmental stability allows organisms to survive and reproduce successfully without the need for genetic variation. In contrast, temperate grasslands experience strong seasonal changes, the arctic tundra has extremely cold and harsh conditions, and deciduous forests show marked seasonal variation, all of which favor sexual reproduction rather than asexual reproduction.
Q5. Assertion: Secondary sewage treatment is also called biological treatment.
Reason: It involves the use of heterotrophic aerobic microbes to consume organic matter.
Correct Answer: (a)
The reliance on living organisms for treatment is why it is termed 'biological'.
The reliance on living organisms for treatment is why it is termed 'biological'.
Q6. What is common to the following plants Nepenthes, Psilotum, Rauwolfia and Aconitum ?
Correct Answer: (c)
These plants are highly valued for medicinal or other properties and are currently threatened by over-harvesting from the wild.
These plants are highly valued for medicinal or other properties and are currently threatened by over-harvesting from the wild.
Q7. Assertion: Sex education in schools is necessary.
Reason: It provides right information and discourages children from believing in myths about sex-related aspects.
Correct Answer: (a)
Providing correct information is the primary goal of sex education.
Providing correct information is the primary goal of sex education.
Q8. Reduced form of ubiquinone is:
Correct Answer: (b)
When ubiquinone (Q) accepts two electrons and two protons, it is reduced to ubiquinol (QH2).
When ubiquinone (Q) accepts two electrons and two protons, it is reduced to ubiquinol (QH2).
Q9. 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.
Q10. Which of the following phylum is being described by the given statements?
(i) These are primitive multicellular animals and have cellular level of organization.
(ii) Digestion is intracellular.
(iii) They have a water transport or canal system.
(iv) They reproduce asexually by fragmentation and sexually by formation of gametes.
(i) These are primitive multicellular animals and have cellular level of organization.
(ii) Digestion is intracellular.
(iii) They have a water transport or canal system.
(iv) They reproduce asexually by fragmentation and sexually by formation of gametes.
Correct Answer: (a)
These are characteristics of sponges (Phylum Porifera).
These are characteristics of sponges (Phylum Porifera).
Q11. Match the acronyms for Infertility treatment:
| A. AI | Artificial Insemination |
|---|---|
| B. IUI | Intra-Uterine Insemination |
| C. ART | Assisted Reproductive Technologies |
Correct Answer: (a)
Standard terminology in Section 3.5.
Standard terminology in Section 3.5.
Q12. Caffeine inhibits the secretion of ADH. Prior to an exam, you have a large coffee. During the exam, you can expect
Correct Answer: (b)
ADH normally increases water reabsorption in the collecting duct. By inhibiting ADH, caffeine reduces water permeability of the collecting duct, resulting in less water reabsorption and increased urine production.
ADH normally increases water reabsorption in the collecting duct. By inhibiting ADH, caffeine reduces water permeability of the collecting duct, resulting in less water reabsorption and increased urine production.
Q13. Which of the following statement (s) is/are not correct?
(i) Calyx and corolla are reproductive organs of a flower.
(ii) Zygomorphic flower can be divided into two equal radial halves in any radial plane.
(iii) Flowers without bracts are termed as bracteate.
(iv) Parthenocarpic fruit is formed after fertilization of the ovary.
(v) In legumes, seed is non-endospermic.
(vi) Radical buds develop on roots.
(i) Calyx and corolla are reproductive organs of a flower.
(ii) Zygomorphic flower can be divided into two equal radial halves in any radial plane.
(iii) Flowers without bracts are termed as bracteate.
(iv) Parthenocarpic fruit is formed after fertilization of the ovary.
(v) In legumes, seed is non-endospermic.
(vi) Radical buds develop on roots.
Correct Answer: (a)
Calyx/corolla are accessory organs. Zygomorphic is bilateral symmetry (only one plane). Flowers without bracts are ebracteate. Parthenocarpic fruits form without fertilization.
Calyx/corolla are accessory organs. Zygomorphic is bilateral symmetry (only one plane). Flowers without bracts are ebracteate. Parthenocarpic fruits form without fertilization.
Q14. Refer to the figure, which shows a pedigree of an inherited trait.
Based on this pedigree, which of the following most likely describes the inheritance of this trait?
Based on this pedigree, which of the following most likely describes the inheritance of this trait?
Correct Answer: (d)
(D) In this pedigree, both females and males are affected, but only females appear to be able to pass the trait on to the next generation—these are hallmarks of mitochondrial inheritance. Autosomal traits are equally likely in both sexes, so choices (A) and (B) are incorrect. Sex-linked traits are more likely to appear in males than females, so choice (C) is incorrect.
(D) In this pedigree, both females and males are affected, but only females appear to be able to pass the trait on to the next generation—these are hallmarks of mitochondrial inheritance. Autosomal traits are equally likely in both sexes, so choices (A) and (B) are incorrect. Sex-linked traits are more likely to appear in males than females, so choice (C) is incorrect.
