Q: The Na\textsuperscript{+}/K\textsuperscript{+} pump moves ions across the plasma membrane. Which of the following is TRUE about its function?

It uses ATP to move Na\textsuperscript{+} out and K\textsuperscript{+} in against their gradients.

Q: During an action potential, which event occurs first?

Voltage-gated Na\textsuperscript{+} channels open, causing depolarization.

Q: Which of the following is TRUE about the Na\textsuperscript{+}/glucose symporter in intestinal epithelial cells?

It uses the energy stored in the Na\textsuperscript{+} gradient to move glucose against its gradient.

Question 1

Which of the following molecules is most likely to cross a lipid bilayer by simple diffusion?

Accepted Answer

O	extsubscript{2}

Question 2

A cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

It will lose water and shrink (crenate/plasmolyze).

Question 3

Which statement best describes facilitated diffusion?

Accepted Answer

It uses membrane proteins to move solutes down their concentration gradient.

Question 4

The rate of simple diffusion across a membrane is proportional to which of the following?

Accepted Answer

The difference in solute concentration across the membrane ($\Delta [S]$)

Question 5

Which of the following best explains why ions such as Na	extsuperscript{+} and K	extsuperscript{+} cannot cross the lipid bilayer by simple diffusion?

Accepted Answer

They are charged and interact unfavorably with the hydrophobic core of the bilayer.

Question 6

Which of the following transport mechanisms is responsible for the uptake of glucose into erythrocytes when blood glucose is high?

Accepted Answer

Facilitated diffusion via GLUT1 uniport carrier

Question 7

The Na	extsuperscript{+}/K	extsuperscript{+} pump moves ions across the plasma membrane. Which of the following is TRUE about its function?

Accepted Answer

It uses ATP to move Na	extsuperscript{+} out and K	extsuperscript{+} in against their gradients.

Question 8

Which equation best represents the free energy change ($\Delta G$) for passive transport of a solute across a membrane?

Accepted Answer

$\Delta G = RT \ln \left( \frac{[S]_{out}}{[S]_{in}} \right)$

Question 9

A neuron at rest has more Na	extsuperscript{+} outside and more K	extsuperscript{+} inside. What is the typical resting membrane potential?

Accepted Answer

$-65$ mV

Question 10

During an action potential, which event occurs first?

Accepted Answer

Voltage-gated Na	extsuperscript{+} channels open, causing depolarization.

Question 11

Which of the following is TRUE about the Na	extsuperscript{+}/glucose symporter in intestinal epithelial cells?

Accepted Answer

It uses the energy stored in the Na	extsuperscript{+} gradient to move glucose against its gradient.

Question 12

Which of the following statements about ion channels is FALSE?

Accepted Answer

They undergo conformational changes to transport ions one at a time.

Question 13

A mutation in the CFTR chloride channel leads to cystic fibrosis. What is the primary cellular defect caused by this mutation?

Accepted Answer

Impaired chloride ion transport across epithelial membranes

Question 14

Which neurotransmitter is most commonly found at vertebrate neuromuscular junctions and is excitatory?

Accepted Answer

Acetylcholine

Question 15

Which of the following best describes the difference between carrier proteins and channel proteins?

Accepted Answer

Carrier proteins bind solutes and undergo conformational changes; channel proteins form open pores.

Question 16

Which of the following is a direct consequence of the Na	extsuperscript{+}/K	extsuperscript{+} pump activity in animal cells?

Accepted Answer

A net negative charge inside the cell relative to outside

Question 17

Which of the following neurotransmitters is inhibitory in the central nervous system?

Accepted Answer

GABA

Question 18

A patient is given curare, which blocks nicotinic acetylcholine receptors. What is the expected effect?

Accepted Answer

Prevention of depolarization at the neuromuscular junction

Question 19

Which of the following best describes the process of osmosis?

Accepted Answer

Movement of water across a selectively permeable membrane in response to solute concentration differences

Question 20

Which of the following is TRUE about the propagation of an action potential along an axon?

Accepted Answer

It is self-reinforcing and moves in one direction due to refractory periods.

Membrane Transport: Mechanisms and Principles

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