Question

It is a matter of chance whether a couple will have male or female child. Justify the statement.

Answer 1

Sex of child in humans is determined by the kind of male haploid gamete that combines with the female egg. The chromosome in the 23rd pair of a male gamete will be either X nor Y. The female egg has an X chromosome. As a result, if the male gamete with the X chromosome fuses with the female egg the child will be female. In the same way if the male gamete with the Y chromosome fuses with the female egg the child will be male.

Complete Answer:
- In human beings, the sex of the baby is determined by the sperm. The sperm gamete is hetero gamatic because just about half of them contain the X chromosome which will result in a girl and about half of them contain the Y chromosome which will result in a boy. In contrast the ova gamete is homogametic, or in other words each of its cells possess the X chromosome.
- Therefore the ova gamete does not influence the baby’s sex. Consequently when a sperm penetrates the ova and fertilization occurs there are two possible results that is XX or a girl and XY or a boy.
- Sex determination in human beings is done by XY method, allosomes are X and Y chromosomes. The amount of chromosomes in human beings is 46. Females are homogametic which is XX and males are heterogametic that is XY. The Y-chromosome gives maleness in human beings.
- A gene consists of two parts, known as alleles, one inherited from both. The gene that is accepted from both parents, which causes some men to have more sons and some to have more daughters, may give explanation why we get the number of men and women approximately balanced in a population.
- If there will be too many males in the population, example females will without any difficulty find a mate, thus men who have more daughters will pass on more of their genes causing more females to be born in later generations.
So we can conclude that the sex of the baby is mainly determined by the male chromosomes. The chance of getting a girl or boy baby will depend upon the chromosomes present in father’s sperm.

Note: Men choose the sex of a baby depending on even their sperm is carrying an X or Y chromosome. An X chromosome links with the mothers X chromosome to produce a baby girl XX and a Y chromosome will combine with the mother's to make a baby boy XY.