Question 1

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

Accepted Answer

A flexible bilayer of phospholipids with proteins embedded or attached, allowing lateral movement.

Question 2

Phospholipids are described as amphipathic molecules. What does 'amphipathic' mean in this context?

Accepted Answer

They contain both hydrophilic and hydrophobic regions.

Question 3

Which of the following adaptations would you expect in the cell membranes of fish living in extremely cold environments?

Accepted Answer

A high proportion of unsaturated hydrocarbon tails in phospholipids.

Question 4

What is the primary function of cholesterol in animal cell membranes at low temperatures?

Accepted Answer

It prevents tight packing of phospholipids, maintaining fluidity.

Question 5

Which type of membrane protein penetrates the hydrophobic core of the lipid bilayer and often spans the entire membrane?

Accepted Answer

Integral proteins

Question 6

A patient with familial hypercholesterolemia is found to have defective LDL receptor proteins. What is the most likely consequence?

Accepted Answer

Cholesterol accumulates in the blood, increasing risk of heart disease.

Question 7

Which of the following molecules can most easily cross the plasma membrane without the aid of a transport protein?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 8

Which equation best represents the energy requirement for active transport by the sodium-potassium pump?

Accepted Answer

$$\mathrm{ATP \rightarrow ADP + P_i}$$

Question 9

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

Accepted Answer

Synthesis of phospholipids

Question 10

A nerve cell responds to an electrical stimulus by opening potassium ion channels. What type of transport is this?

Accepted Answer

Facilitated diffusion through gated channels

Question 11

Which process allows a cell to engulf large particles, such as bacteria, by extending pseudopodia?

Accepted Answer

Phagocytosis

Question 12

During receptor-mediated endocytosis, what triggers the formation of a coated vesicle?

Accepted Answer

Binding of solute to receptor proteins

Question 13

Which of the following best explains why facilitated diffusion is considered passive transport?

Accepted Answer

It moves solutes down their concentration gradient without energy input.

Question 14

In plants, which pump is primarily responsible for generating membrane potential?

Accepted Answer

Proton pump

Question 15

Which of the following equations describes the electrochemical gradient that drives ion diffusion across membranes?

Accepted Answer

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

Question 16

A patient suffering from severe diarrhea is given a solution containing both glucose and sodium chloride. Why is this treatment effective?

Accepted Answer

Glucose and sodium are absorbed together via cotransporters in the intestine.

Question 17

Which of the following statements about bulk transport is correct?

Accepted Answer

Exocytosis and endocytosis are types of bulk transport for large molecules.

Question 18

Which type of transport protein is responsible for the rapid movement of water across the plasma membrane?

Accepted Answer

Aquaporin

Question 19

Which of the following best describes the sidedness of membranes?

Accepted Answer

The composition and distribution of proteins, lipids, and carbohydrates are asymmetrical across the membrane.

Question 20

Which of the following is a real-world example of cell-surface proteins affecting disease susceptibility?

Accepted Answer

Individuals lacking CCR5 co-receptor are immune to HIV infection.

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

Study Guide - Practice Questions