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

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

Question 1

A 70-kg man has a total body water volume of 42 L. If the intracellular fluid (ICF) is 2/3 of the total body water, what is the volume of the ICF?

Accepted Answer

28 L

Question 2

Which of the following best describes the distribution of sodium (Na+) and potassium (K+) ions in the body’s fluid compartments?

Accepted Answer

Na+ is high in the ECF, K+ is high in the ICF

Question 3

A cell is placed in a solution containing 200 mOsM nonpenetrating solutes. The cell’s internal osmolarity is 300 mOsM nonpenetrating solutes. What will happen to the cell?

Accepted Answer

The cell will swell because the solution is hypotonic.

Question 4

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

Accepted Answer

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

Question 5

A patient receives an intravenous (IV) solution of 1 L of 300 mOsM NaCl. What is the effect on the patient’s ECF and ICF volumes?

Accepted Answer

ECF volume increases, ICF volume does not change

Question 6

Which of the following is a property of carrier proteins but NOT channel proteins?

Accepted Answer

They never form an open channel between the two sides of the membrane.

Question 7

The Na+-K+-ATPase is an example of which type of membrane transport?

Accepted Answer

Primary active transport

Question 8

A solution contains 250 mOsM NaCl (nonpenetrating) and 250 mOsM urea (penetrating). What is the tonicity of this solution relative to a cell with 300 mOsM nonpenetrating solutes?

Accepted Answer

Hypotonic, because only nonpenetrating solutes determine tonicity

Question 9

Which of the following best explains why potassium iodide (KI) diffuses faster than Congo red in an agar gel experiment?

Accepted Answer

KI has a smaller molecular size than Congo red.

Question 10

Which of the following statements about the resting membrane potential is correct?

Accepted Answer

It is due to a small leak of K+ out of the cell, leaving the inside negative.

Question 11

A 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 to the cell.

Question 12

Which of the following is the correct Nernst equation for calculating the equilibrium potential for an ion?

Accepted Answer

$$E_{ion} = \frac{61}{z} \log \frac{[ion]_{out}}{[ion]_{in}}$$

Question 13

Which of the following best describes the function of the GLUT transporter in most cells?

Accepted Answer

It allows glucose to move down its concentration gradient by facilitated diffusion.

Question 14

In the context of cystic fibrosis, what is the primary defect in the CFTR protein?

Accepted Answer

It is a nonfunctional chloride channel.

Question 15

Which of the following is a property 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 16

A cell is placed in a solution containing 400 mOsM urea (penetrating) and 100 mOsM NaCl (nonpenetrating). The cell’s internal osmolarity is 300 mOsM nonpenetrating solutes. What will happen to the cell?

Accepted Answer

The cell will swell because the solution is hypotonic.

Question 17

Which of the following best explains why plasma proteins are not found in the interstitial fluid?

Accepted Answer

Plasma proteins are too large to cross the capillary wall.

Question 18

Which of the following is a feature of vesicular transport?

Accepted Answer

It requires ATP and can move large molecules or particles.

Question 19

In transepithelial glucose absorption in the intestine, which transporter is responsible for moving glucose from the epithelial cell into the extracellular fluid?

Accepted Answer

GLUT transporter

Membrane Dynamics: Structure, Function, and Transport Mechanisms

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