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1. Question: Taenia solium can be found in (a) pig (b) cow (c) goat (d) dog
Topic: Parasitology / Animal Kingdom (Platyhelminthes)
Correct Answer: (a) pig
Explanation: Taenia solium, commonly known as the pork tapeworm, uses pigs as its intermediate host. Humans are the definitive host (where the adult tapeworm lives). Pigs become infected by ingesting eggs or gravid proglottids, and the larvae (cysticerci) encyst in their muscles.
Why other options are incorrect:
- (b) cow: Cows are the intermediate host for Taenia saginata, the beef tapeworm.
- (c) goat: Goats are not the typical intermediate host for Taenia solium.
- (d) dog: Dogs can be hosts for other tapeworms (like Echinococcus granulosus or Dipylidium caninum), but not typically Taenia solium as an intermediate host.
2. Question: Proboscis is a structure that is mostly found in (a) molluscs (b) amphibians (c) insects (d) reptiles
Topic: Animal Kingdom / Anatomy & Adaptations
Correct Answer: (c) insects
Explanation: A proboscis is an elongated, often tubular, feeding or sucking mouthpart. It is a characteristic feature of many insects, particularly those that feed on liquids like nectar (butterflies, moths), blood (mosquitoes), or plant sap.
Why other options are incorrect:
- (a) molluscs: Some molluscs (like certain snails) have a radula for scraping food, not typically a proboscis for sucking.
- (b) amphibians: Amphibians typically have wide mouths with sticky tongues for catching prey.
- (d) reptiles: Reptiles have varied mouth structures (jaws, teeth, tongues) adapted for their diets, but not usually a sucking proboscis.
3. Question: Which of the following is an adaptation for water conservation? (a) prominent stomata in leaves (b) spiny leaves (c) spongy mesophyll (d) broad leaves
Topic: Plant Anatomy & Physiology / Adaptations (Xerophytes)
Correct Answer: (b) spiny leaves
Explanation: Plants adapted to arid environments (xerophytes) need to conserve water. Reducing the surface area available for transpiration is a key strategy. Modifying leaves into spines drastically reduces this surface area, minimizing water loss. Spines also deter herbivores.
Why other options are incorrect:
- (a) prominent stomata in leaves: Prominent or numerous stomata generally increase the potential for water loss through transpiration, the opposite of conservation. Xerophytes often have sunken stomata or fewer stomata.
- (c) spongy mesophyll: This layer facilitates gas exchange within the leaf; while its structure can be adapted, its presence isn’t primarily a water conservation feature compared to modifying the entire leaf shape.
- (d) broad leaves: Broad leaves have a large surface area, which maximizes light absorption but also increases water loss through transpiration. This is typical of plants in moist environments.
4. Question: The digestive enzyme that is present in the saliva is (a) renin (b) ptyalin (c)chymotrypsin (d) pepsin
Topic: Digestive System / Enzymes
Correct Answer: (b) ptyalin
Explanation: Ptyalin is another name for salivary amylase. It is an enzyme present in the saliva of humans and some other animals that begins the digestion of carbohydrates by breaking down starch into smaller sugars like maltose.
Why other options are incorrect:
- (a) renin: An enzyme found primarily in the stomach of infants that helps curdle milk protein (casein). Also refers to a hormone involved in blood pressure regulation (part of the renin-angiotensin system).
- (c) chymotrypsin: A protease (protein-digesting enzyme) produced by the pancreas and active in the small intestine.
- (d) pepsin: The main protease produced in the stomach (secreted as pepsinogen), active in acidic conditions.
5. Question: Plants that have special structures for trapping and digesting insects are (a) saprophytic (b) carnivorous (c) parasitic (d) symbiotic
Topic: Plant Biology / Modes of Nutrition / Adaptations
Correct Answer: (b) carnivorous
Explanation: Carnivorous plants (or insectivorous plants) have evolved adaptations to trap and digest insects and other small animals. They typically grow in nutrient-poor soils (especially low in nitrogen) and supplement their nutrition by obtaining nutrients from their prey. Examples include Venus flytraps, pitcher plants, and sundews.
Why other options are incorrect:
- (a) saprophytic: Organisms (like fungi, some bacteria) that obtain nutrients from dead organic matter.
- (c) parasitic: Plants (like dodder, mistletoe) that obtain nutrients directly from another living plant (the host).
- (d) symbiotic: Describes any close and long-term interaction between two different biological species. While carnivory is an interaction, “symbiotic” is too general and includes mutualism, commensalism, and parasitism. Carnivorous is the specific term.
6. Question: Which of the following is a waste product of an insect? (a) uric acid (b) mucilage (c) alkaloids (d) sweat
Topic: Excretory System / Animal Physiology (Insects)
Correct Answer: (a) uric acid
Explanation: Insects, like birds and reptiles, primarily excrete nitrogenous wastes in the form of uric acid. Uric acid is relatively non-toxic and requires very little water for excretion (it’s often excreted as a semi-solid paste), which is a significant adaptation for water conservation, especially in terrestrial environments.
Why other options are incorrect:
- (b) mucilage: A viscous secretion produced by plants and some microorganisms, not a primary insect waste product.
- (c) alkaloids: Nitrogen-containing organic compounds produced mainly by plants, often toxic or pharmacologically active; not an insect excretory product.
