Red-green colorblindness is a X-linked recessive trait in humans.If a woman who is a carrier for red-green colorblindness marries a normal male,what percent of their sons will be colorblind?

Question

Quizplus · Accepted Answer

Since the trait is X-linked recessive, the woman who is a carrier for red-green colorblindness has one normal X chromosome and one X chromosome that carries the colorblindness gene. When she has children, she will randomly pass on one of her two X chromosomes to each child. If she passes on her normal X chromosome, the child will not be colorblind. If she passes on her X chromosome with the colorblindness gene, the child will be colorblind. 
Therefore, there is a 50% chance that any son she has will inherit her X chromosome with the colorblindness gene and be colorblind, and a 50% chance that he will inherit her normal X chromosome and not be colorblind.

Red-Green Colorblindness Is a X-Linked Recessive Trait in Humans