What Is the Reason for the Prevalence of the Sickle-Cell

question 16

Multiple Choice

What is the reason for the prevalence of the sickle-cell allele in African populations?

• A) Sickled cells are better able to clot blood.
• B) African populations tend to be at higher altitudes, and sickled cells better bind oxygen in these environments.
• C) Heterozygotes have some resistance to the parasite that causes malaria.
• D) Sickled cells help prevent vitamin A deficiency among African populations.

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Definitions:

Loud Noise

A type of environmental stimulus characterized by high amplitude sound waves, which can potentially cause hearing damage or stress.

Unconditioned Response

Is an automatic, natural reaction to a stimulus that occurs without prior conditioning or learning, such as salivating in response to food.

Fear of Loud Noise

An instinctual or conditioned response to loud sounds, often involving feelings of anxiety or panic.

Conditioned Response

A learned reaction to a previously neutral stimulus that results from repeated exposure to a stimulus paired with a response.