Study Biology

Question 2

(Multiple Choice)

A rare,curly winged mutant of Drosophila was found in nature.A mating of this fly with a true-breeding,normal laboratory stock produced progeny in the ratio 1 curly winged to 1 normal (both sexes had the same ratio).All curly winged progeny of this cross,mated with normal progeny of the same cross,again yielded 1 curly winged to 1 normal fly.When mated with one another,the curly winged progeny of the first cross yielded a progeny of 623 curly : 323 normal.This ratio strongly suggests which of the following?


A)Curly and normal are in the 3:1 ratio expected from intercrossing monohybrid genotypes for a recessive mutant allele (curly).
B)Curly and normal are in the 3:1 ratio expected from intercrossing monohybrid genotypes for a dominant mutant allele (curly).
C)The curly winged parent of the curly ×\times curly cross is homozygous.
D)Flies homozygous for the curly allele are lethal and never survive.
E)The gene for curly is sex-linked.

Answer

D

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