Question 1

Which of the following best describes the function of dendrites in a neuron?

Accepted Answer

They receive input signals from other neurons or sensory receptors.

Question 2

An action potential in a neuron is characterized by which of the following properties?

Accepted Answer

It is propagated only if the stimulus exceeds a threshold value.

Question 3

Which equation describes the exponential decrease of voltage along an axon when a steady voltage $$V_0 is $$applied?

Accepted Answer

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

Question 4

What is the typical value of the peak potential reached during an action potential inside the axon?

Accepted Answer

$$+30\,mV$$

Question 5

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

Accepted Answer

The action potential only occurs if the stimulus is strong enough to exceed the threshold, and its magnitude does not depend on stimulus strength.

Question 6

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

Accepted Answer

By the release and diffusion of a chemical substance (neurotransmitter).

Question 7

If the length constant $$\lambda of an $$axon is $$0.8\,mm$$, what percentage of the original voltage $$V_0$$ remains at a distance $$0.8\,mm$$ from the point of application?

Accepted Answer

37%

Question 8

Which of the following is NOT a class of neuron described in the study materials?

Accepted Answer

Glial neuron

Question 9

A patient receives a stimulus to a nerve that does NOT exceed the threshold value. What is the expected response?

Accepted Answer

No action potential is generated.

Question 10

Which property of the action potential allows fast-acting axons to propagate signals at speeds up to $$100\,m/s$$?

Accepted Answer

The presence of myelin sheaths and the cable-like structure of the axon.

Question 11

Which of the following best describes the role of the axon in a neuron?

Accepted Answer

It conducts electrical impulses away from the cell body.

Question 12

During an action potential, after the peak is reached, the membrane potential rapidly decreases to approximately what value before returning to the resting state?

Accepted Answer

$$-90\,mV$$

Question 13

Which of the following is a correct sequence of events during synaptic transmission in the vertebrate nervous system?

Accepted Answer

Action potential arrives at nerve ending → chemical substance released → substance diffuses across synapse → adjacent cell is stimulated

Question 14

Which of the following experimental methods is commonly used to study the properties of nerve impulses?

Accepted Answer

Inserting a probe into the axon and measuring voltage changes with respect to the surrounding fluid.

Question 15

Which of the following best explains why muscle fibers can propagate electrical impulses?

Accepted Answer

They have the same basic mechanism for action potentials as neurons.

Question 16

If a voltage $$V_0 is $$applied at one point on the axon membrane, and the voltage at $$x = 0.8\,mm is$$ $$0.37V_0$$, what is the value of the length constant $$\lambda$$?

Accepted Answer

$$\lambda = 0.8\,mm$$

Question 17

Which of the following is a real-life application of understanding the action potential in neurons?

Accepted Answer

Developing treatments for neurological disorders such as epilepsy.

Question 18

Which of the following statements about the duration of action potentials in muscle fibers compared to neurons is correct?

Accepted Answer

The duration is usually longer in muscle fibers (about 20 ms).

Question 19

Which of the following best describes the function of interneurons?

Accepted Answer

They transmit information between sensory neurons and motor neurons.

Question 20

A researcher applies a steady voltage $$V_0 to an $$axon and measures the voltage at various distances. At what distance $$x$$ will the voltage drop to $$V_0/e$ of its original value, according to the cable equation?

Accepted Answer

$$x = \lambda$$

Biophysics: Electrobiology – Nervous System, Action Potentials, and Axon Circuits

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