Sex-Linked Inheritance Problem Set

Problem 7: Red-green color blindness in humans


A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color blindness (or alternatively, hemophilia), marries a normal male. What proportion of their male progeny will have red-green color blindness (or alternatively, will be hemophiliac)?

A. 100%

B. 75%

C. 50%

Half the sons would be expected to inherit the allele from their mother and be afflicted because they are hemizygous. Half the daughters would be carriers like their mothers.

D. 25%

E. 0%

The Biology Project
University of Arizona
Updated: July 15, 1999
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