Final answer:
When a hyperpolarizing graded potential and a depolarizing graded potential of similar magnitudes coincide, they cancel each other out, resulting in no change. No action potential is fired off, as they are all-or-none events, requiring the membrane to reach a specific threshold.
Step-by-step explanation:
If a hyperpolarizing graded potential and a depolarizing graded potential of similar magnitudes arrive at the trigger zone at the same time, they will essentially cancel each other out, resulting in option B) Nothing. They will cancel each other out. Action potentials are all-or-none events, meaning that either the membrane reaches the threshold and everything occurs as specified, or it does not reach the threshold and nothing happens.
An action potential is generated when the net effect of all graded potentials reaches the threshold of excitation, typically -55 mV. If graded potentials negate each other, the membrane potential does not reach this threshold, and no action potential is generated. Furthermore, stronger stimuli do not create bigger action potentials; rather, they can trigger action potentials more frequently.
Graded potentials are small changes in membrane potential that can either cause depolarization (becoming less negative) or hyperpolarization (becoming more negative). Depolarizing potentials may result from Na+ or Ca2+ entering the cell, while hyperpolarizing potentials can be due to K+ leaving the cell or Cl- entering. These potentials individually influence the membrane potential but must summate to a level that crosses the threshold to initiate an action potential.