KCET 2024 Biology Question Paper: Download Question Paper with Solution PDF

Updated on, Dec 26, 2024

KCET 2024 Biology Question Paper is available here for download. KCET Biology question paper was conducted on April 18, 2024 by Karnataka Examination Authority (KEA). KCET 2024 Biology question paper consists of 60 questions to be attempted in 80 minutes for a total of 60 marks.

KCET 2024 Biology Question Paper with Answer Key PDF

KCET 2024 Biology Question Paper with Answer Key	Download	Check Solutions

KCET 2024 Biology Question Paper with Solution

Question	Answer	Detailed Solution
1. Which among the following is used to treat Emphysema? (A) Human Hormone - alpha-Antitrypsin (B) Human alpha-Interferon (C) Human protein - alpha-Antitrypsin (D) Human alpha-Lactalbumin	(C) Human protein - alpha-Antitrypsin	Emphysema is a chronic respiratory disease caused by damage to alveoli, often due to excessive enzymatic activity. Human protein alpha-Antitrypsin acts as a protease inhibitor and helps protect lung tissues by inhibiting elastase, an enzyme that breaks down lung elasticity.
2. Homeostasis is a condition where the organisms: (A) Maintain a constant internal environment in an ever-changing external environment (B) Do not maintain a constant internal environment (C) Change their internal environment according to their external environment (D) Change their internal environment when the external environment is constant	(A) Maintain a constant internal environment in an ever-changing external environment	Homeostasis is the ability of an organism to regulate its internal conditions, such as temperature, pH, and electrolyte balance, to maintain optimal physiological processes regardless of external changes. For example, humans regulate body temperature through sweating or shivering.
3. Which of the following is not a parasitic adaptation? (A) Loss of unnecessary sense organs (B) Absence of adhesive organs or suckers (C) Loss of digestive system (D) High reproductive capacity	(B) Absence of adhesive organs or suckers	Parasites often develop specialized structures, such as adhesive organs or suckers, to attach to their host and ensure survival. Their adaptations include high reproductive rates and loss of organs unnecessary for a parasitic lifestyle. The absence of adhesive organs contradicts the typical features of parasites.
4. DNA polymerase of Thermus aquaticus is: (A) Thermolabile (B) Thermophobic (C) Exonuclease (D) Thermostable	(D) Thermostable	The DNA polymerase derived from Thermus aquaticus (Taq polymerase) remains active at high temperatures, making it essential for Polymerase Chain Reaction (PCR), where repeated heating cycles are required for DNA denaturation and synthesis.
5. If a recombinant DNA bearing a gene for resistance to Ampicillin is transferred into E.coli cells, host cells become transformed into Ampicillin-resistant cells. What happens when these E.coli are grown on a medium containing Ampicillin? (A) Non-transformants will grow and transformants will die (B) Non-transformants will die and transformants will grow (C) Both non-transformants and transformants will die (D) Both non-transformants and transformants will grow	(B) Non-transformants will die and transformants will grow	Transformants have a plasmid containing the Ampicillin-resistance gene, enabling them to produce proteins that neutralize Ampicillin, allowing growth in its presence. Non-transformants lack this gene and are unable to survive in the Ampicillin medium.
6. Which of the following is based on the principle of antigen-antibody interaction? (A) PCR (B) ELISA (C) rDNA technology (D) Gel Electrophoresis	(B) ELISA	ELISA (Enzyme-Linked Immunosorbent Assay) utilizes the specific binding of antigens and antibodies to detect the presence of pathogens, proteins, or other biomolecules. It is commonly used in medical diagnostics for conditions like HIV.
7. A strict protection of biodiversity hotspots could reduce the ongoing mass extinction by almost: (A) 20% (B) 25% (C) 30% (D) 35%	(C) 30%	Biodiversity hotspots are areas rich in unique species that are under threat. Strict protection measures, such as preventing habitat destruction and poaching, can significantly reduce the extinction rate of endemic species, potentially up to 30%.
