“It is a matter of chance whether a couple will have a male or a female child.” Justify this statement by drawing a flow chart.
Sex of the child is determined at time of fertilization when male and female gametes fuse to form zygote. The females have a pair of XX chromosomes and produce gametes with equal number of chromosomes. Whereas males have a pair if XY chromosomes so half of gametes possess X chromosome and half have Y chromosome. But when a sperm carrying X chromo-some, child born will be a girl. However, if a sperm carrying Y chromosome, fertilises an ocum which carries X chromosome, then fertilises an ovum which carries X chromosome, child born will be a boy. So sperm determines the sex of the child.