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Which are the correct statements regarding ozone depletion? (i) Chlorofluorocarbons (CFCs) are the main cause of ozone depletion. (ii) Ozone depletion increases harmful ultraviolet radiation reaching earth. (iii) Ozone hole is prominently observed over Antarctica. (iv) Ozone depletion protects humans from global warming.
ANSWER: (A) Explanation: Ozone depletion is mainly caused by chlorofluorocarbons (CFCs) from refrigerants, air-conditioners, and aerosols. CFCs release chlorine that destroys ozone molecules, thinning the protective layer. This allows harmful ultraviolet rays to reach Earth, causing skin cancer, catRead more
ANSWER: (A)
Explanation: Ozone depletion is mainly caused by chlorofluorocarbons (CFCs) from refrigerants, air-conditioners, and aerosols. CFCs release chlorine that destroys ozone molecules, thinning the protective layer. This allows harmful ultraviolet rays to reach Earth, causing skin cancer, cataracts, and crop damage. The ozone hole, seen prominently over Antarctica, highlights this issue. Ozone depletion differs from global warming, which concerns heat retention.
See lessIf pea plants with round and green seeds (RRyy) are crossed with pea plants having wrinkled and yellow seeds (rrYY), the seeds developed by the plants of F1 generation will be: (A) 50% round and green (B) 75% wrinkled and green (C) 100% round and yellow (D) 75% wrinkled and yellow
ANSWER: (C) Explanation: Parent cross: RRyy × rrYY Gametes: R y (from RRyy) and r Y (from rrYY) F₁ genotype: RrYy (all offspring same) Traits: R (round) is dominant over r (wrinkled). Y (yellow) is dominant over y (green). So, all F₁ seeds will show round and yellow phenotype. Thus, the plants of F₁Read more
ANSWER: (C)
Explanation:
Traits:
So, all F₁ seeds will show round and yellow phenotype. Thus, the plants of F₁ generation will produce 100% round and yellow seeds.
See lessThe decomposers in an ecosystem: (A) synthesise inorganic material from similar forms (B) synthesise organic compounds from simpler carbon compound (C) convert organic material into inorganic forms (D) convert inorganic materials into organic compounds
ANSWER: (C) Explanation: Decomposers like bacteria and fungi break down dead plants, animals, and organic waste into simpler inorganic substances such as carbon dioxide, water, and minerals. These products are returned to the environment, where producers reuse them for photosynthesis and growth. ThuRead more
ANSWER: (C)
Explanation: Decomposers like bacteria and fungi break down dead plants, animals, and organic waste into simpler inorganic substances such as carbon dioxide, water, and minerals. These products are returned to the environment, where producers reuse them for photosynthesis and growth. Thus, decomposers recycle nutrients, clean the ecosystem of waste, and maintain the balance of nature.
See lessAssertion (A): A human child bears all the basic features of human beings. Reason (R): It looks exactly like its parents, showing very little variations.
ANSWER: (C) Explanation: Assertion (A): A human child bears all the basic features of human beings. Reason (R): It looks exactly like its parents, showing very little variations. The assertion is true because a child always shows the basic human characteristics. The reason is false because a child dRead more
ANSWER: (C)
Explanation: Assertion (A): A human child bears all the basic features of human beings.
Reason (R): It looks exactly like its parents, showing very little variations.
- The assertion is true because a child always shows the basic human characteristics.
- The reason is false because a child does not look exactly like its parents but shows variations due to sexual reproduction.
See lessAssertion (A): The amount of ozone in the atmosphere began to drop sharply in the 1980s. Reason (R): The oxygen atoms combine with molecular oxygen to form ozone.
ANSWER: (C) Explanation: Assertion (A): The amount of ozone in the atmosphere began to drop sharply in the 1980s. Reason (R): The oxygen atoms combine with molecular oxygen to form ozone. The assertion is true, as ozone depletion was first observed prominently in the 1980s. The reason is false, becaRead more
ANSWER: (C)
Explanation: Assertion (A): The amount of ozone in the atmosphere began to drop sharply in the 1980s.
Reason (R): The oxygen atoms combine with molecular oxygen to form ozone.
- The assertion is true, as ozone depletion was first observed prominently in the 1980s.
- The reason is false, because the drop was due to CFCs breaking ozone, not due to oxygen forming ozone.
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