- (d) sweat: Produced by sweat glands in mammals for thermoregulation and excretion of some wastes (like urea, salts); insects do not sweat.
7. Question: The sensory cell that responds to dim light is called (a) cone (b) rod (c) pupil (d) iris
Topic: Sense Organs / The Eye / Photoreception
Correct Answer: (b) rod
Explanation: The retina of the eye contains two main types of photoreceptor cells: rods and cones. Rod cells are highly sensitive to light intensity and are responsible for vision in dim light (scotopic vision). They do not detect colour.
Why other options are incorrect:
- (a) cone: Cone cells are responsible for colour vision (photopic vision) and function best in bright light. They are less sensitive to light intensity than rods.
- (c) pupil: The opening in the center of the iris that allows light to enter the eye. It’s not a sensory cell.
- (d) iris: The coloured part of the eye, a muscular diaphragm that controls the size of the pupil, regulating the amount of light entering. It’s not a sensory cell.
8. Question: The opening of the guard cells of the epidermis in plants is by the process of (a) diffusion (b) osmosis (c) active transportation (d) transpiration
Topic: Plant Physiology / Stomata Function
Correct Answer: (b) osmosis
Explanation: Stomata (pores on the leaf surface) are surrounded by two guard cells. The opening and closing of the stomata are primarily regulated by changes in the turgor pressure of these guard cells. When guard cells actively transport ions (like K+) into the cell, their solute concentration increases. This causes water to enter the guard cells via osmosis, increasing their turgor pressure. The specific shape of the guard cells causes them to bow outwards when turgid, opening the stoma. The reverse process (ions leave, water leaves by osmosis) causes them to become flaccid and close the stoma.
Why other options are incorrect:
- (a) diffusion: While gas exchange through the open stoma occurs by diffusion, the opening mechanism itself is driven by turgor changes due to osmosis.
- (c) active transportation: Active transport is involved in moving ions into or out of the guard cells, which leads to the osmotic movement of water, but osmosis is the direct process causing the turgor change and opening/closing.
- (d) transpiration: The process of water vapour loss through the stomata, not the mechanism that opens them. Transpiration rates influence stomatal opening/closing, but it’s not the opening process itself.
9. Question: In humans, excretion of isotonic urine is associated with (a) proximal convoluted tubule (b) distal convoluted tubule (c) Bowman’s capsule (d) loop of Henle
Topic: Excretory System / Kidney Function / Nephron Physiology
Correct Answer: (a) proximal convoluted tubule
Explanation: Isotonic means having the same solute concentration (osmolarity) as the surrounding fluid (in this case, blood plasma). As the filtrate passes from Bowman’s capsule into the proximal convoluted tubule (PCT), a large amount of solutes (like NaCl, glucose, amino acids) and water are reabsorbed in roughly equal proportions. This means that while the volume of the filtrate decreases significantly, its osmolarity remains essentially the same as that of the initial filtrate and the surrounding cortical interstitial fluid, i.e., it remains isotonic.
Why other options are incorrect:
- (b) distal convoluted tubule: Urine osmolarity is adjusted here (becoming hypotonic or hypertonic) depending on the body’s hydration status, under hormonal control (ADH, aldosterone).
- (c) Bowman’s capsule: Contains the initial filtrate, which is isotonic to blood plasma. However, the question asks where excretion (processing within the tubule system) of isotonic urine occurs. Significant processing and reabsorption start in the PCT, maintaining isotonicity initially.
- (d) loop of Henle: This structure creates the medullary osmotic gradient. The filtrate becomes hypertonic as it descends and hypotonic as it ascends, so it’s not isotonic throughout this section.
10. Question: The correct arrangement of food classes of the same quantity in the descending order of magnitude of energy values in animals is (a) protein, fats and oils, water and carbohydrates (b) carbohydrates, fats and oils, water and protein (c) fats and oils, carbohydrates, protein and water (d) water, fats and oils, carbohydrates and protein
Topic: Biochemistry / Nutrition / Energy Metabolism
Correct Answer: (c) fats and oils, carbohydrates, protein and water
Explanation: The energy content per gram of major food classes varies. Fats and oils provide the most energy (approximately 9 kcal/g or 37 kJ/g). Carbohydrates and proteins provide roughly similar amounts of energy, significantly less than fats (approximately 4 kcal/g or 17 kJ/g). Water provides no metabolic energy. Therefore, the descending order of energy value for the same quantity (mass) is Fats/Oils > Carbohydrates ≈ Proteins > Water.
Why other options are incorrect:
- (a), (b), (d): These options incorrectly order the energy values, particularly placing fats/oils lower than carbohydrates or proteins, or placing water higher than energy-yielding nutrients.
11. Question: Which of the following substances is not a complex carbohydrate? (a) starch (b) Glucose (c)cellulose (d) glycogen
Topic: Biochemistry / Carbohydrates
Correct Answer: (b) Glucose
Explanation: Complex carbohydrates (polysaccharides) are large molecules made up of long chains of simple sugar units (monosaccharides). Glucose is a monosaccharide – a simple sugar – and is the building block for many complex carbohydrates.
Why other options are incorrect:
- (a) starch: A major storage polysaccharide in plants, composed of long chains of glucose units.
