Question 1

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

Accepted Answer

The membrane consists of a bilayer of phospholipids with proteins embedded and able to move laterally.

Question 2

Which property of phospholipids is most critical for the spontaneous formation of biological membranes?

Accepted Answer

Their amphipathic nature, having both hydrophilic and hydrophobic regions.

Question 3

A cell is placed in a solution and swells until it bursts. What type of solution is the cell in, and what process is responsible?

Accepted Answer

Hypotonic solution; osmosis

Question 4

Which equation best represents the net movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$J_{water} = k (C_{water, outside} - C_{water, inside})$

Question 5

Which of the following best explains why only 'free' water molecules move across a selectively permeable membrane during osmosis?

Accepted Answer

Bound water molecules are attached to solutes and cannot diffuse freely.

Question 6

Dr. Agre received the Nobel Prize for discovering aquaporins. What is the primary function of aquaporins in cells?

Accepted Answer

Allow rapid diffusion of water molecules across the membrane.

Question 7

Which process requires energy input from the cell and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 8

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

Accepted Answer

It will lose water and become plasmolyzed.

Question 9

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

Accepted Answer

Providing structural support to the cell wall

Question 10

During phagocytosis, which cellular process is primarily involved?

Accepted Answer

Endocytosis of large particles

Question 11

Which scenario best illustrates facilitated diffusion?

Accepted Answer

Glucose moving into a cell through a specific transport protein down its concentration gradient.

Question 12

Which equation describes the rate of simple diffusion across a membrane?

Accepted Answer

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

Question 13

What is the main difference between passive and active transport?

Accepted Answer

Active transport requires energy and moves substances against their concentration gradient, while passive transport does not require energy and moves substances down their gradient.

Question 14

Which process is responsible for the uptake of large molecules such as proteins into a cell?

Accepted Answer

Endocytosis

Question 15

A red blood cell is placed in a solution with lower solute concentration than its cytoplasm. What will happen?

Accepted Answer

Water will enter the cell, causing it to swell and possibly burst.

Question 16

Which of the following best describes the role of ATP in active transport?

Accepted Answer

ATP provides energy to move molecules against their concentration gradient.

Question 17

Which of the following is true about membrane selectivity?

Accepted Answer

Only nonpolar and small molecules can diffuse directly through the lipid bilayer.

Question 18

Which process involves the fusion of vesicles with the plasma membrane to release contents outside the cell?

Accepted Answer

Exocytosis

Question 19

Which of the following best explains why plant cells do not burst in hypotonic solutions?

Accepted Answer

The cell wall provides structural support and prevents bursting.

Question 20

Which of the following is a real-world example of membrane transport affecting human health?

Accepted Answer

Cystic fibrosis results from a defective chloride channel protein, affecting ion transport across membranes.

Membrane Structure, Function, and Transport in Cells

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