Question 1

Which of the following best describes the difference between exergonic and endergonic reactions in terms of Gibbs free energy ($$\Delta G$$)?

Accepted Answer

Exergonic reactions have $$\Delta G  0$$ and require energy input.

Question 2

A scientist is studying a metabolic pathway in which the final product inhibits the activity of the first enzyme in the pathway. What is this regulatory mechanism called?

Accepted Answer

Feedback inhibition

Question 3

Which of the following statements about ATP hydrolysis is correct?

Accepted Answer

ATP hydrolysis releases about 7.3 kcal/mol of energy and is highly exergonic.

Question 4

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

Enzymes have active sites with unique shapes and chemical environments that only fit specific substrates.

Question 5

A patient with nonalcoholic fatty liver disease is found to have intestinal bacteria with increased anabolic activity. How might this contribute to obesity?

Accepted Answer

Anabolic activity in bacteria could increase the synthesis of energy-rich molecules, which may be absorbed by the host and contribute to fat storage.

Question 6

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

Accepted Answer

Each enzyme has an optimal temperature at which its activity is highest; activity decreases above or below this temperature.

Question 7

Which of the following best describes the role of redox reactions in cellular metabolism?

Accepted Answer

Redox reactions couple the loss of electrons (oxidation) from one molecule with the gain of electrons (reduction) by another, transferring energy within the cell.

Question 8

Which of the following is a correct statement about the first law of thermodynamics?

Accepted Answer

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

Question 9

A competitive inhibitor of an enzyme works by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 10

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

Accepted Answer

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

Question 11

Which of the following best describes the effect of substrate concentration on the rate of an enzyme-catalyzed reaction?

Accepted Answer

The reaction rate increases with substrate concentration but eventually plateaus when the enzyme becomes saturated.

Question 12

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

Accepted Answer

Providing energy to the reaction in the form of ATP hydrolysis.

Question 13

Which of the following statements about metabolic pathways is correct?

Accepted Answer

Metabolic pathways are regulated and can evolve new steps through retro-evolution or patchwork evolution.

Question 14

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

Accepted Answer

The synthesis of proteins from amino acids.

Question 15

Which of the following molecules is an electron carrier that is reduced during cellular respiration?

Accepted Answer

NADH

Question 16

Which of the following best describes the effect of pH on enzyme activity?

Accepted Answer

Each enzyme has an optimal pH, and activity decreases above or below this value.

Question 17

Which of the following is a correct statement about the role of phosphorylation in enzyme regulation?

Accepted Answer

Phosphorylation can either activate or deactivate enzymes by changing their shape.

Question 18

Which of the following is true about cofactors and coenzymes?

Accepted Answer

Cofactors are inorganic ions, while coenzymes are organic molecules that assist enzyme function.

Chapter 8: Energy and Enzymes – An Introduction to Metabolism

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