Consider these phylogenetic trees. the first tree is based on physical characteristics. the second tree is based on structure, genetics, and evolutionary history. which can be concluded from a comparison of the two phylogenetic trees? a. phylogenetic trees are not subject to change. b. classification can change with new discoveries and evidence. c. classification does not change with more evidence. d. phylogenetic trees are inaccurate.

The classification for Opossum changes between the two trees. So the answer is B. Classification can change with new discoveries and evidence.

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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