The Genes for Light Eyes (Lt; Light) and Straw Bristles

Essay

The genes for light eyes (lt; light) and straw bristles (stw; straw) are tightly linked on chromosome 2 in Drosophila melanogaster. The Malpighian tubes of lt larvae and adults are maternally affected in that Malpighian tubes of lt/lt organisms, whose mothers were lt^+/lt and have more yellow pigment than those from lt/lt mothers. There is no maternal effect associated with the straw locus. Give the phenotypes of the offspring from the following crosses.
Female Male
Cross #1: lt stw/lt stw lt⁺stw⁺/lt stw
Cross #2: lt⁺ stw/lt stw lt stw⁺/lt stw
Cross #3: lt⁺ stw⁺/lt stw lt stw/lt stw