Question

In pea plants, the gene for round seed (R) is dominant, and wrinkled seeds (r) are recessive. The endosperm of the pea is also either starchy, a dominant gene (S), or waxy (s). What can be said of a fully heterozygous, dihybrid cross?

A. It is impossible to secure offspring that are homozygous for both dominant genes.
B. It is impossible to secure offspring that are homozygous for both recessive genes.
C. It is impossible to secure offspring that are homozygous for one dominant gene such as round seed and homozygous recessive for the other recessive waxy gene.
D. All of these choices are impossible combinations in a dihybrid cross.
E. All of these choices are possible combinations in a dihybrid cross.

Answer 1

Correct answer is option "E"

Explanation:

• Dihybrid cross is the cross between two different genes that differ in two observed traits.
• The phenotypes of the posterity from a heterozygous dihybrid cross with two autonomous characteristics, for example, the RrYy x RrYy model, show a 9:3:3:1 proportion. In a cross including pea plants heterozygous for green level pods (GgFf), 9/16 plants have green level pods, 3/16 have green choked pods, 3/16 have yellow level pods, and 1/16 have yellow contracted pods. Notice that two of these blends are the first parental phenotypes (green level units, and yellow tightened cases) and two are new phenotypic mixes (green choked cases, and yellow level cases).
• Hence, the correct answer is option E " All of these choices are possible combinations in a dihybrid cross.