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

Question 1

Which model best describes the structure of the plasma membrane, as shown in the first image, and what is its significance?

Accepted Answer

The fluid mosaic model, which describes a dynamic arrangement of lipids and proteins allowing selective permeability.

Question 2

In the context of membrane transport, which equation represents the movement of solutes down their concentration gradient during passive diffusion?

Accepted Answer

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

Question 3

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

Accepted Answer

Their amphipathic nature, having both hydrophobic and hydrophilic regions.

Question 4

A cell placed in a hypertonic solution will:

Accepted Answer

Shrink as water leaves the cell.

Question 5

Which process is illustrated in the second image, and what is the main function of the structure shown?

Accepted Answer

Enzyme catalysis; the structure is an enzyme facilitating the conversion of substrates to products.

Question 6

Which equation best represents the hydrolysis of ATP, a process that powers cellular work?

Accepted Answer

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

Question 7

Which statement best explains why diffusion across a membrane is considered passive transport?

Accepted Answer

It occurs without any energy input from the cell.

Question 8

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

Accepted Answer

Facilitating the rapid diffusion of water across the membrane.

Question 9

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

Accepted Answer

ATP transfers energy released from exergonic reactions to drive endergonic reactions.

Question 10

Which scenario illustrates feedback inhibition in a metabolic pathway?

Accepted Answer

A product of the pathway binds to an enzyme early in the pathway, reducing its activity.

Question 11

Which equation represents the second law of thermodynamics as it relates to biological systems?

Accepted Answer

$ \Delta S > 0 $

Question 12

Which type of transport requires energy and moves solutes against their concentration gradient?

Accepted Answer

Active transport

Question 13

Which statement best describes the effect of a competitive inhibitor on enzyme activity?

Accepted Answer

It binds to the active site, preventing substrate binding.

Question 14

Which process is responsible for the uptake of large particles by a cell, such as bacteria or debris?

Accepted Answer

Phagocytosis

Question 15

Which term describes the ability of a solution to cause a cell to gain or lose water?

Accepted Answer

Tonicity

Question 16

Which equation best represents an exergonic reaction?

Accepted Answer

$ \Delta G < 0 $

Question 17

Which feature of enzymes allows them to catalyze specific reactions, as shown in the second image?

Accepted Answer

The specificity of the active site for the substrate.

Question 18

Which mechanism allows cells to export bulky molecules, such as proteins or polysaccharides?

Accepted Answer

Exocytosis

Question 19

Which statement best explains why polar or charged substances require transport proteins to cross the cell membrane?

Accepted Answer

They cannot dissolve in the hydrophobic interior of the lipid bilayer.

Question 20

Which factor determines whether enzyme inhibition is reversible or irreversible?

Accepted Answer

The nature of the inhibitor's binding to the enzyme.

Chapter 5: The Working Cell – Membrane Structure, Transport, Energy, and Enzymes

Study Guide - Practice Questions