This document discusses a genetic cross between Drosophila flies. A homozygous Roughened fly was mated with a homozygous raisin fly, producing all Roughened F1 offspring. These F1 females were then mated with homozygous raisin males, resulting in F2 offspring that included both Roughened and raisin phenotypes. The document asks to diagram the cross and determine the number of each phenotype to calculate the distance between the rai and R genes.

1. Roughened eye ( R ) is a dominant allele on Drosophila chromosome three. A homozygous
Roughened fly is mated to a homozygous raisin fly, yielding all Roughened F 1 offspring. F 1
females are then mated to homozygous raisin males, yielding the following F 2 offspring: a.
Diagram the cross. (1 point) b. Determine the NCO and SCO offspring and calculate the distance
(in mu) between rai and R . (1 point)