Question

if you cross two heterozygous parents (aa x aa), what percent of offspring will also be heterozygous (aa)? a 100% b 50% c 75% d 25%

Explanation:

Step1: Create Punnett square

Parents: \(Aa\times Aa\). Possible gametes: \(A\) and \(a\) from each parent.

$$\begin{array}{|c|c|c|} \hline & A & a \\ \hline A & AA & Aa \\ \hline a & Aa & aa \\ \hline \end{array}$$

Step2: Count heterozygous offspring

There are 4 total offspring. Number of \(Aa\) (heterozygous) is 2.
The proportion of \(Aa\) is \(\frac{2}{4}\)

Step3: Convert proportion to percentage

\(\frac{2}{4}\times100\% = 50\%\)

Answer:

B. 50%