Q15. You set up four RT-qPCR reactions all containing the same amount of total RNA. When the reactions are complete, you see that you have 10,000 units of fluorescence after 20 cycles for sample A, after 25 cycles for sample B, after 18 cycles for sample C, and after 22 cycles for sample D. Which of the samples had the most copies of target mRNA at the start of the RT-qPCR?
Correct Answer: (c)
In quantitative PCR, the 'cycle threshold' (Ct or Cq) is the cycle number where the fluorescence signal crosses a specific level. A lower Ct value indicates that the target sequence reached the threshold sooner, meaning there was a higher starting concentration of the target mRNA. Sample C reached the threshold in only 18 cycles, the fewest among the group.
In quantitative PCR, the 'cycle threshold' (Ct or Cq) is the cycle number where the fluorescence signal crosses a specific level. A lower Ct value indicates that the target sequence reached the threshold sooner, meaning there was a higher starting concentration of the target mRNA. Sample C reached the threshold in only 18 cycles, the fewest among the group.
Q16. The epidermis fights microbial infections by
Correct Answer: (d)
The skin acts as a first line of defense through multiple mechanisms: acidic pH inhibits microbial growth, lysozyme breaks down bacterial cell walls, and mucus traps pathogens, making all options correct.
The skin acts as a first line of defense through multiple mechanisms: acidic pH inhibits microbial growth, lysozyme breaks down bacterial cell walls, and mucus traps pathogens, making all options correct.
Q17. Which one of the given graph shows the effect of pH on the velocity of a typical enzymatic reaction (V) ?
Correct Answer: (c)
Enzyme activity relative to pH or temperature typically follows a bell-shaped curve (c), with a peak at the optimum value and declining activity on either side.
Enzyme activity relative to pH or temperature typically follows a bell-shaped curve (c), with a peak at the optimum value and declining activity on either side.
Q18. Thiobacillus is a group of bacteria helpful in carrying out:
Correct Answer: (d)
Thiobacillus and Pseudomonas are the primary bacteria responsible for the denitrification process in the nitrogen cycle.
Thiobacillus and Pseudomonas are the primary bacteria responsible for the denitrification process in the nitrogen cycle.
Q19. Which one is the first Gibberellins to be discovered and remains the most intensively studied form?
Correct Answer: (c)
There are more than 100 gibberellins known, but GA3 was the first to be discovered and is the most common form used in research.
There are more than 100 gibberellins known, but GA3 was the first to be discovered and is the most common form used in research.
Q20. The oral contraceptive 'Saheli' was developed at:
Correct Answer: (a)
‘Saheli’–a new oral contraceptive for the females–was developed by scientists at Central Drug Research Institute (CDRI) in Lucknow, India.
‘Saheli’–a new oral contraceptive for the females–was developed by scientists at Central Drug Research Institute (CDRI) in Lucknow, India.
Q21. You are studying renal function in different species of mammals found in very different environments. The desert species would be expected to have
Correct Answer: (b)
Desert mammals must conserve water efficiently. Longer loops of Henle create a stronger osmotic gradient in the kidney medulla, allowing greater water reabsorption and the production of highly concentrated urine.
Desert mammals must conserve water efficiently. Longer loops of Henle create a stronger osmotic gradient in the kidney medulla, allowing greater water reabsorption and the production of highly concentrated urine.
Q22. Association between mycobiont and phycobiont are found in
Correct Answer: (c)
Lichens are symbiotic associations between a fungus (mycobiont) and an alga (phycobiont).
Lichens are symbiotic associations between a fungus (mycobiont) and an alga (phycobiont).
Q23. What property of DNA causes it to move toward the positive electrode in gel electrophoresis?
Correct Answer: (d)
The phosphates in the backbone of the DNA double helix have a slight negative charge and are attracted to the positive electrode. The nitrogen atoms in the nitrogenous bases are not charged, so choice (A) is incorrect. Hydrogen bonds between the base pairs do not result in a net negative charge, so choice (B) is incorrect. The oxygen atoms in the deoxyribose sugars are not charged, and thus choice (C) is incorrect.
The phosphates in the backbone of the DNA double helix have a slight negative charge and are attracted to the positive electrode. The nitrogen atoms in the nitrogenous bases are not charged, so choice (A) is incorrect. Hydrogen bonds between the base pairs do not result in a net negative charge, so choice (B) is incorrect. The oxygen atoms in the deoxyribose sugars are not charged, and thus choice (C) is incorrect.
Q24. Which of the following is responsible for the formation of an embryonic shoot called axillary bud?
Correct Answer: (b)
The shoot apical meristem is the source of cells that form axillary buds in the axils of leaves.
The shoot apical meristem is the source of cells that form axillary buds in the axils of leaves.
