I. Male Drosophila from a true-breeding wild-type stock were irradiated with X-rays and then mated with females from a true-breeding stock carrying the following recessive mutations on the X...

I. Male Drosophila from a true-breeding wild-type
stock were irradiated with X-rays and then mated with
females from a true-breeding stock carrying the following recessive mutations on the X chromosome:
yellow body (y), crossveinless wings (cv), cut wings
(ct), singed bristles (sn), and miniature wings (m).
These markers are known to map in the order:
y - cv - ct - sn - m
Most of the female progeny of this cross were phenotypically wild type, but one female exhibited ct and sn
phenotypes. When this exceptional ct sn female was
mated with a male from the true-breeding wild-type
stock, twice as many females as males appeared
among the progeny.
a. What is the nature of the X-ray-induced mutation
present in the exceptional female?
b. Draw the X chromosomes present in the exceptional ct sn female as they would appear during
pairing in meiosis.
c. What phenotypic classes would you expect to see
among the progeny produced by mating the exceptional ct sn female with a normal male from a truebreeding wild-type stock? List males and females
separately.