Biology for IGCSE & O level - Inheritance (Section 11 - No. 49)
If a woman is colorblind and her partner has normal vision, what is the probability of their son being colorblind (assuming colorblindness is X-linked recessive)?
0%
25%
50%
100%
Explication
Since the mother is colorblind, she has two recessive alleles. The son will always receive one X chromosome from the mother; therefore, he will always be colorblind.