Question 1

Which of the following best explains why phospholipids form a bilayer in aqueous environments?

Accepted Answer

Their hydrophilic heads interact with water, while their hydrophobic tails avoid water.

Question 2

A freshwater Paramecium lives in a hypotonic environment. Which cellular structure and process are most critical for its survival?

Accepted Answer

Contractile vacuole; osmoregulation

Question 3

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Membranes with more unsaturated fatty acids remain fluid at lower temperatures.

Question 4

A red blood cell is placed in a solution and swells until it bursts. Which of the following best describes the solution?

Accepted Answer

Hypotonic

Question 5

Which of the following molecules would most easily diffuse through a pure phospholipid bilayer without the help of a transport protein?

Accepted Answer

Oxygen ($$O_2)$$

Question 6

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

Accepted Answer

It will plasmolyze because water leaves the cell.

Question 7

Which of the following best describes the function of the sodium-potassium pump in animal cells?

Accepted Answer

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

Question 8

Which of the following is an example of facilitated diffusion?

Accepted Answer

Glucose entering a cell via a carrier protein

Question 9

A patient has a genetic disorder causing defective LDL receptor proteins. What is the most likely consequence?

Accepted Answer

Cholesterol will accumulate in the blood, increasing risk of heart disease.

Question 10

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

The cell takes in specific molecules after they bind to receptors clustered in coated pits.

Question 11

Which of the following equations best represents the movement of water during osmosis?

Accepted Answer

$$H_2O$$ moves from a region of lower solute concentration to higher solute concentration.

Question 12

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

Accepted Answer

Synthesis of phospholipids

Question 13

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

Accepted Answer

It will become flaccid due to no net water movement.

Question 14

Which of the following best describes the electrochemical gradient?

Accepted Answer

It is the combined effect of a chemical gradient and an electrical gradient across a membrane.

Question 15

Which of the following scenarios is an example of cotransport?

Accepted Answer

A proton pump creating an $$H^+$$ gradient that drives sucrose uptake into a plant cell.

Question 16

Which of the following statements about the sidedness of membranes is correct?

Accepted Answer

The inside and outside faces of membranes have distinct compositions of proteins, lipids, and carbohydrates.

Question 17

Which of the following best explains why facilitated diffusion does not require energy?

Accepted Answer

Molecules move down their concentration gradient with the help of transport proteins.

Question 18

Which of the following is a real-life example of bulk transport via exocytosis?

Accepted Answer

A pancreatic cell releasing insulin into the bloodstream.

Question 19

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

Accepted Answer

They provide a hydrophilic channel for rapid water movement across the membrane.

Question 20

A scientist observes that a certain molecule crosses the plasma membrane only when a specific protein is present, and the process requires ATP. Which type of transport is this?

Accepted Answer

Active transport

Membrane Structure and Function: Study Notes (Campbell Biology, Chapter 7)

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