Question 1

Which of the following best describes the permeability of a typical cell membrane to ions?

Accepted Answer

Cell membranes are impermeable to ions unless specific ion channels or transporters are present.

Question 2

Which mechanism does NOT require energy for ion transport across the cell membrane?

Accepted Answer

Facilitated diffusion through ion channels

Question 3

The membrane potential is composed of which two components?

Accepted Answer

Chemical gradient and electrical gradient

Question 4

What is the typical value (in millivolts) of a resting membrane potential in most animal cells?

Accepted Answer

$$-70\ 	ext{mV}$$

Question 5

Which pump is primarily responsible for establishing and maintaining the resting membrane potential, and what is its energy source?

Accepted Answer

Na+/K+ ATPase; energy from ATP hydrolysis

Question 6

During one cycle of the Na+/K+ pump, how many sodium and potassium ions are transported, and how many ATP molecules are consumed?

Accepted Answer

3 Na+ out, 2 K+ in, 1 ATP consumed

Question 7

Which of the following is NOT a type of gated ion channel?

Accepted Answer

ATP-gated channel

Question 8

Depolarization of a neuron refers to:

Accepted Answer

A decrease in membrane potential, making the inside less negative relative to the outside

Question 9

What is the primary function of the myelin sheath in neurons?

Accepted Answer

To increase the speed of action potential conduction via saltatory conduction

Question 10

Why were giant squid neurons historically used in studies of membrane potential?

Accepted Answer

Their large diameter made them easier to manipulate and measure electrical properties

Question 11

Patch clamping is a technique used to:

Accepted Answer

Measure the electrical activity of individual ion channels

Question 12

Which type of ion channel is primarily found in the axon hillock, and what is its significance?

Accepted Answer

Voltage-gated Na+ channels; initiates action potentials when threshold is reached

Question 13

What is the effect of opening ligand-gated ion channels in the dendrites of a neuron?

Accepted Answer

Generation of graded potentials that can be excitatory or inhibitory

Question 14

If a stimulus does not reach the threshold at the axon hillock, what happens?

Accepted Answer

No action potential is generated

Question 15

Which equation can be used to calculate the equilibrium potential for a specific ion across a membrane?

Accepted Answer

$$E_{	ext{ion}} = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{outside}}}{[	ext{ion}]_{	ext{inside}}} ight)$$

Question 16

What is the difference between absolute and relative refractory periods in neurons?

Accepted Answer

Absolute refractory period: no new action potential can be generated; Relative refractory period: a stronger stimulus can generate an action potential

Question 17

Saltatory conduction differs from contiguous conduction in that:

Accepted Answer

Saltatory conduction involves action potentials jumping between nodes of Ranvier, increasing speed

Question 18

What happens when an action potential reaches the axon terminal?

Accepted Answer

Voltage-gated Ca2+ channels open, triggering neurotransmitter release

Question 19

Which of the following best describes the effect of an SSRI (Selective Serotonin Reuptake Inhibitor) on neurotransmitter fate?

Accepted Answer

It blocks serotonin reuptake, increasing its concentration in the synaptic cleft

Question 20

Temporal summation in neurons refers to:

Accepted Answer

Multiple graded potentials occurring at the same location in rapid succession

Cell Biology Study Guide: Membrane Potential and Neuronal Function

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