In some families, either rural or urban, females are tortured for giving birth to a female child. They do…
In some families, either rural or urban, females are tortured for giving birth to a female child. They do not seem to understand the scientific reason behind the birth of a boy or a girl. In fact the mother is not responsible for the sex of the child and it has been genetically proved that the sex of a newborn is determined by what the child inherits from the father.
(a) State the basis on which the sex of a newborn baby is determined in humans.
(b) Why is the pair of sex chromosomes called a mismatched pair in males ?
(c) How is the original number of chromosomes present in the parents restored in the progeny ?
Solution
(a) If X chromosome of male sperm fuses with X chromosome of female ova, girl child is born.
If Y chromosome of male sperm fuses with X chromosome of female ova, boy child is born.
Alternate answer: [diagram showing male gametes X,Y and female gamete X combining to give XX (Female) and XY (Male) offspring]
(b) Because one is a normal sized 'X' while the other is a short one 'Y'.
(c) *During formation of germ cell/gametes the chromosome number is reduced to half.
*When two germ cells from two individuals combine to form a new individual, they restore the original number of chromosomes.