In Drosophila, the gene for scalloped wings (sd) is a sexlinked recessive and th
ID: 52563 • Letter: I
Question
In Drosophila, the gene for scalloped wings (sd) is a sexlinked recessive and the gene for shaven bristles (sv) is an autosomal recessive. A wild type female whose father was scalloped and shaven is mated with a shaven male.
A. What is the genotype of the male?
What is the expected proportion of wild type flies among the offspring?
What is the expected proportion of scalloped males among the offspring?
What proportion of the offspring are expected to be either shaven
females or scalloped males?
E. What is the probability that the first two offspring will be wild type females?
Explanation / Answer
A. The genotype of male is svsv.
B. Expected proportion of wild type flies among offspring are
SDsv X svsv = 1/2 x 1/2 = 1/4 or 25%.
C. Expected proportion of scalloped males among the offspring would be 1/4 or 25%.
D. The proportion of the offspring are expected to be either shaven females or scalloped males is 1/4 or 25%.
E. The probability for first two offspring will be wild type females = 1/4 x 1/4 = 1/16 or 0.0625%.