Answer:
During depolarization, the membrane potential rapidly shifts from negative to positive. As the sodium ions rush back into the cell, they add positive charge to the cell interior, and change the membrane potential from negative to positive.
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To carry out life processes like breathing, respiration, digestion, excretion etc.
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Answer:
According to Darwin's theory of evolution, new species evolved as a result of natural selection.
Explanation:
- Darwin proposed that speciation could readily occur through the prolonged action of Natural selection.
- Natural selection allows the 'survival of the fittest' i.e. a more fit organism will have a better chance of survival than the less fit one.
- The result of Natural selection could be positive,negative or balancing.
- Evolutionary process in which the genetic changes confer a higher fitness to increase frequency of the organism over time in population is called positive selection.
- Evolutionary process in which genetic changes decreases the organism's fitness resulting in its disappearance from the population is called Negative selection.
- It may happen that a mutation benefits hetero-zygotes but not homo-zygotes and alleles maintain a intermediate frequency in population.This evolutionary process is called balancing selection.
There are valves in the vessels that prevents backflow, just like in the viens. ... the lymph vessels to ensure that the flow of lymph
It is called THERAPEUTIC INDEX. Therapeutic index is the comparison of the amount of a particular drug that causes the desired therapeutic effects and the amount that causes toxicity. The index can be low or high. A drug with a low therapeutic index will require only a small increase in dose to produce toxic effects in users.
