Question

Two fruit flies that are heterozygous for body color and eye color are crossed. Brown body color is dominant to black body color. Red eye color is dominant to brown eye color.

Answer 1

Answer:

This question is incomplete, the complete question is:

Two fruit flies that are heterozygous for body color and eye color are crossed. Brown body color is dominant to black body color. Red eye color is dominant to brown eye color. Use the Punnett square to determine the ratio of offspring with: Brown body and red eyes : Brown body and brown eyes : Black body and red eyes : Black body and brown eyes :

The answer is:

Brown body and red eyes : 9

Brown body and brown eyes : 3 Black body and red eyes : 3 Black body and brown eyes : 1

Explanation:

This question is a typical dihybrid cross involving two different genes. One coding for body color and the other for eye color. The allele for Brown body color (B) is dominant to the allele for black body color (b) in the first gene while the allele for Red eye color (R) is dominant to the allele for brown eye color (r) in the second gene.

In a cross between two parents that are heterozygous for the two genes i.e. BbRr × BbRr, each parent will produce the following possible allelic combinations of gametes:

BbRr- BR, Br, bR, and br

Using these gametes in a punnet square (see attached image), 16 possible offsprings will be produced in the ratio 9:3:3:1 where the offsprings and their possible genotypes are;

Brown body and red eyes (B_R_): 9

Brown body and brown eyes (B_rr): 3

Black body and red eyes (bbR_): 3

Black body and brown eyes (bbrr): 1