Question

In pea plants yellow (G) is dominant to green (g) and round (R) is dominant wo wrinkled (r). In the cross GgRR x GgRr, what is the probability that yellow, round peas are homozygous dominant for the yellow/green gene?

A) GGRR
B) GgRr
C) ggRR
D) ggrr

Answer 1

The probability that yellow, round peas are homozygous dominant for the yellow/green gene (GGRR) in the cross GgRR x GgRr is 25%.

Step-by-step explanation:

To determine the probability that yellow, round peas are homozygous dominant for the yellow/green gene in the cross GgRR x GgRr, we must first identify the potential genotypes for the yellow/green gene in the progeny. Individual G is dominant over green g, so only offspring with GG or Gg genotype will be yellow. Since both chosen parents have at least one G allele, and all offspring will inherit an R allele and therefore be round, we focus on the yellow/green gene.

For an offspring to be homozygous dominant GG, it must inherit a G allele from both parents. The cross of Gg (first parent) by Gg (second parent) can yield GG, Gg, Gg, or Gg. Out of these, only GG represents the homozygous dominant condition. The Punnett square will show that this occurs 1/4 of the time (25%). Therefore, the probability is 25%.