8. Identify the incorrect match with respect to recently extinct animals and their place of extinction according to the IUCN Red List: (A) Dodo - Mauritius (B) Quagga - Africa (C) Thylacine - Australia (D) Steller’s Sea Cow - North America	(D) Steller’s Sea Cow - North America	Steller’s Sea Cow was last seen in the Bering Sea and is native to the Arctic region, not North America. The other matches are accurate based on historical records.
9. According to the hypothesis proposed by environmental biologists, a relatively constant environment in tropics promotes: (A) Niche specialization and lesser species diversity (B) Niche specialization and greater species diversity (C) Niche diversity and lesser species specialization (D) Niche diversity and greater species specialization	(B) Niche specialization and greater species diversity	Stable tropical climates promote the evolution of highly specialized ecological niches, allowing greater coexistence of diverse species without competition, thereby increasing species diversity.
10. In the prevention of air pollution, the role of a scrubber is to remove: (A) Particulate SO2 (B) Liquid SO2 (C) Gaseous SO2 (D) Liquid SO3	(C) Gaseous SO2	Scrubbers are air pollution control devices that trap harmful gases like sulfur dioxide (SO2) from industrial emissions. These devices use water or chemical solutions to neutralize and remove pollutants, ensuring cleaner air.
11. Match List-I with List-II and choose the correct answer. List-I: 1) Nitrogen rich fertilizers 2) Carbon dioxide 3) Carbon monoxide 4) CFC’s List-II: p) Ozone depletion q) Eutrophication r) Greenhouse effect s) Air pollutant (A) 1-p, 2-q, 3-r, 4-s (B) 1-q, 2-r, 3-s, 4-p (C) 1-r, 2-s, 3-p, 4-q (D) 1-s, 2-p, 3-q, 4-r	(B) 1-q, 2-r, 3-s, 4-p	- Nitrogen-rich fertilizers contribute to eutrophication in water bodies, leading to excessive algal growth. - Carbon dioxide is a key contributor to the greenhouse effect, trapping heat in the Earth's atmosphere. - Carbon monoxide is an air pollutant that binds to hemoglobin, reducing oxygen transport in the body. - CFCs (Chlorofluorocarbons) cause ozone depletion by releasing chlorine atoms that degrade ozone molecules in the stratosphere.
12. Following representations P, Q, and R denote a few steps of Griffith's Experiment. Identify the correct one(s). Steps: P. R strain → Inject into mice → Mice die Q. S strain (Heat killed) → Inject into mice → Mice die R. R strain → Inject into mice → Mice live (A) P only (B) R only (C) P and R (D) Q and R	(B) R only	Griffith's experiment demonstrated transformation by showing that non-virulent R strain bacteria do not kill mice unless combined with heat-killed virulent S strain bacteria. R strain alone is harmless, as seen in step R. Steps P and Q are incorrect representations of Griffith’s findings.
13. In tRNA, the region that binds with mRNA is: (A) Anticodon loop of tRNA (B) Amino acid acceptor end of tRNA (C) Amino acyl synthetase loop of tRNA (D) Ribosomal binding loop of tRNA	(A) Anticodon loop of tRNA	The anticodon loop of tRNA contains a sequence of three nucleotides that pairs specifically with the complementary codon on mRNA during translation. This ensures that the correct amino acid is incorporated into the growing polypeptide chain.
14. The mRNA has Untranslated Regions (UTRs): (A) At 3' -end beyond Terminator codon (B) At 5' -end before AUG (C) At both 3' -end and 5' -end beyond Terminator codon and before AUG respectively (D) AUG and Terminator codon flank the UTR	(C) At both 3' -end and 5' -end beyond Terminator codon and before AUG respectively	Untranslated regions (UTRs) are non-coding sequences at the 5' and 3' ends of mRNA. The 5' UTR regulates translation initiation, while the 3' UTR influences mRNA stability, localization, and translation efficiency. These regions are crucial for post-transcriptional control.
