Q: Which equation correctly represents the movement of water during osmosis?

$\text{Water moves from an area of lower solute concentration to an area of higher solute concentration}$

Question 1

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

Accepted Answer

A dynamic structure with proteins embedded in or attached to a fluid phospholipid bilayer.

Question 2

Which type of molecule is most likely to diffuse rapidly across a pure phospholipid bilayer without the aid of a transport protein?

Accepted Answer

A small hydrophobic molecule such as $O_2$.

Question 3

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

Accepted Answer

It will swell and possibly burst because water will move into the cell.

Question 4

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It involves transport proteins that help specific molecules cross the membrane down their concentration gradient.

Question 5

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

Accepted Answer

Active transport

Question 6

Which of the following best explains why plant cells do not burst when placed in a hypotonic solution?

Accepted Answer

The cell wall exerts turgor pressure that counteracts the influx of water.

Question 7

A patient with familial hypercholesterolemia has high blood cholesterol due to a defect in which cellular process?

Accepted Answer

Receptor-mediated endocytosis of LDL particles

Question 8

Which of the following is a function of membrane proteins?

Accepted Answer

Catalyzing metabolic reactions

Question 9

If a cell is placed in a solution where the solute concentration is higher outside the cell than inside, what type of solution is this, and what will happen to the cell?

Accepted Answer

Hypertonic; the cell will lose water and shrink.

Question 10

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

It stabilizes membrane fluidity across temperature changes.

Question 11

A scientist observes that a certain molecule crosses the plasma membrane only when a specific protein is present, and the process does not require ATP. Which transport mechanism is most likely involved?

Accepted Answer

Facilitated diffusion

Question 12

Which equation correctly represents the movement of water during osmosis?

Accepted Answer

$	ext{Water moves from an area of lower solute concentration to an area of higher solute concentration}$

Question 13

Which of the following statements about active transport is correct?

Accepted Answer

It requires energy, often from ATP hydrolysis.

Question 14

Which of the following is NOT a function of cell-surface membrane proteins?

Accepted Answer

DNA replication

Question 15

A plant cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will undergo plasmolysis as water leaves the cell.

Question 16

Which of the following best describes the function of aquaporins?

Accepted Answer

They provide channels for rapid diffusion of water molecules.

Question 17

Which of the following scenarios best illustrates bulk transport across the plasma membrane?

Accepted Answer

A white blood cell engulfing a bacterium via phagocytosis.

Question 18

Which of the following statements about the sodium-potassium pump is true?

Accepted Answer

It uses ATP to move $Na^+$ out of the cell and $K^+$ into the cell against their concentration gradients.

Question 19

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 charged and cannot pass through the hydrophobic core of the membrane.

Question 20

A cell is placed in an isotonic solution. Which of the following best describes the movement of water?

Accepted Answer

There is no net movement of water across the membrane.

Cellular Membranes and Transport Mechanisms

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