20. why are scientific theories changed but never thrown away?

Scientific Theory change but not thrown away because scientist continue looking for possibilities and exact proportion to prove such theory, though it is change because they always conducted hypnosis in every theory and once it proves something different they conduct another hypothesis for more actual 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.  

read more on -

hi, natural selection of the peppered moth during the industrial revolution in 19th-century england is an example of an outlier in the study of evolution. during this time, pollution from factories filled the forests, coating trees in a layer of soot—turning white trees black

mark as brainlest

gokuson