15. In a structural gene, the template DNA strand has nucleotide sequences: 3' ATGCATGCATGCATGC 5'. Find the correct and complementary nucleotide sequence on the coding strand. (A) 5' ATGCATGCATGCATGC 3' (B) 3' GCATGCATGCATGCAT 5' (C) 5' TACGTACGTACGTACG 3' (D) 3' TACGTACGTACGTACG 5'	(C) 5' TACGTACGTACGTACG 3'	The coding strand of DNA has the same nucleotide sequence as the mRNA (except thymine is replaced with uracil). The complementary sequence to the given template strand is derived by base pairing: adenine with thymine and cytosine with guanine, maintaining antiparallel orientation.
16. Read the following statements: Statement I: All vertebrates develop a row of vestigial gill slits during the embryonic stage. Statement II: Embryos always pass through the adult stages of other animals. (A) Statement I is correct, Statement II is incorrect. (B) Statement I is incorrect, Statement II is correct. (C) Both Statements I and II are correct. (D) Both Statements I and II are incorrect.	(A) Statement I is correct, Statement II is incorrect.	During embryonic development, all vertebrates exhibit vestigial gill slits, reflecting their evolutionary ancestry. However, the idea that embryos pass through the adult stages of other animals (recapitulation theory) has been disproved. Embryonic development is better explained by shared evolutionary traits rather than a progression through adult forms of other species.
17. Which of the following exhibits a haplodiplontic lifecycle? (A) Fucus (B) Chlamydomonas (C) Gelidium (D) Ectocarpus	(D) Ectocarpus	Ectocarpus has a haplodiplontic lifecycle, where both haploid (gametophyte) and diploid (sporophyte) stages are multicellular and alternate during its lifecycle. This alternation provides genetic diversity and adaptation advantages. Other options either exhibit haplontic or diplontic lifecycles.
18. Identify the phylum which shows the following characteristics: 1. Animals are exclusively marine, radially symmetrical, and diploblastic. 2. Body bears eight external rows of ciliated comb plates which help in locomotion. 3. Digestion is both extracellular and intracellular. 4. Reproduction only by sexual modes. (A) Coelenterata (B) Mollusca (C) Arthropoda (D) Ctenophora	(D) Ctenophora	Ctenophora, commonly known as comb jellies, are marine organisms that use ciliary comb plates for locomotion. They are radially symmetrical, diploblastic, and rely on both extracellular and intracellular digestion. Reproduction in Ctenophora is typically sexual, and they exhibit bioluminescence, making them unique among marine animals.
19. When a flower has both stamens and carpels, it is described as: (A) Asexual (B) Unisexual (C) Bisexual (D) Dioecious	(C) Bisexual	A bisexual flower contains both stamens (male reproductive organs) and carpels (female reproductive organs) within the same flower. This structure enables self-pollination, though cross-pollination may still occur. Examples include flowers of hibiscus and mustard.
20. Ciliated epithelial cells are present in: (A) Kidneys (B) Intestines (C) Blood Vessels (D) Bronchioles	(D) Bronchioles	Ciliated epithelial cells line the bronchioles of the respiratory system. These cells are equipped with hair-like structures (cilia) that beat rhythmically to move mucus and trapped particles out of the airways, maintaining clear passages for efficient gas exchange.
21. Which of the following statements is correct with reference to vacuoles? (A) It is membrane bound and contains storage proteins and lipids. (B) It is membrane bound and contains water and excretory substances. (C) It lacks membrane and contains air. (D) It lacks membrane and contains water and excretory substances.	(B) It is membrane bound and contains water and excretory substances.	Vacuoles are large, membrane-bound organelles found primarily in plant cells. They store water, ions, excretory substances, and other molecules. In addition to maintaining turgor pressure (internal hydrostatic pressure), vacuoles play a key role in waste storage and cell elongation.
