A man who is a dwarf with achondroplasia and normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Dwarfism caused by achondroplasia is autosomal dominant, and red-green color blindness is X-linked recessive. What proportion of their sons would be color blind and of normal height?
A) none
B) half
C) one out of four
D) all

Question

Quizplus · Accepted Answer

The man is heterozygous for achondroplasia (Dd) and has normal vision (XY). The woman is homozygous recessive for normal height (dd) and is color-blind (XcXc). Sons inherit the Y chromosome from their father and one X chromosome from their mother. All sons will inherit the Xc from their mother, making them color-blind. For height, they have a 50% chance of inheriting the recessive allele (d) from their father, making them of normal height. Thus, half of the sons will be color-blind and of normal height.

A Man Who Is a Dwarf with Achondroplasia and Normal