Question 1

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

Accepted Answer

Catabolic pathways break down large molecules into smaller ones and release energy, while anabolic pathways use energy to build complex molecules from simpler ones.

Question 2

Which of the following best explains why ATP has a high potential energy?

Accepted Answer

ATP contains three phosphate groups with clustered negative charges that repel each other.

Question 3

A chemical reaction has $$\Delta G = -5$$ kcal/mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will proceed spontaneously.

Question 4

Which equation correctly represents the standard free-energy change for a reaction?

Accepted Answer

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

Question 5

During a redox reaction, which of the following statements is true?

Accepted Answer

Oxidation is the loss of electrons and reduction is the gain of electrons.

Question 6

Which of the following best describes how enzymes lower the activation energy of a reaction?

Accepted Answer

Enzymes bring substrates together in precise orientation and stabilize the transition state.

Question 7

A researcher observes that increasing the substrate concentration in an enzyme-catalyzed reaction eventually leads to a plateau in reaction rate. What is the most likely explanation?

Accepted Answer

All enzyme active sites are occupied, and the reaction has reached saturation.

Question 8

Which of the following is an example of competitive inhibition in enzyme regulation?

Accepted Answer

A molecule binds to the enzyme's active site, preventing substrate binding.

Question 9

Which statement about feedback inhibition in metabolic pathways is correct?

Accepted Answer

Feedback inhibition occurs when the final product of a pathway inhibits an earlier enzyme, preventing overproduction.

Question 10

Which of the following factors can affect enzyme activity by altering the enzyme's structure?

Accepted Answer

Temperature and pH

Question 11

Which molecule acts as an electron carrier by accepting two electrons and two protons to form its reduced state?

Accepted Answer

FADH$$_2$$

Question 12

What is the primary role of phosphorylation in enzyme regulation?

Accepted Answer

It changes the enzyme's shape, which can activate or deactivate its function.

Question 13

Which of the following best describes the relationship between enthalpy ($$\Delta H) $$and exothermic reactions?

Accepted Answer

Exothermic reactions have a negative $$\Delta H$$ and release heat.

Question 14

Which of the following is true regarding the first law of thermodynamics?

Accepted Answer

Energy is conserved and can only be transferred or transformed.

Question 15

A scientist is studying metabolic pathways in bacteria associated with obesity. Which change in bacterial metabolism could increase the risk of obesity in patients?

Accepted Answer

Increased anabolic activity that synthesizes storage molecules from nutrients.

Question 16

Which of the following statements about entropy ($$\Delta S) is $$correct?

Accepted Answer

A positive $$\Delta S$$ indicates an increase in disorder.

Question 17

Which of the following is NOT a way that enzymes can be regulated?

Accepted Answer

Changing the DNA sequence of the enzyme after translation

Question 18

Which of the following is a correct statement about metabolic pathways?

Accepted Answer

Metabolic pathways are series of reactions, each catalyzed by a different enzyme.

Question 19

Which of the following is a real-world example of energetic coupling in cells?

Accepted Answer

The use of ATP hydrolysis to drive the synthesis of glucose from smaller molecules.

Question 20

Which of the following statements about enzyme saturation kinetics is correct?

Accepted Answer

At high substrate concentrations, reaction rate plateaus because all enzyme active sites are occupied.

Chapter 8: Energy and Enzymes – An Introduction to Metabolism

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