Answer:
The correct answer is - 6 chromatids.
Explanation:
Prophase is the stage in the cell cycle that is known for the condensation and disappearance of the nucleolus. In this stage chromosome become more compacts and the sister chromatids are still together and not separated. These sister chromatids are joined together with the centromere.
Centromere do not allow sister chromatids to move away and makes it intact. The number of centromere is the number of chromosme present in the prophase and half of the sister chromatids that means if there us 3 centromere than the number of sister chromatids will be 6.
Evaporation exceeds precipitation
Answer:
Increased frequency of the allele for sickle cell anemia
Explanation:
Sickle cell anemia is fatal in homozygous genotype. The homozygous genotype having two copies of the allele for sickle cell anemia is not favored by natural selection due to its reduced survival success.
However, the heterozygous genotype for sickle cell anemia with one allele for the disease exhibit malaria resistant. The presence of one allele is not fatal for the organisms as the presence of one normal allele ensures the formation of some normal hemoglobin protein and RBCs to support the oxygen delivery to the body parts.
The increased survival success of heterozygous genotype in malaria-prone regions allowed their natural selection. This increased the frequency of allele for the sickle cell anemia in the gene pool of the local population and increased the frequency of heterozygous dominant genotype.
