Who have natural and artificail selection gizmo doc i need help with eveything

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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climate change and pollution

i think the answer is a.keratin is the pigment responsible for skin color.

answer///alimentary canal/gastrointestinal tract.digestive (gi);