Question

How many pairs of chromosomes are present in human beings? Out of these how many are sex chromosomes? How many types of sex chromosomes are found in human beings? "The sex of a newborn child is a matter of chance and none of the parents may be considered responsible for it". Draw a flow chart showing determination of sex of a newborn to justify this statement.(Delhi - 2015)

Answer 1

Explanation:

Twenty-three pairs of chromosomes are present in human beings. Out of these, one pair is the sex chromosomes. Two types of sex chromosomes are found in human beings: X and Y. Males contain one X chromosome and one Y chromosome (XY), while females contain two copies of X chromosomes (XX).

Answer 2

|$\large\mathrm\purple{Explanation}$|

Sex of child in humans is set by the sort of male haploid sex cell that fuses with the feminine egg. Throughout meiosis, all the gametes created by females contain solely the X chromosome (A + X), whereas males manufacture 2 varieties of gametes, 1/2 gametes with X- and 1/2 with Y-chromosome (A + X and A + Y). Fertilization of egg (A + X) with sperm cell carrying A+X chromosomes ends up in female descendant (AA + XX). Fertilization of egg (A+ X) with sperm cell carrying A+Y chromosomes ends up in teenager (AA + XY).