The four main types of macromolecules are organic. what does organic mean in this context. A. it is made only of carbon
B. it is produced without the use of pesticides.
C. it is a very large molecule.
D. it is made from or produced by a living organism.

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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the answer is 1. photosynthesis. glad to