A group of scientists wants to observe the adaptation of a foreign fish species in a river ecosystem. To do this, they want to enclose the top and sides of a section of a river to block light and matter from entering the area. Evaluate whether this experimental system is an isolated system. Justify your answer based on the definition of an isolated system.

yes because a thermodynamic system (isolated system) enclosed by rigid immovable walls through which neither mass nor energy can pass.

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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