Color deficiency is more common in men than in women because
A) women cannot inherit the gene from their fathers.
B) the gene is located on the Y chromosome.
C) men get more copies of the gene than do women.
D) crossing over occurs only in women.
E) men have only one X chromosome.

Question

Quizplus · Accepted Answer

Color deficiency is more common in men than in women because the genes responsible for the most common forms of color vision deficiency are located on the X chromosome. Men have only one X chromosome (and one Y chromosome), so a single defective gene on their X chromosome will result in color deficiency. Women have two X chromosomes, so a defective gene on one of their X chromosomes can often be compensated for by a normal gene on the other X chromosome, making them less likely to exhibit color deficiency.

Color Deficiency Is More Common in Men Than in Women