Q: Why do cells never reach equilibrium in their metabolic pathways?

Because cells are open systems with a constant flow of materials, preventing equilibrium.

Q: ATP hydrolysis is used to drive endergonic reactions in cells. Which of the following statements is correct regarding this process?

ATP hydrolysis releases energy, which is used to phosphorylate other molecules, making them more reactive.

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

By increasing the free energy change ($\Delta G$) of the reaction.

Question 1

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

Accepted Answer

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

Question 2

A diver climbs to the top of a platform and then jumps into the water. Which of the following best describes the energy transformations that occur during this process?

Accepted Answer

The diver converts kinetic energy to potential energy while climbing, and potential energy to kinetic energy while diving.

Question 3

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

Accepted Answer

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

Question 4

A brown bear eats a fish and then runs at high speed. According to the second law of thermodynamics, what happens to the energy from the fish?

Accepted Answer

Some energy is used for movement, but a significant portion is lost as heat, increasing the entropy of the surroundings.

Question 5

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

Accepted Answer

$\Delta G = G_{final} - G_{initial}$

Question 6

Which of the following is true for a spontaneous chemical reaction in a cell?

Accepted Answer

The reaction has a negative $\Delta G$ and decreases the system's free energy.

Question 7

Which of the following best describes an exergonic reaction?

Accepted Answer

It releases free energy and is spontaneous, with $\Delta G < 0$.

Question 8

Why do cells never reach equilibrium in their metabolic pathways?

Accepted Answer

Because cells are open systems with a constant flow of materials, preventing equilibrium.

Question 9

ATP hydrolysis is used to drive endergonic reactions in cells. Which of the following statements is correct regarding this process?

Accepted Answer

ATP hydrolysis releases energy, which is used to phosphorylate other molecules, making them more reactive.

Question 10

The conversion of glutamic acid to glutamine in cells is endergonic ($\Delta G = +3.4$ kcal/mol). When coupled with ATP hydrolysis ($\Delta G = -7.3$ kcal/mol), what is the net $\Delta G$ for the overall reaction?

Accepted Answer

$\Delta G = -3.9$ kcal/mol

Question 11

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

Accepted Answer

By increasing the free energy change ($\Delta G$) of the reaction.

Question 12

A researcher increases the substrate concentration in an enzyme-catalyzed reaction but observes no further increase in reaction rate. What is the most likely explanation?

Accepted Answer

The enzyme is saturated, and all active sites are occupied.

Question 13

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

Accepted Answer

The active site of an enzyme has a unique shape that fits only specific substrates, and the induced fit enhances this specificity.

Question 14

Which of the following environmental factors can affect enzyme activity in a cell?

Accepted Answer

Temperature, pH, and chemicals that specifically influence the enzyme.

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

Question 16

Which of the following statements about ATP is correct?

Accepted Answer

ATP consists of adenine, ribose, and three phosphate groups.

Question 17

Which of the following best describes the role of ATP in mechanical work within the cell?

Accepted Answer

ATP binds noncovalently to motor proteins and is hydrolyzed, causing a shape change that moves the protein.

Question 18

Which of the following is a real-world example of an exergonic reaction in human metabolism?

Accepted Answer

The breakdown of glucose during cellular respiration.

Question 19

Why is the hydrolysis of ATP considered exergonic?

Accepted Answer

Because it results in a decrease in free energy ($\Delta G < 0$) and releases energy that can be used to do work.

Question 20

Which of the following best explains why heat is not a useful energy source for driving chemical reactions in living cells?

Accepted Answer

Heat is nonselective and can denature proteins, while enzymes provide specificity and lower activation energy without damaging cellular components.

Chapter 6: An Introduction to Metabolism – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards