What is the purpose of the stem structure on a plant?

stem are the plays a vital role on the plant. in a plant, stem have four main function which supports: the elevation of leaves, flowers and fruits. the stem keep the leaves in the light and provide a plane for the plant to keep its flowers and fruits. transports of fluids between the roots and the shoots in the xylem and phloem.

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 sphincter muscles at the end of the digestive tract is the anus.