Question

Assertion (A): The disease sicklecell anaemia is an example of natural selection in human population.

Reason (R): It saves Africans from the fatal disease of malaria in heterozygous condition.

Options

• Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

• Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

• Assertion (A) is true but reason (R) is false.

• Both assertion (A) and reason (R) are false.

Answer 1

Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

Explanation:

Heterozygous individuals have increased resistance to malaria, so the sickle-cell allele can persist in malarial regions. This survival advantage is an example of natural selection.