Q: Which of the following is a correct application of Fick’s Law for the rate of diffusion ($$R_{diffusion}$$)?

$$R_{diffusion} \propto \text{surface area} \times \text{concentration gradient} \times \text{membrane permeability}$$

Question 1

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

Accepted Answer

Osmolarity refers to the number of solute particles per unit volume, while tonicity describes the effect of a solution on cell volume.

Question 2

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

Accepted Answer

The solution is hypotonic relative to the cell.

Question 3

According to Fick’s Law, which of the following changes would increase the rate of diffusion across a cell membrane?

Accepted Answer

Increasing the concentration gradient across the membrane.

Question 4

Given the equation for osmolarity $$C = \frac{S}{V}$$, where $$S is $$the number of solutes (in mOsm) and $$V is $$the volume (in L), what happens to the osmolarity if you double the volume without changing the number of solutes?

Accepted Answer

Osmolarity is halved.

Question 5

Which of the following is NOT a factor that affects membrane permeability according to Fick’s Law?

Accepted Answer

Temperature of the extracellular fluid.

Question 6

A patient is given an intravenous solution that is hypertonic to their red blood cells. What is the most likely outcome for the cells?

Accepted Answer

The cells will shrink as water leaves them.

Question 7

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient via a membrane protein, without energy input.

Question 8

Which of the following is a correct application of Fick’s Law for the rate of diffusion ($$R_{diffusion}$$)?

Accepted Answer

$$R_{diffusion} \propto 	ext{surface area} 	imes 	ext{concentration gradient} 	imes 	ext{membrane permeability}$$

Question 9

Which of the following statements about membrane transporters is TRUE?

Accepted Answer

Carrier proteins never form an open channel between both sides of the membrane.

Question 10

A cell uses a symport carrier to move glucose into the cell along with sodium ions. Which of the following best describes this process?

Accepted Answer

Secondary active transport, because sodium moves down its gradient and glucose moves against its gradient.

Question 11

Which of the following best explains why changing the composition of the lipid layer can alter membrane permeability?

Accepted Answer

Altering lipid composition can increase or decrease the ease with which molecules cross the membrane.

Question 12

Which of the following is an example of homeostasis in the human body?

Accepted Answer

Regulation of blood glucose levels after eating a meal.

Question 13

If a cell is placed in a solution with a lower concentration of non-penetrating solutes than the cell’s cytoplasm, what will happen?

Accepted Answer

Water will enter the cell, causing it to swell.

Question 14

Which of the following is a function of membrane receptor proteins?

Accepted Answer

Transmitting signals from the extracellular environment to the cell’s interior.

Question 15

A solution contains 600 mOsm of solutes in 2 L of water. What is its osmolarity?

Accepted Answer

$$C = \frac{600\ 	ext{mOsm}}{2\ 	ext{L}} = 300\ 	ext{mOsm/L}$$

Question 16

Which of the following best describes the movement of water in osmosis?

Accepted Answer

Water moves from an area of low solute concentration to an area of high solute concentration.

Question 17

Which of the following is a property of channel proteins?

Accepted Answer

They create a water-filled pore that allows specific molecules to pass through.

Question 18

Which of the following is a correct statement about the distribution of body fluids?

Accepted Answer

About two-thirds of body fluid is intracellular, and one-third is extracellular.

Question 19

Which of the following best describes the function of the SGLT protein in the intestine or kidney?

Accepted Answer

It co-transports sodium and glucose into the cell, using the sodium gradient to drive glucose uptake.

Osmolarity, Tonicity, Diffusion, and Membrane Transport in Human Physiology

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