Question

question 3
1 pts
a woman who is heterozygous for a particular x - linked recessive trait marries a phenotypically normal man. what percentage of their sons will show the recessive phenotype?
25
100
0
50

Explanation:

Step1: Determine parental genotypes

Let $X^A$ be the normal allele and $X^a$ be the recessive allele. The woman is heterozygous, so her genotype is $X^AX^a$. The man is phenotypically normal, so his genotype is $X^AY$.

Step2: Analyze inheritance for sons

Sons inherit the Y - chromosome from the father and an X - chromosome from the mother. The possible X - chromosomes from the mother are $X^A$ and $X^a$ with equal probability.

Step3: Calculate probability

The probability of a son getting the $X^a$ chromosome from the mother is $\frac{1}{2}$ or 50%.

Answer:

D. 50