Eyeless is a recessive gene on chromosome 4 of drosophila melanogaster. flies homozygous for ey have tiny eyes or no eyes at all. a male fly trisomic for chromosome 4 with genotype +/+/ey is crossed with a normal, diploid eyeless female.

what proportion of their progeny will be eyeless?

a. 1/6

b. 1/3

c. 1/2

d. 2/3

e. 1/8

f. 1/4

g. 3/8

h. 5/8

i. 3/4

A. 1/6

Explanation:

A male fly trisomic for chromosome 4 with genotype +/+/ey is crossed with a normal, diploid eyeless female. i.e

δ  +/+/ey                                                                 ey/ey ⊕

+, +, +/+, ey, +/ey, +/ey                ×                         ey/ey

ey/+,  +/ey,  +/+/ey,  ey/ey,  +/ey/ey,  +/ey/ey

ey/+,  +/ey,  +/+/ey,  ey/ey,  +/ey/ey,  +/ey/ey

=2/12

=1/6

the answer to your question is:

c. complementary base-pairing