Question 1

Which statement best describes the 1st Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Energy is neither created nor destroyed, but can change forms within biological systems.

Question 2

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

Accepted Answer

The molecule that gains electrons is reduced.

Question 3

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

Accepted Answer

ATP contains high-energy phosphate bonds that, when hydrolyzed, release energy to drive cellular processes.

Question 4

Which of the following reactions is exergonic?

Accepted Answer

A reaction with $$ \Delta G \u003c 0 $$

Question 5

Why does the hydrolysis of ATP release energy?

Accepted Answer

Because the products (ADP and inorganic phosphate) form more stable bonds than the reactants, resulting in a net release of energy.

Question 6

Which of the following best describes the role of enzymes in biochemical reactions?

Accepted Answer

Enzymes lower the activation energy, increasing the rate of the reaction.

Question 7

A reaction in a cell has $$ \Delta G = +5 $$ kcal/mol. Which of the following must occur for this reaction to proceed?

Accepted Answer

It must be coupled to an exergonic reaction with $$ \Delta G \u003c -5 $$ kcal/mol.

Question 8

Which of the following is an example of an anabolic pathway?

Accepted Answer

The synthesis of proteins from amino acids.

Question 9

What is the effect of a competitive inhibitor on enzyme activity?

Accepted Answer

It binds to the active site, blocking substrate binding.

Question 10

Which of the following statements about the ATP cycle is correct?

Accepted Answer

ATP is continuously recycled in cells, coupling exergonic and endergonic reactions.

Question 11

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

Accepted Answer

Catabolic pathways release energy that can be used to drive anabolic pathways.

Question 12

Which of the following is true regarding the regulation of enzyme activity?

Accepted Answer

Allosteric activators change the enzyme's shape to allow substrate binding.

Question 13

Which of the following statements about redox reactions is correct?

Accepted Answer

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

Question 14

Why is the reduction of NAD+ to NADH considered endergonic?

Accepted Answer

Because it requires an input of energy and is not spontaneous.

Question 15

Which of the following best explains why the products of a biochemical reaction often have less potential energy than the reactants?

Accepted Answer

Because the products have more stable bonds than the reactants.

Question 16

Which of the following is a correct example of reaction coupling in cells?

Accepted Answer

ATP hydrolysis (exergonic) is used to drive the synthesis of glucose-6-phosphate (endergonic).

Question 17

Which of the following statements about enzyme cofactors is correct?

Accepted Answer

Cofactors can be nonprotein molecules or inorganic ions required for enzyme function.

Question 18

A patient is diagnosed with a metabolic disorder in which their cells cannot efficiently couple exergonic and endergonic reactions. Which of the following cellular processes would most likely be directly impaired?

Accepted Answer

Synthesis of macromolecules such as proteins and nucleic acids.

Question 19

Which of the following best describes the effect of adding a phosphate group to an enzyme (phosphorylation)?

Accepted Answer

It changes the enzyme's 3-D shape, which can activate the enzyme by revealing an active site.

Question 20

Which of the following is true about the maximum rate of an enzyme-catalyzed reaction?

Accepted Answer

It is reached when all enzyme molecules are bound to substrate.

Bioenergetics I: Enzymes and Biochemical Reactions

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