- (c) cellulose: A structural polysaccharide found in plant cell walls, composed of long chains of glucose units linked differently than in starch.
- (d) glycogen: The main storage polysaccharide in animals and fungi, composed of highly branched chains of glucose units.
12. Question: The bacteria that convert soil nitrate into atmospheric nitrogen are called (a) nitrifying bacteria (b) denitrifying bacteria (c) putrefying bacteria (d) saprophytic bacteria
Topic: Ecology / Biogeochemical Cycles (Nitrogen Cycle)
Correct Answer: (b) denitrifying bacteria
Explanation: Denitrification is a crucial step in the nitrogen cycle where bacteria convert nitrates (NO3-) back into gaseous nitrogen (N2), which is then released into the atmosphere. This process typically occurs under anaerobic (low oxygen) conditions in the soil. Examples include Pseudomonas and Paracoccus.
Why other options are incorrect:
- (a) nitrifying bacteria: Convert ammonia (NH3) or ammonium (NH4+) into nitrites (NO2-) and then nitrates (NO3-). This process is called nitrification.
- (c) putrefying bacteria: Decomposers that break down proteins in dead organic matter, releasing ammonia (ammonification).
- (d) saprophytic bacteria: A general term for bacteria that feed on dead organic matter (decomposers), including putrefying bacteria. Denitrifying bacteria have a specific role in nitrogen conversion distinct from general decomposition.
13. Question: The main reason for immunizing children is to, (a) stimulate the production of blood (b) stimulate the production of antibodies (c) increase the production of white blood cells (d) destroy pathogens in their bodies
Topic: Immune System / Health & Disease / Vaccination
Correct Answer: (b) stimulate the production of antibodies
Explanation: Immunization (vaccination) works by introducing a harmless form of a pathogen (or its components, like antigens) into the body. This triggers the adaptive immune system to mount a response, including the production of specific antibodies and memory cells (memory B cells and T cells) against that pathogen. If the child later encounters the actual pathogen, the immune system can mount a much faster and stronger response due to these pre-existing antibodies and memory cells, preventing or lessening the severity of the disease.
Why other options are incorrect:
- (a) stimulate the production of blood: Immunization does not directly stimulate overall blood production (hematopoiesis).
- (c) increase the production of white blood cells: While an immune response involves the proliferation of specific white blood cells (lymphocytes), the primary goal and long-term benefit of vaccination is the generation of specific antibodies and memory.
- (d) destroy pathogens in their bodies: Vaccines generally contain weakened, inactivated, or components of pathogens, not live, virulent ones to be destroyed immediately. The goal is to prepare the immune system for future encounters, not fight a current infection (that’s the role of treatments like antibiotics/antivirals if an infection occurs).
14. Question: How do we justify the absence of digestive system in tapeworm? (a) it does not feed (b) it is too small (c) its body absorbs digested food (d) it has no enzymes
Topic: Animal Physiology / Parasitology / Adaptations
Correct Answer: (c) its body absorbs digested food
Explanation: Tapeworms are endoparasites living within the nutrient-rich environment of a host’s intestine. The host performs the digestion, breaking down complex food molecules into simple, absorbable units. The tapeworm is highly adapted to absorb these pre-digested nutrients directly across its specialized body surface (tegument). Having no need to digest food itself, it has evolutionarily lost its own digestive system.
Why other options are incorrect:
- (a) it does not feed: It feeds parasitically by absorbing nutrients from the host.
- (b) it is too small: Tapeworms can grow very large (several meters long); size is not the reason for lacking a gut.
- (d) it has no enzymes: While it lacks digestive enzymes, this is a consequence of its mode of nutrition, not the reason for the absence of the entire system. The ability to absorb already digested food (c) is the primary justification.
15. Question: If a body has blood type O and his mother has blood type A, what is the likely genotype of his father? (a) AB (b) AO (c) BB (d) AA
Topic: Genetics / Human Genetics / Blood Groups (ABO)
Correct Answer: (b) AO
Explanation:
- Blood type O corresponds to the genotype ii. The child inherited one ‘i’ allele from the mother and one ‘i’ allele from the father.
- The mother has blood type A. Her genotype could be IAIA or IAi. Since she must have passed an ‘i’ allele to her child (who is ii), the mother’s genotype must be IAi.
- The father must also have contributed an ‘i’ allele to the child.
- Let’s check the father’s possible genotypes:
- (a) AB (genotype IAIB): Can only pass IA or IB. Cannot produce an ‘O’ child.
- (b) AO (genotype IAi): Can pass IA or i. Could pass ‘i’ to the child. Possible.
- (c) BB (genotype IBIB): Can only pass IB. Cannot produce an ‘O’ child. (Note: If father was BO (IBi), he could also produce an ‘O’ child).
- (d) AA (genotype IAIA): Can only pass IA. Cannot produce an ‘O’ child.
- Therefore, among the given options, the only genotype for the father that allows him to contribute the necessary ‘i’ allele is AO (IAi). A father with genotype BO (IBi) or O (ii) could also potentially father an O child with this mother, but those aren’t the options provided in this exact form. AO is the most likely given these choices.
Why other options are incorrect:
- (a) AB (IAIB): Cannot pass an ‘i’ allele.
