Questions: Question 12 The mechanisms that produce and maintain the resting membrane potential do so by producing a slight excess of positive ions on the outer surface of the plasma membrane. slight excess of negative ions on the outer surface of the plasma membrane. balanced distribution of positive and negative ions between the outer and inner surface of the plasma membrane. reduction of ions on the outer surface of the plasma membrane.

The answer is the first one: a slight excess of positive ions on the outer surface of the plasma membrane.

Explanation for each option:

1. Slight excess of positive ions on the outer surface of the plasma membrane: This is correct. The resting membrane potential is maintained by the sodium-potassium pump, which actively transports three sodium ions (Na⁺) out of the cell and two potassium ions (K⁺) into the cell. This results in a slight excess of positive ions on the outer surface of the plasma membrane compared to the inner surface, which is relatively negative.

2. Slight excess of negative ions on the outer surface of the plasma membrane: This is incorrect. The outer surface of the plasma membrane has a slight excess of positive ions, not negative ions.

3. Balanced distribution of positive and negative ions between the outer and inner surface of the plasma membrane: This is incorrect. The resting membrane potential is characterized by an imbalance, with the inner surface being more negative relative to the outer surface.

4. Reduction of ions on the outer surface of the plasma membrane: This is incorrect. The resting membrane potential involves the active transport of ions, not a reduction in the number of ions on the outer surface.

Summary: The mechanisms that produce and maintain the resting membrane potential do so by producing a slight excess of positive ions on the outer surface of the plasma membrane.