5.
a student examines a living cell through a microscope. observing w
following would indicate that the cell is eukaryotic?
a. cell wall
b. cytoplasm
c. plasma membrane
d. membrane-bound nucleus

D. membrane-bound nucleus

Explanation:

By process of elimination you can easily get your answer.

All cells have a plasma membrane all cells have a cytoplasm eukaryotic plant cells have a cell wall. All the things I have listed are present in both prokaryotes and eukaryotes with the exception of the cell wall but i specified that plant cells can have cell walls. so which of the four hasn’t been mentioned D. membrane-bound nucleus and that is because prokaryotes have a nucleoid which consist of genetic material and that’s about it they prokaryotes lack membrane bound organelles so they couldn't have a nucleus.

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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