$\text{Phospholipid} = \text{Hydrophilic head} + 2 \times \text{Hydrophobic tails}$

Question 1

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

Accepted Answer

Their amphiphilic nature, with hydrophilic heads and hydrophobic tails

Question 2

A drug designed to mimic the action of a natural ligand and activate a membrane receptor is called a(n):

Accepted Answer

Agonist

Question 3

Which of the following best describes the arrangement of phospholipids in the plasma membrane?

Accepted Answer

Hydrophilic heads face the extracellular fluid and cytosol, while hydrophobic tails face each other

Question 4

Which equation best represents the amphiphilic nature of a phospholipid molecule?

Accepted Answer

$	ext{Phospholipid} = 	ext{Hydrophilic head} + 2 	imes 	ext{Hydrophobic tails}$

Question 5

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

Accepted Answer

Synthesizing DNA

Question 6

A patient is given an antihistamine to block the action of histamine at its receptor. The antihistamine acts as a(n):

Accepted Answer

Antagonist

Question 7

Which type of membrane protein spans the entire plasma membrane and is also known as a transmembrane protein?

Accepted Answer

Integral protein

Question 8

The fluid mosaic model describes the plasma membrane as:

Accepted Answer

A dynamic structure with proteins and lipids moving within the bilayer

Question 9

Which of the following membrane components is most directly involved in cell recognition and identification?

Accepted Answer

Glycoproteins and glycolipids

Question 10

Cholesterol in the plasma membrane primarily functions to:

Accepted Answer

Stabilize membrane fluidity during temperature changes

Question 11

Which of the following best explains why the phospholipid bilayer is effective at separating the extracellular fluid (ECF) from the cytosol?

Accepted Answer

The hydrophobic tails repel water, creating a barrier to most water-soluble substances

Question 12

Peripheral proteins differ from integral proteins in that peripheral proteins:

Accepted Answer

Are found only on one side of the plasma membrane

Question 13

A membrane protein that binds to a chemical messenger and triggers a change in the cell is functioning as a:

Accepted Answer

Receptor

Question 14

Which of the following is a correct multi-step pathway for a ligand-receptor interaction at the plasma membrane?

Accepted Answer

Ligand binds to receptor $\rightarrow$ receptor changes shape $\rightarrow$ intracellular signaling cascade is triggered

Question 15

Which of the following membrane proteins is most likely to be directly involved in catalyzing chemical reactions at the cell surface?

Accepted Answer

Enzyme

Question 16

If a mutation caused all membrane proteins to lose their ability to link adjacent cells, which tissue function would be most affected?

Accepted Answer

Cell-to-cell communication and anchoring

Question 17

Which of the following best describes the role of membrane proteins in maintaining homeostasis?

Accepted Answer

They act as channels, carriers, enzymes, and receptors to regulate the internal environment

Question 18

A cell is exposed to a temperature drop. Which plasma membrane component helps maintain membrane fluidity under these conditions?

Accepted Answer

Cholesterol

Question 19

Which of the following is a correct application of the fluid mosaic model in a medical context?

Accepted Answer

Membrane proteins can move laterally, allowing immune cells to adapt their surface markers during inflammation

Question 20

Which equation best represents the separation of water by the phospholipid bilayer?

Accepted Answer

$	ext{ECF} \mid 	ext{Hydrophilic head} \mid 	ext{Hydrophobic tails} \mid 	ext{Hydrophilic head} \mid 	ext{Cytosol}$

Structure and Components of the Plasma Membrane

Study Guide - Practice Questions