Question

when two heterozygous parents are crossed (aa x aa), what percent of the offspring will have a dominant phenotype?
a 100%
b 25%
crossing two heterozygous parents give us 25% aa and 25% aa. although the phenotype of aa is the recessive type, there are three types of offspring genotypes.
c 50%
d 75%

Explanation:

Step1: Recall Punnett Square for Aa × Aa

Each parent (Aa) can produce two types of gametes: A and a. The Punnett square for this cross is:

	A	a
a	Aa	aa

Step2: Determine Genotypes and Phenotypes

• Genotypes: AA (25%), Aa (50%), aa (25%).
• Phenotypes: Dominant phenotype (AA or Aa) occurs in 25% + 50% = 75% of offspring (since AA and Aa show dominant trait, aa shows recessive).

Answer:

d. 75%