In Drosophila, normal eyes are brick red in color. Homozygotes for recessive alleles at the brownlocus (bw/bw) have brown eyes.
Homozygotes for recessive alleles at the cinnabar locus (cn/cn) have bright red eyes. The two genes interact: bw/bw; cn/cn have white eyes. If a pure-breeding brown is crossed to a pure-breeding cinnabar fly, color eyes will the F1 have and what proportion of the F2 will be white? A.brown, 3/16
THe answer is D because this is dihybrid cross and we cross bwbw RR( normal red eye gene) x RR cncn. The F1 progeny has R in all locus of these genes so all will be R as heterozygous. When F1 progeny crossed, the 1/4 of bw cross and 1/4 of cn cross habe bwbw/cncn and will be white. So it will be 1/4x1/4 = 1/16
