Natural Selection Can Maintain Genetic Variation by Favoring Heterozygous Genotypes

question 53

Essay

Natural selection can maintain genetic variation by favoring heterozygous genotypes. In equatorial Africa, the best genotype to have for hemoglobin is heterozygous (HbA / HbS). In the United States of America, there is no advantage to the heterozygous genotype. HbA codes for normal hemoglobin, whereas HbS codes for an abnormal hemoglobin that causes red blood cells to become distorted in shape (sickle cell). Explain why the heterozygous state is advantageous in Africa, but not in the USA. What has happened to the sickle cell allele in Africa? What has happened to the sickle cell allele in the United States?

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Comparison With Other Cultures

The practice of examining similarities and differences among various cultural practices, values, and norms to understand human behavior and society.

Self-serving Bias

The tendency to attribute positive events to one's own character but attribute negative events to external factors.

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