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SolveItNCERT · CBSE · NEET

NCERT Exemplar · Class 10 Science Control and Coordination

53 questions · 53 still being checked

Multiple Choice Questions 11–20 (part 2 of 5)

  1. Exercise 11

    The main function of abscisic acid in plants is to
    (a)
    increase the length of cells
    (b)
    promote cell division
    (c)
    inhibit growth
    (d)
    promote growth of stem

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    NCERT’s answer
    (c)
    (c) inhibit growth. Abscisic acid is the plant's stress hormone; it promotes stomatal closure and seed/bud dormancy, generally suppressing growth rather than promoting it.

  2. Exercise 12

    Which of the following is not associated with growth of plant?
    (a)
    Auxin
    (b)
    Gibberellins
    (c)
    Cytokinins
    (d)
    Abscisic acid

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    NCERT’s answer
    (d)
    (d) Abscisic acid. Auxin, gibberellins and cytokinins promote elongation, cell division or growth; abscisic acid instead inhibits growth and induces dormancy, so it does not belong with the other three.

  3. Exercise 13

    Iodine is necessary for the synthesis of which hormone?
    (a)
    Adrenaline
    (b)
    Thyroxin
    (c)
    Auxin
    (d)
    Insulin

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    NCERT’s answer
    (b)
    (b) Thyroxin. The thyroid gland needs iodine to synthesise thyroxine, \(\displaystyle \mathrm{T_4}\), which regulates carbohydrate, protein and fat metabolism for balanced growth of the body.

  4. Exercise 14

    Choose the incorrect statement about insulin
    (a)
    It is produced from pancreas
    (b)
    It regulates growth and development of the body
    (c)
    It regulates blood sugar level
    (d)
    Insufficient secretion of insulin will cause diabetes

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    NCERT’s answer
    (b)
    (b) It regulates growth and development of the body. Insulin from the pancreas lowers blood sugar by promoting glucose uptake and glycogen storage; growth hormone controls growth and development.

  5. Exercise 15

    Select the mis-matched pair
    (a)
    Adrenaline : Pituitary gland
    (b)
    Testosterone: Testes
    (c)
    Estrogen : Ovary
    (d)
    Thyroxin : Thyroid gland

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    NCERT’s answer
    (a)
    (a) Adrenaline is secreted by the adrenal medulla, not the pituitary gland; the other three pairs -- testosterone/testes, estrogen/ovary, thyroxin/thyroid -- are correctly matched.

  6. Exercise 16

    The shape of guard cells changes due to change in the
    (a)
    protein composition of cells
    (b)
    temperature of cells
    (c)
    amount of water in cells
    (d)
    position of nucleus in the cells

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    NCERT’s answer
    (c)
    (c) Guard cells swell and become turgid when water enters, bowing outward to open the stomatal pore; loss of water makes them flaccid and the pore closes.

  7. Exercise 17

    The growth of tendril in pea plants is due to
    (a)
    effect of light
    (b)
    effect of gravity
    (c)
    rapid cell divisions in tendrillar cells that are away from the support
    (d)
    rapid cell divisions in tendrillar cells in contact with the support

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    NCERT’s answer
    (c)
    (c) Cells on the side away from the support divide and elongate faster than those touching it, so the tendril curves and coils around the support (thigmotropism).

  8. Exercise 18

    The growth of pollen tubes towards ovules is due to
    (a)
    hydrotropism
    (b)
    chemotropism
    (c)
    geotropism
    (d)
    phototropism

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    NCERT’s answer
    (b)
    (b) The pollen tube grows down the style following a chemical gradient released by the ovule -- movement of a growing part towards a chemical stimulus is chemotropism.

  9. Exercise 19

    The movement of sunflower in accordance with the path of sun is due to
    (a)
    phototropism
    (b)
    geotropism
    (c)
    chemotropism
    (d)
    hydrotropism

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    NCERT’s answer
    (a)
    (a) The sunflower head turns to track the sun's position through the day -- growth movement of a plant part in response to light is phototropism.

  10. Exercise 20

    The substance that triggers the fall of mature leaves and fruits from plants is due to
    (a)
    auxin
    (b)
    gibberellin
    (c)
    abscisic acid
    (d)
    cytokinin

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    NCERT’s answer
    (c)
    (c) Abscisic acid is the growth-inhibiting hormone that promotes senescence and abscission, triggering mature leaves and fruits to fall; auxin, gibberellin and cytokinin instead promote growth.