In pea plants, the allele for round seed shape (R) is dominant over the allele for wrinkled seed shape (r). If a plant heterozygous for seed shape (Rr) is crossed with a plant homozygous recessive (rr), what percentage of the progeny will have round seeds?

Step-by-step solution

1. Identify the genotypes of the parents: Rr (heterozygous) and rr (homozygous recessive).
2. Write the possible gametes from each parent: Rr produces R and r; rr produces only r.
3. Set up the Punnett square using these gametes.
4. The square gives the genotypes: Rr, Rr, rr, rr.
5. Count the offspring with at least one dominant allele R: there are two Rr out of four.
6. Convert the count to percentage: (2/4) × 100 = 50%.

Concept tested: Monohybrid cross – phenotype ratio

Published 25 August 2026 · How this solution was prepared and checked

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