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.
There are 23 pairs of chromosomes present in human beings. There is 1 pair of sex chromosomes present in human beings. The chromosomes which determines the sex of a person are called sex chromosomes. There are two types of sex chromosomes, one is called X chromosomes and the other is called Y chromosome. Male contain one X chromosome and one Y chromosome ( XY) , while females contain two X chromosomes (X X). Flor chart showing determination of sex of a child. (i) A male has one X-chromosome and one Y-chromosome. Thus, half the male gametes have X-chromosomes and the other half have Y-chromosomes. (ii) A female has two X-chromosomes. Thus all female gametes have only X-chromosomes. (iii) If a sperm carrying Y-chromosome fertilises an ovum carrying X-chromosome, then the child born will be a boy. (iv) If a sperm carrying X-chromosome fertilises an ovum carrying X-chromosome, then the child born will be a girl. Therefore it is the sperm from the father which determines the sex of the child.
