Question

two sisters have a father who is homozygous for his recessive blue eyes and a mother who is dominant for her heterozygous brown eyes. one sister has blue eyes and the other has brown eyes. which of the following explains the difference in the eye color of the sisters?
a each sister inherited the same combination of alleles from their parents that determined their eye color.
b one of the sisters inherited all of her alleles from the mother, and the other sister inherited all of her alleles from the father.
c the sister with the blue eyes had only one allele for determining eye color, and the sister with brown eyes had two alleles.
d the sister with blue eyes inherited a different combination of alleles from both parents than the combination inherited by the sister with brown eyes.

Explanation:

Alleles are different forms of a gene. Each parent contributes one allele for a trait. Eye - color is determined by alleles. The sister with blue eyes (recessive trait) must have received two recessive alleles (one from each parent). The sister with brown eyes (dominant trait) could have received one dominant allele (from the mother, who is heterozygous for brown eyes) and one recessive allele (from the father, who is homozygous recessive for blue eyes). This means they have different allele combinations from both parents.

Answer:

D. The sister with blue eyes inherited a different combination of alleles from both parents than the combination inherited by the sister with brown eyes.