lack of proper medical care for sicklers
carriers being more resistant to malaria
mosquito vectors
wildlife intermediate hosts
Explanation
No explanation available
Video Explanation
No video available
Post your Contribution
Discussions (7)
The correct answer is B. carriers being more resistant to malaria.
Why? (The Heterozygote Advantage)
This is a classic example of natural selection known as heterozygote advantage.
The Sickle-Cell Trait: People with normal hemoglobin have the genotype AA. People with sickle-cell anemia have the genotype SS. People who inherit one of each gene have the genotype AS—they are carriers (they have the sickle-cell trait but usually do not suffer from the severe disease).
The Malaria Connection: The malaria parasite (Plasmodium falciparum) multiplies inside red blood cells. However, it struggles to survive and reproduce inside the slightly altered red blood cells of AS carriers.
Survival of the Fittest: In regions where malaria is highly prevalent (like parts of Africa and the Mediterranean), individuals with normal hemoglobin (AA) frequently die from severe malaria. Individuals with sickle-cell anemia (SS) historically faced high mortality rates from the disease itself.
Because AS carriers are naturally protected against severe malaria and do not suffer from full-blown sickle-cell anemia, they survive at much higher rates. As they survive and reproduce, they continuously pass both the normal A gene and the sickle S gene down to the next generation, keeping the sickle-cell gene persistent in the human population.
