Type of transport protein alternates between two shapes, transporting the solute across the membrane through shape changes.

The correct answer is- carrier protein

Explanation:

Carrier proteins are involved in the transport of a substance across the membrane. They bind to substance specifically and are involved in both facilitated diffusion and active transport.

They usually change their conformation or shape to transport the molecule across the cell. When they bind to a molecule they change their shape and then they get into their normal shape when the molecule gets transported across the membrane.

The rate of diffusion by using carrier protein is higher than simple diffusion. So the correct answer is carrier protein.

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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