A dominant allele (K) is necessary for normal hearing.A dominant allele (M) at a different, unlinked locus results in deafness no matter which other alleles are present.If a kkMm individual is crossed with a Kkmm individual, _______ percent of the offspring will be deaf.
A) 0
B) 25
C) 50
D) 67
E) 75

Question

Quizplus · Accepted Answer

The kkMm individual can only pass on a k allele for the first gene, and either an M or m allele for the second gene. The Kkmm individual can pass on either a K or k allele for the first gene, and only m alleles for the second gene. The presence of an M allele causes deafness regardless of the other alleles. Therefore, 50% of the offspring (those receiving an M allele from the kkMm parent) will be deaf due to the M allele, and an additional 25% will be deaf due to receiving kk alleles (since they need a K allele for normal hearing and can only get a k allele from the kkMm parent). Thus, 75% of the offspring will be deaf.

A Dominant Allele (K) Is Necessary for Normal Hearing