Which term best describes the all-or-none property of action potentials?

Which term best describes the all-or-none property of action potentials?

• A. Graded potential
• B. Resting potential
• C. Action potential
• D. Refractory potential

Answer: (C)

The all-or-none property refers to how an action potential behaves: once the membrane depolarizes to threshold, a full, uniform spike is produced every time, regardless of whether the initial stimulus was just enough to reach threshold or well above it. Subthreshold stimuli fail to trigger any spike, while reaching threshold reliably yields a rapid depolarization, a consistent peak, and a brief, predictable duration that propagates along the axon without fading. This is what distinguishes action potentials from graded potentials, which vary in size with stimulus strength and can diminish with distance. Resting potential is simply the baseline membrane potential when the neuron is not firing, and there isn’t a standard term like “refractory potential”—the correct related concept is the refractory period, during which new action potentials are temporarily harder or impossible to elicit. So the best description of the all-or-none property is the action potential itself.

The all-or-none property refers to how an action potential behaves: once the membrane depolarizes to threshold, a full, uniform spike is produced every time, regardless of whether the initial stimulus was just enough to reach threshold or well above it. Subthreshold stimuli fail to trigger any spike, while reaching threshold reliably yields a rapid depolarization, a consistent peak, and a brief, predictable duration that propagates along the axon without fading. This is what distinguishes action potentials from graded potentials, which vary in size with stimulus strength and can diminish with distance. Resting potential is simply the baseline membrane potential when the neuron is not firing, and there isn’t a standard term like “refractory potential”—the correct related concept is the refractory period, during which new action potentials are temporarily harder or impossible to elicit. So the best description of the all-or-none property is the action potential itself.