Most of the u. s. has a climate. tropical subtropical temperate polar

Temperate is the right answer.

In the southeast seashores of the U.S, the hot-temperate region stretches to the River Mississippi and across the Gulf Coast; the region is greatly influenced by the mild, humid tropic air mass that arises above the Gulf of Mexico. The extended frost-free period passes 200 days. Torrid air flows north in February and controls the zone till November when polar continental winds irregularly penetrate.

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 menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.