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

$$ \text{Rate of diffusion} = \text{membrane permeability} \times \text{membrane surface area} \times \text{concentration gradient} $$

Q: Which equation is used to calculate the equilibrium potential for an ion across a membrane?

$$ E = \frac{61}{z} \log \left( \frac{[\text{ion}]_{\text{out}}}{[\text{ion}]_{\text{in}}} \right) $$

Question 1

Which of the following best describes the concept of homeostasis in relation to body fluid compartments?

Accepted Answer

Homeostasis refers to the maintenance of a stable internal environment, but does not mean equilibrium between fluid compartments; the body is in osmotic equilibrium but chemical and electrical disequilibrium.

Question 2

A cell is placed in a solution and swells. Which statement best explains the tonicity of the solution?

Accepted Answer

The solution is hypotonic to the cell.

Question 3

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

Accepted Answer

$$ 	ext{Rate of diffusion} = 	ext{membrane permeability} 	imes 	ext{membrane surface area} 	imes 	ext{concentration gradient} $$

Question 4

Which of the following statements about osmolarity and tonicity is correct?

Accepted Answer

Osmolarity describes the concentration of solutes, while tonicity describes the effect of a solution on cell volume.

Question 5

A patient receives an intravenous solution containing 2 OsM glucose. Compared to their cells (1 OsM glucose), what is the osmolarity and expected effect on cell volume?

Accepted Answer

The solution is hyperosmotic and cells will shrink.

Question 6

Which of the following is a property of simple diffusion across the cell membrane?

Accepted Answer

It is faster for smaller and more lipophilic molecules.

Question 7

Which type of membrane protein is responsible for forming open, water-filled passageways that allow ions to move across the membrane?

Accepted Answer

Channel proteins

Question 8

The sodium-potassium pump (Na$$^+-K$^+-$$ATPase) is an example of which type of transport?

Accepted Answer

Primary active transport

Question 9

Which of the following best describes the mechanism of secondary active transport?

Accepted Answer

It uses the energy stored in the concentration gradient of one molecule to move another molecule against its gradient.

Question 10

A cell membrane is permeable to K$$^+$$ but not to Na$$^+. If K$^+$$ leak channels are inserted, what will happen to the membrane potential?

Accepted Answer

The cell will develop a negative membrane potential inside due to K$$^+$$ leaving the cell.

Question 11

Which equation is used to calculate the equilibrium potential for an ion across a membrane?

Accepted Answer

$$ E = \frac{61}{z} \log \left( \frac{[	ext{ion}]_{	ext{out}}}{[	ext{ion}]_{	ext{in}}} ight) $$

Question 12

Which of the following is true regarding facilitated diffusion?

Accepted Answer

It uses carrier proteins to move molecules down their concentration gradient.

Question 13

Which process is responsible for the uptake of large particles, such as bacteria, into a cell?

Accepted Answer

Phagocytosis

Question 14

During insulin secretion in pancreatic beta cells, which event directly triggers exocytosis of insulin-containing vesicles?

Accepted Answer

Opening of voltage-gated Ca$$^{2+}$$ channels and influx of Ca$$^{2+}$$

Question 15

Which of the following best describes the difference between paracellular and transcellular epithelial transport?

Accepted Answer

Transcellular transport requires crossing two membranes and may involve both active and passive mechanisms, while paracellular transport occurs through junctions between adjacent cells.

Question 16

Which property is NOT characteristic of carrier-mediated transport?

Accepted Answer

Ability to form continuous open channels across the membrane

Question 17

Which of the following would increase the rate of simple diffusion of a lipophilic molecule across a cell membrane?

Accepted Answer

Increasing the lipid solubility of the molecule

Question 18

Which statement about bulk flow is correct?

Accepted Answer

Bulk flow is the movement of fluids (gases and liquids) from regions of high pressure to low pressure.

Question 19

Which of the following is a clinical implication of understanding osmolarity and tonicity?

Accepted Answer

It helps determine the appropriate intravenous solution to administer to patients to avoid cell swelling or shrinking.

Membrane Dynamics: Osmosis, Transport, and Membrane Potential

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