Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in metabolism?

Accepted Answer

Catabolic pathways release energy by breaking down complex molecules, while anabolic pathways consume energy to build complex molecules.

Question 2

A cell is placed in a closed thermos and sealed. According to thermodynamic principles, what type of system does this represent, and what is a key characteristic of this system?

Accepted Answer

An isolated system; it does not exchange energy or matter with its surroundings.

Question 3

Which equation correctly represents the change in Gibbs free energy ($\Delta G$) for a chemical reaction?

Accepted Answer

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

Question 4

During cellular respiration, glucose is broken down in the presence of oxygen. This process is an example of which type of metabolic pathway and why?

Accepted Answer

Catabolic, because it releases energy by breaking down glucose.

Question 5

Which of the following statements about the second law of thermodynamics is correct?

Accepted Answer

Every energy transfer increases the entropy of the universe.

Question 6

A reaction has $\Delta G = -10$ kcal/mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 7

Which of the following best explains why ATP hydrolysis releases energy?

Accepted Answer

The products of ATP hydrolysis have lower free energy than ATP, making the reaction exergonic.

Question 8

A scientist adds a competitive inhibitor to an enzyme-catalyzed reaction. What is the most likely effect on the reaction rate, and how can this effect be overcome?

Accepted Answer

The reaction rate will decrease, and the effect can be overcome by adding more substrate.

Question 9

Which of the following is an example of energy coupling in a cell?

Accepted Answer

The use of ATP hydrolysis to drive the synthesis of glutamine from glutamic acid and ammonia.

Question 10

Which of the following statements about enzyme function is correct?

Accepted Answer

Enzymes lower the activation energy ($E_a$) but do not change the overall $\Delta G$ of the reaction.

Question 11

A patient is exposed to a toxin that acts as a noncompetitive inhibitor of a key metabolic enzyme. What is the most likely effect on the enzyme's activity?

Accepted Answer

The inhibitor binds to a different site, changing the enzyme's shape and reducing its activity.

Question 12

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

Accepted Answer

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

Question 13

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

Accepted Answer

The end product of a metabolic pathway binds to an enzyme early in the pathway, decreasing its activity.

Question 14

Which of the following statements about the localization of enzymes within a eukaryotic cell is correct?

Accepted Answer

Some enzymes are compartmentalized within organelles, such as mitochondria, to increase metabolic efficiency.

Question 15

A reaction in a cell has $\Delta G = +5$ kcal/mol. Which of the following is true about this reaction?

Accepted Answer

It is endergonic and requires an input of energy.

Question 16

Which of the following best explains why living cells are considered open systems?

Accepted Answer

They exchange both energy and matter with their surroundings.

Question 17

Which of the following is NOT a way that enzymes lower the activation energy ($E_a$) of a reaction?

Accepted Answer

Increasing the temperature of the reaction.

Question 18

A mutation causes an enzyme to lose its ability to bind its cofactor. What is the most likely consequence?

Accepted Answer

The enzyme will lose its catalytic activity.

Question 19

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

Accepted Answer

ATP couples exergonic and endergonic reactions by transferring a phosphate group.

Question 20

A researcher observes that an enzyme's activity increases as the substrate binds to one of its subunits, making it easier for additional substrate molecules to bind. This is an example of:

Accepted Answer

Cooperativity

Chapter 8: An Introduction to Metabolism – Study Notes

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