- (c) BB (IBIB): Cannot pass an ‘i’ allele.
- (d) AA (IAIA): Cannot pass an ‘i’ allele.
16. Question: The organism above is found in soils rich in (a) mud (b) sand (c) clay (d) humus
Topic: Ecology / Soil Biology (Assuming Earthworm)
Correct Answer: (d) humus
Explanation: Assuming the organism depicted (but not shown in text) is an earthworm, they thrive in soils that are rich in organic matter (humus). Humus provides food for the earthworms (they feed on decaying organic material) and helps maintain soil moisture and aeration, creating a favorable environment.
Why other options are incorrect:
- (a) mud: While needing moisture, excessively waterlogged mud (often low in oxygen) is not ideal.
- (b) sand: Sandy soils drain quickly, are often low in organic matter, and can be abrasive. Not the preferred habitat.
- (c) clay: Clay soils can become compacted, waterlogged, and difficult to burrow through, although earthworms help aerate them. Soils with high humus content are generally preferred over pure heavy clay.
17. Question: The branch of biology that deals with the principles of classification of organisms is known as (a) population dynamics (b) ecology (c) taxonomy (d) nomenclature
Topic: Classification / Taxonomy
Correct Answer: (c) taxonomy
Explanation: Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics and evolutionary relationships. It includes the principles and practices of classification (arranging organisms into hierarchical groups like kingdom, phylum, class, order, family, genus, species) and nomenclature (assigning formal scientific names).
Why other options are incorrect:
- (a) population dynamics: The study of how populations change in size and structure over time due to factors like birth rates, death rates, immigration, and emigration. Part of ecology.
- (b) ecology: The study of the interactions between organisms and their environment, including other organisms.
- (d) nomenclature: Specifically refers to the system of naming organisms (e.g., binomial nomenclature), which is a part of taxonomy, but taxonomy encompasses the broader principles of classification as well.
18. Question: The presence of a large number of ____ is an evidence that a cell utilizes a lot of energy (a) Ribosomes (b) vacuoles (c) mitochrondria (d) endoplasmic reticulum
Topic: Cell Biology / Organelles and Function
Correct Answer: (c) mitochrondria
Explanation: Mitochondria (singular: mitochondrion) are often called the “powerhouses” of the cell because they are the primary sites of cellular respiration. This process breaks down glucose and other fuel molecules in the presence of oxygen to generate large amounts of ATP (adenosine triphosphate), the main energy currency of the cell. Cells with high energy demands (like muscle cells, nerve cells) typically have numerous mitochondria. (Note: correct spelling is mitochondria).
Why other options are incorrect:
- (a) Ribosomes: Sites of protein synthesis. Cells actively producing proteins have many ribosomes, but this reflects protein production, not necessarily overall energy utilization rate (though protein synthesis requires energy).
- (b) vacuoles: Membrane-bound sacs with various functions, including storage (water, nutrients, waste) and maintaining turgor pressure (in plants). Large central vacuoles are typical of plant cells; not directly indicative of high energy use.
- (d) endoplasmic reticulum: Involved in protein synthesis/modification (Rough ER) and lipid synthesis/detoxification (Smooth ER). Important, but mitochondria are the direct indicators of high ATP production capacity.
19. Question: Kreb’s cycle occurs in the (a) nucleus (b) ribosomes (c) cytoplasm (d) mitochrondria
Topic: Cellular Respiration / Metabolism
Correct Answer: (d) mitochrondria
Explanation: The Krebs cycle (also known as the citric acid cycle) is a central stage of aerobic cellular respiration. In eukaryotic cells, it takes place within the mitochondrial matrix, the innermost compartment of the mitochondrion. (Note: correct spelling is mitochondria).
Why other options are incorrect:
- (a) nucleus: Contains the cell’s genetic material (DNA) and controls cell activities; site of DNA replication and transcription, not Krebs cycle.
- (b) ribosomes: Sites of protein synthesis.
- (c) cytoplasm: The initial stage of glucose breakdown, glycolysis, occurs in the cytoplasm. The pyruvate produced then enters the mitochondria for the Krebs cycle (if oxygen is present).
20. Question: A purple colour was obtained when sodium hydroxide solution and a drop of copper sulphate solution were added to a food substance. The food is likely to be a (a) sugar (b) protein (c) fat (d) carbohydrate
Topic: Biochemistry / Food Tests (Biuret Test)
Correct Answer: (b) protein
Explanation: This describes the Biuret test. When sodium hydroxide (an alkali) and a few drops of copper(II) sulfate solution are added to a substance containing peptide bonds (found in proteins and polypeptides), the copper(II) ions react with the peptide bonds in the alkaline conditions to form a violet/purple-coloured complex. This indicates the presence of protein.
Why other options are incorrect:
- (a) sugar: Reducing sugars are tested using Benedict’s or Fehling’s solution (giving red/orange precipitate on heating). Non-reducing sugars require hydrolysis first. Sugars don’t give a purple color with Biuret reagents.
- (c) fat: Fats (lipids) are tested using emulsion tests (e.g., with ethanol and water) or Sudan III/IV stains (giving red/orange colour).
- (d) carbohydrate: General term. Starch (a carbohydrate) is tested using iodine solution (giving blue-black colour). Simple sugars (carbohydrates) are tested as in (a).
