Question 1

Which of the following best describes the relationship between osmotic equilibrium, chemical disequilibrium, and electrical disequilibrium in the human body?

Accepted Answer

Osmotic equilibrium means water and solute concentrations are equal, while chemical and electrical disequilibrium refer to differences in solute and charge distribution across compartments.

Question 2

A patient receives an intravenous solution that is hyperosmotic but isotonic to their cells. Which of the following best explains this scenario?

Accepted Answer

The solution contains both penetrating and nonpenetrating solutes, but the concentration of nonpenetrating solutes matches that of the cell.

Question 3

Which equation would you use to calculate the equilibrium potential for a single ion across a membrane, and what does it represent?

Accepted Answer

$$E_{ion} = \frac{61}{z} \log \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$; it represents the membrane potential at which the net movement of that ion is zero.

Question 4

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

Accepted Answer

Increasing the membrane surface area.

Question 5

A red blood cell is placed in a solution and swells until it bursts. Which of the following best describes the tonicity and osmolarity of the solution relative to the cell?

Accepted Answer

The solution is hypotonic and could be hyposmotic or isosmotic.

Question 6

Which of the following best explains why glucose is considered a nonpenetrating solute once inside the cell?

Accepted Answer

Glucose is immediately phosphorylated to glucose-6-phosphate, preventing it from leaving the cell.

Question 7

Which of the following transport processes requires energy directly from ATP hydrolysis?

Accepted Answer

Primary active transport

Question 8

A cell is placed in a solution containing 1 OsM NaCl and 1 OsM urea. Assuming urea is a penetrating solute and NaCl is nonpenetrating, what will happen to the cell?

Accepted Answer

The cell will swell because the solution is hypotonic.

Question 9

Which of the following best describes the function of the Na+/K+ ATPase in maintaining membrane potential?

Accepted Answer

It pumps 3 Na+ out of the cell and 2 K+ into the cell, creating and maintaining concentration gradients.

Question 10

Which of the following is a property of carrier-mediated transport but NOT simple diffusion?

Accepted Answer

Saturation at high substrate concentrations

Question 11

A patient with severe diarrhea loses 1.1 lbs of body weight. Approximately how much fluid should be replaced to restore their fluid balance?

Accepted Answer

500 mL

Question 12

Which of the following best describes the difference between osmolarity and tonicity?

Accepted Answer

Tonicity describes the effect of a solution on cell volume, while osmolarity measures the total concentration of solute particles.

Question 13

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

Accepted Answer

Na+-glucose symporter using the Na+ gradient to move glucose into the cell

Question 14

Which of the following is true regarding the resting membrane potential of a typical cell?

Accepted Answer

It is typically around $$-70 mV$$, with the inside of the cell being negative relative to the outside.

Question 15

Which of the following best describes the process of transcytosis?

Accepted Answer

Transport of large molecules across an epithelium via endocytosis, vesicular transport, and exocytosis

Question 16

Which of the following would most likely cause depolarization of a cell membrane?

Accepted Answer

Influx of Na+ ions into the cell

Question 17

Which of the following is a property of open (leak) channels in the cell membrane?

Accepted Answer

They allow ions to move freely across the membrane without regulation.

Question 18

Which of the following best explains why the human body cannot rely solely on diffusion for nutrient delivery to all cells?

Accepted Answer

Diffusion is too slow over long distances in the body.

Question 19

Which of the following is true regarding the movement of water across cell membranes?

Accepted Answer

Water moves freely through aquaporin channels and is driven by solute concentration gradients.

Membrane Dynamics: Osmosis, Tonicity, and Transport Mechanisms

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