Question

Suppose that r, red, and sc, scarlet, are two recessive eye-color mutations that lie 20 map units apart on the Drosophila X chromosome, and that each causes a red eye color in place of the wild type purple color.

A. If a female from pure-breeding rr stock is mated with a red-eyed (sc) male, what phenotypes will the F1 sons and daughters display?

B. If these F1 flies are interbred, what will be that phenotypic ratios among the F2 granddaughters and grandsons?