21. Question: A sample of wet soil of a given weight was heated to constant weight. The loss in weight is due to loss of (a) water (b) humus (c) water and humus (d) inorganic matter
Topic: Ecology / Soil Science
Correct Answer: (a) water
Explanation: Heating wet soil, especially at temperatures typically used for drying to constant weight (around 105°C), drives off the volatile component, which is primarily water. The weight difference between the initial wet soil and the final dry soil represents the mass of water that evaporated.
Why other options are incorrect:
- (b) humus: Humus is the stable organic matter component of soil. While very high temperatures (ashing) can burn off humus, standard drying to constant weight aims to remove only water. Significant loss of humus requires much higher temperatures.
- (c) water and humus: Only water is significantly lost during standard drying.
- (d) inorganic matter: This refers to the mineral components (sand, silt, clay), which are non-volatile and remain after heating/drying.
22. Question: Adenine pairs with thymine because (a) one is a purine with thymine because (a) one is a purine base and the other, a pyrimidine (b) they are both purines (c) they are both pyrimidines (d) the two occur in the same nucleic acid (Note: Redundant phrasing in option (a) assumed to mean “one is a purine and the other, a pyrimidine”)
Topic: Molecular Biology / DNA Structure
Correct Answer: (a) one is a purine base and the other, a pyrimidine
Explanation: In the DNA double helix, base pairing follows specific rules (Chargaff’s rules). Adenine (A) always pairs with Thymine (T), and Guanine (G) always pairs with Cytosine (C). Adenine and Guanine are purines (double-ring structures). Cytosine and Thymine are pyrimidines (single-ring structures). The pairing always involves one purine and one pyrimidine (A with T, G with C). This specific pairing is due to the complementary shapes and the pattern of hydrogen bonds they can form (A-T form two hydrogen bonds, G-C form three). The purine-pyrimidine pairing ensures the consistent width of the DNA double helix.
Why other options are incorrect:
- (b) they are both purines: Purines (A, G) do not pair with each other in the standard DNA helix.
- (c) they are both pyrimidines: Pyrimidines (C, T) do not pair with each other in the standard DNA helix.
- (d) the two occur in the same nucleic acid: While true that both A and T are found in DNA, this doesn’t explain why they specifically pair with each other. The purine-pyrimidine structure and hydrogen bonding potential are the reasons.
23. Question: What is the role of the red head in male Agama lizard? (a) To scare other males (b) for camouflaging against predators (c) to attract female lizards for mating purposes (d) for respiration
Topic: Animal Behaviour / Ecology / Communication
Correct Answer: (c) to attract female lizards for mating purposes
Explanation: In many Agama lizard species, dominant males develop bright breeding colouration, often including a strikingly coloured head (red, orange, or blue depending on the species). This bright colouration serves primarily as a sexual signal to attract females and also often functions in territorial displays to intimidate rival males. Attracting mates is a key role.
Why other options are incorrect:
- (a) To scare other males: While the bright colour is part of the display that establishes dominance and can intimidate rivals, attracting females is considered a primary function.
- (b) for camouflaging against predators: Bright colours are conspicuous and generally the opposite of camouflage. Non-dominant males or females often have duller, more cryptic colouration.
- (d) for respiration: Head colour has no direct role in the process of breathing.
24. Question: An example of an endospermous seed is (a) bean seed (b) cotton seed (c) cashew nut (d) maize grain
Topic: Plant Biology / Seeds / Embryology
Correct Answer: (d) maize grain
Explanation: Seeds can be classified based on whether the endosperm (nutritive tissue) persists in the mature seed. In endospermous (or albuminous) seeds, the endosperm remains as the primary food storage tissue for the embryo. Maize (corn), along with other cereals like wheat and rice, and castor bean, are classic examples. In non-endospermous (or exalbuminous) seeds, the endosperm is absorbed by the cotyledons during development, and the fleshy cotyledons themselves become the main food storage organs.
Why other options are incorrect:
- (a) bean seed: Beans are non-endospermous; the large cotyledons store the food.
- (b) cotton seed: Generally considered non-endospermous or having very little endosperm; food is stored mainly in the cotyledons.
- (c) cashew nut: The “nut” is the seed, which is non-endospermous; the fleshy cotyledons store food. (The fleshy cashew “apple” is the swollen pedicel).
25. Question: The movement response of cockroach away from a light source can be described as (a)positive phototaxism (b) positive phototropism (c) negative phototropism (d) negative phototaxism
Topic: Animal Behaviour / Responses to Stimuli
Correct Answer: (d) negative phototaxism
Explanation:
- Taxis: A directed movement response of a motile organism towards or away from a stimulus.
- Tropism: A growth response of a plant towards or away from a stimulus.
- Photo-: Refers to light as the stimulus.
- Positive: Movement towards the stimulus.
- Negative: Movement away from the stimulus.
Cockroaches are motile organisms (animals) that move away from light. Therefore, their response is negative phototaxis.
Why other options are incorrect: - (a) positive phototaxism: Movement towards light (like moths).
- (b) positive phototropism: Growth of a plant towards light (like a plant shoot).
- (c) negative phototropism: Growth of a plant away from light (like plant roots, though gravity is usually the primary stimulus).
