SolveItClass 9 · NCERT

NCERT Solutions · Class 9 Science Reproduction: How Life Continues

24 questions · 22 still being checked

Pause and Ponder 11.6–11.7 (part 10 of 19)

  1. Exercise 11.6

    Ravi suddenly notices that he is growing taller rapidly, his shoulders are broadening, and his voice cracks. What stage of life is he entering?

    Not cross-checked

    NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.

    NCERT’s answer
    Adolescence
    Ravi is entering adolescence — the stage at which puberty brings about sexual maturation.
    A rapid gain in height, broadening shoulders and a cracking voice are the physical changes of this stage in boys.
    They are brought about by the hormone produced by the testes, which also starts and controls the production of sperm.
    Sexual maturity — the body becoming capable of reproduction — comes gradually at this stage, but emotional maturity takes longer to develop.

  2. Exercise 11.7

    Rina’s period occurs every 28\displaystyle 28 days. Her last period was on the 5th of March. On which day is she most likely to get her next period?
    NCERT’s answer
    2nd April
    Her next period is most likely on 2nd April.
    NCERT_Solution_Class9_Science_Ch11_PP_Q11-7
    Her cycle length is \(\displaystyle 28\) days and the last period began on $\displaystyle 5$ March, so the next one begins \(\displaystyle 28\) days later: \(\displaystyle 5 + 28 = 33\).
    March has \(\displaystyle 31\) days, so day \(\displaystyle 33\) of March is \(\displaystyle 33 - 31 = 2\) → $\displaystyle 2$ April.
    This is an expected date, not a fixed one: the chapter gives the cycle as repeating typically every \(\displaystyle 21\)–\(\displaystyle 35\) days, so it can shift by a few days.