Question 1

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

Accepted Answer

A dynamic structure where lipids and proteins can move laterally within the bilayer.

Question 2

Which type of membrane lipid is most abundant in the plasma membrane?

Accepted Answer

Phospholipids

Question 3

What is the main function of cholesterol in the plasma membrane?

Accepted Answer

To stabilize membrane fluidity across temperature changes

Question 4

Which equation best represents the Nernst equation for calculating the equilibrium potential of an ion across a membrane?

Accepted Answer

$$E = \frac{RT}{zF} \ln \frac{[ion]_{out}}{[ion]_{in}}$$

Question 5

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

Accepted Answer

Energy storage

Question 6

A mutation in the gene encoding the CFTR protein leads to cystic fibrosis. What is the primary defect caused by this mutation?

Accepted Answer

Defective chloride ion transport across epithelial membranes

Question 7

Which process describes the movement of water across a semipermeable membrane from a region of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Question 8

Which type of membrane transport requires energy in the form of ATP?

Accepted Answer

Active transport

Question 9

Which of the following membrane proteins is responsible for the rapid transmission of nerve impulses?

Accepted Answer

Voltage-gated sodium channel

Question 10

Which of the following best explains why phospholipids form bilayers in aqueous environments?

Accepted Answer

Phospholipids have hydrophilic heads and hydrophobic tails, causing them to arrange with tails inward and heads outward.

Question 11

Which of the following is a real-world example of a disease caused by a defect in membrane receptor function?

Accepted Answer

Familial hypercholesterolemia due to defective LDL receptor

Question 12

Which of the following statements about membrane carbohydrates is correct?

Accepted Answer

They play a key role in cell recognition and adhesion.

Question 13

Which of the following best describes the role of the Na+/K+ ATPase pump in cells?

Accepted Answer

It actively transports 3 Na+ ions out and 2 K+ ions into the cell, maintaining membrane potential.

Question 14

Which of the following is a function of glycoproteins in the plasma membrane?

Accepted Answer

Facilitating cell-cell recognition and immune response

Question 15

Which of the following is a consequence of increased cholesterol content in the plasma membrane?

Accepted Answer

Decreased membrane fluidity at high temperatures

Question 16

Which process is illustrated by the movement of glucose into cells via GLUT transporters?

Accepted Answer

Facilitated diffusion

Question 17

Which of the following best describes the role of membrane proteins in signal transduction?

Accepted Answer

They bind extracellular signals and initiate intracellular responses.

Question 18

Which of the following is a medical consequence of defective ABC transporters in cell membranes?

Accepted Answer

Multidrug resistance in cancer cells

Question 19

Which of the following is a correct statement about the biogenesis of cellular membranes?

Accepted Answer

Membranes are formed by the complexation of preexisting membranes and lipid synthesis in the endoplasmic reticulum.

Question 20

Which of the following is a real-world example of a drug acting on membrane transporters to exert its therapeutic effect?

Accepted Answer

SSRIs blocking serotonin reuptake transporters in neurons

Biological Membranes: Structure, Composition, and Function

Study Guide - Practice Questions