Answer:
Step-by-step explanation:
Sickle-Cell Disease- An inherited blood disorder where red blood cells become sickle/crescent shaped. It is when the body produces red blood cells that are unstable!
As for why areas where malaria is common have high frequencies of the sickle-cell allele, It is believed by some as an example of natural selection at play. An interesting pattern of incidence of sickle cell has been observed in Africa, where malaria is a widely prevalent disease. The relation between sickle cell and anemia gains further ground on the fact, that there is a greater incidence of sickle cell in the African lowland populations, where malaria is severe and widespread than among their highland counterparts. It is believed that sickle cell provides resistance against the malarial parasite.
(I hope that answers question 1)