A colour blind woman marries a man with normal vision. Their sons are going to be:

Options

A. All normal
B. Half colour blind and Half normal
C. One-fourth will be normal and Three fourth will be colour blind.
D. All colour blind.

Answer

D

Explanation

A female will be colour blind if the mother is a carrier and her father is colourblind. If she marries a man with a normal vision, the sons are going to be colour blind. It mostly affects the males as the genes that cause red-green colour blindness are present on the X-chromosome and males have only one X-chromosome as compared to the presence of two X-chromosomes in females.
A female heterozygous for the colour blindness. trait will have a normal vision because the defective gene will be present on only one X chromosome and its effect is suppressed by her dominant normal gene on and the defective gene is recessive, thus she acts as a carrier and passes the disorder to some of her sons only and daughter will be colour blind if the mother is a carrier and her father is colourblind.