Question

Which one of the following conditions of the zygotic cell will produce a normal human female child?

• A. Only heterologous X chromosome
• B. One X and one Y chromosome
• C. Two homologous X chromosome
• D. Only one Y chromosome

Answer 1

The correct option is C Two homologous X chromosome

The chromosome pattern in the human female is XX and that in the male is XY. Therefore, all the haploid gametes produced by the female (ova) have the sex chromosome X whereas in the male gametes (sperms) the sex chromosome could be either X or Y, hence, 50 per cent of sperms carry the X chromosome while the other 50 percent carry the Y. After fusion of the male and female gametes the zygote would carry either XX or XY depending on whether the sperm carrying X or Y fertilised the ovum. The zygote carrying XX would develop into a female baby and XY would form a male baby.