Select the correct location.

In pea plants, the allele for inflated pod seed, [tex]\( I \)[/tex], is dominant over the allele for constricted pod seed, [tex]\( i \)[/tex]. The Punnett square shows a cross for this trait. Which offspring will be homozygous dominant?

[tex]\[
\begin{array}{|c|c|c|}
\hline
& I & i \\
\hline
i & Ii & ii \\
\hline
I & II & Ii \\
\hline
\end{array}
\][/tex]

A. [tex]\( Ii \)[/tex]

B. [tex]\( ii \)[/tex]

C. [tex]\( II \)[/tex]

D. [tex]\( Ii \)[/tex]



Answer :

Let's analyze the given scenario step by step:

1. In pea plants, the allele for inflated pod type, [tex]\( I \)[/tex], is dominant over the allele for constricted pod type, [tex]\( i \)[/tex].
2. We need to fill in the Punnett square to determine the genotype of the offspring.

First, we start with the given Punnett square framework:
[tex]\[ \begin{array}{|c|c|c|} \hline & I & i \\ \hline i & & \\ \hline I & & \\ \hline \end{array} \][/tex]

Placing the alleles accordingly on the top and side, we then proceed to fill in the squares by combining the alleles from the top and side columns.

Step-by-step, we combine the alleles:

- The top row and first column: [tex]\( i \times I = iI \)[/tex]
- The top row and second column: [tex]\( i \times i = ii \)[/tex]
- The bottom row and first column: [tex]\( I \times I = II \)[/tex]
- The bottom row and second column: [tex]\( I \times i = Ii \)[/tex]

Filling these into the Punnett square, we get:

[tex]\[ \begin{array}{|c|c|c|} \hline & I & i \\ \hline i & iI & ii \\ \hline I & II & Ii \\ \hline \end{array} \][/tex]

Now, let's identify the offspring genotypes:

- [tex]\( iI \)[/tex]: Heterozygous dominant for inflated pod
- [tex]\( ii \)[/tex]: Homozygous recessive for constricted pod
- [tex]\( II \)[/tex]: Homozygous dominant for inflated pod
- [tex]\( Ii \)[/tex]: Heterozygous dominant for inflated pod

The offspring that will be homozygous dominant (having two dominant [tex]\( I \)[/tex] alleles) is located in the:
[tex]\[ \begin{array}{|c|c|c|} \hline & I & i \\ \hline i & iI & ii \\ \hline I & \mathbf{II} & Ii \\ \hline \end{array} \][/tex]

So, the correct location for the homozygous dominant offspring is in the intersection of the second row and the second column, where the genotype is [tex]\( II \)[/tex].