Homozygotes with two sickle-cell alleles are selected against because of mortality. However, heterozygotes for sickle-cell allele experience little effects of sickle allele and are more likely to survive malaria. The net effect of this exposure produced evolutionary change in areas where malaria is endemic by ________.
A) causing sickle-cell allele
B) increasing sickle-cell allele frequency
C) distortion of red blood cells
D) increasing the number of infected mosquitoes

Question

Quizplus · Accepted Answer

In areas where malaria is endemic, the selective advantage of heterozygotes for the sickle-cell allele increases their survival chances. This leads to an increased frequency of the sickle-cell allele in the population, as they are more likely to survive and reproduce. Therefore, the net effect of exposure to malaria is an increase in the frequency of the sickle-cell allele, which is beneficial for survival in areas where malaria is prevalent.

Homozygotes with Two Sickle-Cell Alleles Are Selected Against Because of Mortality