1. Plants carry out both photosynthesis and respiration, but the amount of oxygen released during photosynthesis is far greater than the amount consumed during respiration. In photosynthesis, plants release large volumes of oxygen as a by-product while producing glucose. Although they use some oxygen fRead more

    Plants carry out both photosynthesis and respiration, but the amount of oxygen released during photosynthesis is far greater than the amount consumed during respiration. In photosynthesis, plants release large volumes of oxygen as a by-product while producing glucose. Although they use some oxygen for their own energy needs during respiration, this is comparatively very small. Additionally, the vast number of plants on Earth constantly replenish the atmosphere with oxygen. Hence, the overall balance ensures no shortage of oxygen in the atmosphere.

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  2. ANSWER: Explain the multiple excretion way in plants. Gaseous waste: Oxygen released during photosynthesis and carbon dioxide during respiration diffuse out through stomata. Excess water: Removed by transpiration from stomata and lenticels. Storage of wastes: Resins and gums are deposited in dead xyRead more

    ANSWER: Explain the multiple excretion way in plants.

    1. Gaseous waste: Oxygen released during photosynthesis and carbon dioxide during respiration diffuse out through stomata.
    2. Excess water: Removed by transpiration from stomata and lenticels.
    3. Storage of wastes: Resins and gums are deposited in dead xylem.
    4. Special products: Tannins, latex, and essential oils accumulate in leaves, bark, or fruits.
    5. Leaf fall: In autumn, wastes are discarded along with shedding leaves.
      Plants thus excrete by multiple simple ways without specialised organs.
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  3. In the process of respiration – (i) state the function of alveoli. (ii) state the function of stomata. (i) Alveoli in humans: Provide a very large surface area for gas exchange. Thin walls allow oxygen to diffuse into blood and carbon dioxide out. Rich network of capillaries ensures efficient transpRead more

    In the process of respiration – (i) state the function of alveoli. (ii) state the function of stomata.

    (i) Alveoli in humans: Provide a very large surface area for gas exchange. Thin walls allow oxygen to diffuse into blood and carbon dioxide out. Rich network of capillaries ensures efficient transport of gases.

    (ii) Stomata in plants: Tiny pores on leaves regulate exchange of oxygen, carbon dioxide, and water vapor. Guard cells control opening and closing. Help plants balance respiration, photosynthesis, and water loss.

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  4. ANSWER: Biological magnification refers to the progressive increase in concentration of harmful, non-biodegradable substances such as pesticides, DDT, or mercury as they pass along a food chain. Producers absorb small amounts from soil or water. Herbivores consume many plants, and carnivores eat sevRead more

    ANSWER: Biological magnification refers to the progressive increase in concentration of harmful, non-biodegradable substances such as pesticides, DDT, or mercury as they pass along a food chain. Producers absorb small amounts from soil or water. Herbivores consume many plants, and carnivores eat several herbivores, so the concentration rises at each level.

    For example, pesticides sprayed on crops enter grass → eaten by grasshoppers → eaten by frogs → eaten by snakes → eaten by eagles. The eagle, being the top consumer, suffers the maximum effect.

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  5. ANSWER: Paralysis of the right side of the body usually indicates damage to the left hemisphere of the cerebrum. The cerebrum controls voluntary actions, learning, memory, and thinking. Each hemisphere controls opposite sides of the body, so damage to the left affects the right side. The motor areaRead more

    ANSWER: Paralysis of the right side of the body usually indicates damage to the left hemisphere of the cerebrum. The cerebrum controls voluntary actions, learning, memory, and thinking. Each hemisphere controls opposite sides of the body, so damage to the left affects the right side. The motor area of the cerebrum sends signals to muscles for movement. If injured, nerve impulses cannot pass, causing paralysis.

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