Sex-Linked Inheritance Problem Set 2

Problem 4: Genetic evidence for crossing over in male flies

If we mated the F1 female and male flies from the cross obtained in problem 3, what male phenotype in the F2 generation would be evidence that crossing over had occured during gamete formation?

Daughters were tan-bodied, red-eyed, heterozygous for both eye and body color. The sons were yellow-bodied, red-eyed hemizygous.

A. White eyes and tan bodies
B. Red eyes and tan bodies
C. Red eyes and yellow bodies
D. White eyes and yellow bodies and red eyes and tan bodies
Either white eyes and yellow bodies or red eyes and tan bodies are combinations of alleles on the X chromosome that did not occur in either original parent. This is evidence for crossing over of the X-chromosome in the F1 females.
E. White eyes and yellow bodies

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Updated: July 15, 1999
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