A man who is a dwarf due to achondroplasia and has normal vision marries a color-blind woman of normal height.The man's father was 6 feet tall,and both the woman's parents were of average height.Achondroplasia is autosomal dominant,and red-green color blindness is X-linked recessive.
They have a daughter who is a dwarf with normal color vision.What is the probability that she is heterozygous for both genes?
A)0%
B)25%
C)50%
D)100%

Question

Quizplus · Accepted Answer

The daughter inherits the dominant allele for achondroplasia from her father, making her a dwarf, and she must inherit a normal X chromosome from her father (since he has normal vision and males have only one X chromosome). Since she has normal color vision, she must also inherit a normal X chromosome from her mother (who must be heterozygous for color blindness, carrying one normal and one color-blind allele). Therefore, the daughter is heterozygous for both genes by necessity.

A Man Who Is a Dwarf Due to Achondroplasia and Has