Question 1

Which of the following molecules is most likely to diffuse directly through the phospholipid bilayer of a cell membrane without the assistance of a transport protein?

Accepted Answer

O$$_2$$

Question 2

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

Accepted Answer

It will swell and possibly burst because water moves into the cell by osmosis.

Question 3

Which of the following best describes facilitated diffusion?

Accepted Answer

Passive movement of molecules down their concentration gradient with the help of membrane proteins.

Question 4

A cell uses a sodium-potassium pump to maintain a high concentration of K$$^{+}$$ inside and Na$$^{+}$$ outside. Which type of transport is this, and what is the energy source?

Accepted Answer

Active transport; energy from ATP hydrolysis

Question 5

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water from an area of low solute concentration to high solute concentration.

Question 6

A plant cell is placed in a hypertonic solution. What is the most likely outcome for the cell?

Accepted Answer

The cell will lose water and undergo plasmolysis.

Question 7

Which of the following best explains why ions such as Na$$^{+}$$ and K$$^{+}$$ cannot easily cross the lipid bilayer?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the membrane.

Question 8

Which of the following is an example of coupled transport (cotransport) in cells?

Accepted Answer

A sucrose-H$$^{+}$$ symporter using the H$$^{+}$$ gradient to import sucrose against its concentration gradient.

Question 9

Which of the following best describes the function of aquaporins in the cell membrane?

Accepted Answer

They allow for the facilitated diffusion of water across the membrane.

Question 10

A cell is placed in an isotonic solution. What will happen to the net movement of water across the cell membrane?

Accepted Answer

There will be no net movement of water.

Question 11

Which of the following is NOT a characteristic of active transport?

Accepted Answer

Occurs spontaneously without energy input

Question 12

A cell uses a symporter to move two substances across the membrane. Which statement is true about this process?

Accepted Answer

Both substances move in the same direction across the membrane.

Question 13

Which of the following best explains why glucose requires a transport protein to cross the cell membrane?

Accepted Answer

Glucose is a large, polar molecule that cannot diffuse through the hydrophobic core.

Question 14

Which of the following scenarios best illustrates the concept of an electrochemical gradient?

Accepted Answer

A difference in both ion concentration and charge across a membrane.

Question 15

If a cell expends energy to move Ca$$^{2+}$$ ions from a region of low concentration to a region of high concentration, which equation best represents the change in free energy ($$\Delta G) $$for this process?

Accepted Answer

$$\Delta G \u003e 0$$

Question 16

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 17

A patient is given an intravenous solution that is hypertonic relative to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

The cells will lose water and shrink.

Question 18

Which of the following is an example of an antiporter?

Accepted Answer

A protein that moves Na$$^{+}$$ and K$$^{+} in $$opposite directions across the membrane.

Question 19

Which of the following best explains why maintaining concentration gradients across membranes is important for cells?

Accepted Answer

It enables the cell to perform work, such as ATP synthesis and nutrient uptake.

Cell Membranes and Transport Mechanisms

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