What do stabilizing selection and disruptive selection have in common? ?

Variation

Explanation:

In natural selection, variation happens to produce more fit organisms. The natural selection is a different type such as stabilizing selection, directional selection, and disruptive selection. In both cases, variation occurs but the variation rate is different.  Therefore, the common thing between stabilizing selection and disruptive selection is variation. The variation rate is slow in stabilizing selection. Hence in this selection less phenotype characters are seen. In disruptive selection, variation is random and extreme. Thus more phenotype individuals are formed due to disruptive selection.

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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organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.