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MCQ practice · SSC Biology Board questions · Chapter 12: Heredity in Organisms and Biological Evolution

Dhaka Board 2021

Sumi will have a son if-

  1. i. a Y-carrying sperm comes from the husband
  2. ii. an X-carrying sperm comes from the husband
  3. iii. the fertilised zygote is XY

Think it through first, then pick an option.

  1. a i and ii
  2. b i and iii
  3. c ii and iii
  4. d i, ii and iii
Answer and explanation

Correct answer: b i and iii

If a Y-carrying sperm comes from the husband (i) and the zygote is XY (iii), a son is born.

Why the other options are wrong

  • a i and ii: i is right, but an X-carrying sperm (ii) gives a girl, so ii is wrong.
  • c ii and iii: ii is wrong; an X sperm gives a girl, not a boy.
  • d i, ii and iii: ii is wrong, so all three together are not correct.