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.
ANSWER:
Needed to form cell membranes
I hope I was of help to you :)
Nutrients move through the ecosystem<span> in biogeochemical </span>cycles<span>. A biogeochemical </span>cycle<span> is a circuit/pathway by which a </span>chemical<span> element moves through the biotic and the abiotic factors of an</span>ecosystem<span>. It is inclusive of the biotic factors, or living organisms, rocks, air, water, and </span>chemicals<span>.</span>
Answer:
no population at maximum density............. The carrying capacity is the maximum number of individuals that the environment can sustain.
