Question

Why does a pea plant with the genotype Rr have round seeds, not wrinkled ones.

Answer 1

R is the dominant allele ( codes for round seeds). The dominant allele will be “dominant” or expressed over the recessive allele which is r or wrinkled. So with Rr the dominant allele/ trait masks the recessive trait

Answer 2

Wrinkled peas need to have genotype rr, since the wrinkled trait (r) is recessive