Question 1

Which of the following best describes the electrochemical gradient across a cell membrane?

Accepted Answer

It is the sum of the chemical gradient and the electrical gradient across the membrane.

Question 2

The transmembrane potential (ΔV or Vm) is defined as:

Accepted Answer

The difference in electrical charge between inside and outside the cell.

Question 3

If the inside of a cell is more negative than the outside, what is the sign of the transmembrane potential (ΔV)?

Accepted Answer

Negative

Question 4

Which equation correctly represents the transmembrane potential?

Accepted Answer

$$\Delta V = \psi_{in} - \psi_{out}$$

Question 5

Which type of ion channel is responsible for opening in response to the binding of a specific molecule, such as a neurotransmitter?

Accepted Answer

Ligand-gated ion channel

Question 6

Facilitated diffusion of charged ions across a biological membrane is:

Accepted Answer

Driven by a difference in the electrochemical gradient.

Question 7

Which of the following statements is TRUE about signal-gated ion channels?

Accepted Answer

They respond to the presence of intracellular signaling molecules.

Question 8

The voltage-gated potassium channels associated with an action potential provide an example of what type of membrane transport?

Accepted Answer

Facilitated diffusion

Question 9

Which of the following is NOT a type of ion channel described in the study materials?

Accepted Answer

ATP-gated ion channel

Question 10

A neuron at rest has a membrane potential of $$-70 mV. If $$the membrane suddenly becomes permeable to Na$$^+$$ ions, what will happen to the membrane potential?

Accepted Answer

It will become less negative (depolarize).

Question 11

Which of the following best explains why K$$^+$$ ions move out of a neuron during repolarization?

Accepted Answer

The electrochemical gradient favors K$$^+$$ efflux.

Question 12

Which of the following is a correct statement about leak ion channels?

Accepted Answer

They remain open, allowing leakage of ions down their electrochemical gradients.

Question 13

Which of the following scenarios would result in the establishment of an opposite gradient for cations across a membrane?

Accepted Answer

When $$\Delta V = 0$$

Question 14

Which of the following is a multi-step process involving both chemical and electrical gradients?

Accepted Answer

Facilitated diffusion of Na$$^+$$ through a voltage-gated channel

Question 15

A mutation causes a ligand-gated ion channel to remain open even in the absence of its ligand. What is the most likely consequence?

Accepted Answer

Unregulated ion flow across the membrane

Question 16

Which of the following is a real-world example of a mechanically-gated ion channel?

Accepted Answer

A channel that opens in response to sound waves in the ear

Question 17

Which of the following best describes the role of the chemical gradient in ion transport?

Accepted Answer

It is the difference in ion concentration between two regions.

Question 18

Which of the following is NOT a factor that influences the movement of charged ions across a membrane?

Accepted Answer

Membrane thickness

Question 19

A cell is placed in a solution with a high concentration of Cl$$^-$$ ions outside and a low concentration inside. If the membrane is permeable to Cl$$^-$$, what will happen?

Accepted Answer

Cl$$^-$$ ions will move into the cell down their chemical gradient.

Question 20

Which of the following best explains why facilitated diffusion is necessary for the transport of ions across the cell membrane?

Accepted Answer

Ions are charged and cannot pass through the hydrophobic core of the membrane without assistance.

Membrane Transport of Ions and Electrochemical Gradients

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