Question 1

Which of the following statements best describes the difference between an exergonic and an endergonic reaction?

Accepted Answer

Exergonic reactions release energy and have $$\Delta G  0.$$

Question 2

A cell needs to drive an endergonic reaction ($$\Delta G \u003e 0). $$Which strategy would allow the cell to make this reaction proceed?

Accepted Answer

Couple the endergonic reaction with an exergonic reaction such as ATP hydrolysis.

Question 3

Which equation correctly relates free energy change ($$\Delta G$$), enthalpy change ($$\Delta H$$), temperature ($$T$$), and entropy change ($$\Delta S$$)?

Accepted Answer

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

Question 4

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

Accepted Answer

Enzymes decrease the activation energy ($$E_a) $$required for reactions to proceed.

Question 5

A scientist observes that a reaction proceeds much faster in the presence of an enzyme, but the overall free energy change ($$\Delta G) is $$unchanged. What is the best explanation?

Accepted Answer

The enzyme decreases the activation energy ($$E_a) $$but does not affect $$\Delta G.$$

Question 6

Which of the following is an example of competitive inhibition of an enzyme?

Accepted Answer

A molecule binds to the active site, preventing the substrate from binding.

Question 7

Which of the following best describes allosteric regulation of an enzyme?

Accepted Answer

A regulatory molecule binds to a site other than the active site, altering enzyme activity.

Question 8

In a metabolic pathway, the end product binds to an enzyme early in the pathway and inhibits its activity. This is an example of:

Accepted Answer

Feedback inhibition

Question 9

Which of the following statements about glycolysis is correct?

Accepted Answer

Glycolysis produces a net gain of 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose.

Question 10

During glycolysis, which molecule has the highest potential energy?

Accepted Answer

Glucose

Question 11

Which of the following best explains why phosphoenolpyruvate (PEP) has more potential energy than pyruvate?

Accepted Answer

PEP contains a high-energy phosphate bond that is broken to generate ATP.

Question 12

Where does pyruvate processing occur in eukaryotic cells?

Accepted Answer

Mitochondrial matrix

Question 13

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

Accepted Answer

Enzymes from different organisms may have different optimal temperatures and pH values.

Question 14

A patient is given a drug that binds to an enzyme's allosteric site and increases its activity. This is an example of:

Accepted Answer

Allosteric activation

Question 15

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP provides energy by transferring a phosphate group to other molecules.

Question 16

Which of the following is a correct summary of the four steps of cellular respiration?

Accepted Answer

Glycolysis, pyruvate processing, citric acid cycle, electron transport and oxidative phosphorylation

Question 17

A researcher adds a competitive inhibitor to an enzyme-catalyzed reaction. What will happen to the reaction rate if the substrate concentration is greatly increased?

Accepted Answer

The reaction rate will increase and may approach the rate without inhibitor.

Question 18

Which of the following best explains why enzymes are not consumed during the reactions they catalyze?

Accepted Answer

Enzymes are unchanged after the reaction and can be reused.

Question 19

Which of the following is a real-life example of feedback inhibition?

Accepted Answer

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

Study guide 12

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