Having one copy of the ______ gene may protect you from malaria, but two copies may increase risk of death from malaria.

• A. Hemoglobin S gene
• B. Sickle Cell Anemia
• C. Ferritin gene
• D. Glucose-6-Phosphate Dehydrogenase

Answer: (B)

This is about heterozygote advantage: having one copy of the gene that encodes hemoglobin S can protect against malaria, while having two copies leads to sickle cell disease. In someone with one HbS allele, red blood cells are partly altered, making it harder for the malaria parasite to thrive, which lowers malaria risk. But with two HbS alleles, sickle cell disease causes chronic anemia and other complications; during malaria infection, these problems can worsen outcomes, increasing the risk of severe illness or death. So, the protective state comes from the HbS allele itself, not the disease name. The other options don’t describe this protective allele in the same way.