26. Question: If the cross of a red-flowered plant with a white-flowered plant produces a pink-flowered plant, it is an example of (a) codominance (b) convergent evolution (c) incomplete dominance (d) linkage
Topic: Genetics / Inheritance Patterns
Correct Answer: (c) incomplete dominance
Explanation: Incomplete dominance occurs when the heterozygous phenotype is an intermediate blend between the two homozygous phenotypes. Neither allele is completely dominant over the other. In this case, red (RR) crossed with white (WW or rr) produces pink (RW or Rr), an intermediate colour.
Why other options are incorrect:
- (a) codominance: Both alleles are fully and simultaneously expressed in the heterozygote, resulting in a phenotype that shows both traits distinctly (e.g., human AB blood type, roan cattle with both red and white hairs). Pink is a blend, not distinct red and white patches.
- (b) convergent evolution: The independent evolution of similar features in different lineages, not a pattern of inheritance within a cross.
- (d) linkage: The tendency for genes located close together on the same chromosome to be inherited together; describes the relationship between different genes, not the expression pattern of alleles for a single gene.
27. Question: What is the number of alleles controlling blood groups in humans? (a) 2 (b) 3 (c) 4 (d) 5
Topic: Genetics / Human Genetics / Multiple Alleles (ABO Blood Group)
Correct Answer: (b) 3
Explanation: The ABO blood group system in humans is controlled by a single gene (the I gene) that has three common alleles: IA, IB, and i. IA codes for antigen A, IB codes for antigen B, and i codes for no antigen. Although there are three alleles in the population, any individual diploid person can only possess a maximum of two of these alleles (e.g., IAIA, IAi, IBIB, IBi, IAIB, ii).
Why other options are incorrect:
- (a) 2: Many traits are controlled by two alleles, but ABO is the classic example of multiple (more than two) alleles.
- (c) 4, (d) 5: There are only three main alleles (IA, IB, i) controlling the ABO system.
28. Question: In terms of the number individuals, which of the following taxa is the most inclusive? (a) specie (b) order (c) class (d) family
Topic: Classification / Taxonomy / Linnaean Hierarchy
Correct Answer: (c) class
Explanation: The Linnaean system of classification is hierarchical. The major ranks, from most inclusive (broadest group, potentially largest number of individuals globally, though species number varies) to least inclusive (most specific), are typically: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species. A class contains one or more related orders, an order contains one or more related families, and a family contains one or more related genera, and a genus contains one or more related species. Therefore, among the options given, Class is the highest and most inclusive rank.
Why other options are incorrect:
- (a) specie (species): The least inclusive (most specific) rank among the options.
- (b) order: More inclusive than family and species, but less inclusive than class.
- (d) family: More inclusive than species (and genus), but less inclusive than order and class.
29. Question: In the alimentary system of a bird, the function of teeth is carried out by the (a) tongue (b) gizzard (c) beak (d) crop
Topic: Animal Anatomy & Physiology / Digestive System (Birds)
Correct Answer: (b) gizzard
Explanation: Birds lack teeth. Instead, they have a specialized part of the stomach called the gizzard (or muscular stomach). The gizzard has thick, muscular walls and often contains small stones or grit swallowed by the bird. It mechanically grinds food, performing the function analogous to chewing with teeth in mammals.
Why other options are incorrect:
- (a) tongue: Used for manipulating food, but not for grinding.
- (c) beak: Used for obtaining, tearing, or cracking food, depending on the bird’s diet, but not for the fine grinding that occurs in the gizzard.
- (d) crop: An enlargement of the esophagus used primarily for storing food temporarily before it passes to the stomach; some softening may occur, but not grinding.
30. Question: Exhaled air differs from inhaled air in that is (a) usually has more water vapour (b) is usually lower in temperature (c) has less amount of carbon (iv) oxide (d) often has more oxygen (Note: “(iv) oxide” assumed to mean carbon dioxide)
Topic: Respiratory System / Gas Exchange
Correct Answer: (a) usually has more water vapour
Explanation: As air passes through the respiratory passages (nasal cavity, pharynx, larynx, trachea, bronchi), it is warmed to body temperature and humidified (saturated with water vapour). Therefore, exhaled air contains significantly more water vapour than the inhaled air (unless the inhaled air was already fully saturated and at body temperature).
Why other options are incorrect:
- (b) is usually lower in temperature: Exhaled air is warmed to body temperature (around 37°C), so it’s usually warmer than inhaled ambient air.
- (c) has less amount of carbon dioxide: Cellular respiration produces carbon dioxide as a waste product, which diffuses from the blood into the alveoli. Therefore, exhaled air has a higher concentration of carbon dioxide than inhaled air.
- (d) often has more oxygen: Oxygen diffuses from the inhaled air in the alveoli into the blood to be used in cellular respiration. Therefore, exhaled air has a lower concentration of oxygen than inhaled air.
