In Drosophila melanogaster white eyes w is an Xlinked recess

In Drosophila melanogaster, white eyes (w) is an X-linked recessive mutation. Normal eyes are red (W). At the autosomal wing shape locus, normal shaped wings (V_g) are dominant to vestigial wings (v_g). The following cross was made: X^WX^W Vgvg x X^W Y Vgvg What proportion of the progeny from this cross will have red eyes? Write your as a numerical value rounded properly to 4 decimal digits. Do not write the answer as a fraction or percentage.

Solution

Answer: 0.5

Reason:

Assume that the gene coding for Red eyes is W and the gene coding for white eyes is w; W is dominant over w and X-linked. Similarly, the gene coding for normal wings is V and the gene coding for vestigial wings is v; V is dominant over v.

XwXw Vv * XWY Vv --à XwXW V_ (6/16, red eyed, normal wings), XWXw vv (2/16, red eyed, vestigial wing), XwY V_ (6/16, white eyes, normal wings), XwY vv (2/16, white eyes, vestigial wings)

From this cross, all females are red eyed, i.e. 50% of the progeny --> 0.5%