Question

A woman has only daughters, analyse the situation genetically and provide a suitable explanation.

Answer 1

Women have two X chromosomes and men have one X and one Y chromosome. Hence a female produces gametes which are all of the same kind and only contribute in one chromosome to the zygote. The other chromosome comes from the male and it can be either X or Y chromosome.

Case 1. If an X chromosome arrives from the male then the zygote will have XX condition and the resulting offspring will be a female (daughter).

Case 2. If a Y chromosome arrives from the male then the zygote will have XY condition and the resulting offspring will be a male (son).

Hence this woman has only daughters because only the sperms containing the X chromosome fertilized the ovum each time.