31. Question: The ability of a chameleon to change its colour is an adaptive feature for (a) attack (b) defence (c) display (d) attraction (Correction: Options should likely cover camouflage, communication, thermoregulation)
Topic: Animal Behaviour & Physiology / Adaptation
Correct Answer: (b) defence / (c) display (Context Dependent – Best Answer Choice requires nuance)
Explanation: Chameleons change colour for several reasons, primarily related to communication (social signaling/display) and camouflage (defence). They change colour to signal mood (aggression, stress), intent towards other chameleons (mating readiness, territoriality), and to blend in with their surroundings to avoid predators. Thermoregulation (darker colours absorb more heat) can also play a role. Among the limited options:
- Defence: Camouflage is a form of defence against predators.
- Display: Signaling mood or intent to rivals or potential mates is a form of display.
Given the typical contexts, both (b) and (c) represent valid primary functions. Without further context, it’s hard to pick definitively between defence (camouflage) and display (communication). Often, display/communication is emphasized in modern understanding over just camouflage. If forced to choose from these simplified options, (b) defence (via camouflage) is a widely understood function. (c) Display captures the communication aspect.
(Self-correction: Let’s re-evaluate based on typical exam question intent. Camouflage for predator avoidance is a very strong adaptive feature). Let’s lean towards Defence/Camouflage.
Why other options are incorrect:
- (a) attack: Colour change isn’t primarily an offensive weapon for attacking prey.
- (d) attraction: While display includes attracting mates, “attraction” alone is too narrow compared to the broader communication/display functions.
(Reconsidering): If ‘display’ encompasses communication with rivals and mates, it’s quite broad. If ‘defence’ primarily means camouflage, that’s also strong. Let’s assume the question might favor the camouflage aspect. Final decision leans towards (b) Defence. However, acknowledging (c) Display is also valid.
32. Question: Primary growth in plants is brought about by the activity of the (a) epidermis (b) endodermis (c) mesophyll (d) meristem
Topic: Plant Anatomy & Physiology / Growth / Meristems
Correct Answer: (d) meristem
Explanation: Primary growth in plants refers to growth in length (of roots and stems) and the formation of primary tissues. This growth originates from cell divisions in apical meristems, which are located at the tips of roots and shoots (stems/buds). Meristems are regions of undifferentiated cells capable of continuous cell division.
Why other options are incorrect:
- (a) epidermis: The outermost layer of cells, a primary tissue produced by the apical meristem, providing protection. It doesn’t cause primary growth.
- (b) endodermis: A layer of cells in the root cortex (and sometimes stems) that regulates water and nutrient movement into the vascular tissue. A primary tissue, not the source of growth.
- (c) mesophyll: The ground tissue in leaves, specialized for photosynthesis. A primary tissue, not the source of growth.
33. Question: Which of the following processes is not an example of a reflex action? (a) sneezing (b) beating of the heart (c) blinking of the eye (d) reading
Topic: Nervous System / Reflexes
Correct Answer: (d) reading
Explanation: A reflex action is an involuntary, rapid, and stereotyped response to a specific stimulus. It typically involves a reflex arc (sensory receptor, sensory neuron, interneuron (optional), motor neuron, effector). Reading is a complex cognitive process involving conscious visual processing, interpretation of symbols, comprehension, and integration in higher brain centers (cerebrum). It is a voluntary and learned activity, not an involuntary reflex.
Why other options are incorrect:
- (a) sneezing: A reflex triggered by irritation in the nasal passages to forcefully expel the irritant.
- (b) beating of the heart: While influenced by the autonomic nervous system and hormones, the basic heart rhythm is intrinsic, and its rate adjustment involves reflex control (e.g., baroreceptor reflex). It’s fundamentally involuntary.
- (c) blinking of the eye: Can be voluntary, but the rapid, involuntary blink in response to a foreign object approaching the eye (corneal reflex) or bright light is a protective reflex.
34. Question: The following are examples of discontinuous variation except (a) sex type (b) skin colour (c) fingerprint (d) ability to taste PTC
Topic: Genetics / Variation
Correct Answer: (b) skin colour
Explanation: Discontinuous variation involves traits that fall into distinct, separate categories (e.g., blood groups A, B, AB, O). Continuous variation involves traits that show a smooth range of phenotypes between two extremes (e.g., height, weight). Skin colour in humans is influenced by multiple genes (polygenic inheritance) and environmental factors, resulting in a wide spectrum of continuous shades rather than distinct categories.
Why other options are incorrect:
- (a) sex type: In most species, individuals fall into distinct categories (male or female), representing discontinuous variation.
- (c) fingerprint: Fingerprint patterns (loops, whorls, arches) fall into distinct categories, exhibiting discontinuous variation (though the ridge count can be seen as continuous).
- (d) ability to taste PTC (phenylthiocarbamide): This is largely controlled by a single gene with dominant (taster) and recessive (non-taster) alleles, resulting in distinct categories (taster vs. non-taster) – a classic example of discontinuous variation.
35. Question: Which of the following is an anabolic process? (a) excretion (b) photosynthesis (c) respiration (d) photolysis
Topic: Metabolism / Bioenergetics
Correct Answer: (b) photosynthesis
Explanation: Metabolism consists of anabolism and catabolism. Anabolism refers to metabolic processes that build complex molecules from simpler ones, requiring energy input (endergonic). Photosynthesis uses light energy to synthesize complex organic molecules (glucose) from simple inorganic molecules (CO2 and H2O). It is a prime example of an anabolic process.
