Use of double mutants has been invaluable in studying developmental pathways. In C. elegans, sex is determined by the ratio of sets of autosomes to X chromosomes. A diploid male has one X, and diploid hermaphrodites have two X's. The loss-of-function gene her-1 produces XO worms that are hermaphrodites, but XX worms are unaffected. Mutation of a second gene, tra, causes the XX to develop as male. Given this information, what would be the phenotype of a tra, her-1 double mutant?
A)a male nematode
B)a female nematode
C)a hermaphrodite
D)an intersex variant
E)lethality

Question

Quizplus · Accepted Answer

The tra, her-1 double mutant would be a male nematode because the tra mutation would cause the XX worms to develop as male, and the her-1 mutation would have no effect on the XX worms.

Use of Double Mutants Has Been Invaluable in Studying Developmental