Question 1

Which of the following best describes the difference between potential and kinetic energy in biological systems?

Accepted Answer

Potential energy is stored in covalent bonds and concentration gradients, while kinetic energy is the energy of movement, such as breaking bonds or moving molecules.

Question 2

Which of the following reactions is an example of a catabolic (exergonic) process in cells?

Accepted Answer

Hydrolysis of ATP to ADP and $$P_i$$

Question 3

A redox reaction involves the transfer of electrons. In the reaction below, which molecule is oxidized?

$$\mathrm{C_2H_5OH} + \mathrm{NAD^+} \rightarrow \mathrm{CH_3CHO} + \mathrm{NADH} + \mathrm{H^+}$$

Accepted Answer

$$\mathrm{C_2H_5OH} ($$ethanol)

Question 4

According to the second law of thermodynamics, which of the following statements is true about energy transformations in cells?

Accepted Answer

Energy transformations proceed spontaneously to increase entropy ($$S) $$and make matter more stable.

Question 5

Which of the following best explains why ATP is considered the 'energy currency' of the cell?

Accepted Answer

ATP contains high-energy covalent bonds that, when broken, release energy that can be used to drive endergonic reactions.

Question 6

A reaction has a $$\Delta G of$$ $$-31 kJ/$$mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will proceed spontaneously.

Question 7

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy but do not change the overall $$\Delta G of $$the reaction.

Question 8

A scientist wants to measure the ATP concentration in a sample using the luciferase-luciferin reaction. Which of the following best explains how this assay works?

Accepted Answer

The amount of light produced is directly proportional to the amount of ATP present in the sample.

Question 9

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

Accepted Answer

The final product of a pathway binds to an allosteric site on the first enzyme, decreasing its activity.

Question 10

Which of the following best describes the role of NAD$$^+ in $$cellular metabolism?

Accepted Answer

NAD$$^+$$ acts as an electron acceptor, becoming reduced to NADH.

Question 11

Which of the following statements about enzyme regulation is correct?

Accepted Answer

Allosteric activators increase enzyme activity by binding to a site other than the active site.

Question 12

A metabolic pathway is regulated by the concentration of its final product. When the product accumulates, it inhibits the first enzyme in the pathway. This is an example of:

Accepted Answer

Feedback inhibition

Question 13

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of the enzyme has a unique shape and chemical environment that matches only specific substrates.

Question 14

Which of the following is true about the hydrolysis of ATP?

Accepted Answer

It releases energy that can be used to drive other cellular processes.

Question 15

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

Accepted Answer

It will bind to an allosteric site, changing the enzyme's shape and reducing its activity.

Question 16

Which of the following best describes the function of a coenzyme in an enzymatic reaction?

Accepted Answer

A coenzyme is a non-protein molecule that assists enzymes, often by carrying electrons or chemical groups.

Question 17

Which of the following scenarios illustrates the concept of reaction coupling in metabolism?

Accepted Answer

The hydrolysis of ATP ($$\Delta G = -31 kJ/$$mol) is used to drive the phosphorylation of glucose ($$\Delta G = +17 kJ/$$mol), making the overall reaction exergonic.

Question 18

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

Accepted Answer

Increasing substrate concentration up to the enzyme's saturation point

Question 19

Which of the following best explains why enzymes are sensitive to changes in pH?

Accepted Answer

Changes in pH can alter the charge and shape of amino acids at the active site, affecting substrate binding and catalysis.

Energy and Metabolism: Principles, Redox Reactions, and Enzyme Function

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