Question 1

Which component of the fluid mosaic model is primarily responsible for the amphipathic nature of cellular membranes?

Accepted Answer

Phospholipid bilayer

Question 2

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

Accepted Answer

Hypotonic

Question 3

Which of the following best explains why unsaturated fatty acids increase membrane fluidity?

Accepted Answer

Their double bonds create kinks, preventing tight packing of phospholipids.

Question 4

Which type of membrane protein spans the entire phospholipid bilayer and is involved in transport?

Accepted Answer

Integral/transmembrane protein

Question 5

A cell uses a Na/K pump to maintain its electrochemical gradient. Which equation best represents the energy required for this active transport?

Accepted Answer

$$ \Delta G = RT \ln \left( \frac{[Na^+]_{in}}{[Na^+]_{out}} \right) + zF\Delta \Psi $$

Question 6

Which process allows a cell to engulf large particles, such as bacteria, by wrapping its plasma membrane around them?

Accepted Answer

Phagocytosis

Question 7

Facilitated diffusion differs from simple diffusion in that it:

Accepted Answer

Uses transport proteins to move substances down their concentration gradient

Question 8

Which of the following is a function of glycoproteins on the extracellular side of the plasma membrane?

Accepted Answer

Cell-cell recognition and signaling

Question 9

During osmoregulation, a plant cell in a hypertonic environment will:

Accepted Answer

Lose water and undergo plasmolysis

Question 10

Which of the following statements about carrier proteins is correct?

Accepted Answer

They undergo conformational changes to transport molecules across the membrane.

Question 11

A cell is placed in an isotonic solution. What will happen to the net movement of water across its plasma membrane?

Accepted Answer

There will be no net movement of water.

Question 12

Which process is responsible for the uptake of specific molecules, such as cholesterol, via ligand binding to cell surface receptors?

Accepted Answer

Receptor-mediated endocytosis

Question 13

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

Accepted Answer

It stabilizes membrane fluidity across temperature changes.

Question 14

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

Accepted Answer

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

Question 15

Which of the following is NOT a feature of the fluid mosaic model?

Accepted Answer

Membrane proteins are fixed and immobile.

Question 16

Which type of transport protein allows water molecules to cross the plasma membrane rapidly?

Accepted Answer

Aquaporin channel protein

Question 17

Which process requires energy to move molecules against their concentration gradient?

Accepted Answer

Active transport

Question 18

A neuron uses a proton pump to maintain its membrane potential. Which of the following best describes this process?

Accepted Answer

Active transport using ATP to move protons against the electrochemical gradient

Question 19

Which of the following is an example of bulk transport across the plasma membrane?

Accepted Answer

Exocytosis of neurotransmitters

Question 20

A cell is exposed to a toxin that blocks all carrier proteins. Which process will be most directly affected?

Accepted Answer

Facilitated diffusion of glucose

Cellular Membranes: Structure, Function, and Transport Mechanisms

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