Why other options are incorrect:
- (a) excretion: The process of removing metabolic waste products from the body. Not primarily a building-up or breaking-down process in the metabolic sense, more of removal.
- (c) respiration (cellular respiration): A catabolic process that breaks down complex organic molecules (like glucose) to release energy (exergonic), producing simpler molecules (CO2 and H2O).
- (d) photolysis: Specifically refers to the splitting of water molecules using light energy during the light-dependent reactions of photosynthesis. It’s a part of photosynthesis (an anabolic process overall), but itself is a breakdown (lysis) reaction, albeit one that fuels the building process. Photosynthesis (b) is the best answer for the overall anabolic process.
36. Question: Amoeba engulfs food particles by means of its (a) pseudopodia (b) food vacuoles (c) contractile vacuole (d) cytoplasmic membrane
Topic: Protist Biology / Cell Biology / Feeding Mechanisms
Correct Answer: (a) pseudopodia
Explanation: Amoeba feeds by phagocytosis. It extends temporary cytoplasmic projections called pseudopodia (false feet) around a food particle. The pseudopodia fuse, enclosing the particle within a membrane-bound vesicle inside the cytoplasm. This vesicle is called a food vacuole. The pseudopodia are the structures used for the engulfing process.
Why other options are incorrect:
- (b) food vacuoles: The membrane-bound sac containing the engulfed food particle after phagocytosis; formed by the action of pseudopodia.
- (c) contractile vacuole: Involved in osmoregulation (expelling excess water), not food engulfment.
- (d) cytoplasmic membrane (cell membrane): The outer boundary involved in forming the pseudopodia and the food vacuole, but the pseudopodia are the specific structures extended for engulfment.
37. Question: The type of association in which one organism benefits and the other neither benefits nor suffers any harm is called (a) mutualism (b) parasitism (c) saprophytism (d) commensalism
Topic: Ecology / Symbiosis
Correct Answer: (d) commensalism
Explanation: Commensalism is a symbiotic relationship where one species benefits, and the other species is unaffected (neither harmed nor helped). Example: Barnacles attaching to a whale.
Why other options are incorrect:
- (a) mutualism: Both species benefit from the interaction (e.g., nitrogen-fixing bacteria in legume roots).
- (b) parasitism: One species (the parasite) benefits at the expense of the other species (the host), which is harmed (e.g., tapeworm in human gut).
- (c) saprophytism: A mode of nutrition where organisms feed on dead organic matter (decomposition), not typically considered a symbiotic interaction between living organisms in the same way as the others.
38. Question: Intercoastal muscles are found in the ____ region (a) limb (b) abdominal (c) head (d) chest
Topic: Musculoskeletal System / Respiratory System / Anatomy
Correct Answer: (d) chest
Explanation: The intercostal muscles (external and internal) are located in the spaces between the ribs (costae) in the chest wall (thorax). They play a crucial role in the mechanics of breathing by elevating and depressing the rib cage to change the volume of the thoracic cavity.
Why other options are incorrect:
- (a) limb: Limbs have muscles specific for their movement (e.g., biceps, triceps, quadriceps).
- (b) abdominal: The abdominal wall has muscles like the rectus abdominis and obliques.
- (c) head: The head has muscles for facial expression, chewing (mastication), and moving the head itself.
39. Question: Meiosis involves the following except (a) exchange of genes (b) production of four daughter cells (c) production of cells with haploid number of chromosomes (d) production of cells with diploid number of chromosomes
Topic: Cell Biology / Cell Division (Meiosis)
Correct Answer: (d) production of cells with diploid number of chromosomes
Explanation: Meiosis is a specialized type of cell division that reduces the chromosome number by half, creating haploid cells (gametes or spores) from diploid cells. Key features include: exchange of genetic material between homologous chromosomes (crossing over – part of (a)), two rounds of division resulting in four daughter cells (b), and the resulting daughter cells being haploid (n) (c). Meiosis starts with a diploid cell but produces haploid cells. Producing diploid cells is characteristic of mitosis (or fertilization).
Why other options are incorrect:
- (a) exchange of genes: Crossing over (genetic recombination) occurs during Prophase I of meiosis.
- (b) production of four daughter cells: Meiosis involves two successive divisions (Meiosis I and Meiosis II), typically resulting in four cells.
- (c) production of cells with haploid number of chromosomes: This is the fundamental purpose of meiosis – to reduce the chromosome number from diploid (2n) to haploid (n).
40. Question: The network of blood capillaries in the kidney capsule is referred to as (a) capsule (b) glomerulus (c) pelvis (d) pyramid
Topic: Excretory System / Kidney Anatomy / Nephron Structure
Correct Answer: (b) glomerulus
Explanation: The Bowman’s capsule (kidney capsule) is a cup-shaped structure at the beginning of the nephron. It surrounds a dense network (tuft) of capillaries called the glomerulus. Blood enters the glomerulus via the afferent arteriole and leaves via the efferent arteriole. Filtration of blood occurs from the glomerulus into the Bowman’s capsule.
Why other options are incorrect:
- (a) capsule: Refers to the Bowman’s capsule itself, the structure surrounding the capillary network.
- (c) pelvis: The renal pelvis is the central collecting region of the kidney.
- (d) pyramid: Renal pyramids are cone-shaped structures forming the medulla of the kidney.
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