If a colour blind man marries a woman who is homozygous for normal colour vision,the probability of their son being colour blind is :

Options

A. 0
B. 0.5
C. 0.75
D. 1

Answer

A

Explanation

If a colourblind man marries a woman who is homozygous for normal colour vision the the probability of their son being colourblind is zero, Colour blindness is a recessive sex-linked trait in which the eye fails to distinguish between red and green colour. In females colour blindness appears only when both sex chromosomes carry reccesive gene(XcXc) However in human males, the defect appears due to single reccesive gene (XcY) because Y-chromosome does not carry gene for colour vision This disease shows criss-cross inheritance
Thus there is zero probability of son being colourblind