Which of the following statements about biodiversity is true? a. changes to biodiversity always positively affect an ecosystem. b. changes to biodiversity always negatively affect an ecosystem. c. changes to biodiversity can positively and negatively affect on an ecosystem. d. changes to biodiversity never affect an ecosystem. select the best answer from the choices provided

c. it is a hit or miss, so c is the most likely answer

all of the above

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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