For most genes on the human x chromosome, what percent of xy males with a mutant allele on the x chromosome will express the mutant phenotype?

a., 0%
b., 25%
c., 50%
d., 100%
e., there is insufficient data to predict

D. 100%

Explanation:

In humans, males have only one copy of the X chromosome in their cells. Therefore, human males express all the X-linked genes present on their X chromosomes irrespective of the recessive or dominant nature of the allele. This occurs since males do not have one more copy of the X chromosome to carry another allele for the gene. So, all the X-linked alleles present on the X-chromosomes of the human males are expressed.

For example, human males with genotype X^cY and X^hY express colorblindness and hemophilia respectively. Though, human females express these recessive X-linked disorders in homozygous genotype only.

correct answer is a. and d.

you know they are heterozygous for a trait because they have it as jj or jj.