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Q1. The primary function of antibodies is to:
The primary function of antibodies is to neutralize antigens. Antibodies bind to antigens (foreign substances like bacteria and viruses) and mark them for destruction by other immune cells. They do not transport oxygen (red blood cells do this), produce hormones (endocrine glands do this), or digest food (digestive system does this).
Q2. Methanogens are commonly found in:
Methanogens are commonly found in the rumen of cattle and other ruminants. They are anaerobic bacteria that help in the digestion of cellulose by producing methane gas. They are also found in marshes and swamps. They are not found in tree bark, ocean surface, or human lungs.
Q3. Immunoglobulin is another name for:
Immunoglobulin is another name for antibody. Antibodies are also called immunoglobulins. They are glycoproteins produced by the immune system to identify and neutralize antigens. Vitamins, enzymes, and hormones are different types of biological molecules.
Q4. Antibodies are highly specific because each one fits an antigen like a:
Antibodies are highly specific because each one fits an antigen like a lock and key. This means that a specific antibody can bind only to a specific antigen. This specificity is the basis of the immune system’s ability to target particular pathogens.
Q5. Diatoms play a major role in the global:
Diatoms play a major role in the global oxygen cycle. Through photosynthesis, they produce a significant portion of the Earth’s oxygen. They are important primary producers in aquatic ecosystems and contribute to the carbon cycle as well.
Q6. Vaccines contain:
Vaccines contain dead or weakened pathogens (bacteria or viruses) that stimulate the immune system to produce antibodies without causing disease. This prepares the immune system to fight off the actual pathogen in the future. Vaccines do not contain antibiotics, hormones, or antibodies directly.
Q7. Symbiosis differs from parasitism because in symbiosis:
Symbiosis differs from parasitism because in symbiosis, both organisms benefit (mutualism). In parasitism, one organism benefits while the other is harmed. The key distinction is the outcome for the organisms involved.
Q8. Nicotine addiction occurs mainly due to its effect on:
Nicotine addiction occurs mainly due to its effect on nerve cells in the brain. Nicotine stimulates the release of dopamine, a neurotransmitter associated with pleasure and reward, leading to addiction. It does not primarily affect muscles, bones, or skin.
Q9. Thermophiles survive best at:
Thermophiles survive best at very high temperatures. They are organisms that thrive in hot environments, such as hot springs and deep-sea hydrothermal vents. “Thermo” means heat, and “phile” means loving. They are adapted to temperatures often above 60°C.
Q10. Archaebacteria can survive extreme conditions because of their:
Archaebacteria can survive extreme conditions because of their unique cell membrane composition. Their membrane lipids are different from those of other organisms, providing stability under harsh conditions like high temperature, high salt, or acidic environments. They are prokaryotes and do not have a true nucleus.
Q11. Diatoms contribute significantly to:
Diatoms contribute significantly to marine food chains. As primary producers, they form the base of the aquatic food web. They are consumed by zooplankton and other small organisms, which are then eaten by larger animals. They are not significant to land, mountain, or desert ecosystems.
Q12. Diatoms are called nature’s glasshouses because of their:
Diatoms are called nature’s glasshouses because their cell walls are made of silica, which is like glass. These cell walls (frustules) are transparent, rigid, and highly ornamented. The silica content gives them a glass-like appearance.
Q13. Archaebacteria are sometimes called living fossils because they:
Archaebacteria are sometimes called living fossils because they have changed little over time. They are among the oldest life forms on Earth and have survived through billions of years, retaining many primitive characteristics. They are not extinct, not very large, and do not live in forests.
Q14. Composting is an eco-friendly method because it:
Composting is an eco-friendly method because it reduces organic waste by converting it into useful compost. This reduces the amount of waste sent to landfills and produces a valuable soil amendment. It does not release toxins, pollute air, or produce plastic.
Q15. Vermicompost contains enzymes produced by:
Vermicompost contains enzymes produced by microorganisms. During the vermicomposting process, bacteria and fungi in the digestive system of earthworms and in the compost produce enzymes that break down organic matter. Insects, plants, and animals are not the direct sources of these enzymes.
Q16. Earthworms are called farmer’s friends because they:
Earthworms are called farmer’s friends because they improve soil fertility. They aerate the soil, improve drainage, and produce nutrient-rich castings (worm poop) that are excellent fertilizers. They do not increase soil acidity, kill insects, or reduce crops.
Q17. Immunity passed from mother to child through breast milk is:
Immunity passed from mother to child through breast milk is natural passive immunity. It is “natural” because it occurs naturally without medical intervention. It is “passive” because the baby receives antibodies from the mother rather than producing its own. This provides temporary protection.
