Question

explain with the help of a figure that father is responsible for the sex of a child

Answer 1

The male gamete from the father has 2 different kind of chromosomes. The X chromosomes and the Y chromosome.
The female gamete i.e the ova has only the X chromosome.
If the X chromosome sperm fuses with the egg the offspring is a girl.
If the Y chromosome sperm fuses with the egg, the offspring is a boy.
Hence the father is responsible for the child' s gender.

Answer 2

Possibility is equal.in sex determination,chromosomes of father determines whether child is male or female.The no.of Male gamets which carry X-Chromosomes and the no.of Gamets which carry X-Chromosomes and the no.of Gamets which Y chromosomes r equal..so,possiblity of fusion of male gamets having X Or Y chromosomes with Ovum Which has only X-Chromosomes