Question

if you cross two heterozygous parents (aa x aa), what percent of offspring will also be heterozygous (aa)?
a 50%
b 75%
when we cross two heterozygous parents, we can get 75% of the dominant phenotype, not the genotype.
c 25%
d 100%

Explanation:

Step1: Create Punnett Square

For parents \( Aa \times Aa \), the possible gametes from each parent are \( A \) and \( a \). The Punnett square is:

	\( A \)	\( a \)
\( a \)	\( Aa \)	\( aa \)

Step2: Count Heterozygous (\( Aa \)) Offspring

From the Punnett square, the genotypes are \( AA \), \( Aa \), \( Aa \), \( aa \). The number of \( Aa \) (heterozygous) is 2 out of 4 total offspring.

Step3: Calculate Percentage

To find the percentage, use the formula \( \text{Percentage} = \frac{\text{Number of } Aa}{\text{Total Offspring}} \times 100\% \). Substituting the values: \( \frac{2}{4} \times 100\% = 50\% \).

Answer:

a. 50%