To determine the ratio of genotypes in the offspring, we need to create a Punnett square based on the parents' genotypes.
Let's define:
- "D" as the dominant allele for dimples.
- "d" as the recessive allele for no dimples.
Given:
- The mom is heterozygous for dimples, so her genotype is "Dd".
- The dad is homozygous for no dimples, so his genotype is "dd".
We set up the Punnett square as follows:
```
d d
+----+----+
D | Dd | Dd |
+----+----+
d | dd | dd |
+----+----+
```
Here’s what each cell of the Punnett square represents:
- The offsprings represented by the cells in the first column are from the combination of the mom's "D" allele and the dad's "d" allele, resulting in "Dd".
- The offsprings represented by the cells in the second column are from the combination of the mom's "d" allele and the dad's "d" allele, resulting in "dd".
From this Punnett square, we can see the genotypic ratio of the offspring:
- 2 out of 4 cells (50%) have the genotype "Dd", which would result in individuals having dimples (because the allele for dimples, "D", is dominant).
- 2 out of 4 cells (50%) have the genotype "dd", which would result in individuals having no dimples (because they have two copies of the recessive allele "d").
In summary, when a mom who is heterozygous for dimples (Dd) is crossed with a dad who is homozygous for no dimples (dd), the Punnett square correctly representing this cross is:
[tex]\[
\begin{array}{c|c|c}
& d & d \\
\hline
D & Dd & Dd \\
\hline
d & dd & dd \\
\end{array}
\][/tex]
Therefore, the genotypic ratio of the offspring will be:
- 50% heterozygous (Dd) with dimples
- 50% homozygous recessive (dd) with no dimples
