Final answer:
The action potential is the physiological process most directly dependent on membrane potential, crucial for nerve impulse transmission and muscle contraction.
Step-by-step explanation:
The physiological process most directly dependent on membrane potential is the generation of an action potential. The resting membrane potential of a cell is a dynamic equilibrium maintained by the Na+/K+ pump, resulting in a voltage difference across the membrane due to the distribution of ions. An action potential occurs when a stimulus causes a sudden influx of Na+ ions through voltage-gated channels, leading to depolarization. Successive opening of voltage-gated K+ channels allows K+ to exit the cell, leading to repolarization. This rapid change in membrane potential is essential for nerve impulse conduction and muscle contraction.