Question

Assertion :A sickle-cell anaemia is an example of natural selection in human population in Africa. Reason: It saves Africans from fatal disease of malaria in heterozygous condition.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

• Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
• The sickle-cell gene has become common in Africa because the sickle-cell trait confers some resistance to falciparum malaria during a critical period of early childhood.
• Sickle cell disease is due to a recessive allele of the haemoglobin gene.
• So in these regions, people with sickle cell trait are more likely to survive and reproduce.
• Hence, A sickle-cell anaemia is an example of natural selection in the human population in Africa as It saves Africans from the fatal disease of malaria in heterozygous condition.
• So, the correct answer is ' Both Assertion and Reason are correct, Reason is the correct explanation for Assertion'.