Q25. Match the organisms given in column-I with their common name given in column-II and choose the correct option.
| Column-I (Organisms) | Column-II (Common name) |
|---|---|
| A. Pennatula | I. Sea-lily |
| B. Antedon | II. Sea-pen |
| C. Echinus | III. Sea-urchin |
| D. Cucumaria | IV. Sea-cucumber |
Correct Answer: (a)
A-II; B-I; C-III; D-IV. (Option A uses letters C, D which matches the table rows).
A-II; B-I; C-III; D-IV. (Option A uses letters C, D which matches the table rows).
Q26. In citric acid cycle, energy bond (GTP) is produced as a result of conversion of:
Correct Answer: (c)
The conversion of Succinyl-CoA to Succinic Acid is a substrate-level phosphorylation step that yields one GTP (or ATP).
The conversion of Succinyl-CoA to Succinic Acid is a substrate-level phosphorylation step that yields one GTP (or ATP).
Q27. With regard to Sieve tube elements, consider the following statements:
1. A mature sieve element does not have cytoplasm
2. The nucleus and vacuole are absent in mature sieve element
Which of the statement(s) given above is/are correct?
1. A mature sieve element does not have cytoplasm
2. The nucleus and vacuole are absent in mature sieve element
Which of the statement(s) given above is/are correct?
Correct Answer: (d)
A mature sieve tube element has peripheral cytoplasm and a large vacuole, but it lacks a nucleus.
A mature sieve tube element has peripheral cytoplasm and a large vacuole, but it lacks a nucleus.
Q28. Relative fitness
Correct Answer: (a)
Fitness is a measure of the relative ability of an individual (or a specific phenotype/genotype) to survive and reproduce in a given environment. It is usually expressed relative to the most successful phenotype in the population, which is assigned a fitness value of 1.0.
Fitness is a measure of the relative ability of an individual (or a specific phenotype/genotype) to survive and reproduce in a given environment. It is usually expressed relative to the most successful phenotype in the population, which is assigned a fitness value of 1.0.
Q29. 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.
Q30. Which are correct for 'Blastocyst' implantation?
(i) Trophoblast attaches to endometrium.
(ii) Inner cell mass differentiates into embryo.
(iii) Uterine cells divide rapidly to cover blastocyst.
(i) Trophoblast attaches to endometrium.
(ii) Inner cell mass differentiates into embryo.
(iii) Uterine cells divide rapidly to cover blastocyst.
Correct Answer: (a)
The process and participants of implantation.
The process and participants of implantation.
Q31. Two bacteria found to be very useful in genetic engineering experiments are
Correct Answer: (a)
E. coli is a primary host for gene cloning, and Agrobacterium tumefaciens is used as a vector for plant genetic engineering.
E. coli is a primary host for gene cloning, and Agrobacterium tumefaciens is used as a vector for plant genetic engineering.
Q32. 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.
Q33. Identify the wrong statement in context of heartwood
Correct Answer: (b)
Heartwood is non-functional for conduction; water transport is the role of the peripheral sapwood.
Heartwood is non-functional for conduction; water transport is the role of the peripheral sapwood.
Q34. In the Irish Setter, the overall red coat color is controlled by the melanocortin receptor. When this receptor is bound by MSH, dark eumelanin is produced. When bound by an antagonist, red pheomelanin is made. The red color is likely due to a mutation in the
Correct Answer: (b)
If the red coat color is caused by the antagonist successfully out-competing MSH or MSH failing to bind, a mutation that prevents the receptor from binding MSH would leave the receptor constantly available to the antagonist, leading to the permanent production of red pigment.
If the red coat color is caused by the antagonist successfully out-competing MSH or MSH failing to bind, a mutation that prevents the receptor from binding MSH would leave the receptor constantly available to the antagonist, leading to the permanent production of red pigment.
Q35. If you wanted to study the use of ATP during a single contraction cycle within a muscle cell, which of the following processes would you use?
Correct Answer: (b)
A twitch is a single, brief contraction and relaxation cycle of a muscle fiber in response to a single action potential. This makes it the ideal unit for studying the molecular events and energy consumption of one contraction cycle.
A twitch is a single, brief contraction and relaxation cycle of a muscle fiber in response to a single action potential. This makes it the ideal unit for studying the molecular events and energy consumption of one contraction cycle.
Q36. Which of the following is correct
Correct Answer: (a)
Option (a) correctly describes a mammal (Macropus).
Option (a) correctly describes a mammal (Macropus).
Q37. Hormones released from the pituitary gland have two different sources. Those that are produced by the neurons of the hypothalamus are released through the _____________, and those produced within the pituitary are released through the _____________.
Correct Answer: (b)
The posterior pituitary (neurohypophysis) stores and releases hormones produced by hypothalamic neurons (such as ADH and oxytocin). The anterior pituitary (adenohypophysis) synthesizes and secretes its own hormones (such as GH and ACTH).
