Question 1

Which of the following best describes the role of the sodium-potassium ATPase pump in maintaining the resting membrane potential (RMP) of a neuron?

Accepted Answer

It actively transports 3 Na+ out of the cell and 2 K+ into the cell, maintaining a negative charge inside.

Question 2

A neuron at rest has a membrane potential of approximately $$-70\ \mathrm{mV}. $$What is the primary reason for this negative charge inside the cell?

Accepted Answer

The cell membrane is more permeable to K+ than to Na+, leading to K+ efflux.

Question 3

Which type of ion channel is responsible for the continuous passive movement of ions across the neuronal membrane, contributing to the resting membrane potential?

Accepted Answer

Non-gated (leak) channels

Question 4

A neurotransmitter binds to a ligand-gated Na+ channel on a neuron's dendrite. What is the most likely immediate effect on the membrane potential?

Accepted Answer

Depolarization due to Na+ inflow

Question 5

Which equation best represents the voltage difference measured across a neuron's membrane at rest?

Accepted Answer

$$V_{m} = V_{ECF} - V_{ICF}$$

Question 6

If a neuron is exposed to a chemical that opens ligand-gated K+ channels, what will happen to the membrane potential?

Accepted Answer

It will become more negative (hyperpolarization).

Question 7

Which of the following best explains why ions cannot freely cross the phospholipid bilayer of the cell membrane?

Accepted Answer

Ions are hydrophilic and require protein channels to cross.

Question 8

Which of the following is TRUE about graded (local) potentials?

Accepted Answer

They vary in magnitude depending on stimulus strength and are reversible.

Question 9

A patient is given a drug that blocks all non-gated (leak) K+ channels in neurons. What is the most likely effect on the resting membrane potential?

Accepted Answer

The RMP will become less negative, approaching zero.

Question 10

Which of the following best describes the electrochemical gradient?

Accepted Answer

It is the sum of the chemical (concentration) and electrical (charge) gradients that drive ion movement.

Question 11

During a graded potential, what determines the magnitude of the change in membrane potential?

Accepted Answer

The strength of the stimulus and the number of ligand-gated channels opened

Question 12

Which of the following is a characteristic of graded potentials but NOT action potentials?

Accepted Answer

They are decremental and fade with distance from the stimulus.

Question 13

What is the effect of opening ligand-gated Na+ channels at the postsynaptic membrane of a neuron?

Accepted Answer

Excitatory postsynaptic potential (EPSP) due to depolarization

Question 14

Which of the following events is most likely to occur if the membrane potential becomes more negative than $$-70\ \mathrm{mV}$$?

Accepted Answer

Hyperpolarization

Question 15

A muscle fiber receives acetylcholine at the neuromuscular junction. What is the immediate effect on the muscle cell membrane?

Accepted Answer

Opening of ligand-gated Na+ channels, leading to depolarization

Question 16

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

Accepted Answer

Non-gated (leak) channel

Question 17

If the stimulus that caused a graded potential is removed, what happens to the membrane potential?

Accepted Answer

It returns to the resting membrane potential (RMP).

Question 18

Which of the following best describes the effect of opening ligand-gated K+ channels on a postsynaptic neuron?

Accepted Answer

It causes hyperpolarization and an inhibitory effect.

Question 19

Which of the following statements about the resting membrane potential (RMP) is CORRECT?

Accepted Answer

The RMP is maintained by both passive leak channels and active pumps.

Question 20

Which of the following is the correct sequence of events for a graded potential caused by a neurotransmitter?

Accepted Answer

Neurotransmitter binds → ligand-gated channel opens → ion movement → change in membrane potential

Cellular Electricity and Electrophysiology: Resting and Graded Membrane Potentials

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