Round seeds (R) are completely dominant over wrinkled seeds (r). You cross a plant that is homozygous for round seeds (male) with a plant that is heterozygous for round seeds (female). Use a Punnett square to determine the expected genotypic and phenotypic ratios for the offspring. What is the male plant’s genotype?. What is the female plant’s genotype? What are the male plant’s gametes? What are the female plant’s gametes? What is the expected genotypic ratio of the offspring? What is the phenotypic ratio of the offspring?

Genotype of the male parent: Homozygous  (RR)

Phenotype of the male parent: Round seeds

Gametes for the male parent: R and R

Genotype of the female parent: Heterozygous Rr

Phenotype of the female parent: Round seeds

Gametes for the female parent: R and r

To determine the genotypic and phenotypic ratio of the offspring, lets make a punnet square:

         R          r

R       RR        Rr

R       RR        Rr

Genotype ratio of the offspring: 2:2

50% of the offspring will be homozygous round whereas 50% will be heterozygous round.

Phenotypic ratio of the offspring: 1

All of the offspring will be round hence the phenotypic ration will be 1 (100%).