AP BIOLOGY

Detailed explanation-1: -Since the ratio of the X chromosome and the Y chromosome in a male gamete is 50:50. The statistical probability of male or female infants is also 50:50.

Detailed explanation-2: -The sex of an infant is determined by the type of sex chromosome contributed by the male gamete. Since the ratio of male gametes containing X chromosome and those containing Y chromosome is 50:50, the statistical probability of male or a female infant is also 50 : 50.

Detailed explanation-3: -In normal meiosis, one primary spermatocyte ultimately becomes four sperm cells: X, X, Y, and Y. Therefore, if meiosis is normal and no other factors are involved, there should be a 50% chance of conceiving a boy or girl.

Detailed explanation-4: -In most industrialized countries about 105 boys are born for every 100 girls, for a ratio of 1.05, known as the secondary sex ratio, or SSR; the primary sex ratio is the ratio at conception. This is often expressed as the percentage of boys among all births, or about 51.2 percent.

Detailed explanation-5: -Assertion, In each pregnancy there is always 50 per cent probability of either a male or a female child. <br> Reason: The genetic makeup of the sperm determines the sex of the child. In human being, the statistical probability of getting either a male or female child is 50:50 .