Question

Which of the following statements best predicts what would happen in response to a prolonged epidemic of malaria in a population with no previous exposure to malaria?

Answer 1

I don't have the options, but I can make a prediction:

Take a look at what happened when, for the first time, native Americans were exposed to smallpox. Because they had never been exposed to smallpox before, they had no biological immunity to it, and it killed a lot of them, as in whole tribes.

So, the same thing would happen here:

The population would quickly be wiped out.

Answer 2

The frequency of the sickle-cell allele (s) would increase.

Step-by-step explanation:

Because both those affected by sickle-cell disease and carriers who possess only one sickle-cell allele are much more resistant to malaria, these two genotypes would be selected for during a prolonged epidemic of the illness. Since the homozygous dominant genotype (SS) would be the most susceptible to death from malaria, those with Ss and ss genotypes would be more likely to reproduce and pass their genes on to the next generation. This means that, over time, the frequency of the sickle-cell allele (s) would increase.

Such a scenario has been used to explain the continued existence of the sickle-cell gene in many parts of Africa, where malaria is still widespread and rates of sickle-cell disease are much higher than other areas of the world. In the absence of malaria, however, the sickle-cell gene would be purely disadvantageous and, in any given population, would eventually cease to exist. (got it right on study island)