Question

In pea plants, yellow seed color is completely dominant to green seed color.

A pure yellow-seeded plant is crossed with a pure green-seeded plant. What
alleles will be present in the body cells of the offspring?

Answer 1

We need to use a Punnett Square to figure this out.

Step-by-step explanation:

Let's say that for the pea plants, Big Y represents the color yellow while Little y is the color green. If Big Y is dominant (which determines the plant's color) it means the plant is yellow. If Little y is dominant, the plant is green.

A phenotype (the genetic makeup of the offspring) would be green if it's genotype was Yy , or YY. It would be yellow if it was yy.

Both "parent" plant's genotype is "pure" which I'd presume means homozygous (two big letters). We need to use a mono-hybrid cross (4 squares, 1 trait) and cross the parents to see what we get.

MOM PEA PLANT - yy (green, homozygous recessive)

DAD PEA PLANT - YY (yellow, homozygous dominant)

OFFSPRING - 100% Yy (yellow, heterozygous)

There is no way that the parents could make a green plant with their genotypes. So the probability is that 100% of their offspring would be yellow, with the phenotype Yy.

Answer 2

Assuming that the Alleles are uppercase Y for the dominant yellow and lowercase y for the recessive green, the alleles present in the hybrid plant will be Yy, and the color would be yellow as it is a dominant trait.