Ans: Heterozygous genotype is exemplified by sickle-cell anaemia.Sickle-cell anaemia is caused by a recessive disease that affects the development of blood cells.As a result, people with heterozygous genes display the dominant phenotype, preventing sickle-cell anaemia.The structure of red blood cells transforms to a sickle shape in sickle-cell anaemia, making them small and unable to carry adequate oxygen.As a result, such persons profit from the heterozygous genotype of the gene that causes sickle-cell anaemia.