The posterior pituitary (neurohypophysis) stores and releases hormones produced by hypothalamic neurons (such as ADH and oxytocin). The anterior pituitary (adenohypophysis) synthesizes and secretes its own hormones (such as GH and ACTH).
Q38. Which of the following plants is used to extract the blue dye?
Correct Answer: (b)
Indigofera tinctoria is a member of Fabaceae widely used for extracting natural indigo dye.
Indigofera tinctoria is a member of Fabaceae widely used for extracting natural indigo dye.
Q39. Regarding the placenta:
(i) It supplies oxygen and nutrients to the embryo.
(ii) It removes carbon dioxide and waste.
(iii) It secretes hCG, hPL, and estrogens.
(i) It supplies oxygen and nutrients to the embryo.
(ii) It removes carbon dioxide and waste.
(iii) It secretes hCG, hPL, and estrogens.
Correct Answer: (a)
Placenta is vital for both metabolic exchange and endocrine support.
Placenta is vital for both metabolic exchange and endocrine support.
Q40. Which pairing of structure and function is incorrect?
Correct Answer: (d)
All listed pairings are correct: erythrocytes transport oxygen via hemoglobin, platelets function in clotting, and plasma transports wastes, nutrients, and hormones. Therefore, none of the pairings is incorrect.
All listed pairings are correct: erythrocytes transport oxygen via hemoglobin, platelets function in clotting, and plasma transports wastes, nutrients, and hormones. Therefore, none of the pairings is incorrect.
Q41. 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.
Q42. Leaves become modified into spines in
Correct Answer: (d)
In xerophytic plants like Opuntia, leaves are modified into spines to reduce water loss, and the stem becomes photosynthetic.
In xerophytic plants like Opuntia, leaves are modified into spines to reduce water loss, and the stem becomes photosynthetic.
Q43. Initial step of TCA cycle to yield citric acid starts with the condensation of:
Correct Answer: (a)
The cycle begins with the reaction of the 2-carbon Acetyl group with the 4-carbon Oxaloacetic Acid (OAA) and water to form the 6-carbon Citric Acid.
The cycle begins with the reaction of the 2-carbon Acetyl group with the 4-carbon Oxaloacetic Acid (OAA) and water to form the 6-carbon Citric Acid.
Q44. What is a proteome?
Correct Answer: (c)
While the genome is the complete set of genetic material, the proteome is the entire set of proteins expressed by a cell, tissue, or organism at a given time under specific conditions. It is much more complex and dynamic than the genome.
While the genome is the complete set of genetic material, the proteome is the entire set of proteins expressed by a cell, tissue, or organism at a given time under specific conditions. It is much more complex and dynamic than the genome.
Q45. Which of the following is used as an experimental material for making rapid advances in tracing path of carbon in Calvin cycle & other photosynthetic research ?
Correct Answer: (a)
Calvin used unicellular green algae like Chlorella and Scenedesmus in his radioactive carbon labeling experiments.
Calvin used unicellular green algae like Chlorella and Scenedesmus in his radioactive carbon labeling experiments.
Q46. An example of a trait that involves multiple gene inheritance in plants is seed size. If seed size involves three genes (A, B, and C), in which each dominant allele contributes to increased seed size, which of the following genotypes would result in the smallest seed?
Correct Answer: (d)
(D) AaBbCc has the least number of dominant alleles (three) out of all the answer choices given. So the additive effect of the alleles in that genotype would be the least, and this genotype would result in the smallest seed. Since each dominant allele contributes to increased seed size, choice (A) is incorrect because it has the highest number of dominant alleles out of all the answer choices given. So it would produce the largest seeds. Choices (B) and (C) are incorrect because they both have four dominant alleles, so they both would produce larger seeds than choice (D).
(D) AaBbCc has the least number of dominant alleles (three) out of all the answer choices given. So the additive effect of the alleles in that genotype would be the least, and this genotype would result in the smallest seed. Since each dominant allele contributes to increased seed size, choice (A) is incorrect because it has the highest number of dominant alleles out of all the answer choices given. So it would produce the largest seeds. Choices (B) and (C) are incorrect because they both have four dominant alleles, so they both would produce larger seeds than choice (D).
Q47. Motor neurons stimulate muscle contraction via the release of
Correct Answer: (c)
Motor neurons release the neurotransmitter acetylcholine (ACh) into the synaptic cleft at the neuromuscular junction. ACh binds to receptors on the muscle fiber's sarcolemma, triggering an action potential that leads to contraction.
Motor neurons release the neurotransmitter acetylcholine (ACh) into the synaptic cleft at the neuromuscular junction. ACh binds to receptors on the muscle fiber's sarcolemma, triggering an action potential that leads to contraction.
Q48. A transverse section of stem is stained first with safranin and then with fast green following the usual schedule of double staining for the preparation of a permanent slide. What would be the colour of the stained xylem and phloem?
Correct Answer: (a)
Safranin is a basic dye that stains lignified tissues (xylem) red, whereas fast green is an acidic dye that stains non-lignified tissues (phloem) green.
