Question 1

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

Accepted Answer

Kinetic energy is the energy of motion, such as thermal energy, while potential energy is stored in the position or configuration of molecules, such as chemical energy in bonds.

Question 2

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

Accepted Answer

Energy is conserved; it can be transferred or transformed but not created or destroyed.

Question 3

A chemical reaction has a negative $$\Delta H$$ and a positive $$\Delta S. $$According to the Gibbs free energy equation $$\Delta G = \Delta H - T\Delta S$$, what can you conclude about the spontaneity of this reaction?

Accepted Answer

The reaction is spontaneous because $$\Delta G is $$negative.

Question 4

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

Accepted Answer

Enzymes allow reactions to occur at rates sufficient for life by lowering the activation energy barrier.

Question 5

Which of the following scenarios describes an example of energetic coupling in a cell?

Accepted Answer

The energy released from ATP hydrolysis is used to drive an endergonic reaction, such as the synthesis of glutamine from glutamate and ammonia.

Question 6

Which of the following is true about redox reactions in metabolism?

Accepted Answer

Oxidation and reduction always occur together, transferring energy via electrons.

Question 7

A scientist adds a competitive inhibitor to an enzyme-catalyzed reaction. What is the most likely effect?

Accepted Answer

The inhibitor binds to the active site, preventing substrate binding.

Question 8

Which of the following best describes feedback inhibition in a metabolic pathway?

Accepted Answer

The final product of the pathway inhibits an earlier enzyme, preventing overproduction.

Question 9

Which of the following statements about ATP is correct?

Accepted Answer

ATP contains three phosphate groups whose negative charges repel each other, giving ATP high potential energy.

Question 10

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction that is currently operating at low substrate concentration?

Accepted Answer

Increasing the substrate concentration.

Question 11

A mutation causes an enzyme's active site to change shape so that it no longer binds its substrate. What is the most likely consequence?

Accepted Answer

The enzyme will lose its catalytic activity.

Question 12

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

Accepted Answer

The synthesis of proteins from amino acids.

Question 13

Which of the following best explains why enzyme activity is affected by pH?

Accepted Answer

pH affects the charge on acidic and basic groups within the enzyme, altering its shape and reactivity.

Question 14

Which of the following is true about the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity increases with temperature up to an optimal point, after which it decreases due to denaturation.

Question 15

Which of the following molecules is a common electron carrier in cellular respiration that is reduced to form NADH?

Accepted Answer

NAD+

Question 16

A reaction has $$\Delta H = +10 kJ/$$mol and $$\Delta S = +0.05 kJ/($$mol\cdot K). At what temperature (in Kelvin) does this reaction become spontaneous? (Recall: $$\Delta G = \Delta H - T\Delta S$$ and a reaction is spontaneous when $$\Delta G \u003c 0.)$$

Accepted Answer

$$T \u003e 200 K$$

Question 17

Which of the following best describes the role of phosphorylation in enzyme regulation?

Accepted Answer

Phosphorylation is a reversible covalent modification that can activate or deactivate enzymes by changing their shape.

Question 18

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

Accepted Answer

Changing the overall $$\Delta G of $$the reaction.

Question 19

Which of the following statements about metabolic pathways is correct?

Accepted Answer

Metabolic pathways can be regulated by feedback inhibition, where the end product inhibits an early enzyme in the pathway.

Energy and Enzymes: An Introduction to Metabolism (Chapter 8 Study Notes)

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