Question 1

Which of the following best describes the amphipathic nature of phospholipids in the plasma membrane?

Accepted Answer

Phospholipids have both hydrophilic heads and hydrophobic tails, allowing them to form bilayers in aqueous environments.

Question 2

A researcher observes that a certain membrane protein can be easily removed from the plasma membrane by washing the cell with a high-salt solution. What type of protein is this most likely to be?

Accepted Answer

Peripheral membrane protein

Question 3

Which of the following changes would most likely increase the fluidity of a cell membrane at low temperatures?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in the phospholipids

Question 4

A mutation causes a cell to lack the CCR5 co-receptor on its surface. What is a likely consequence of this mutation?

Accepted Answer

The cell will be resistant to HIV infection because the virus cannot enter without CCR5.

Question 5

Which experimental technique provides evidence for the lateral movement of membrane proteins within the lipid bilayer?

Accepted Answer

Fluorescence Recovery After Photobleaching (FRAP)

Question 6

Which of the following best explains why sodium ions (Na⁺) cannot easily cross the plasma membrane without the help of a transport protein?

Accepted Answer

The hydrophobic core of the phospholipid bilayer repels charged ions like Na⁺.

Question 7

Which of the following statements about cholesterol in animal cell membranes is correct?

Accepted Answer

Cholesterol acts as a fluidity buffer, decreasing membrane fluidity at high temperatures and increasing it at low temperatures.

Question 8

A cell is exposed to a toxin that disrupts the function of the Golgi apparatus. Which of the following processes would be most directly affected?

Accepted Answer

Modification and sorting of glycoproteins destined for the plasma membrane

Question 9

Which of the following is a function of membrane proteins that distinguishes them from phospholipids?

Accepted Answer

Facilitating signal transduction pathways

Question 10

Which of the following best describes the effect of increasing the length of fatty acid tails in membrane phospholipids?

Accepted Answer

Longer fatty acid tails increase hydrophobic interactions, resulting in decreased membrane fluidity.

Question 11

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

Accepted Answer

Synthesizing DNA for cell division

Question 12

A scientist observes that a certain protein spans the entire plasma membrane and has hydrophilic regions exposed to both the extracellular and intracellular environments. This protein is best classified as:

Accepted Answer

A transmembrane protein

Question 13

Which of the following best explains why glycolipids are primarily found on the extracellular face of the plasma membrane?

Accepted Answer

They are involved in cell signaling and communication with the external environment.

Question 14

Which of the following mechanisms does NOT require energy input from the cell?

Accepted Answer

Passive transport

Question 15

A bacterium living in cold environments adapts by modifying its membrane lipid composition. Which change would you expect to observe?

Accepted Answer

An increase in the proportion of shorter fatty acid tails

Question 16

Which of the following statements about the fluid mosaic model of membranes is correct?

Accepted Answer

Membranes are composed of a dynamic mixture of lipids, proteins, and carbohydrates that can move laterally within the layer.

Question 17

Which of the following best describes the process of exocytosis?

Accepted Answer

A vesicle fuses with the plasma membrane, releasing its contents outside the cell.

Question 18

Which of the following is a real-life example of the importance of membrane proteins in medicine?

Accepted Answer

Individuals lacking the CCR5 co-receptor are resistant to HIV infection.

Question 19

Which of the following statements about the sidedness (asymmetry) of biological membranes is true?

Accepted Answer

The asymmetrical distribution of proteins, lipids, and carbohydrates is established during membrane synthesis and is critical for proper cell function.

Bio 100 LEC Chapter 7 Part 1

Study Guide - Practice Questions

Study Guide - Flashcards