Question 1

Which of the following best describes the property of action potentials in neurons?

Accepted Answer

They are constant in magnitude and duration, independent of stimulus intensity.

Question 2

A nerve impulse is generated only if the stimulus exceeds a certain threshold value. What happens to the membrane potential during the peak of an action potential?

Accepted Answer

It rises to about $$+30\,mV.$$

Question 3

Which structure in a neuron is primarily responsible for conducting electrical impulses away from the cell body?

Accepted Answer

Axon

Question 4

In the vertebrate nervous system, how is the action potential typically transmitted across the synapse?

Accepted Answer

By the release and diffusion of a chemical substance

Question 5

If a steady voltage $$V_0 is $$applied at one point in the axon membrane, the voltage at a distance $$x$$ from the point of application is given by:

Accepted Answer

$$V(x) = V_0$ e$$^{-x/\lambda}$$

Question 6

At a distance of $$0.8\,mm$$ from the point where a steady voltage is applied to an axon, the voltage decreases to what percentage of its original value?

Accepted Answer

37%

Question 7

Which of the following is NOT a class of neuron?

Accepted Answer

Glial neuron

Question 8

Which of the following best explains why the action potential is considered 'all-or-none'?

Accepted Answer

Once the threshold is reached, the action potential always has the same magnitude and duration.

Question 9

Which of the following is a correct statement about the propagation speed of action potentials in fast-acting axons?

Accepted Answer

They can propagate at speeds up to $$100\,m/sec.$$

Question 10

What is the typical duration of an action potential in muscle fibers compared to neurons?

Accepted Answer

Longer in muscle fibers (about 20 msec)

Question 11

Which of the following is the correct sequence for the transmission of a nerve impulse from one neuron to another?

Accepted Answer

Dendrite → Axon → Synapse → Adjacent cell

Question 12

Which of the following best describes the role of interneurons?

Accepted Answer

They transmit information between neurons.

Question 13

A researcher injects a chemical stimulus into a neuron. What is the expected result if the stimulus does NOT reach the threshold value?

Accepted Answer

No action potential is generated.

Question 14

Which of the following is true about the synaptic gap (synapse) between neurons?

Accepted Answer

It is about $$1\,nm = 10$$^{-9}$$\,m$$ wide.

Question 15

Which of the following best describes the function of sensory neurons?

Accepted Answer

They receive stimuli from sensory organs and convey messages about the environment.

Question 16

In the axon cable model, what does the parameter $$\lambda ($$lambda) represent?

Accepted Answer

The distance over which the voltage decreases to $$37\% of $$its original value

Question 17

Which of the following is a real-life application of understanding action potentials in muscle fibers?

Accepted Answer

Diagnosing neuromuscular diseases using electromyography (EMG)

Question 18

A patient has a mutation that increases the threshold for action potential generation in neurons. What is a likely physiological effect?

Accepted Answer

Decreased likelihood of nerve impulses being generated

Question 19

Which of the following best explains why the voltage across the axon membrane decreases exponentially with distance from the point of application?

Accepted Answer

The axon behaves like an electrical cable with resistance and capacitance, causing voltage decay.

Biophysics: Electrobiology of Neurons and Axons

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