Question 1

Which of the following best describes a metabolic pathway?

Accepted Answer

A series of specific chemical reactions, each catalyzed by a specific enzyme, that transforms a molecule into a new product.

Question 2

Which statement about catabolic and anabolic pathways is correct?

Accepted Answer

Catabolic pathways break down complex molecules into simpler compounds, releasing energy.

Question 3

Which of the following is an example of the first law of thermodynamics as it applies to living systems?

Accepted Answer

Energy from food is transformed into kinetic energy for movement, but the total energy remains constant.

Question 4

According to the second law of thermodynamics, which of the following is true about energy transformations in biological systems?

Accepted Answer

Some energy becomes unusable, often lost as heat, increasing the entropy of the surroundings.

Question 5

A chemical reaction has a $$ \Delta G  ($$change in free energy) of $$ -5 $$ kcal/mol. Which of the following statements is true?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 6

Which of the following best explains how ATP powers cellular work?

Accepted Answer

By transferring a phosphate group to another molecule, making it more reactive.

Question 7

The hydrolysis of ATP to ADP and inorganic phosphate ($$ 	ext{ATP} ightarrow 	ext{ADP} + 	ext{P}_i ) $$has a $$ \Delta G  of$$ $$ -7.3 $$ kcal/mol. If an endergonic reaction has a $$ \Delta G  of$$ $$ +3.4 $$ kcal/mol, what is the overall $$ \Delta G $$ when these reactions are coupled?

Accepted Answer

$$ -3.9 $$ kcal/mol

Question 8

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

Accepted Answer

Increasing the temperature of the reaction.

Question 9

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 pathway will be blocked at the step catalyzed by the defective enzyme, leading to accumulation of the substrate.

Question 10

Which of the following best describes feedback inhibition in a metabolic pathway?

Accepted Answer

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

Question 11

Which of the following statements about enzyme activity is correct?

Accepted Answer

Enzyme activity can be affected by pH, temperature, and salt concentration.

Question 12

A competitive inhibitor decreases the rate of an enzyme-catalyzed reaction by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 13

Which of the following is an example of an allosteric inhibitor?

Accepted Answer

A molecule that binds to a site other than the active site, causing the enzyme to change shape and become less active.

Question 14

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

Accepted Answer

They exchange energy and matter with their surroundings.

Question 15

Which of the following scenarios illustrates energy coupling in a cell?

Accepted Answer

Using the energy released from ATP hydrolysis to drive an endergonic reaction.

Question 16

If a reaction in a cell has $$ \Delta G \u003e 0 $$, which of the following is true?

Accepted Answer

The reaction is endergonic and requires an input of energy.

Question 17

Which of the following is a real-life example of entropy increasing in a biological system?

Accepted Answer

The breakdown of starch into glucose molecules during digestion.

Question 18

Which of the following statements about ATP is correct?

Accepted Answer

ATP consists of a ribose sugar, adenine base, and three phosphate groups.

Question 19

Which of the following best describes the role of cofactors in enzyme activity?

Accepted Answer

Cofactors are nonprotein helpers that are required for some enzymes to function properly.

Question 20

A scientist adds a noncompetitive inhibitor to an enzyme-catalyzed reaction. What is the most likely effect?

Accepted Answer

The inhibitor binds to a site other than the active site, causing the enzyme to change shape and reducing its activity.

Introduction to Metabolism and Biochemical Reactions

Study Guide - Practice Questions

Study Guide - Flashcards