Safranin is a basic dye that stains lignified tissues (xylem) red, whereas fast green is an acidic dye that stains non-lignified tissues (phloem) green.
Q49. Identify the phases from the graph given below that shows the change in DNA content during various phases (A to D) of mitotic cell cycle.
| A | B | C | D | |
|---|---|---|---|---|
| (a) | G2 | G1 | S | M |
| (b) | G2 | S | G1 | M |
| (c) | G1 | S | G2 | M |
| (d) | M | G1 | S | G2 |
Correct Answer: (c)
A is G1 (2C DNA), B is S (DNA increasing to 4C), C is G2 (4C DNA), and D is M (DNA dropping back to 2C).
A is G1 (2C DNA), B is S (DNA increasing to 4C), C is G2 (4C DNA), and D is M (DNA dropping back to 2C).
Q50. How do the muscles move your hand through space?
Correct Answer: (d)
Muscles generate movement by contracting and by being attached to bones across joints. When a muscle contracts, it pulls one bone toward another, resulting in movement of the hand through space. Muscles do not actively lengthen; they relax.
Muscles generate movement by contracting and by being attached to bones across joints. When a muscle contracts, it pulls one bone toward another, resulting in movement of the hand through space. Muscles do not actively lengthen; they relax.
Q51. If you hold your breath for a long time, body CO2 levels are likely to ________, and the pH of body fluids is likely to ________.
Correct Answer: (c)
When breathing is suspended, carbon dioxide (CO2) accumulates in the blood. CO2 reacts with water to form carbonic acid, which dissociates into hydrogen ions (H+) and bicarbonate. An increase in H+ concentration directly causes the pH to decrease (become more acidic).
When breathing is suspended, carbon dioxide (CO2) accumulates in the blood. CO2 reacts with water to form carbonic acid, which dissociates into hydrogen ions (H+) and bicarbonate. An increase in H+ concentration directly causes the pH to decrease (become more acidic).
Q52. The total requirement of ATP & NADPH for each molecule of CO2 fixed & reduced in photosynthesis in the Calvin cycle is
Correct Answer: (c)
Per CO2 molecule fixed, the Calvin cycle consumes 3 molecules of ATP (2 in reduction, 1 in regeneration) and 2 molecules of NADPH (in reduction).
Per CO2 molecule fixed, the Calvin cycle consumes 3 molecules of ATP (2 in reduction, 1 in regeneration) and 2 molecules of NADPH (in reduction).
Q53. Synapsis occurs between
Correct Answer: (d)
Synapsis is the pairing of homologous chromosomes during the zygotene stage of prophase I.
Synapsis is the pairing of homologous chromosomes during the zygotene stage of prophase I.
Q54. 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.
Q55. You experience a longer period than normal between meals. Your body’s response to this will be to produce
Correct Answer: (b)
During periods of fasting (between meals), blood glucose levels drop. The pancreas responds by secreting glucagon, which stimulates the liver to break down glycogen into glucose and release it into the blood, thereby raising blood sugar levels back to homeostatic levels.
During periods of fasting (between meals), blood glucose levels drop. The pancreas responds by secreting glucagon, which stimulates the liver to break down glycogen into glucose and release it into the blood, thereby raising blood sugar levels back to homeostatic levels.
Q56. Which of the following statements is/are correct ?
(i) The endomembrane system includes plasma membrane, ER, Golgi complex, lysosomes and vacuoles.
(ii) ER helps in the transport of substances, synthesis of proteins, lipoproteins and glycogen.
(iii) Ribosomes are involved in protein synthesis.
(iv) Mitochondria help in oxidative phosphorylation and generation of ATP.
(i) The endomembrane system includes plasma membrane, ER, Golgi complex, lysosomes and vacuoles.
(ii) ER helps in the transport of substances, synthesis of proteins, lipoproteins and glycogen.
(iii) Ribosomes are involved in protein synthesis.
(iv) Mitochondria help in oxidative phosphorylation and generation of ATP.
Correct Answer: (a)
Statement (i) is incorrect because the plasma membrane is not considered part of the endomembrane system. (ii), (iii), and (iv) are correct functions of their respective organelles.
Statement (i) is incorrect because the plasma membrane is not considered part of the endomembrane system. (ii), (iii), and (iv) are correct functions of their respective organelles.
Q57. Which one of the following acts as the “alarm signal” to activate the body’s adaptive immune system by stimulating helper T cells?
Correct Answer: (b)
Interleukin-1 is a cytokine released by macrophages and antigen-presenting cells. It functions as an alarm signal by activating helper T cells, thereby linking innate immunity to adaptive immunity.
Interleukin-1 is a cytokine released by macrophages and antigen-presenting cells. It functions as an alarm signal by activating helper T cells, thereby linking innate immunity to adaptive immunity.
Q58. 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.
Q59. Which of the following is an example of a density-dependent effect on population growth?
