Question

Duchenne muscular dystrophy is an X-linked recessive disorder.

A Punnett square is shown. The columns are labeled Upper X m and Upper Y. The rows are labeled x Upper M and x m.

What is the probability that a female offspring of the cross that is shown above would have a recessive allele for Duchenne muscular dystrophy disorder?
0 percent
25 percent
50 percent
100 percent

Answer 1

100 percent.

Explanation: Mother = X^M X^m, father = X^m Y. Female offspring genotypes from the Punnett square are X^M X^m and X^m X^m — both carry at least one recessive X^m allele.