Question 1

Which of the following best describes the concept of 'free energy' ($$\Delta G) in a $$biological system?

Accepted Answer

The portion of a system's energy that can perform work when temperature and pressure are uniform, as in a living cell.

Question 2

A cell carries out the following reaction: $$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O. $$Which of the following statements is TRUE regarding this reaction?

Accepted Answer

It is a catabolic and exergonic reaction, releasing free energy.

Question 3

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 4

Which of the following best explains why ATP is considered the 'energy currency' of the cell?

Accepted Answer

ATP hydrolysis releases free energy that can be used to drive endergonic reactions.

Question 5

A scientist measures the $$\Delta G of a $$reaction and finds it to be negative. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will proceed spontaneously.

Question 6

Which of the following is an example of feedback inhibition in a metabolic pathway?

Accepted Answer

The final product of a pathway binds to an enzyme that acts early in the pathway, inhibiting its activity.

Question 7

Which of the following best describes the difference between competitive and noncompetitive enzyme inhibitors?

Accepted Answer

Competitive inhibitors resemble the substrate and bind to the active site, while noncompetitive inhibitors bind elsewhere and change the enzyme's shape.

Question 8

If a cell is unable to regenerate ATP from ADP and inorganic phosphate, what is the most likely consequence?

Accepted Answer

The cell will be unable to perform essential work and will eventually die.

Question 9

Which of the following scenarios best illustrates the concept of energy coupling in cellular metabolism?

Accepted Answer

The hydrolysis of ATP is used to drive the active transport of ions against their concentration gradient.

Question 10

Which of the following statements about enzymes is TRUE?

Accepted Answer

Enzymes lower the activation energy barrier, allowing reactions to occur more rapidly.

Question 11

A metabolic pathway is regulated by the end product binding to an enzyme at a site other than the active site, causing a conformational change. This is an example of:

Accepted Answer

Allosteric regulation

Question 12

Which of the following best explains why most metabolic pathways are regulated at multiple steps?

Accepted Answer

To allow for fine-tuned control and efficient use of resources in response to cellular needs.

Question 13

During a laboratory experiment, a student adds a competitive inhibitor to an enzyme-catalyzed reaction. Which of the following changes would most likely be observed?

Accepted Answer

The reaction rate decreases, but can be restored by increasing substrate concentration.

Question 14

Which of the following is a correct statement about the relationship between catabolic and anabolic pathways?

Accepted Answer

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

Question 15

A patient is diagnosed with a genetic disorder that results in a nonfunctional enzyme in a metabolic pathway. Which of the following is the most likely consequence?

Accepted Answer

The substrate for the defective enzyme will accumulate, and the pathway's end product will be deficient.

Question 16

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

Accepted Answer

Enzyme activity increases with temperature up to an optimal point, then decreases as the enzyme denatures.

Question 17

Which of the following is an example of an exergonic reaction in a living cell?

Accepted Answer

The hydrolysis of ATP to ADP and inorganic phosphate.

Question 18

A researcher observes that the addition of a certain molecule to an enzyme-catalyzed reaction decreases the reaction rate, but the effect is not reversed by increasing substrate concentration. What type of inhibitor is most likely involved?

Accepted Answer

Noncompetitive inhibitor

Question 19

Which of the following best explains why living organisms require a constant input of energy?

Accepted Answer

To maintain order and carry out cellular processes in accordance with the Second Law of Thermodynamics.

Question 20

Which of the following statements about the regeneration of ATP is correct?

Accepted Answer

ATP is regenerated from ADP and inorganic phosphate by endergonic reactions such as cellular respiration.

Metabolism and Thermodynamics in Biology: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards