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 first parent?
A)AA
B)Aa
C)aa
D)The answer cannot be determined from this information.

Question

Quizplus · Accepted Answer

The first parent must be heterozygous (Aa) because crossing Aa with aa results in a 1:1 ratio of dominant to recessive phenotypes, which matches the observed offspring ratio (4 recessive out of 9 total).

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