Write short note on inheritance of colour blindness in man.

Explanation

Colour blindness is a recessive sex-linked trait in which an individual fails to distinguish between red and green colours. The recessive allele is carried by X-chromosomes. In female, it appears only when both the sex chromosomes carry the gene `(X^(C )X^(C ))`. The females function as carriers in the presence of a single recessive gene `(XX^(C ))` while in males the defect appears in the presence of a single recessive gene `(X^(C )Y)` because Y-chromosome does not carry any gene for colour vision.