$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy}$

Question 1

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

Accepted Answer

Diverse protein molecules are embedded in a fluid phospholipid bilayer, allowing for selective permeability.

Question 2

A red blood cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

It will shrink as water leaves the cell, a process called crenation.

Question 3

Which type of transport requires energy input from the cell?

Accepted Answer

Active transport

Question 4

What is the primary function of aquaporins in the plasma membrane?

Accepted Answer

To facilitate rapid diffusion of water across the membrane

Question 5

Which equation correctly represents the hydrolysis of ATP?

Accepted Answer

$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy}$

Question 6

A cell uses receptor-mediated endocytosis to import cholesterol. Which feature distinguishes this process from phagocytosis?

Accepted Answer

It uses specific membrane receptors to bind and concentrate the target molecule.

Question 7

Which of the following best explains why diffusion across a membrane is considered passive transport?

Accepted Answer

It does not require energy input and moves molecules down their concentration gradient.

Question 8

Which statement about enzyme function is correct?

Accepted Answer

Enzymes lower the activation energy and are reusable.

Question 9

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Blocking substrate molecules from entering the active site.

Question 10

Which of the following is an example of an exergonic reaction?

Accepted Answer

Cellular respiration breaking down glucose to release energy

Question 11

What is the main role of glycoproteins in the plasma membrane?

Accepted Answer

To serve as identification tags recognized by other cells

Question 12

Which law of thermodynamics explains why no energy transformation is 100% efficient?

Accepted Answer

Second law: Energy transfers increase disorder (entropy), with some energy lost as heat.

Question 13

A plant cell in a hypotonic solution will:

Accepted Answer

Become turgid as water enters the cell.

Question 14

Which process is responsible for the export of large molecules, such as proteins, from a cell?

Accepted Answer

Exocytosis

Question 15

Which of the following best describes the coupling of exergonic and endergonic reactions in cells?

Accepted Answer

ATP hydrolysis releases energy from exergonic reactions, which is used to drive endergonic processes.

Question 16

Which membrane protein is responsible for relaying messages from signaling molecules into the cell?

Accepted Answer

Receptor protein

Question 17

If a cell actively transports $\mathrm{Ca}^{2+}$ ions out of the cytoplasm, where will calcium concentration be higher?

Accepted Answer

Outside the cell

Question 18

Which scenario illustrates feedback inhibition in a metabolic pathway?

Accepted Answer

The final product of a pathway inhibits an enzyme involved earlier in the pathway.

Question 19

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses transport proteins to move substances down their concentration gradient without energy input.

Question 20

Which property of phospholipids is most important for the formation of biological membranes?

Accepted Answer

Their amphipathic nature, with hydrophilic heads and hydrophobic tails.

The Working Cell: Membrane Structure, Function, and Cellular Processes

Study Guide - Practice Questions