Question

What is the basis of sex-determination in human beings? Explain.

Answer 1

Human beings exhibit male heterogamy. The sex chromosomes in a male human are XY and in a female in XX. Since males have X and Y chromosomes, they are responsible for the sex determination while the human female (XX) produces only one type of gametes containing X chromosomes. The sex of the baby is determined by the type of male gamete that fuses with the female gamete.

If the sperm with the X chromosome fertilizes the egg, the baby will have XX chromosome and be a girl. On the other hand, if the fertilizing sperm contains Y chromosome, then the baby produced will be a boy.

Hence, it is a matter of chance that determines the sex of a baby. There is an equal probability of the fertilizing sperm have an X or Y chromosome. Thus, it is the genetic makeup of the sperm that determines the sex of the baby.