The all or none law of nerve impulse conduction states that
Correct answer: D. any stimulus at or above threshold produces an action potential of the same size
- A. a stronger stimulus produces a larger action potential
- B. an impulse can travel in either direction along the axon
- C. every stimulus produces an impulse regardless of its strength
- D. any stimulus at or above threshold produces an action potential of the same size
Explanation
Once threshold is reached the sodium channels open fully, so the size of the spike is fixed by the ion gradients and not by how strong the stimulus was. Stimulus intensity is coded instead by the frequency of impulses and by how many neurones are firing. A stimulus below threshold produces no impulse at all, so it is not true that every stimulus produces one.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
About Neurons and Nerve Impulse
Neurons receive and transmit information through dendrites, the cell body and axons. The topic explains resting potential, depolarization, repolarization, refractory periods and saltatory conduction, followed by synaptic transmission through neurotransmitters. An action potential is distinct from the graded potential produced at a receptor.
Practise Coordination and Control
1,687 free Coordination and Control MCQs from Biology, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Biology questions like this
Biology is on 8 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Neurons and Nerve Impulse questions
The rapid depolarisation phase of an action potential is caused by
The resting potential of about minus 70 millivolts across the membrane of a neurone is maintained mainly by
A myelinated neurone conducts impulses faster than an unmyelinated one because
During the refractory period a neurone
Transmission across a chemical synapse is one way because
The resting membrane potential is approximately