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NCERT Exemplar · Class 10 Science How do Organisms Reproduce?

58 questions · 58 still being checked

Multiple Choice Questions 21–27 (part 3 of 6)

  1. Exercise 21

    Reproduction is essential for living organisms in order to
    (a)
    keep the individual organism alive
    (b)
    fulfill their energy requirement
    (c)
    maintain growth
    (d)
    continue the species generation after generation

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    NCERT’s answer
    (d)
    (d) Continue the species generation after generation. Reproduction is not needed by an individual to stay alive or to grow; it exists solely to replace organisms that die, keeping the species going.

  2. Exercise 22

    During adolescence, several changes occur in the human body. Mark one change associated with sexual maturation in boys
    (a)
    loss of milk teeth
    (b)
    increase in height
    (c)
    cracking of voice
    (d)
    weight gain

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    NCERT’s answer
    (c)
    (c) cracking of voice — testosterone enlarges the larynx at puberty, deepening the voice; height and weight rise are general growth, milk-tooth loss happens earlier, none tied to sexual maturation.

  3. Exercise 23

    In human females, an event that reflects onset of reproductive phase is
    (a)
    growth of body
    (b)
    changes in hair pattern
    (c)
    change in voice
    (d)
    menstruation

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    NCERT’s answer
    (d)
    (d) menstruation — menarche (the first menstrual cycle) marks the onset of the reproductive phase in girls; body growth, hair pattern and voice change are general puberty changes, not reproductive-phase markers.

  4. Exercise 24

    In human males, the testes lie in the scrotum, because it helps in the
    (a)
    process of mating
    (b)
    formation of sperm
    (c)
    easy transfer of gametes
    (d)
    all the above

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    NCERT’s answer
    (b)
    (b) formation of sperm — the scrotum keeps testes about \(\displaystyle 2\text{-}3\,^\circ\mathrm{C}\) below body temperature, a condition spermatogenesis needs; it plays no direct role in mating or gamete transfer.

  5. Exercise 25

    Which among the following is not the function of testes at puberty?
    (i)
    formation of germ cells
    (ii)
    secretion of testosterone
    (iii)
    development of placenta
    (iv)
    secretion of estrogen
    (a) (i) and (ii)
    (b) (ii) and (iii)
    (c) (iii) and (iv)
    (d) (i) and (iv)

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    NCERT’s answer
    (c)
    (c) (iii) and (iv) — testes at puberty form germ cells and secrete testosterone; placenta develops in the pregnant uterus and estrogen is ovarian, neither is a testicular function.

  6. Exercise 26

    The correct sequence of organs in the male reproductive system for transport of sperms is
    (a)
    testis → vasdeferens → urethra
    (b)
    testis → ureter → urethra
    (c)
    testis → urethra → ureter
    (d)
    testis → vasdeferens → ureter

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    NCERT’s answer
    (a)
    (a) testis → vas deferens → urethra — sperm leave the testis via the vas deferens and exit through the urethra; the ureter carries urine from the kidney, not sperm, ruling out the other options.

  7. Exercise 27

    Which among the following diseases is not sexually transmitted?
    (a)
    Syphillis
    (b)
    Hepatitis
    (c)
    HIV - AIDS
    (d)
    Gonorrhoea

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    NCERT’s answer
    (b)
    (b) Hepatitis — spread mainly through contaminated food and water (A, E) or blood (B, C); syphilis, gonorrhoea and HIV-AIDS are the classic sexually transmitted diseases.