Question

In fruit flies, the gene for red eyes (R) is dominant and the gene for sepia eyes (r) is recessive. If a red-eyed heterozygous fly (Rr) mates with a sepia-eyed homozygous fly (rr), what are the possible genotypes of their offspring? (Hint: You many want to complete a Punnett square.)
Rr only
RR, Rr, and rr
Rr and rr
RR and Rr

Answer 1

The correct answer is Rr and rr.

F1:    Rr x rr
F2:   Rr Rr rr rr
F1 is the first generation, parents
F2 is the possible genotypes fo offspring
It means that there is 50%possibility for heterozygous (red eyed) and 50% for homozygous (sepia eyed).