Answer:
Natural selection is an adaptative mechanism that modifies gene frequencies (allele frequencies) in the whole population across generations
Explanation:
According to the evolutionary theory proposed by Darwin, natural selection is the main process that leads to evolution. Natural selection can be defined as a mechanism through which populations adapt and change. The organisms better adapted to their environment will have more chances to survive and reproduce, and therefore they will pass their genes (and favorable traits) to the next generation. This process is able to modify the allele frequencies in the whole population, thereby changing and adapting (i.e., evolving) across generations.
As in Plant ; Meristematic cells have high no of mitochondria as they have to duvide continuously!!
and in animal as for example , take a liver cell , they have high number of smooth endoplamic reticulum as they have to detoxify toxic materials !!
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Enzymes catalyze reactions by lowering the activation energy of the reaction. Enzymes are made of proteins, and therefore the answer here is B. Protein molecules.
If plaque buildup reduces the radius of the artery by a factor of 2, the flow rate becomes 1/16th of the original.
Coronary heart disease results from a deposition of plaque in the blood vessels which transport blood to the heart. When the flow of blood to the heart is hampered or obstructed, the heart can be harmed due to a deficiency of oxygen.
Moreover, if a large section of plaque that is deposited gets displaced from an artery wall, it can get stick in other arteries in the body as well, including those present in the brain.
For convenience, an assumption can be made that the artery is cylindrical in shape with a radius of R. The flow rate of a viscous fluid (blood in this case) is determined by Poiseuille's Law, i.e. Q = (π/8) (ΔP/ηl)r4.
To learn more about Poiseuille's Law here
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