Q18. The main advantage of symbiosis is improved:
The main advantage of symbiosis is improved survival for the organisms involved. In mutualistic relationships, both partners benefit, making them better able to survive in their environment. It does not increase mutation rate, competition, or predation.
Q19. In lichens, algae provide food while fungi provide:
In lichens, algae provide food through photosynthesis while fungi provide shelter, protection, and absorb water and minerals. The fungus also protects the algae from harsh environmental conditions. This is a mutualistic symbiotic relationship.
Q20. Immunity developed after recovering from a disease is:
Immunity developed after recovering from a disease is natural active immunity. It is “natural” because it occurs through natural infection. It is “active” because the body’s immune system produces its own antibodies and memory cells after fighting off the disease.
Q21. Symbiotic relationships are most common in:
Symbiotic relationships are most common in stable environments where organisms have had long periods to co-evolve. Stable environments provide the opportunity for complex interactions like symbiosis to develop. Laboratories, extreme environments, and artificial ecosystems are less typical.
Q22. Diatomaceous earth is commonly used as a:
Diatomaceous earth is commonly used as a natural insecticide. The sharp edges of the diatom frustules (silica shells) damage the exoskeletons of insects, causing them to dehydrate and die. It is not used as a plastic substitute, fuel, or medicine.
Q23. Immunization programmes mainly aim to:
Immunization programmes mainly aim to prevent diseases by building immunity in individuals and populations. They do not directly increase population, improve digestion, or cure diseases (though they prevent them from occurring).
Q24. Vermicompost is safer than chemical fertilizers because it:
Vermicompost is safer than chemical fertilizers because it contains no toxic chemicals. It is organic and does not introduce harmful substances into the soil or food chain. Chemical fertilizers can contain synthetic chemicals that may be harmful to the environment and human health.
Q25. Coelenterates are called diploblastic because they have:
Coelenterates are called diploblastic because they have two germ layers: the ectoderm (outer layer) and endoderm (inner layer). They lack the mesoderm, which is present in triploblastic animals. The two layers surround a jelly-like mesoglea.
Q26. Non-biodegradable waste mainly accumulates in:
Non-biodegradable waste mainly accumulates in food chains. Substances like plastics and heavy metals do not break down and can be concentrated as they move up the food chain through a process called biomagnification. They do not accumulate in the carbon, water, or nitrogen cycles.
Q27. Biodegradable waste returns nutrients to the soil through:
Biodegradable waste returns nutrients to the soil through decomposition. Microorganisms break down the organic matter, releasing nutrients like nitrogen, phosphorus, and potassium back into the soil. Condensation, erosion, and leaching are different processes.
Q28. The body cavity of coelenterates is known as:
The body cavity of coelenterates is known as the gastrovascular cavity. It serves both digestive and circulatory functions. It is a sac-like cavity with a single opening that functions as both mouth and anus. Haemocoel, coelom, and pseudocoelom are found in other animal groups.
Q29. Sweating in humans is an example of:
Sweating in humans is an example of homeostasis. It is a mechanism to maintain body temperature within a normal range. When the body overheats, sweat glands produce sweat, and the evaporation of sweat cools the body. This is a homeostatic response to temperature change.
Q30. Vermicomposting is faster than normal composting because:
Vermicomposting is faster than normal composting because earthworms eat waste rapidly. The worms consume organic matter and excrete nutrient-rich castings, speeding up the decomposition process. Chemical additions, heat production, and sunlight are not the primary reasons for the increased speed.
Q31. Antibodies help in immunity by forming:
Antibodies help in immunity by forming antigen-antibody complexes. When an antibody binds to an antigen, it forms a complex that neutralizes the antigen and marks it for destruction by other immune cells. This is a key step in the immune response.
Q32. Coca alkaloids increase alertness by stimulating the:
Coca alkaloids (like cocaine) increase alertness by stimulating the brain and nervous system. They act as stimulants, increasing activity in the central nervous system and leading to feelings of increased energy and alertness. They do not primarily affect kidneys, liver, or just the heart.
Q33. Lichen represents a symbiotic association between:
Lichen represents a symbiotic association between algae and fungus. The algae (or cyanobacterium) provides food through photosynthesis, and the fungus provides shelter and nutrients. This is a classic example of mutualism.
Q34. Osmosis plays a major role in maintaining:
Osmosis plays a major role in maintaining cell size and shape. By controlling the movement of water into and out of cells, osmosis ensures that cells remain turgid and functional. It does not directly maintain body colour, cell division, or genetic material.
