Question

In garden pea plants, the allele for inflated pod shape, I, is dominant over that for constricted pod shape, i. Consider a cross between a garden pea plant that is homozygous for inflated pod shape and a plant that is homozygous for constricted pod shape. Create a Punnett square to determine the possible genotypes and phenotypes of the offspring.

Answer 1

Parents: II (homozygous inflated) × ii (homozygous constricted)

Gametes:
- II parent → I, I
- ii parent → i, i

Punnett square:

I | I
--------------
i | Ii | Ii
--------------
i | Ii | Ii

Offspring genotypes: 100% Ii (heterozygous)
Offspring phenotypes: 100% inflated pods (I is dominant over i)

(If these F1 heterozygotes were crossed with each other, the F2 phenotypic ratio would be ~3 inflated : 1 constricted.)