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Reaching the Age of Adolescence — Science STD 8 — Question

Gujarat BoardEnglish MediumSTD 8ScienceReaching the Age of Adolescence4 Marks
Question
Explain how sex is determined in the unborn baby.
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Answer

The two chromosomes that determine the sex of the unborn baby are called sex chromosomes named $X$ chromosomes and chromosomes. A female has two $X$ chromosomes, while a male has one $X$ and one $Y$ chromosome. The gametes (egg and sperm) have only one set of chromosomes. Thus, in females all the egg cells contain $X$ chromosomes while in males, half sperm have $X$ chromosomes and half sperms have $Y$ chromosomes. When a sperm containing $X$ chromosome fertilizes the egg, the zygote would have $XX$ chromosomes and develop into a female child. If the sperm contributes a $Y$ chromosome to the egg (ovum) at fertilization, the zygote would develop into a male child. Thus, father is responsible for the sex of the baby which is born.

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