If an individual with a dominant phenotype is crossed with an individual with a recessive phenotype,4 of their 9 offspring show the recessive phenotype.What is the genotype of the dominant parent?
A)AA
B)Aa
C)aa
D)either AA or Aa
E)either Aa or aa

Question

Quizplus · Accepted Answer

If the dominant parent had a homozygous dominant genotype (AA), then all offspring would have the dominant phenotype. If the dominant parent had a heterozygous genotype (Aa), then there is a 1 in 4 chance for each offspring to inherit the recessive allele from both parents (resulting in a recessive phenotype). Therefore, the best choice for the genotype of the dominant parent is either Aa or AA. However, since 4 of the 9 offspring showed the recessive phenotype, it is more likely that the dominant parent was heterozygous (Aa) rather than homozygous dominant (AA).

If an Individual with a Dominant Phenotype Is Crossed with an Individual