Q: Which formula best represents the Nernst equation for calculating the equilibrium potential for an ion?

$$E = \frac{RT}{zF} \ln \left( \frac{[\text{ion}]_{\text{out}}}{[\text{ion}]_{\text{in}}} \right)$$

Question 1

Which of the following best describes the primary function of the plasma membrane in a typical human cell?

Accepted Answer

It acts as a selectively permeable barrier, regulating the movement of substances into and out of the cell.

Question 2

Which type of membrane transport requires energy directly from ATP hydrolysis to move substances against their concentration gradient?

Accepted Answer

Primary active transport

Question 3

A red blood cell is placed in a hypertonic solution. What will happen to the cell, and why?

Accepted Answer

It will shrink because water leaves the cell to the area of higher solute concentration.

Question 4

Which of the following molecules can pass directly through the lipid bilayer of the plasma membrane without assistance?

Accepted Answer

Small, nonpolar molecules like O$$_2$$

Question 5

What is the main difference between channel proteins and carrier proteins in facilitated diffusion?

Accepted Answer

Channel proteins provide a hydrophilic pathway for ions and small molecules, while carrier proteins undergo conformational changes to move specific substances.

Question 6

Which equation best represents the movement of molecules during simple diffusion?

Accepted Answer

$$J = -D \frac{dC}{dx}$$

Question 7

The sodium-potassium pump is an example of which type of membrane transport?

Accepted Answer

Primary active transport

Question 8

Which of the following best explains why the resting membrane potential of a neuron is typically around -70 mV?

Accepted Answer

The membrane is most permeable to K$$^{+}$$ ions due to leak channels, but also slightly permeable to Na$$^{+}$$, making the potential slightly more positive than the K$$^{+}$$ equilibrium potential.

Question 9

Which of the following is a correct example of secondary active transport?

Accepted Answer

Na$$^{+}-$$glucose cotransporter uses the Na$$^{+}$$ gradient created by the Na$$^{+}-K$^{+}$$ pump to move glucose into the cell against its concentration gradient.

Question 10

A patient with severe edema is given a hypertonic saline solution intravenously. What is the physiological rationale for this treatment?

Accepted Answer

Hypertonic solution draws water from the tissues into the blood, reducing swelling.

Question 11

Which of the following statements about desmosomes is correct?

Accepted Answer

Desmosomes anchor adjacent cells together, providing mechanical strength to tissues.

Question 12

Which process is described by the movement of water from an area of lower solute concentration to an area of higher solute concentration across a selectively permeable membrane?

Accepted Answer

Osmosis

Question 13

Which of the following best describes the role of cholesterol in the plasma membrane?

Accepted Answer

Cholesterol increases membrane fluidity and stability.

Question 14

A cell is placed in a solution and water moves into the cell, causing it to swell. What type of solution is the cell in?

Accepted Answer

Hypotonic

Question 15

Which formula best represents the Nernst equation for calculating the equilibrium potential for an ion?

Accepted Answer

$$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{out}}}{[	ext{ion}]_{	ext{in}}} ight)$$

Question 16

Which of the following is NOT a function of the plasma membrane?

Accepted Answer

Synthesizing ATP for cellular energy

Question 17

Which of the following best describes the movement of Na$$^{+}$$ and K$$^{+}$$ ions by the sodium-potassium pump?

Accepted Answer

3 Na$$^{+}$$ ions are pumped out of the cell and 2 K$$^{+}$$ ions are pumped into the cell per ATP hydrolyzed.

Question 18

Which of the following best explains why polar molecules require transport proteins to cross the plasma membrane?

Accepted Answer

Polar molecules are repelled by the hydrophobic core of the lipid bilayer.

Question 19

Which of the following is an example of an antiporter?

Accepted Answer

Na$$^{+}-K$^{+}$$ pump, which moves Na$$^{+}$$ out and K$$^{+} in $$simultaneously.

The Plasma Membrane: Structure, Function, and Transport Mechanisms

Study Guide - Practice Questions

Study Guide - Flashcards