Question 1

Which property of phospholipids is primarily responsible for the formation of the plasma membrane bilayer?

Accepted Answer

Their amphipathic nature, containing both hydrophobic and hydrophilic regions

Question 2

A scientist observes that a cell membrane becomes more rigid as the temperature decreases. Which change in membrane composition would help maintain fluidity under these conditions?

Accepted Answer

Increase the proportion of unsaturated fatty acids in the membrane

Question 3

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

Accepted Answer

A bilayer of phospholipids with proteins embedded and moving within it

Question 4

In the Frye and Edidin experiment, mouse and human cells were fused and membrane proteins were labeled with fluorescent tags. What did the mixing of colors in the hybrid cell demonstrate?

Accepted Answer

Membrane proteins can move laterally within the plane of the membrane

Question 5

Which of the following molecules would most easily cross a plasma membrane by simple diffusion?

Accepted Answer

Oxygen ($\mathrm{O_2}$)

Question 6

Cholesterol acts as a 'fluidity buffer' in animal cell membranes. What is its effect at low temperatures?

Accepted Answer

It prevents tight packing of phospholipids, maintaining membrane fluidity

Question 7

Which type of membrane protein is most likely to function as a receptor for signaling molecules?

Accepted Answer

Integral membrane protein

Question 8

A patient receives a blood transfusion with the wrong blood type. Which membrane component is most directly responsible for the immune reaction?

Accepted Answer

Glycoproteins with specific carbohydrate chains

Question 9

Which of the following statements about passive transport is correct?

Accepted Answer

It relies on the potential energy of the concentration gradient

Question 10

A bacterium is found living in hot springs at temperatures above $70^\circ$C. Which membrane adaptation would you expect to find?

Accepted Answer

A high proportion of saturated fatty acids in its membrane

Question 11

Which equation best describes the net movement of molecules during diffusion?

Accepted Answer

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

Question 12

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

Accepted Answer

Synthesis of phospholipids

Question 13

A cell is placed in a solution containing a high concentration of a nonpolar molecule. What is most likely to happen?

Accepted Answer

The nonpolar molecule will rapidly diffuse across the plasma membrane

Question 14

Which of the following best explains why membranes are described as 'selectively permeable'?

Accepted Answer

They allow some substances to cross more easily than others

Question 15

Which of the following would most likely decrease the fluidity of a plasma membrane at room temperature?

Accepted Answer

Increasing the proportion of saturated fatty acids

Question 16

Which statement about the sidedness (asymmetry) of plasma membranes is correct?

Accepted Answer

It is established during membrane synthesis in the ER and Golgi apparatus

Question 17

Which of the following is a real-world example of cell-cell recognition mediated by membrane carbohydrates?

Accepted Answer

The determination of human blood types (A, B, AB, O)

Question 18

Which of the following statements about diffusion is true?

Accepted Answer

Each substance diffuses down its own concentration gradient independently

Question 19

A mutation causes a membrane protein to lose its hydrophobic region. What is the most likely consequence?

Accepted Answer

The protein will be unable to embed in the membrane

Question 20

Which of the following best describes the movement of phospholipids within the plasma membrane?

Accepted Answer

They move laterally within the plane of the membrane

Chapter 7: Membrane Structure and Function – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards