The cladogram above diagrams the evolutionary history of chordates. Which group of animals was the first land dweller?
A) birds
B) mammals
C) lungfish
D) amphibians

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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i am positive it is c. condensing but i may be wrong

the darker peppered moth species were favored due to the fact that the industrial revolution had made all the nearby trees a darker color instead of white.