Question

The continued occurrence of sickle-cell disease in parts of Africa with malaria is due to ______.

Options

• disruptive selection

• continual mutation

• fitness of the heterozygote

• gene flow between populations

Answer 1

The continued occurrence of sickle-cell disease in parts of Africa with malaria is due to fitness of the heterozygote.

Explanation:

The continued occurrence of sickle-cell disease in parts of Africa with malaria is due to the heterozygous individuals having a selective advantage. Heterozygotes carry one normal hemoglobin allele and one sickle-cell allele, which confer resistance to malaria without the severe effects of sickle-cell disease. This heterozygote advantage maintains the sickle-cell allele in populations where malaria is common.