Question

In pea plants, the yellow seed allele (Y) is dominant over the green seed allele (y). What is the phenotypic ratio of yellow seeds to green seeds in the F2 generation resulting from a cross between two true-breeding parents, one with YY and one with yy?

Answer 1

3 yellow : 1 green

Step-by-step explanation:

Yellow seed allele (Y) is dominant over the green seed allele (y).

A cross between two true breeding parents is done: YY x yy

The F1 offspring would be heterozygous Yy.

If the F1 is selfed (Yy x Yy) the expected ratios for the F2 generation according to Mendel's law of segregation would be:

• 1/4 YY (yellow)
• 2/4 Yy (yellow)
• 1/4 yy (green)

So 3/4 seeds of the F2 would be yellow because they have a dominant Y allele, and 1/4 would be green.

The phenotypic ratio will be 3 yellow : 1 green