Deep water currents affect the number of organisms found in the area by circulating nutrients due to upwelling. Upwelling is a process where cold water surfaces and encourages nutrients to the surface. When exposed to sunlight, they initiate energy which keeps the flow of the ecosystem.
I believe the answer is During<span> prophase
</span>The nucleus during mitosis. Micrographs illustrating the progressive stages ofmitosis<span> in a plant cell. </span>During<span> prophase, the chromosomes condense, the </span>nucleolus<span>disappears, and the </span>nuclear envelope<span> breaks down. At metaphase, the condensed chromosomes </span>
<span>taken or considered over a short time period; short-term.</span>
Answer:
Because natural selection selects for it. Thus it persists.
Explanation:
You have to understand heterozygote advantage. Basically, it's where heterozygotes have an advantage over homozygotes. In the case of sickle cell disease, heterozygotes have an advantage, and natural selection favors whatever is advantageous. Thus, because heterozygotes each have one recessive sickle-cell allele, as natural selection favors the heterozygotes, the recessive sickle-cell allele persists and remains in the gene pool.