Correct Answer: (c)
Density-dependent effects intensify as population density increases. Limited access to cool burrows when population size is high directly links survival to population density.
Density-dependent effects intensify as population density increases. Limited access to cool burrows when population size is high directly links survival to population density.
Q60. 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.
Q61. Match the product in Column I with the microbe in Column II:
| Column I (Product) | Column II (Microbe) |
|---|---|
| A. Citric acid | (I) Acetobacter aceti |
| B. Acetic acid | (II) Aspergillus niger |
| C. Butyric acid | (III) Lactobacillus |
| D. Lactic acid | (IV) Clostridium butylicum |
Correct Answer: (a)
Standard chemical-microbe matches from section 8.2.3.
Standard chemical-microbe matches from section 8.2.3.
Q62. Assertion: Ladybird is a biocontrol agent.
Reason: It helps get rid of mosquitoes.
Correct Answer: (a)
Ladybirds target aphids; Dragonflies target mosquitoes.
Ladybirds target aphids; Dragonflies target mosquitoes.
Q63. Match column-I (scientists) with column-II (discovery) and select the correct option.
| Column-I | Column-II |
|---|---|
| A. Leeuwenhoek | I. First saw and described a living cell |
| B. Robert Brown | II. Presence of cell wall is unique to plant cells |
| C. Schleiden | III. Discovered the nucleus |
| D. Schwann | IV. All plants are composed of different kind of cells |
Correct Answer: (a)
Leeuwenhoek first saw living cells; Robert Brown discovered the nucleus; Schleiden concluded all plants are made of cells; Schwann identified the unique nature of cell walls in plants.
Leeuwenhoek first saw living cells; Robert Brown discovered the nucleus; Schleiden concluded all plants are made of cells; Schwann identified the unique nature of cell walls in plants.
Q64. When the environment changes from year to year and different phenotypes have different fitness in different environments,
Correct Answer: (b)
This scenario describes oscillating selection. Because the environmental conditions are not constant, the direction of selection fluctuates. Phenotypes that are advantageous during a wet year may be disadvantageous during a dry year, leading to a balanced maintenance of genetic variation within the population over time.
This scenario describes oscillating selection. Because the environmental conditions are not constant, the direction of selection fluctuates. Phenotypes that are advantageous during a wet year may be disadvantageous during a dry year, leading to a balanced maintenance of genetic variation within the population over time.
Q65. 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.
Q66. Which of the following methods of horizontal transmission of genetic material would be most likely to lead to new variants of the COVID-19 virus?
Correct Answer: (b)
(B) Transduction involves the transfer of genetic material by viral transmission. Transformation, transposition, and conjugation do not involve viruses, so choices (A), (C), and (D) are incorrect.
(B) Transduction involves the transfer of genetic material by viral transmission. Transformation, transposition, and conjugation do not involve viruses, so choices (A), (C), and (D) are incorrect.
Q67. Which one of the following pairs, is not correctly matched?
Correct Answer: (b)
Gibberellic acid generally promotes growth and delays leaf fall/senescence; it does not cause it.
Gibberellic acid generally promotes growth and delays leaf fall/senescence; it does not cause it.
Q68. Consider the following statements about conversion of succinyl-CoA to succinic acid in the TCA cycle:
(1) During this step, a molecule of ATP is synthesised.
(2) In a coupled reaction ATP is converted to ADP with the simmultaneous synthesis of GTP from GDP.
(1) During this step, a molecule of ATP is synthesised.
(2) In a coupled reaction ATP is converted to ADP with the simmultaneous synthesis of GTP from GDP.
Correct Answer: (a)
Statement (1) is correct. Statement (2) is nonsensical; the synthesis of GTP is the primary reaction, often coupled with converting ADP to ATP.
Statement (1) is correct. Statement (2) is nonsensical; the synthesis of GTP is the primary reaction, often coupled with converting ADP to ATP.
Q69. The fruits can be left on the tree longer so as to extend the market period. This is due to which function of GA ?
Correct Answer: (b)
Gibberellins delay senescence, which allows fruits like citrus to remain on the tree longer before being harvested.
Gibberellins delay senescence, which allows fruits like citrus to remain on the tree longer before being harvested.
Q70. Building block of nucleic acid is ________.
Correct Answer: (a)
Nucleic acids (DNA and RNA) are polymers made up of repeating units called nucleotides.
Nucleic acids (DNA and RNA) are polymers made up of repeating units called nucleotides.
Q71. Which of the following is the primary method by which carbon dioxide is transported to the lungs?
Correct Answer: (d)
While some CO2 is dissolved in plasma or bound to hemoglobin (carbaminohemoglobin), approximately 70% of the carbon dioxide in the blood is transported in the form of bicarbonate ions (HCO3–), which are formed within red blood cells and then diffuse into the plasma.
