In humans, the allele for red-green color blindness is X-linked and recessive (X^r; the dominant allele is called X^R). A man with normal color vision marries a color-blind woman who gives birth to a color-blind daughter. From this, we can tell that A) the woman is X^RX^r. B) the man must be a carrier for the color blindness allele. C) the daughter must be heterozygous. D) the man is probably NOT the father of the daughter.

Question

Quizplus · Accepted Answer

A color-blind daughter must inherit one X^r allele from each parent. Since the father has normal vision, he must have an X^R allele, making it impossible for him to pass on an X^r allele. Therefore, he is probably not the father.

In Humans, the Allele for Red-Green Color Blindness Is X-Linked