Final answer:
An action potential is an all-or-none event that does not vary in size when the threshold for activation is reached or surpassed. A stronger stimulus will not cause a bigger action potential, but can lead to a higher frequency of action potentials.
Step-by-step explanation:
An action potential is an all-or-none event, which means that its size is not affected by the size of the stimulus once the threshold is reached. If the input (stimulus) is below the threshold, no action potential will occur. If the threshold is reached or surpassed, the neuron will fire an action potential that peaks at the same voltage (+30 mV), regardless of how much stronger the stimulus is compared to the threshold. Therefore, an action potential would not be greater if an input was transmitted onto the same branch; it would either trigger another identical action potential or not trigger one at all.
When a stronger stimulus is applied, it doesn't increase the size of an individual action potential but can cause action potentials to occur more rapidly. The frequency of action potentials can indeed carry information about the strength of a stimulus, affecting things like the sensation of pain or muscle contraction intensity, but the individual action potentials themselves do not vary in size.