Question

18. Brown eyes (B) are dominant to blue eyes (b). The presence of freckles (F) is dominant to the absence of freckles (f). What is the probability that two people who are heterozygous for both traits will have a child that has blue eyes and no freckles?

Answer 1

For bbff we have only 6.3% probability

Explanation:

If the parents are heterozygous for both traits, them they are represented by:

BbFf × BbFf

Parent 1: BbFf

Parent 2: BbFf

We have to find the percentage of occurence of bb × ff, which is a child that has blue eyes and no freckles, with no dominant factor.

By distributing the possibilities in a Punnett square, vide picture. We have the following possibilities:

Genotype Count Percent

bBfF 4 25

BBfF 2 12.5

bBFF 2 12.5

bBff 2 12.5

bbfF 2 12.5

BBFF 1 6.3

BBff 1 6.3

bbFF 1 6.3

bbff 1 6.3

For bbff we have only 6.3% probability