A loss-of-function recessive mutation in gene brown (bw) makes the normal red eye color brown. This gene resides on the second chromosome. A loss-of-function recessive mutation in the gene ebony (e) makes body color of the fly darker. It resides on the third chromosome of Drosophila. I give you flies with wild type eye color and normal gray body color. Set up a cross to test if the flies I gave you are: true-breeding wild type for both genes, or heterozygous just for the bw locus.