The persistence of the sickle-cell anemia allele in the African population is the result of
A) a high rate of mutation of the normal allele to the sickle-cell anemia allele.
B) the advantage of the heterozygous form over the homozygous forms.
C) nonrandom mating.
D) a decline in the occurrence of malaria in Africa.
E) genetic drift.

Question

Quizplus · Accepted Answer

The heterozygous individuals (carriers) of the sickle-cell anemia allele have an advantage over homozygous individuals in regions where malaria is prevalent. This is because carriers are less likely to get malaria, as the malaria parasite has a harder time infecting red blood cells that contain the sickle-cell trait. Therefore, carriers have a higher reproductive success and the allele is maintained in the population. This is an example of heterozygous advantage or balanced polymorphism.

The Persistence of the Sickle-Cell Anemia Allele in the African