Question 1

Which of the following molecules would most readily diffuse across a protein-free artificial lipid bilayer, as shown in the diagrams above?

Accepted Answer

O$$_2$$

Question 2

A red blood cell is placed in a hypotonic solution. What is the most likely outcome, and why?

Accepted Answer

The cell will swell and may lyse because water enters by osmosis.

Question 3

Which of the following best describes the difference between simple diffusion and facilitated diffusion?

Accepted Answer

Facilitated diffusion requires membrane proteins, while simple diffusion does not.

Question 4

The rate of facilitated diffusion through a carrier protein shows which type of relationship to solute concentration?

Accepted Answer

Hyperbolic, because the rate approaches a maximum as carriers become saturated.

Question 5

Which of the following is an example of secondary active transport?

Accepted Answer

Glucose uptake into intestinal cells via the Na$$^+/$$glucose symporter

Question 6

A patient is given an intravenous solution that is hypertonic relative to their red blood cells. What will happen to the cells?

Accepted Answer

They will shrink as water leaves the cells.

Question 7

Which of the following statements about ion channels is TRUE?

Accepted Answer

Ion channels can be gated by voltage, ligands, or mechanical forces.

Question 8

The Na$$^+/K$^+$$ ATPase is an example of which type of transport?

Accepted Answer

Primary active transport

Question 9

Which of the following best explains why glucose cannot cross the plasma membrane by simple diffusion?

Accepted Answer

Glucose is a large uncharged polar molecule and requires a transporter.

Question 10

Which equation best describes the free energy change ($$\Delta G) $$for the movement of an uncharged solute across a membrane?

Accepted Answer

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

Question 11

A plant cell is placed in a hypotonic solution. What is the expected outcome?

Accepted Answer

The cell will become turgid (normal).

Question 12

Which of the following is a property of facilitated diffusion but NOT simple diffusion?

Accepted Answer

Can become saturated at high solute concentrations

Question 13

Which of the following best describes the function of aquaporins?

Accepted Answer

They allow rapid, selective movement of water molecules across the membrane.

Question 14

Which of the following scenarios is an example of antiport transport?

Accepted Answer

Cl$$^-$$ moving into the cell while HCO$$_3^-$$ moves out

Question 15

Which of the following is TRUE about the sodium-glucose symporter in intestinal epithelial cells?

Accepted Answer

It couples the movement of Na$$^+$$ down its gradient to drive glucose uptake against its gradient.

Question 16

Which of the following best explains why the Na$$^+/K$^+$$ ATPase is essential for nerve cell function?

Accepted Answer

It maintains the electrochemical gradients of Na$$^+$$ and K$$^+$$ required for action potentials.

Question 17

Which of the following is a key difference between primary and secondary active transport?

Accepted Answer

Primary active transport uses ATP hydrolysis directly, while secondary active transport uses the energy stored in ion gradients.

Question 18

A mutation in a gene encoding a membrane carrier protein results in the inability to transport a specific amino acid into the cell. Which process is most likely affected?

Accepted Answer

Facilitated diffusion

Question 19

Which of the following best describes the directionality of active transport?

Accepted Answer

It is always away from equilibrium, moving solutes up their concentration gradients.

Ch. 8: Transport Across Membranes-Overcoming the Permeability Barrier

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