What is the answer to number 2? ! : )

For each of the examples, simple diffusion, carrier, and channel mediated, each type involves the flow down a concentration gradient. This means that the molecules flow from an area of high concentration to an area of low concentration. In turn, this allows for a passive process, meaning no ATP is needed! I hope this explains your question.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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