No, the sickle-cell anemia allele won't be eliminated by natural selection.
Sickle-cell anemia trait is controlled by a single gene and the allele (S) for sickle-cell anemia is a harmful autosomal recessive.
It is caused by a mutation in the normal allele (A) for hemoglobin (a protein on red blood cells).
Heterozygotes (AS) with the sickle-cell allele are resistant to malaria, a deadly tropical disease. It is common in many African populations.
In these areas, (S) carriers have been naturally selected, because their red blood cells, containing some abnormal hemoglobin, tend to be in sickle shape when they are infected by the malarial parasite.
Therefore, they are more likely to survive and reproduce. This keeps the S allele in the gene pool.
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B. plastic , the recycling of plastic would conserve fossil fuels
Answer:
c
Explanation:
if the scientist was to look close there skin would be tightened up on the frog it is hard to see but if you look close you could see it
18mg for a 19-50 year old adult female.
To keep in the stored enzymes so it can keep synthesizing at night, even when there is no sunlight. -- Stomata serve two main functions - they allow carbon dioxide to reach the cells in the leaf where the majority of photosynthesis takes place and they allow water to be transpired out off the leaf. During the day, stomata are generally open to allow photosynthesis to take place as quickly as possible. At night, when the lack of light means photosynthesis can't take place, many plants close their stomata to reduce water loss. There is one group of mainly desert plants, known as CAM plants, that keep their stomata closed during the day when water loss would be greatest, and open them at night, using a biochemical method to effectively store carbon dioxide in the leaf overnight.