Final answer:
Very few ions need to move to alter the membrane potential.
Step-by-step explanation:
The statement "Very few ions need to move to alter the membrane potential." is True. The cell membrane is semipermeable, meaning that some ions can cross it while others cannot. In its resting state, the cell membrane is permeable to K+ and Cl-, and impermeable to Na+. Diffusion of K+ and Cl- creates layers of positive and negative charge on the outside and inside of the membrane, resulting in a voltage across the cell membrane. This voltage can be altered by the movement of a few ions.