The correct answer is: stratosphere.
This is because their temperatures are rising instead of decreasing.
There are 4 primary layers of the atmosphere on Earth:
Troposphere (6-20km), the layer that we live in, where the weather occurs. Only nitrogen and oxygen present.
Stratosphere (20-50 km), where the airplanes fly, contains the ozone layer, which absorbs harmful radiation from the sun.
Mesosphere (50-85 km), the coldest region of Earth’s atmosphere (-100 C), protective layer
Thermosphere (80-690), the hottest (1500 C) and the thickest layer which consists of the ionosphere and the exosphere.
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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Meiosis is needed for sexual reproduction, here chromosome number is halved, it provides for mixing up of genes.
mitosis is needed for growth, repair, replacement, asexual reproduction.
it maintains same chromosome number
Answer:
Microtubules play an important role in cell division by contributing to the formation of the mitotic spindle, which plays a part in the migration of duplicated chromosomes during anaphase.
Answer:
There is a need to transform the accumulation of acetyl-CoA into the ketone bodies, as one knows that acetyl-CoA is both labile and possess an enormous amount of energy. Hence, acetyl-CoA due to its unstable characteristic is not ideal for circulation within the tissues, and at the same time, the compound acetyl-CoA does not possess the tendency to pass through the cell membrane.
Due to these reasons, the conversion of acetyl-CoA into the ketone bodies is done, the ketone bodies also act as an alternative source of energy. The ketone bodies work as water-soluble correspondents of fatty acids. The production of ketone bodies generally takes place within the liver cells' mitochondrial matrix. The three forms of ketone bodies are beta-hydroxybutyrate, acetoacetate, and acetone.
The production of ketone bodies by the liver cells helps the cells of the brain at the time of starvation, as the brain cannot use fatty acids as an energy source, as the fatty acids cannot pass through the blood-brain barrier.