22. Exoskeleton of Arthropods is made up of a unique complex polysaccharide known as: (A) Hyaluronic Acid (B) Chitin (C) Waxes (D) Cellulose	(B) Chitin	Chitin is a nitrogen-containing polysaccharide found in the exoskeleton of arthropods, such as insects, spiders, and crustaceans. It provides strength and protection while maintaining flexibility. Unlike cellulose, chitin includes nitrogen, which distinguishes it chemically.
23. The enzyme Recombinase is required at which stage of Meiosis I? (A) Pachytene (B) Zygotene (C) Diplotene (D) Diakinesis	(A) Pachytene	During the Pachytene stage of Prophase I in Meiosis I, recombinase facilitates the process of homologous recombination. This process allows the exchange of genetic material between non-sister chromatids of homologous chromosomes, resulting in genetic variation in the offspring.
24. The water potential of pure water is: (A) One (B) More than one (C) Zero (D) Less than zero	(C) Zero	Water potential (Psi) is the measure of potential energy in water and its ability to move. Pure water at standard conditions has a water potential of zero. The addition of solutes decreases the water potential, making it negative, while pressure increases it.
25. Match the pigments given in List I with their colour in the chromatogram given in List II. List I (Pigments): 1. Chlorophyll 'b' 2. Carotenoids 3. Chlorophyll 'a' 4. Xanthophylls List II (Colour in chromatogram): p. Yellow orange q. Orange red r. Yellow s. Blue green t. Yellow green (A) 1-s, 2-t, 3-r, 4-q (B) 1-p, 2-q, 3-r, 4-t (C) 1-t, 2-p, 3-s, 4-r (D) 1-t, 2-p, 3-r, 4-s	(B) 1-p, 2-q, 3-r, 4-t	Plant pigments separate into distinct bands during chromatography due to their solubility and polarity. The correct matches are: - Chlorophyll 'b' appears yellow-green (t). - Carotenoids show yellow-orange (p). - Chlorophyll 'a' appears blue-green (s). - Xanthophylls show yellow (r).
26. Which is the intermediate compound that links the end product of Glycolysis with TCA Cycle? (A) Acetyl CoA (B) Pyruvic Acid (C) OAA (D) Citric Acid	(A) Acetyl CoA	Pyruvic acid, the end product of glycolysis, is converted into Acetyl CoA by the enzyme pyruvate dehydrogenase in the presence of coenzyme A. Acetyl CoA then enters the TCA cycle to participate in oxidative metabolism, generating ATP and electron carriers.
27. Auxins : Apical dominance : : Gibberellins : ............. (A) Adventitious shoot formation (B) Accelerates abscission (C) Closure of stomata (D) Bolting	(D) Bolting	Gibberellins play a role in bolting, the rapid elongation of the stem and flowering in plants like cabbage under conditions such as exposure to long days or cold temperatures. Bolting involves cell elongation and division, which is regulated by gibberellins.
28. The term Uremia refers to: (A) Accumulation of Urea in blood. (B) Presence of Glucose in the urine. (C) Accumulation of Uric acid in blood. (D) Accumulation of Uric acid in kidneys.	(A) Accumulation of Urea in blood.	Uremia results from kidney dysfunction where urea and other nitrogenous waste products build up in the bloodstream. It can lead to symptoms like nausea, fatigue, and confusion. If untreated, it may progress to life-threatening conditions like uremic encephalopathy.
29. The typical 'lub-dub' sounds heard during heartbeat are produced due to: (A) Closure of semilunar valves (B) Closure of bicuspid and tricuspid valves (C) Closure of bicuspid and tricuspid valves followed by semilunar valves (D) Opening of bicuspid and tricuspid valves followed by semilunar valves	(C) Closure of bicuspid and tricuspid valves followed by semilunar valves	The "lub" sound is produced by the closure of atrioventricular (bicuspid and tricuspid) valves during ventricular contraction, while the "dub" sound occurs due to the closure of semilunar valves during ventricular relaxation. These sounds are critical indicators of heart valve health.
