Red-green color blindness is a recessive X-linked trait. If a female is red-green color-blind, which of the following is true?
A) Her mother must be color-blind.
B) Both her parents must be color-blind.
C) Both her parents are carriers of the recessive allele.
D) Her father must be color-blind.
E) Women cannot exhibit red-green color blindness because they have two X chromosomes.

Question

Quizplus · Accepted Answer

Since red-green color blindness is a recessive X-linked trait, a female (XX) must inherit two copies of the recessive allele to express the trait. She inherits one X chromosome from her mother and one from her father. If she is color-blind, she must have received the recessive allele on the X chromosome from her father, making him color-blind. Her mother can be a carrier or color-blind, but must at least carry one recessive allele.

Red-Green Color Blindness Is a Recessive X-Linked Trait