No, the sickle-cell anemia allele won't be eliminated by natural selection.
Sickle-cell anemia trait is controlled by a single gene and the allele (S) for sickle-cell anemia is a harmful autosomal recessive.
It is caused by a mutation in the normal allele (A) for hemoglobin (a protein on red blood cells).
Heterozygotes (AS) with the sickle-cell allele are resistant to malaria, a deadly tropical disease. It is common in many African populations.
In these areas, (S) carriers have been naturally selected, because their red blood cells, containing some abnormal hemoglobin, tend to be in sickle shape when they are infected by the malarial parasite.
Therefore, they are more likely to survive and reproduce. This keeps the S allele in the gene pool.
Learn more about Sickle-cell anemia on
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The answer would be B i believe<span>(a protease) begins the chemical digestion of protein</span>
The answer is C. My explanation is that in the sentence, it has the words “will probably,” next to each other, so that means it is not a fact and it is not a 100% for certain that it will/had happen(ed). People may have different feelings/views about it. Also, all of the other sentences are more direct and do not have those words, and they sounds confident. Hope this helps!
