Question 1

Which of the following best describes the fluid mosaic model of biological membranes?

Accepted Answer

A dynamic arrangement of phospholipids, proteins, and cholesterol that move laterally within the membrane.

Question 2

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

Accepted Answer

Synthesizing proteins.

Question 3

A red blood cell is placed in a solution and swells until it bursts. Which type of solution was the cell placed in, and what process caused this outcome?

Accepted Answer

Hypotonic solution; osmosis of water into the cell.

Question 4

Which molecule most easily diffuses across a biological membrane's lipid bilayer, without help of a protein?

Accepted Answer

O$$_2$$

Question 5

A cell needs to import a large, polar molecule against its concentration gradient. Which transport mechanism will it most likely use?

Accepted Answer

Active transport using a membrane protein and ATP

Question 6

Which of the following statements about diffusion is true?

Accepted Answer

It is the movement of a substance from an area of high concentration to an area of low concentration.

Question 7

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

Accepted Answer

It stabilizes membrane fluidity across temperature changes.

Question 8

A scientist observes that a certain molecule can cross the cell membrane only when a specific protein is present, and the process does not require energy. Which transport process is being observed?

Accepted Answer

Facilitated diffusion

Question 9

Which of the following is a correct statement about integral membrane proteins?

Accepted Answer

They span the entire lipid bilayer.

Question 10

A cell is placed in a solution containing a high concentration of Na$$ ^+ $$ ions. Over time, Na$$ ^+ $$ ions move into the cell through a channel protein, but not against their concentration gradient. Which process is this?

Accepted Answer

Facilitated diffusion

Question 11

Which of the following best explains why large macromolecules like proteins cannot freely diffuse across the plasma membrane?

Accepted Answer

They are too large and often polar, preventing them from passing through the hydrophobic core of the lipid bilayer.

Question 12

Which of the following is NOT a component of the biological membrane according to the fluid mosaic model?

Accepted Answer

DNA

Question 13

A white blood cell engulfs a bacterium by surrounding it with its plasma membrane and forming a vesicle. What is this process called?

Accepted Answer

Phagocytosis

Question 14

Which of the following equations best represents the direction of net diffusion for a solute across a membrane?

Accepted Answer

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

Question 15

If a cell membrane is described as 'selectively permeable,' what does this mean?

Accepted Answer

It regulates what substances can enter or leave the cell.

Question 16

Which of the following best describes the movement of water across a selectively permeable membrane?

Accepted Answer

Osmosis

Question 17

A cell uses ATP to pump ions from an area of low concentration to an area of high concentration. Which type of transport is this?

Accepted Answer

Active transport

Question 18

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

Accepted Answer

Glucose entering a muscle cell via a GLUT transporter.

Question 19

Which of the following statements about the structure of phospholipids is correct?

Accepted Answer

They have one hydrophilic head and two hydrophobic tails.

Question 20

Which of the following best explains why oxygen (O$$_2) $$can diffuse freely across the plasma membrane?

Accepted Answer

It is a small, nonpolar molecule.

Cell Membranes and Membrane Transport: Study Notes for General Biology

Study Guide - Practice Questions

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