Question 1

Which of the following best describes a catabolic pathway in cellular metabolism?

Accepted Answer

A pathway that releases energy by breaking down complex molecules into simpler compounds.

Question 2

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

Accepted Answer

Energy can be transferred and transformed, but it cannot be created or destroyed.

Question 3

A diver climbs to the top of a diving platform, then jumps into the water. Which sequence of energy transformations best describes this process?

Accepted Answer

Potential energy → kinetic energy → heat energy

Question 4

Which of the following equations correctly represents the change in free energy ($$\Delta G) $$for a chemical reaction?

Accepted Answer

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

Question 5

Which of the following statements about enzymes is TRUE?

Accepted Answer

Enzymes speed up reactions by lowering the activation energy barrier.

Question 6

A reaction has a $$\Delta G of$$ $$-20 kJ/$$mol. Which of the following is TRUE about this reaction?

Accepted Answer

It is exergonic and can occur spontaneously.

Question 7

Which of the following best explains why living organisms do not violate the second law of thermodynamics?

Accepted Answer

Organisms decrease their own entropy by increasing the entropy of their surroundings.

Question 8

ATP hydrolysis is used to drive endergonic reactions in cells. Which statement best describes how this occurs?

Accepted Answer

The energy released from ATP hydrolysis is coupled to endergonic reactions, making the overall process exergonic.

Question 9

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

Accepted Answer

A molecule similar in structure to the substrate binds to the active site, blocking substrate binding.

Question 10

A scientist is studying an enzyme-catalyzed reaction. She increases the substrate concentration, but the reaction rate no longer increases. What is the most likely explanation?

Accepted Answer

The enzyme is saturated; all active sites are occupied.

Question 11

Which of the following best describes the role of activation energy ($$E_a) in a $$chemical reaction?

Accepted Answer

$$E_a is $$the energy required to break the bonds of reactants and initiate the reaction.

Question 12

Which of the following is a real-life example of energy coupling in cells?

Accepted Answer

The use of ATP hydrolysis to power the sodium-potassium pump in nerve cells.

Question 13

Which of the following statements about metabolic pathways is correct?

Accepted Answer

Metabolic pathways consist of a series of enzyme-catalyzed reactions that transform a specific molecule into a product.

Question 14

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction that is currently below its optimal temperature?

Accepted Answer

Increasing the temperature to the enzyme's optimal range.

Question 15

Feedback inhibition in a metabolic pathway is best described as:

Accepted Answer

The final product of the pathway inhibits an enzyme that acts early in the pathway.

Question 16

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 that fits only specific substrates.

Question 17

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

Accepted Answer

The synthesis of proteins from amino acids.

Question 18

A patient is given a drug that acts as a noncompetitive inhibitor of an essential enzyme. What is the most likely effect of this drug on the enzyme's activity?

Accepted Answer

It will decrease the enzyme's activity by binding to a site other than the active site, changing the enzyme's shape.

Question 19

Which of the following statements about ATP is correct?

Accepted Answer

ATP is composed of adenine, ribose, and three phosphate groups.

Question 20

Which of the following best describes the effect of increasing enzyme concentration on the rate of an enzyme-catalyzed reaction, assuming unlimited substrate is present?

Accepted Answer

The reaction rate will increase proportionally with enzyme concentration.

Metabolism and Enzymes: Energy, Pathways, and Regulation

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