While some CO2 is dissolved in plasma or bound to hemoglobin (carbaminohemoglobin), approximately 70% of the carbon dioxide in the blood is transported in the form of bicarbonate ions (HCO3–), which are formed within red blood cells and then diffuse into the plasma.
Q72. A plant cell has 12 chromosomes at the end of mitosis. How many chromosomes would it have in the G2-phase of its next cell cycle?
Correct Answer: (c)
Mitosis maintains chromosome number. If a cell has 12 chromosomes after division ($), it will still have 12 chromosomes (each having two sister chromatids) after S-phase ($).
Mitosis maintains chromosome number. If a cell has 12 chromosomes after division ($), it will still have 12 chromosomes (each having two sister chromatids) after S-phase ($).
Q73. The lac repressor, the trp repressor, and CAP are all
Correct Answer: (c)
These regulatory proteins are allosteric, meaning they change their conformation and DNA-binding affinity when they bind to a specific small effector molecule (like lactose, tryptophan, or cAMP). This allows the proteins to toggle between 'on' and 'off' states in response to environmental conditions.
These regulatory proteins are allosteric, meaning they change their conformation and DNA-binding affinity when they bind to a specific small effector molecule (like lactose, tryptophan, or cAMP). This allows the proteins to toggle between 'on' and 'off' states in response to environmental conditions.
Q74. All eukaryotic unicellular organisms belong to
Correct Answer: (b)
In the five-kingdom system, all unicellular eukaryotes are grouped under Kingdom Protista.
In the five-kingdom system, all unicellular eukaryotes are grouped under Kingdom Protista.
Q75. The difference between exponential and logistic growth rates is that
Correct Answer: (d)
Logistic growth incorporates density-dependent factors through carrying capacity (K), which affect birth and death rates as population size increases. Exponential growth does not include such limits.
Logistic growth incorporates density-dependent factors through carrying capacity (K), which affect birth and death rates as population size increases. Exponential growth does not include such limits.
Q76. 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.
Q77. Match column-I (Characters/feature) with column-II (examples) and choose the correct option.
| Column-I (Characters/features) | Column-II (Examples) |
|---|---|
| A. Red dinoflagellates | I. Rhizopus |
| B. Unicellular fungi used to make bread and beer | II. Gonyaulax |
| C. Source of antibiotics | III. Yeast |
| D. Bread mould | IV. Penicillium |
Correct Answer: (c)
A - Gonyaulax (Red dinoflagellate); B - Yeast (Unicellular fungus); C - Penicillium (Antibiotic source); D - Rhizopus (Bread mould).
A - Gonyaulax (Red dinoflagellate); B - Yeast (Unicellular fungus); C - Penicillium (Antibiotic source); D - Rhizopus (Bread mould).
Q78. Mountain climbers may have difficulty at high elevations because
Correct Answer: (a)
At high altitudes, the total atmospheric pressure is lower. Since oxygen still makes up about 21% of the air, its partial pressure (PO2) also decreases. This reduction in PO2 decreases the pressure gradient necessary to drive oxygen diffusion from the lungs into the blood.
At high altitudes, the total atmospheric pressure is lower. Since oxygen still makes up about 21% of the air, its partial pressure (PO2) also decreases. This reduction in PO2 decreases the pressure gradient necessary to drive oxygen diffusion from the lungs into the blood.
Q79. Mitochondria and chloroplast are
1. semi-autonomous organelles
2. formed by division of pre-existing organelles and they contain DNA but lack protein synthesizing machinery
Which one of the following options is correct?
1. semi-autonomous organelles
2. formed by division of pre-existing organelles and they contain DNA but lack protein synthesizing machinery
Which one of the following options is correct?
Correct Answer: (c)
They are semi-autonomous (1 is true). 2 is false because they do possess their own protein synthesizing machinery (70S ribosomes).
They are semi-autonomous (1 is true). 2 is false because they do possess their own protein synthesizing machinery (70S ribosomes).
Q80. Imagine that you are doing an experiment on the movement of ions across neural membranes. Which of the following plays a role in determining the equilibrium concentration of ions across these membranes?
Correct Answer: (d)
The electrochemical gradient is the combined force of the chemical concentration gradient and the electrical gradient (charge difference) across a membrane. Together, these factors determine the direction and equilibrium of ion movement.
The electrochemical gradient is the combined force of the chemical concentration gradient and the electrical gradient (charge difference) across a membrane. Together, these factors determine the direction and equilibrium of ion movement.
Q81. Sex-linked recessive traits in humans are ________ likely to be expressed in ________.
Correct Answer: (c)
(C) Sex-linked genes are more likely to be expressed in males since males have only one X chromosome. Choice (A) is incorrect because sex-linked genes are more likely, not less likely, to be expressed in males. Females have two X chromosomes, so a sex-linked recessive trait is less likely to be expressed in females because a female would have to inherit two copies of the allele while a male would only have to inherit one copy of the allele for it to be expressed. Thus, choices (B) and (D) are both incorrect.
