A color- blind woman marries a man who is not color- blind.All of their sons,but none of their daughters,are color- blind.Which of the following statements correctly explains these results?

Question

Quizplus · Accepted Answer

The gene for color vision is located on the X chromosome. Females have two X chromosomes, while males have one X and one Y chromosome. If the mother carries a recessive allele for color blindness on one of her X chromosomes, she will be a carrier but not color-blind herself. If the father does not carry any color blindness alleles, he will not be color-blind. Each son has a 50% chance of inheriting the mother's X chromosome with the recessive allele for color blindness, which will result in the son being color-blind. However, since daughters have two X chromosomes, they have a 25% chance of inheriting both the mother's normal X chromosome and the father's normal X chromosome, resulting in normal color vision.

A Color- Blind Woman Marries a Man Who Is Not