$$\text{Water moves from a region of low solute concentration to a region of high solute concentration}$$

Question 1

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

Accepted Answer

A double layer of phospholipids with proteins embedded or attached, where both lipids and proteins can move laterally.

Question 2

Phospholipids are described as amphipathic molecules. What does this mean?

Accepted Answer

They have both hydrophobic and hydrophilic regions.

Question 3

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Cholesterol restrains movement of phospholipids at warm temperatures and prevents tight packing at cool temperatures.

Question 4

A red blood cell is placed in a solution and swells until it bursts. Which type of solution was it placed in?

Accepted Answer

Hypotonic

Question 5

Which of the following best explains why ions such as Na$$ ^+ $$ and K$$ ^+ $$ cannot easily cross the plasma membrane without assistance?

Accepted Answer

They are hydrophilic and cannot pass through the hydrophobic core of the membrane.

Question 6

Which of the following is a function of membrane proteins?

Accepted Answer

Facilitating cell-cell recognition

Question 7

A plant cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will become plasmolyzed as water leaves the cell.

Question 8

Which process requires energy input from ATP to move substances against their concentration gradient?

Accepted Answer

Active transport

Question 9

The sodium-potassium pump moves Na$$ ^+ $$ and K$$ ^+ $$ ions across the plasma membrane. Which of the following best describes its action?

Accepted Answer

It moves Na$$ ^+ $$ out of the cell and K$$ ^+ $$ into the cell, both against their concentration gradients.

Question 10

Which of the following best describes receptor-mediated endocytosis?

Accepted Answer

The cell takes in specific molecules after they bind to receptors on the cell surface.

Question 11

Which equation best represents the movement of water during osmosis?

Accepted Answer

$$	ext{Water moves from a region of low solute concentration to a region of high solute concentration}$$

Question 12

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses transport proteins to move substances down their concentration gradient.

Question 13

A patient is given an intravenous (IV) solution that is hypotonic relative to their blood cells. What is the most likely outcome?

Accepted Answer

Their blood cells will swell and may burst as water enters the cells.

Question 14

Which of the following best explains why cholesterol is important in animal cell membranes?

Accepted Answer

It helps maintain membrane fluidity at different temperatures.

Question 15

Which of the following is an example of cotransport?

Accepted Answer

A proton pump creating a gradient that drives the uptake of sucrose against its concentration gradient.

Question 16

Which of the following statements about glycoproteins and glycolipids is correct?

Accepted Answer

They play a key role in cell-cell recognition.

Question 17

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

Accepted Answer

They facilitate the rapid diffusion of water across the membrane.

Question 18

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

Accepted Answer

DNA replication

Question 19

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

There will be no net movement of water into or out of the cell.

Question 20

Which of the following best describes the difference between exocytosis and endocytosis?

Accepted Answer

Exocytosis releases substances from the cell, while endocytosis brings substances into the cell.

Chapter 7: Membranes – Structure and Function

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