Q: A cell uses the sodium-potassium pump to maintain ion gradients. Which equation best represents the energy requirement for this process?

$ \text{ATP} \rightarrow \text{ADP} + \text{P}_i + \text{energy} $

Question 1

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

Accepted Answer

A mosaic of proteins embedded in or attached to a bilayer of phospholipids, with both components able to move laterally.

Question 2

Which property of phospholipids is most responsible for the selective permeability of the plasma membrane?

Accepted Answer

Their amphipathic nature, having both hydrophilic heads and hydrophobic tails.

Question 3

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

Accepted Answer

It will swell and may burst as water enters the cell.

Question 4

Which of the following equations correctly represents the concept of concentration gradient driving passive diffusion?

Accepted Answer

$ \Delta C = C_{high} - C_{low} $

Question 5

Which type of membrane protein is most likely to be involved in cell recognition and immune response?

Accepted Answer

Glycoproteins

Question 6

What is the main function of cholesterol in the plasma membrane at low temperatures?

Accepted Answer

It prevents tight packing of phospholipids, maintaining membrane fluidity.

Question 7

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

Facilitated diffusion involves transport proteins that help move substances across the membrane.

Question 8

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

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the lipid bilayer.

Question 9

A cell uses the sodium-potassium pump to maintain ion gradients. Which equation best represents the energy requirement for this process?

Accepted Answer

$ 	ext{ATP} ightarrow 	ext{ADP} + 	ext{P}_i + 	ext{energy} $

Question 10

Which process allows a cell to take in large particles such as bacteria?

Accepted Answer

Phagocytosis

Question 11

Carrier proteins differ from channel proteins in that carrier proteins:

Accepted Answer

Bind to specific molecules and undergo a conformational change to transport them.

Question 12

Which of the following statements about active transport is correct?

Accepted Answer

Active transport requires energy, usually in the form of ATP.

Question 13

A plant cell placed in a hypertonic solution will:

Accepted Answer

Shrink as water leaves the cell, causing plasmolysis.

Question 14

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

Accepted Answer

Synthesizing phospholipids for the membrane.

Question 15

Which equation best represents the net movement of water during osmosis?

Accepted Answer

$ 	ext{Water moves from} \; 	ext{low solute concentration} \; 	ext{to high solute concentration} $

Question 16

Which of the following best describes exocytosis?

Accepted Answer

The fusion of vesicles with the plasma membrane to release contents outside the cell.

Question 17

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

Accepted Answer

Glucose entering a muscle cell via a specific transport protein.

Question 18

Which statement about membrane carbohydrates is correct?

Accepted Answer

They play a key role in cell-cell recognition.

Question 19

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

Accepted Answer

It will remain the same size as water moves in and out at equal rates.

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