30. The functional unit of contraction is a: (A) Portion of myofibril between two successive Z-lines (B) Portion of myofibril between two successive M-lines (C) Centre of the H-zone (D) Centre of the I-band	(A) Portion of myofibril between two successive Z-lines	The sarcomere is the structural and functional unit of muscle contraction. It is defined as the region between two Z-lines, where actin and myosin filaments overlap to facilitate contraction based on the sliding filament theory.
31. Match the parts of the brain given in List I with their functions given in List II. List I (Parts of the brain): 1. Medulla oblongata 2. Hypothalamus 3. Cerebral cortex 4. Limbic system List II (Functions): p. Body temperature q. Olfaction r. Respiration s. Motor function (A) 1-p, 2-r, 3-s, 4-q (B) 1-q, 2-s, 3-r, 4-p (C) 1-s, 2-p, 3-q, 4-r (D) 1-r, 2-p, 3-s, 4-q	(D) 1-r, 2-p, 3-s, 4-q	The medulla oblongata controls vital autonomic functions like respiration and heart rate. The hypothalamus regulates homeostatic processes such as body temperature and hunger. The cerebral cortex governs higher motor functions, decision-making, and voluntary movements. The limbic system is involved in emotions, memory, and olfaction (sense of smell).
32. Hydra reproduces asexually by producing: (A) Zoospores (B) Conidia (C) Buds (D) Gemmule	(C) Buds	Hydra reproduces asexually by budding, where a new organism develops as an outgrowth from the parent’s body. The bud matures, forms all necessary structures, and detaches to become a new individual under favorable environmental conditions.
33. When male and female gametes are morphologically distinct, the condition is known as: (A) Homogametes (B) Heterogametes (C) Hermaphrodites (D) Sexual Dimorphism	(B) Heterogametes	Heterogametes are gametes that differ in size, shape, or function. For example, in humans, the sperm is small and motile, while the ovum is large and non-motile. This distinction facilitates specialized roles in fertilization.
34. The role of Filiform apparatus in synergids is to: (A) Protect the egg apparatus (B) Endosperm formation (C) Guide the entry of pollen tube (D) Prevention of gamete entry	(C) Guide the entry of pollen tube	The Filiform apparatus in synergids secretes chemical signals to guide the pollen tube to the egg apparatus during fertilization. It ensures precise delivery of sperm cells to the egg for successful fertilization.
35. Transfer of pollen grains from the anther to the stigma of another flower of the same plant is called: (A) Xenogamy (B) Autogamy (C) Cleistogamy (D) Geitonogamy	(D) Geitonogamy	Geitonogamy refers to the transfer of pollen between flowers of the same plant. While it appears similar to cross-pollination, it is genetically equivalent to self-pollination since the genetic material originates from the same plant.
36. Match the content of List I with List II: List I: 1. Polyembryony 2. Perisperm 3. False fruit 4. Parthenocarpy List II: p. Black pepper q. Banana r. Lemon s. Apple (A) 1-r, 2-p, 3-s, 4-q (B) 1-p, 2-r, 3-s, 4-q (C) 1-q, 2-p, 3-s, 4-r (D) 1-r, 2-s, 3-p, 4-q	(A) 1-r, 2-p, 3-s, 4-q	- Polyembryony, seen in lemon, refers to the development of multiple embryos from a single fertilized egg. - Perisperm, the persistent nucellus, is found in black pepper. - False fruits like apple develop from floral parts other than the ovary. - Parthenocarpy, as in banana, involves the development of fruit without fertilization.
37. Which of the following hormones is not secreted by human placenta? (A) Progestogen (B) HCG (C) Estrogen (D) LH	(D) LH	The human placenta produces hormones like HCG, progestogen, and estrogen, which support pregnancy and fetal development. However, LH (Luteinizing Hormone) is secreted by the anterior pituitary gland and plays a role in ovulation, not pregnancy maintenance.
