Հարց 78

In a conversation about sex determination, someone says that a mother decides whether her child is a boy or a girl. Which statement sets that right?

The sperm cell that fertilises the egg determines the sex of the childՃիշտ պատասխան
The mother does decide it, because she carries two X chromosomes
The egg cell determines it, because eggs differ from one another at this pair
Neither parent's cells are involved, since the sex is settled by conditions during pregnancy

Բացատրություն

One member of the pair arrives from the mother whatever happens, so the only part of the pairing that can vary is what comes in from the father. Whichever kind of male gamete reaches the egg first fixes the pair, which places the deciding difference on the father's side and not the mother's.

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