Which of the following is not a component of a normal experiment?
a. validity group
b. dependent variable
c. independent variable
d. control group

A. Validity group

Explanation:

An experiment is a type of scientific research in which the researcher manipulates and controls one or more independent variables and observes the variation in the dependent variables concomitantly with the manipulation of the independent variables.

An experiment is composed of variables and groups. In the variables, you can mention:

In a scientific experiment, besides the variables we can notice the presence of groups (two samples) that are compared to test a hypothesis: the control group (also called test group or testimony) and the experimental group.

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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