Question

20 POINTS - MONOHYBRID CROSS

Complete the following monohybrid cross.
Two parents that are heterozygous for brown eyes.

Be sure to identify the genotypes of the parents, complete the Punnett square, identify the phenotypes with genotypes and the ratio of the phenotypes.

What percent of the offspring have blue eyes?

Answer 1

25% of the offspring would have blue eyes if the parents are heterozygous.

Answer 2

We know that for humans brown eyes are dominant over blue eyes and hence brown eyes represent B and blue eyes represent b

A heterozygous parent is the one that has one dominant and one recessive allele in their gene

Here we are given that both the parents are heterozygous

Male = Bb

Female = Bb

Let's draw the Punett's square

( refer figure attached)

Here the genotype percentages are

BB = 25%

Bb = 50%

bb= 25%

The phenotype is the percentage of the offspring that has visible dominant trait and hence one dominant and one recessive trait also gives an outcome of the dominant trait only

Hence the phenotype percentages are

75% brown eyes

25% blue eyes