(C) Sex-linked genes are more likely to be expressed in males since males have only one X chromosome. Choice (A) is incorrect because sex-linked genes are more likely, not less likely, to be expressed in males. Females have two X chromosomes, so a sex-linked recessive trait is less likely to be expressed in females because a female would have to inherit two copies of the allele while a male would only have to inherit one copy of the allele for it to be expressed. Thus, choices (B) and (D) are both incorrect.
Q82. Diuretics are drugs that can be used to treat high blood pressure by increasing urinary output. Possible mechanisms of action in the kidney include
Correct Answer: (b)
Many diuretics work by inhibiting NaCl reabsorption in the loop of Henle or proximal tubule. Reduced salt reabsorption decreases water reabsorption, leading to increased urine output and lowered blood pressure.
Many diuretics work by inhibiting NaCl reabsorption in the loop of Henle or proximal tubule. Reduced salt reabsorption decreases water reabsorption, leading to increased urine output and lowered blood pressure.
Q83. Which of the following group of animals belongs to the same phylum?
Correct Answer: (b)
Prawn, scorpion, and Locusta are all arthropods.
Prawn, scorpion, and Locusta are all arthropods.
Q84. In meiosis, division is
Correct Answer: (a)
Meiosis I reduces the chromosome number by half (reductional). Meiosis II is similar to mitosis and separates sister chromatids (equational).
Meiosis I reduces the chromosome number by half (reductional). Meiosis II is similar to mitosis and separates sister chromatids (equational).
Q85. An ECG measures
Correct Answer: (a)
An electrocardiogram (ECG) records the electrical activity of the heart by detecting changes in electrical potential produced during depolarization and repolarization of cardiac muscle fibers throughout the cardiac cycle. It does not measure ion concentration, force of contraction, or blood volume directly.
An electrocardiogram (ECG) records the electrical activity of the heart by detecting changes in electrical potential produced during depolarization and repolarization of cardiac muscle fibers throughout the cardiac cycle. It does not measure ion concentration, force of contraction, or blood volume directly.
Q86. Given below is the representation of the extent of global diversity of invertebrates. What groups the four portions (A-D) represent respectively?
Correct Answer: (d)
The standard NCERT pie chart for invertebrates shows: A-Insects (largest), B-Molluscs, C-Crustaceans, D-Other animal groups.
The standard NCERT pie chart for invertebrates shows: A-Insects (largest), B-Molluscs, C-Crustaceans, D-Other animal groups.
Q87. In Drosophila (fruit flies), females have two X chromosomes, and males have one X chromosome and one Y chromosome. The eye color gene is located on the X chromosome, and the red-eyed allele is dominant to the white-eyed allele. A heterozygous, red-eyed female is mated with a white-eyed male. Which of the following is the most likely result in their offspring?
Correct Answer: (d)
(D) A heterozygous, red-eyed female fly would have the genotype XRXr, and a white-eyed male fly would have the XrY genotype. The Punnett square for this cross is shown below:
The most likely result would be 50% of both sexes would have red eyes and 50% of both sexes would have white eyes.
(D) A heterozygous, red-eyed female fly would have the genotype XRXr, and a white-eyed male fly would have the XrY genotype. The Punnett square for this cross is shown below:
| XR | Xr | Results | |
| Xr | XRXr | XrXr | 1/4 red-eyed females, 1/4 white-eyed females |
| Y | XRY | XrY | 1/4 red-eyed males, 1/4 white-eyed males |
The most likely result would be 50% of both sexes would have red eyes and 50% of both sexes would have white eyes.
Q88. Which of the following characteristics would cause a country to be considered a high-priority region for conservation efforts?
Correct Answer: (a)
Biodiversity hotspots are identified based on high species richness and a high degree of endemism (species found nowhere else).
Biodiversity hotspots are identified based on high species richness and a high degree of endemism (species found nowhere else).
Q89. Ion transport in root occurs:
(i) passively through channels.
(ii) actively through channels.
(iii) actively through carriers.
(iv) through both symplast and apoplast.
(i) passively through channels.
(ii) actively through channels.
(iii) actively through carriers.
(iv) through both symplast and apoplast.
Correct Answer: (c)
Ions move passively through channels or actively via carrier proteins (pumps), utilizing both apoplastic and symplastic pathways in the root.
Ions move passively through channels or actively via carrier proteins (pumps), utilizing both apoplastic and symplastic pathways in the root.
Q90. Given below is an imaginary pyramid of numbers. What could be one of the possibilities about certain organisms at some of the different levels ?
Correct Answer: (a)
This is a spindle-shaped pyramid. A single tree (PP) supports many herbivorous insects (PC), which are eaten by fewer small birds (SC), followed by a few larger predators (TC).
This is a spindle-shaped pyramid. A single tree (PP) supports many herbivorous insects (PC), which are eaten by fewer small birds (SC), followed by a few larger predators (TC).