Which statements best describe shared characteristics? Select two options. a. Shared characteristics always exist in the common ancestor and in the modern organism
b. Shared characteristics never exist in the common ancestor or in the modern organism.
c. The more characteristics organisms share, the more closely related they are.
d. The fewer characteristics organisms share, the more closely related they are.
e. Shared characteristics can exist among organisms that belong to different species.
f. Shared characteristics only exist among organisms that belong to the same species.

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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false because ozone (o3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it.

global warming is caused primarily by putting too much carbon dioxide into the atmosphere when coal, oil, and natural gas are burned to generate electricity or to run our cars.

explanation: