Question 1

Which statement best describes the difference between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways release energy by breaking down molecules, whereas anabolic pathways consume energy to build molecules.

Question 2

Which of the following best distinguishes kinetic energy from potential energy in biological systems?

Accepted Answer

Kinetic energy is the energy of motion, while potential energy is stored energy due to position or structure.

Question 3

According to the first law of thermodynamics, which of the following is true?

Accepted Answer

Energy can be transferred and transformed, but it cannot be created or destroyed.

Question 4

Which equation correctly represents the Gibbs free energy change ($\Delta G$) for a chemical reaction?

Accepted Answer

$\Delta G = \Delta H - T\Delta S$

Question 5

A reaction has $\Delta G = -20$ kJ/mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 6

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP couples exergonic and endergonic reactions by transferring a phosphate group.

Question 7

Why does a large change in free energy level occur when an enzyme or substrate is phosphorylated?

Accepted Answer

Phosphorylation adds a high-energy phosphate group, increasing the potential energy of the molecule.

Question 8

Which of the following best explains how enzymes lower activation energy in metabolic reactions?

Accepted Answer

Enzymes stabilize the transition state, reducing the energy required to reach it.

Question 9

Given a graph showing the energy changes over the course of a chemical reaction, which point represents the activation energy?

Accepted Answer

The peak of the curve above the reactants before the reaction proceeds to products.

Question 10

Which statement about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is determined by the shape of the active site and the substrate.

Question 11

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 12

Which of the following best describes allosteric regulation of enzyme activity?

Accepted Answer

A molecule binds to a site other than the active site, causing a conformational change that affects enzyme activity.

Question 13

Which scenario best illustrates cooperativity in enzyme regulation?

Accepted Answer

Binding of one substrate molecule increases the affinity of the enzyme for additional substrate molecules.

Question 14

Which of the following is a real-world example of an exergonic reaction in human metabolism?

Accepted Answer

Hydrolysis of ATP to ADP and inorganic phosphate.

Question 15

If an enzyme-catalyzed reaction is inhibited by a molecule that binds to a site other than the active site, what type of inhibition is this?

Accepted Answer

Noncompetitive inhibition

Question 16

Which of the following statements about the second law of thermodynamics is correct?

Accepted Answer

Every energy transfer increases the entropy of the universe.

Question 17

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction?

Accepted Answer

Increasing substrate concentration up to a point of saturation.

Question 18

Which process is an example of an endergonic reaction in living cells?

Accepted Answer

Synthesis of glucose from smaller molecules.

Question 19

A scientist measures the change in free energy for a reaction and finds $\Delta G = 0$. What does this indicate?

Accepted Answer

The reaction is at equilibrium and no net change occurs.

Question 20

Which of the following best explains why enzymes are essential for life?

Accepted Answer

Enzymes allow reactions to occur at rates compatible with life by lowering activation energy.

Study Notes: Introduction to Metabolism

Study Guide - Practice Questions