AP BIOLOGY

Detailed explanation-1: -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-2: -Each time a sperm meets an ovum, there is a 50% chance that it will make a boy and a 50% chance that it will make a girl. It doesn’t matter what happened the time before that: each time an ovum is fertilized, this makes a new zygote that could be a boy or a girl.

Detailed explanation-3: -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 .

Detailed explanation-4: -The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females.