38. In human females, the endometrium of the uterus consists of: (A) Smooth muscle (B) Glandular layer (C) Adipose layer (D) Cartilaginous layer	(B) Glandular layer	The endometrium is the innermost layer of the uterus, rich in glands and blood vessels. It thickens cyclically in response to hormonal changes, preparing for potential implantation of a fertilized egg. If implantation does not occur, it sheds during menstruation.
39. If two primary spermatocytes and two primary oocytes undergo meiosis simultaneously, what will be the ratio of spermatozoa and ova produced at the end of gametogenesis? (A) 2:1 (B) 4:1 (C) 6:2 (D) 1:2	(B) 4:1	Each primary spermatocyte undergoes two meiotic divisions to form four sperm cells, while each primary oocyte produces only one ovum due to unequal cytokinesis, with other cells becoming polar bodies. For two spermatocytes and oocytes, the ratio is 4 spermatozoa to 1 ovum.
40. The Government of India legalized MTP with some strict regulations in the year: (A) 1951 (B) 1961 (C) 1971 (D) 2001	(C) 1971	The Medical Termination of Pregnancy (MTP) Act, 1971, legalized abortion under specific circumstances, such as risks to the mother's health or fetal abnormalities, to ensure safe medical practices. This act reflects India's effort to balance ethical considerations with public health.
41. The process in which a small part of the vas deferens is removed or tied up through a small incision, is called: (A) MTP (B) Vasectomy (C) Tubectomy (D) GIFT	(B) Vasectomy	Vasectomy is a surgical method of male sterilization used as a permanent contraceptive measure. It involves cutting or blocking the vas deferens, preventing sperm from mixing with semen during ejaculation. This procedure does not affect testosterone production or sexual performance.
42. Test cross in pea plant is: (A) A cross between F2 tall plant and recessive parent. (B) A cross between F2 dwarf plant and recessive parent. (C) A cross between F2 tall plant with dominant parent. (D) A cross between two F1 plants.	(A) A cross between F2 tall plant and recessive parent.	A test cross is used to determine the genotype of an organism showing a dominant phenotype. In Mendelian experiments, the organism is crossed with a homozygous recessive parent. For example, in a tall pea plant, this test reveals whether the tall plant is homozygous (TT) or heterozygous (Tt).
43. The genotype ratio of incomplete dominance is: (A) 3:1 (B) 1:2:1 (C) 1:1:2 (D) 9:3:3:1	(B) 1:2:1	In incomplete dominance, the heterozygous phenotype is intermediate between the two homozygous phenotypes. This results in a genotypic ratio of 1:2:1 in the offspring, as seen in cases like the cross between red and white flowers producing pink flowers in heterozygotes.
44. Find the incorrect statement among the following: (A) In sex-linked recessive traits, the gene is transmitted from an unaffected carrier female to some of the male progeny. (B) Accumulation of phenylpyruvic acid in the brain results in mental retardation. (C) Individuals affected by Down’s Syndrome will have congenital heart defects and are more intelligent. (D) Turner’s Syndrome is caused due to the absence of one X chromosome.	(C) Individuals affected by Down’s Syndrome will have congenital heart defects and are more intelligent.	Down’s Syndrome is caused by trisomy of chromosome 21, leading to developmental and intellectual disabilities, as well as congenital heart defects. The statement about increased intelligence is incorrect. Turner’s Syndrome, on the other hand, results from a missing X chromosome (45, X).
45. In a dihybrid cross between a true breeding round yellow seeded and true breeding wrinkled green seeded pea plant, the ratio of segregation of round and wrinkled seed traits in F2 is: (A) 9:1 (B) 3:1 (C) 9:3 (D) 3:3	(B) 3:1	Mendel’s dihybrid cross demonstrated the independent assortment of traits. For seed shape (round vs. wrinkled), the segregation in F2 follows a phenotypic ratio of 3:1. This highlights Mendel’s principle of segregation.
