Genetics: Analysis and Principles 5th Edition by Robert Brooker

Exercise 10

In Drosophila, an allele causing vestigial wings is 12.5 mu away from another allele that causes purple eyes. A third gene that affects body color has an allele that causes black body color. This third gene is 18.5 mu away from the vestigial wings allele and 6 mu away from the allele causing purple eyes. The alleles causing vestigial wings, purple eyes, and black body are all recessive. The dominant (wild-type) traits are long wings, red eyes, and gray body. A researcher crossed wild-type flies to flies with vestigial wings, purple eyes, and black bodies. All F 1 flies were wild type. F 1 female flies were then crossed to male flies with vestigial wings, purple eyes, and black bodies. If 1000 offspring were observed, what are the expected numbers of the following types of flies
Long wings, red eyes, gray body
Long wings, purple eyes, gray body
Long wings, red eyes, black body
Long wings, purple eyes, black body
Short wings, red eyes, gray body
Short wings, purple eyes, gray body
Short wings, red eyes, black body
Short wings, purple eyes, black body
Which kinds of flies can be produced only by a double crossover event