Q: Which equation correctly represents Fick’s Law for the rate of simple diffusion across a membrane?

$$v = P \Delta S / \text{unit area}$$

Question 1

Which of the following molecules is most likely to cross a pure phospholipid bilayer by simple diffusion, without the aid of a transport protein?

Accepted Answer

Oxygen (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 the cell.

Question 3

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

Accepted Answer

Facilitated diffusion moves solutes down their concentration gradient without energy input, while active transport moves solutes up their gradient using energy.

Question 4

Which equation correctly represents Fick’s Law for the rate of simple diffusion across a membrane?

Accepted Answer

$$v = P \Delta S / 	ext{unit area}$$

Question 5

A cell uses a symporter to import glucose along with sodium ions. Which type of transport is this, and what is the energy source?

Accepted Answer

Indirect active transport; sodium ion gradient

Question 6

Which of the following statements about carrier proteins is TRUE?

Accepted Answer

They exhibit saturation kinetics similar to enzymes.

Question 7

What is the main reason ions such as Na\^+ and Cl\^- cannot cross the lipid bilayer by simple diffusion?

Accepted Answer

They are charged and interact unfavorably with the hydrophobic core.

Question 8

Which of the following best describes the function of aquaporins?

Accepted Answer

They allow rapid, selective diffusion of water molecules.

Question 9

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

Cells will shrink as water leaves the cells.

Question 10

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

Accepted Answer

Requirement for a membrane protein

Question 11

The sodium-potassium pump (Na\^+/K\^+ ATPase) is an example of which type of transport, and what is its main function?

Accepted Answer

Direct active transport; maintains high K\^+ inside and high Na\^+ outside the cell

Question 12

Which of the following best explains why facilitated diffusion shows saturation kinetics?

Accepted Answer

The rate is limited by the number of available transport proteins.

Question 13

Which of the following is TRUE about the energetics of transport for uncharged solutes?

Accepted Answer

The equilibrium constant ($$K_{eq}) is $$always 1, so $$\Delta G^\circ is $$always 0.

Question 14

Which of the following is an example of an antiporter?

Accepted Answer

Chloride-bicarbonate exchanger

Question 15

A cell is placed in a solution and water moves into the cell, causing it to swell. Which of the following best describes the solution?

Accepted Answer

Hypotonic

Question 16

Which of the following statements about ion channels is correct?

Accepted Answer

They can be gated by voltage, ligands, or mechanical forces.

Question 17

Which of the following best describes the alternating conformation model of carrier proteins?

Accepted Answer

Carrier proteins bind substrate, change conformation, and release substrate on the other side.

Question 18

Which of the following is a key difference between porins and ion channels?

Accepted Answer

Porins are large and less selective, while ion channels are smaller and highly selective.

Question 19

Which of the following best describes the direction of water movement during osmosis?

Accepted Answer

From low solute concentration to high solute concentration

Membrane Transport Mechanisms in Cell Biology

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