46. Stanley Miller simulated the conditions of pre-biotic Earth using a spark-discharge apparatus. Which organic compounds were observed by him on analyzing the end product of his experiment? (A) Pigments (B) Fats (C) Nitrogen bases (D) Amino acids	(D) Amino acids	Stanley Miller’s experiment demonstrated the spontaneous formation of amino acids from basic chemicals (like methane, ammonia, and water vapor) when exposed to energy sources such as electric sparks, simulating lightning. This experiment supported theories of chemical evolution of life.
47. The most ape-like ancestral primate was: (A) Dryopithecus (B) Ramapithecus (C) Australopithecus (D) Neanderthal man	(A) Dryopithecus	Dryopithecus is an early primate ancestor that exhibited features similar to modern apes. It lived around 15 million years ago and is considered a common ancestor to both apes and humans.
48. The principle of vaccination is based on which property of the immune system? (A) Memory (B) Specificity (C) Diversity (D) Plasticity	(A) Memory	Vaccination stimulates the immune system to produce memory cells specific to a pathogen. These cells "remember" the pathogen and respond rapidly during future exposures, preventing disease development.
49. The genome of HIV replicates in the macrophages with the help of an enzyme called: (A) DNA Polymerase (B) RNA Polymerase (C) Reverse Transcriptase (D) DNA Ligase	(C) Reverse Transcriptase	HIV uses reverse transcriptase to convert its RNA genome into DNA within host macrophages. This DNA integrates into the host genome, allowing viral replication and infection. Reverse transcriptase is a key target in antiretroviral therapy.
50. Read the following statements: Statement I: Morphine is obtained by acetylation of Heroin. Statement II: Cannabinoids are known for their effect on the cardiovascular system. (A) Both Statements I and II are correct. (B) Statement I is correct and Statement II is incorrect. (C) Statement I is incorrect and Statement II is correct. (D) Both Statements I and II are incorrect.	(C) Statement I is incorrect and Statement II is correct.	Morphine is a naturally occurring opiate derived from the poppy plant, whereas heroin is synthesized by acetylation of morphine. Cannabinoids, derived from cannabis plants, affect multiple systems in the body, including the cardiovascular system, where they influence blood pressure and heart rate.
51. Mule is the result of: (A) Out-crossing (B) Cross-breeding (C) Interspecific hybridization (D) Out-breeding	(C) Interspecific hybridization	A mule is an offspring of a male donkey and a female horse, resulting from interspecific hybridization. This process involves mating between individuals of two different species, leading to offspring with a mix of traits from both parents. Mules inherit strength and endurance from both parents but are usually sterile due to differences in chromosome numbers between the species.
52. Identify the bacterial disease among the following: (A) Brown rust of wheat (B) Tobacco mosaic disease (C) Black rot of crucifers (D) Late blight of potato	(C) Black rot of crucifers	Black rot of crucifers is caused by the bacterium \textit{Xanthomonas campestris}. This disease affects cruciferous crops such as cabbage and cauliflower, leading to significant agricultural losses. It spreads through infected seeds and soil, causing yellowing and wilting of leaves.
53. Match the nutrients given in List-I with the source in List-II: List-I: 1. Vitamin A 2. Single cell protein 3. Vitamin C 4. Protein List-II: p. Bitter gourd q. Beans r. Carrots s. Spirulina spp (A) 1-p, 2-q, 3-r, 4-s (B) 1-r, 2-s, 3-p, 4-q (C) 1-p, 2-r, 3-s, 4-q (D) 1-q, 2-s, 3-p, 4-r	(B) 1-r, 2-s, 3-p, 4-q	- Vitamin A, crucial for vision and immune health, is abundant in carrots (r). - Single-cell proteins, a sustainable protein source, are derived from microorganisms like \textit{Spirulina} (s). - Bitter gourd (p) is rich in Vitamin C, an antioxidant supporting immunity. - Beans (q) provide plant-based protein, essential for body repair and growth.
54. The chemical substances produced by some microbes which can kill or retard the growth of other microbes are known as: (A) Statins (B) Streptokinases (C) Cyclosporins (D) Antibiotics	(D) Antibiotics	Antibiotics, such as penicillin, are bioactive compounds produced by microorganisms like fungi and bacteria. They inhibit or kill other microbes by targeting specific pathways, such as cell wall synthesis or protein production. This property makes them vital in treating bacterial infections.
