What term defines kind of species that have been introduced to an ecosystem by man?

Answer;

-Exotic species

Explanation;

-An exotic species or an introduced species ( or alien species, non-indigenous species, or non-native species) is a species living outside its native distributional range, which has arrived there by human activity, either deliberate or accidental.

-The major distinguishing feature between exotic and invasive species is that exotic species is harmless to the ecosystem whereas invasive species is harmful to the ecosystem.

-For example important introduced pest species which include chestnut blight, Dutch elm disease, etc. and plant species such as honeysuckle, buckthorn, etc.

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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after a the power stroke, adp is released, but the cross-bridge formed is still in place. atp then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.