Question 1

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

Accepted Answer

Catabolic pathways break down molecules to release energy, while anabolic pathways use energy to build complex molecules.

Question 2

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

Accepted Answer

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

Question 3

A cell uses ATP to transport ions against their concentration gradient. Which type of work is being performed?

Accepted Answer

Transport work

Question 4

Which of the following best explains why enzymes lower the activation energy ($$E_a) of a $$reaction?

Accepted Answer

Enzymes stabilize the transition state, making it easier for reactants to reach it.

Question 5

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 6

Which of the following is an example of energy transformation in a biological system?

Accepted Answer

The conversion of glucose to carbon dioxide and water during cellular respiration.

Question 7

If a reaction has a negative free energy change ($$\Delta G \u003c 0$$), which of the following is true?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 8

Which of the following environmental factors can affect enzyme activity by altering the enzyme's three-dimensional structure?

Accepted Answer

Temperature and pH

Question 9

A patient is given a drug that acts as a noncompetitive inhibitor of a key metabolic enzyme. What is the most likely effect on the enzyme's activity?

Accepted Answer

The inhibitor binds to a site other than the active site, reducing the enzyme's maximum velocity ($$V_{max}).$$

Question 10

Which molecule acts as the primary energy currency in cells, coupling exergonic and endergonic reactions?

Accepted Answer

ATP

Question 11

During strenuous exercise, muscle cells rapidly break down glucose to generate ATP. Which metabolic pathway is primarily responsible for this process?

Accepted Answer

Catabolic pathway

Question 12

Which of the following best describes the role of NAD$$^+$$ and FAD in cellular respiration?

Accepted Answer

They are electron carriers that transport electrons during redox reactions.

Question 13

A scientist measures the rate of an enzyme-catalyzed reaction at different substrate concentrations and finds that the rate levels off at high substrate concentrations. What is the most likely explanation?

Accepted Answer

The enzyme is saturated; all active sites are occupied.

Question 14

Which of the following scenarios best illustrates the second law of thermodynamics in a biological system?

Accepted Answer

A cell converts chemical energy from glucose into ATP, releasing heat in the process.

Question 15

Which of the following is an example of allosteric regulation of an enzyme?

Accepted Answer

A regulatory molecule binds to a site other than the active site, changing the enzyme's activity.

Question 16

A metabolic pathway is regulated by feedback inhibition. Which of the following best describes this process?

Accepted Answer

The end product of the pathway inhibits an enzyme that acts early in the pathway.

Question 17

Which of the following best explains why ATP is considered a high-energy molecule?

Accepted Answer

The hydrolysis of its terminal phosphate group releases a large amount of free energy ($$\Delta G).$$

Question 18

A researcher adds an inorganic ion to an enzyme reaction and observes increased activity. What is the most likely explanation?

Accepted Answer

The inorganic ion acts as a cofactor, assisting enzyme function.

Question 19

Which of the following equations correctly represents the free energy change of a reaction?

Accepted Answer

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

Question 20

A cell must couple an endergonic reaction ($$\Delta G \u003e 0) to an $$exergonic reaction to proceed. Which molecule is most commonly used for this purpose?

Accepted Answer

ATP

An Introduction to Metabolism: Principles, Pathways, and Enzyme Function

Guida di studio - Domande di pratica

Study guide - Flashcard