55. Select the correct statement from the following: (A) Methanobacterium is an aerobic bacterium found in the rumen of cattle. (B) Biogas is produced by the activity of aerobic bacteria. (C) Biogas is pure methane. (D) Activated sludge in sediment tanks is a rich source of aerobic bacteria.	(D) Activated sludge in sediment tanks is a rich source of aerobic bacteria.	Activated sludge, formed during wastewater treatment, contains aerobic bacteria that degrade organic matter in sewage. These bacteria play a crucial role in reducing pollution and recycling nutrients. Methanobacterium, an anaerobic bacterium, is involved in biogas production but is not aerobic. Biogas is not pure methane; it contains a mixture of gases, including CO$_2$ and traces of other compounds.
56. Which of these enzymes is required to cleave a plasmid? (A) Ligase (B) Endonuclease (C) Exonuclease (D) Polymerase	(B) Endonuclease	Endonucleases, like restriction enzymes, cleave DNA at specific recognition sites. This ability makes them indispensable in genetic engineering, allowing scientists to cut and manipulate plasmid DNA for recombinant DNA technology.
57. The natural reservoir of phosphorus is: (A) Rocks (B) Soil solution (C) Detritus (D) Atmosphere	(A) Rocks	Phosphorus originates from the weathering of phosphate-containing rocks. It is released into soil and water and becomes available to plants, forming the basis of the phosphorus cycle. Unlike nitrogen and carbon, phosphorus does not have a gaseous phase in its biogeochemical cycle.
58. The sequence of communities of primary succession in water is: (A) Phytoplanktons → Scrubs → Free floating hydrophytes → Rooted hydrophytes → Grasses → Trees. (B) Phytoplanktons → Free floating hydrophytes → Rooted hydrophytes → Trees → Scrubs. (C) Free floating hydrophytes → Scrubs → Phytoplanktons → Rooted hydrophytes → Grasses → Trees. (D) Phytoplanktons → Rooted hydrophytes → Free floating hydrophytes → Reed swamps → Marsh meadows → Scrubs → Trees.	(D) Phytoplanktons → Rooted hydrophytes → Free floating hydrophytes → Reed swamps → Marsh meadows → Scrubs → Trees.	Primary succession in aquatic ecosystems begins with phytoplanktons colonizing the water body. Over time, rooted hydrophytes and free-floating plants establish, followed by transitional stages like reed swamps, marsh meadows, scrubs, and finally, terrestrial forests (trees).
59. Match the type of adaptation given in List-I with their examples given in List-II: List-I (Types of adaptation): 1. Biochemical adaptation 2. Behavioural adaptation 3. Physiological adaptation 4. Morphological adaptation List-II (Examples): p. Desert lizards q. Deep sea fishes r. Opuntia s. Kangaroo rats (A) 1-p, 2-q, 3-r, 4-s (B) 1-r, 2-s, 3-p, 4-q (C) 1-q, 2-p, 3-s, 4-r (D) 1-s, 2-r, 3-q, 4-p	(C) 1-q, 2-p, 3-s, 4-r	- Biochemical adaptations are observed in deep-sea fishes (q) to survive high pressure. - Behavioral adaptations in desert lizards (p) include basking to regulate body temperature. - Physiological adaptations, like water conservation in kangaroo rats (s), help in arid environments. - Morphological adaptations in Opuntia (r) include spines replacing leaves to reduce water loss.
60. The annual net primary productivity of the biosphere is approximately: (A) 170 billion tons (B) 55 billion tons (C) 170 million tons (D) 55 million tons	(A) 170 billion tons	Net primary productivity (NPP) is the energy accumulated by plants after respiration. On a global scale, terrestrial and aquatic ecosystems contribute to an estimated annual NPP of 170 billion tons of organic material.