Question 1

Which of the following best describes the structure of the plasma membrane according to the fluid mosaic model?

Accepted Answer

A double layer of phospholipids with proteins and carbohydrates scattered throughout, allowing for fluidity and selective permeability

Question 2

Which of the following molecules can pass directly through the phospholipid bilayer without the help of membrane proteins?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 3

A patient is given an intravenous solution of 3% saline to treat swelling (edema). What is the effect of this hypertonic solution on the patient's cells?

Accepted Answer

Water will move out of the cells, causing them to shrink

Question 4

Which type of cell junction is most important in tissues that experience significant mechanical stress, such as skin?

Accepted Answer

Desmosomes

Question 5

Which of the following best explains why the plasma membrane is described as 'selectively permeable'?

Accepted Answer

It allows some molecules to pass while restricting others based on size, charge, and polarity

Question 6

Which process requires energy in the form of ATP to move substances across the plasma membrane against their concentration gradient?

Accepted Answer

Primary active transport

Question 7

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 8

Which of the following is a function of membrane carbohydrates (glycoproteins and glycolipids)?

Accepted Answer

Act as biological markers for cell recognition

Question 9

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of substances down their concentration gradient with the help of membrane proteins, without energy input

Question 10

Which equation best represents the Nernst equation for calculating the equilibrium potential ($$E_{ion}) $$for a particular ion across the plasma membrane?

Accepted Answer

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

Question 11

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

Accepted Answer

Glucose transport into the cell coupled with sodium influx

Question 12

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

Accepted Answer

It is primarily established by the unequal distribution of potassium ions ($$\mathrm{K^+}) $$across the membrane

Question 13

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

Accepted Answer

It stabilizes membrane fluidity and structure

Question 14

A cell needs to import large macromolecules such as proteins. Which process will it most likely use?

Accepted Answer

Endocytosis

Question 15

Which of the following is true about gap junctions?

Accepted Answer

They allow the passage of ions and small molecules between adjacent cells

Question 16

Which of the following best explains why sodium ions ($$\mathrm{Na^+}) $$cannot cross the plasma membrane by simple diffusion?

Accepted Answer

They are charged and hydrophilic

Question 17

Which of the following is a real-life example of facilitated diffusion?

Accepted Answer

Glucose entering muscle cells via GLUT transporters

Question 18

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

Accepted Answer

From an area of lower solute concentration to higher solute concentration

Question 19

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

Accepted Answer

Synthesizing proteins for export

Question 20

Which of the following best describes a symporter?

Accepted Answer

A protein that moves two substances in the same direction across the membrane

Chapter 3: The Plasma Membrane – Structure, Function, and Transport

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