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 eye.
2 answers:
Answer:
Brown body and red eyes: 9
Brown body and brown eyes: 3 Black body and red eyes : 3
Black body and brown eye: 1
Explanation:
This question involves two genes coding for body color and eye color in fruit flies respectively. The brown body color allele (B) is dominant over the black body color allele (b) in the first gene while the red eye color allele (R) is dominant over the brown eye color allele (r) in the second gene.
In a dihybrid cross between two fruit flies that are heterozygous for both genes i.e. BbRr × BbRr, the allelic combinations of gametes produced by each parent fruit fly will be:
BbRr- BR, Br, bR and br
Using these gametes to complete a punnet square (see attached image), 16 possible offsprings will be produced in a ratio 9:3:3:1 where;
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 eye (BbRr) : 1
Hence, the ratio of the offsprings will be 9:3:3:1
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