Question

In pea plants, the allele for round seeds is dominant to the allele for wrinkled seeds. If a plant that is heterozygous for seed type is crossed with one that has only wrinkled seeds, what percent of their offspring would you expect to have wrinkled seeds?

Answer 1

50%

Step-by-step explanation:

This question involves a gene coding for seed shape. The allele for round seeds (R) is dominant over the allele for wrinkled seeds (r). A heterozygous plant (Rr) will therefore be round seeded.

If a plant that is heterozygous for seed type (Rr) is crossed with one that has only wrinkled seeds (rr), the following gametes will be produced by each parent:

Rr - R and r

rr - r and r

Using these gametes in a punnet square (see attached image), the following offsprings will be produced: Rr, Rr, rr and rr

Rr - Round seeds

rr - wrinkled seeds

1 out of 2 offsprings will be possess wrinkled seeds i.e. 1/2 × 100 = 50%.