Q35. Plastic bags are harmful mainly because they:
Plastic bags are harmful mainly because they decompose slowly. They are non-biodegradable and can persist in the environment for hundreds of years, causing pollution. They are not biodegradable, do not absorb water, and do not improve soil quality.
Q36. Opium latex is collected from Papaver somniferum by:
Opium latex is collected from Papaver somniferum by making incisions on the capsule (seed pod). The incisions cause the latex to ooze out, which is then collected. The leaves, seeds, and roots are not the sources of opium latex.
Q37. Homeostasis failure can lead to:
Homeostasis failure can lead to disease. When the body cannot maintain stable internal conditions, it becomes vulnerable to various disorders. Diabetes, hypothermia, and dehydration are examples of conditions resulting from homeostatic imbalance.
Q38. A plant cell placed in distilled water becomes turgid due to:
A plant cell placed in distilled water becomes turgid due to osmosis. Water enters the cell because the solute concentration inside the cell is higher than the distilled water outside. The cell swells as water enters, becoming turgid. This is due to the movement of water across the selectively permeable cell membrane.
Q39. Composting helps reduce greenhouse gases by lowering:
Composting helps reduce greenhouse gases by lowering methane production. When organic waste decomposes in landfills without oxygen, it produces methane, a potent greenhouse gas. Composting allows the waste to decompose with oxygen, producing less methane and more carbon dioxide.
Q40. Homeostasis helps organisms survive sudden changes in:
Homeostasis helps organisms survive sudden changes in the internal environment, such as temperature, pH, or blood glucose levels. It does not directly help survive changes in the external environment; rather, it maintains internal stability despite external changes.
Q41. Cannabis products mainly affect mental functions because they act on the:
Cannabis products mainly affect mental functions because they act on the central nervous system (brain and spinal cord). The psychoactive compound THC interacts with cannabinoid receptors in the brain, altering perception, mood, and cognition.
Q42. Archaebacteria were the first organisms to live on Earth because they tolerate:
Archaebacteria were the first organisms to live on Earth because they tolerate extreme conditions. Early Earth had harsh conditions like high temperature, high salinity, and absence of oxygen. Archaebacteria were adapted to survive these conditions. They are not associated with oxygen-rich conditions, forests, or only cold climates.
Q43. Antigens are usually found on the surface of:
Antigens are usually found on the surface of pathogens such as bacteria, viruses, and fungi. They are molecules that trigger the immune response. Hormones, vitamins, and enzymes are not usually antigens.
Q44. Diatoms are useful to scientists because they help in:
Diatoms are useful to scientists because they help in studying past climate. Their fossilized frustules are preserved in sediments, and their species composition indicates past environmental conditions. They are used in paleoclimatology to reconstruct climate history.
Q45. Osmosis differs from diffusion because osmosis requires a:
Osmosis differs from diffusion because osmosis requires a selectively permeable membrane. Osmosis is the movement of water across a membrane, while diffusion is the movement of any substance down its concentration gradient without needing a membrane. Both require a concentration gradient.
Q46. Antibodies are produced mainly by:
Antibodies are produced mainly by plasma cells. Plasma cells are derived from B lymphocytes (a type of white blood cell). They are specialized to produce large quantities of antibodies. Platelets are for clotting, nerve cells are for signal transmission, and red blood cells carry oxygen.
Q47. Compost improves soil mainly by increasing its:
Compost improves soil mainly by increasing its water-holding capacity. The organic matter in compost acts like a sponge, holding water and releasing it slowly. It also improves soil structure and aeration. Compost does not increase salinity, acidity, or plastic content.
Q48. Diatom shells accumulate to form:
Diatom shells accumulate to form diatomite (also called diatomaceous earth). This is a sedimentary rock composed of the silica frustules of dead diatoms. Limestone is formed from calcium carbonate, peat from partially decomposed plant matter, and coal from ancient forests.
Q49. Compost is better than raw waste because it is:
Compost is better than raw waste because it is stable and harmless. Raw waste can contain pathogens, weed seeds, and unpleasant odors. Composting breaks down these harmful components, resulting in a safe, stable product that can be used as a soil amendment. It is not plastic-rich, non-organic, or toxic.
Q50. Plant roots absorb water from soil mainly by:
Plant roots absorb water from soil mainly by osmosis. Water enters the root hairs from the soil because the solute concentration in the root cells is higher than in the soil water. This process is passive and does not require energy. Diffusion and active transport are also involved in some aspects of nutrient uptake, but osmosis is the primary mechanism for water absorption.