Question

in the pedigree that is shown, which represents irenes allele combination?
○ $x^{h}x^{h}$
○ $x^{h}x^{h}$
○ $x^{h}x^{h}$
○ $x^{h}y$

Explanation:

Step1: Analyze parental alleles

The father has genotype $X^{H}Y$ and the mother has genotype $X^{H}X^{h}$.

Step2: Determine possible inheritances for daughters

Daughters inherit one X - chromosome from each parent. From the father, daughters will always get $X^{H}$. From the mother, daughters can get either $X^{H}$ or $X^{h}$.

Step3: Consider Irene's phenotype (not shaded)

Since Irene is not affected (not shaded in the pedigree), and she is female, her possible genotype is $X^{H}X^{H}$ or $X^{H}X^{h}$. But considering the mother's genotype $X^{H}X^{h}$, the most likely genotype for Irene (as there is no indication of a homozygous - dominant inheritance pattern from other information) is $X^{H}X^{h}$.

Answer:

$X^{H}X^{h}$