Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: Figure 12.25 Graded Potentials Graded potentials are temporary changes in the membrane voltage, the characteristics of which depend on the size of the stimulus. Some types of stimuli cause depolarization of the membrane, whereas others cause hyperpolarization. It depends on the specific ion channels that are activated in the cell membrane. Answer: membrane voltage
A:
Graded potentials are temporary changes in what, the characteristics of which depend on the size of the stimuli?