During the course of an action potential, the membrane potential rapidly rises and reaches a peak of about +40 mV before falling
to about -75 mV. What causes the fall in membrane potential? A) A decrease in Na+ permeability, and an increase in K+ permeability
B) A decrease in the permeability to both Na+ and K+
C) An increase in Na+ permeability, and a decrease in the K+ permeability
D) An increase in the permeability to both Na and K
A) A decrease in Na+ permeability, and an increase in K+ permeability.
Explanation:
When the potential action reaches a peak of about +40 mv Na+ channels are open and a high number of Na+ ions are entering the inside of the cell. Shortly after this happens the K+ channels will start to open their gates increasing the cell K+ permeability while the Na+ channels will start to close their gates, so the Na+ permeability will decrease. This happens in order to valance the positive charge on the inside of the cell. Normally the inside has a negative charge while the outside has a positive one, as the inside is more positive due to the increase in Na+ permeability at the beginning of the potential action, K+ cations (which are in abundance in the cell) will have to go out through the K+ channels so as to restore the charge valance, that means that there is an increase in K+ permeability.
"Larva" is a stage in the life cycle of an insect among the following choices given in the question that a <span>caterpillar represents. The correct option among all the options that are given in the question is the second option or option "B". I hope that this is the answer that has actually come to your desired help.</span>
A climax community (Figure below) is the end result of ecological succession. The climax community is a stable balance of all organisms in an ecosystem and will remain stable unless a disaster strikes. After the disaster, succession will start all over again.
