Question 1

Which of the following best describes the first law of thermodynamics as it applies to biological systems?

Accepted Answer

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

Question 2

A bear catches a fish and uses the energy from the fish to run. According to the second law of thermodynamics, what happens to some of the energy from the fish?

Accepted Answer

It is lost as heat, increasing the entropy of the surroundings.

Question 3

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

Accepted Answer

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

Question 4

Which of the following statements about exergonic and endergonic reactions is correct?

Accepted Answer

Exergonic reactions release energy and have $$\Delta G \u003c 0.$$

Question 5

ATP hydrolysis is often coupled to endergonic reactions in cells. Why is this coupling necessary?

Accepted Answer

ATP hydrolysis provides the free energy needed to drive nonspontaneous reactions.

Question 6

Which of the following best explains why enzymes are necessary for metabolic reactions?

Accepted Answer

Enzymes lower the activation energy ($$E_A) $$required for reactions to proceed.

Question 7

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 8

Which of the following is an example of feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of a pathway binds to an enzyme early in the pathway, decreasing its activity.

Question 9

Which of the following best describes the difference between catabolic and anabolic pathways?

Accepted Answer

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

Question 10

Which of the following is NOT a way that enzymes lower the activation energy of a reaction?

Accepted Answer

Increasing the free energy of the products.

Question 11

A reaction has $$\Delta G = -7.3$$ kcal/mol. Which of the following statements is true?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 12

Which of the following is a real-life example of the second law of thermodynamics?

Accepted Answer

A room becoming messy over time without cleaning.

Question 13

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Each enzyme catalyzes a specific reaction with a specific substrate.

Question 14

Which of the following is true about the localization of enzymes within a eukaryotic cell?

Accepted Answer

Some enzymes are localized to specific organelles, such as mitochondria.

Question 15

Which of the following is an example of energy coupling in cells?

Accepted Answer

ATP hydrolysis drives the active transport of ions across a membrane.

Question 16

Which of the following best explains why cells are not in equilibrium?

Accepted Answer

Cells are open systems with a constant flow of materials, preventing equilibrium.

Question 17

Which of the following is a function of cofactors in enzyme activity?

Accepted Answer

Cofactors are nonprotein helpers required for enzyme function.

Question 18

A noncompetitive inhibitor decreases the rate of an enzyme-catalyzed reaction by:

Accepted Answer

Binding to a site other than the active site, changing the enzyme's shape.

Question 19

Which of the following is NOT a type of work performed by cells using ATP?

Accepted Answer

Nuclear work, such as DNA replication without enzymes.

Question 20

Which of the following environmental factors can affect enzyme activity?

Accepted Answer

Temperature and pH.

Chapter 8: An Introduction to Metabolism – Study Notes

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