Question 1

Which of the following is an example of potential energy rather than kinetic energy?

Accepted Answer

A molecule of glucose

Question 2

According to the law of conservation of energy, which statement is correct?

Accepted Answer

Energy is neither created nor destroyed; it simply changes form.

Question 3

Which of the following best describes an exothermic reaction?

Accepted Answer

It has a negative $$\Delta H$$ and releases heat energy.

Question 4

Which substance would you expect to have the highest entropy at room temperature?

Accepted Answer

Carbon monoxide gas

Question 5

For the reaction $$C_6H_{12}O_6$ \rightarrow 2 C_2H_5OH + 2 CO_2$, the change in enthalpy is -82$ kJ/mol and the change in entropy is 0.5$ kJ/(mol·K). Under what conditions would this reaction be exergonic?

Accepted Answer

Only at temperatures above 164 K

Question 6

Which of the following is true for all exergonic reactions?

Accepted Answer

The reaction proceeds with a net release of free energy.

Question 7

The synthesis of glucose from carbon dioxide ($$6 CO_2$ + 6 H_2O \rightarrow C_6H_{12}O_6$ + 6 O_2$) is endergonic ($$\Delta G = 686$$ kcal/mol). How do some cells synthesize glucose in photosynthesis?

Accepted Answer

These cells couple nonspontaneous reactions to spontaneous reactions.

Question 8

Which statement is true for ALL redox reactions?

Accepted Answer

They involve the transfer of electrons.

Question 9

When ATP is hydrolyzed into ADP and inorganic phosphate, what happens?

Accepted Answer

Free energy is released.

Question 10

Why would you not expect glucose to burn spontaneously when exposed to oxygen on your lab bench?

Accepted Answer

Energy is required for the sugar and oxygen to reach their transition state.

Question 11

What is the role of the active site of an enzyme?

Accepted Answer

It is involved in the catalytic reaction of the enzyme.

Question 12

Can an enzyme make a nonspontaneous reaction occur spontaneously? Why or why not?

Accepted Answer

No, because enzymes do not affect the overall $$\Delta G of a $$reaction.

Question 13

How might covalent modification of one amino acid at a site distant from the active site of an enzyme alter an enzyme's substrate specificity?

Accepted Answer

By changing the shape of an enzyme

Question 14

What would happen in a metabolic pathway if arginine inhibited Enzyme 3?

Accepted Answer

Build-up of arginine

Question 15

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

Accepted Answer

They lower the activation energy required for the reaction to proceed.

Question 16

Which of the following is a correct application of the Gibbs free energy equation $$\Delta G = \Delta H - T\Delta S$$?

Accepted Answer

A reaction with $$\Delta H  0$$ will be exergonic at all temperatures.

Question 17

Which type of enzyme regulation involves a molecule binding to a site other than the active site, causing a change in enzyme activity?

Accepted Answer

Allosteric regulation

Question 18

If an enzyme is phosphorylated, what is the most likely effect?

Accepted Answer

It becomes active.

Question 19

Which of the following is a real-world example of energetic coupling in cells?

Accepted Answer

The transfer of a phosphate group from ATP to a substrate to drive an endergonic reaction.

Energy and Enzymes: Principles and Biological Applications

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