Question 1

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook.
-Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.
A) exergonic; spontaneous
B) exergonic; endergonic
C) free energy; entropy
D) work; energy
E) entropy; enthalpy

Accepted Answer

Catabolism refers to the breakdown of complex molecules into simpler ones, whereas anabolism refers to the synthesis of complex molecules from simpler ones. Similarly, exergonic reactions release energy, while endergonic reactions require energy input. Thus, the pair of terms that correctly completes the sentence is exergonic; endergonic.

Question 2

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid.
-What is malonic acid's role with respect to succinate dehydrogenase?
A) It is a competitive inhibitor.
B) It blocks the binding of fumarate.
C) It is a noncompetitive inhibitor.
D) It is able to bind to succinate.
E) It is an allosteric regulator.

Accepted Answer

Malonic acid is a competitive inhibitor of succinate dehydrogenase as it resembles its substrate (succinate) and can bind to the active site of the enzyme, preventing succinate from binding and the reaction from occurring. Increasing the concentration of succinate leads to more competition between succinate and malonic acid for binding to the active site, reducing the inhibitory effect of malonic acid.

Question 3

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid.
-Based on this information, which of the following is correct?
A) Succinate dehydrogenase is the enzyme, and fumarate is the substrate.
B) Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.
C) Succinate is the substrate, and fumarate is the product.
D) Fumarate is the product, and malonic acid is a noncompetitive inhibitor.
E) Malonic acid is the product, and fumarate is a competitive inhibitor.

Accepted Answer

C) Succinate is the substrate, and fumarate is the product. This is correct because the enzyme succinate dehydrogenase catalyzes the conversion of succinate to fumarate, indicating that succinate is the substrate and fumarate is the product of the reaction.

Question 4

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook.
-Most cells cannot harness heat to perform work because
A) heat is not a form of energy.
B) cells do not have much heat; they are relatively cool.
C) temperature is usually uniform throughout a cell.
D) heat can never be used to do work.
E) heat must remain constant during work.

Accepted Answer

Temperature is usually uniform throughout a cell, which means there is no temperature gradient to drive the transfer of heat energy into work. In thermodynamics, work can be extracted from a system only when there is a temperature difference that allows heat to flow from a hotter region to a cooler one.

Question 5

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Which of the following in Figure 8.1 would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?
A) a
B) b
C) c
D) d
E) e

Accepted Answer

The answer of The following questions are based on the...

Question 6

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Which of the following represents the ΔG of the reaction in Figure 8.1?
A) a
B) b
C) c
D) d
E) e

Accepted Answer

The answer of The following questions are based on the...

Question 7

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D → A + B, in Figure 8.1?
A) a
B) b
C) c
D) d
E) e

Accepted Answer

The activation energy for the reverse reaction is represented by the difference in energy between the transition state and the reactants. In Figure 8.1, this difference is represented by the height of the barrier between the reactants and the transition state, which is labeled "a".

Question 8

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook.
-Some bacteria are metabolically active in hot springs because
A) they are able to maintain a lower internal temperature.
B) high temperatures make catalysis unnecessary.
C) their enzymes have high optimal temperatures.
D) their enzymes are completely insensitive to temperature.
E) they use molecules other than proteins or RNAs as their main catalysts.

Accepted Answer

The enzymes of bacteria that can live in hot springs have high optimal temperatures, allowing them to function efficiently in these extreme environments.

Question 9

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Which of the following represents the activation energy needed for the noncatalyzed reverse reaction, C + D → A + B, in Figure 8.1?
A) a
B) b
C) c
D) d
E) e

Accepted Answer

The answer of The following questions are based on the...

Question 10

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Which of the following represents the activation energy required for a noncatalyzed reaction in Figure 8.1?
A) a
B) b
C) c
D) d
E) e

Accepted Answer

The activation energy for a noncatalyzed reaction is the energy barrier that must be overcome for reactants to transform into products without the aid of a catalyst. It is represented by the difference in energy between the reactants and the peak of the energy profile for the reaction pathway.

Question 11

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook.
-Which of the following metabolic processes can occur without a net influx of energy from some other process?
A) ADP +  ᵢ → ATP + H₂O
B) C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O
C) 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂
D) amino acids → protein
E) glucose + fructose → sucrose

Accepted Answer

The answer of The following questions are from the end-of-chapter...

Question 12

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Assume that the reaction in Figure 8.1 has a ΔG of -5.6 kcal/mol. Which of the following would be true?
A) The reaction could be coupled to power an endergonic reaction with a ΔG of +6.2 kcal/mol.
B) The reaction could be coupled to power an exergonic reaction with a ΔG of +8.8 kcal/mol.
C) The reaction would result in a decrease in entropy (S) and an increase in the total energy content (H) of the system.
D) The reaction would result in an increase in entropy (S) and a decrease in the total energy content (H) of the system.
E) The reaction would result in products (C + D) with a greater free-energy content than in the initial reactants (A + B).

Accepted Answer

A negative ΔG indicates that the reaction is exergonic, meaning it releases energy and typically results in an increase in entropy (S) and a decrease in the total energy content (H) of the system.

Question 13

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 8.1?
A) a
B) b
C) c
D) d
E) e

Accepted Answer

The activation energy for an enzyme-catalyzed reaction is represented by the energy difference between the reactants and the transition state in the presence of an enzyme. Choice B correctly identifies this energy barrier that must be overcome for the reaction to proceed with the help of the enzyme.

Question 14

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1.
  
Figure 8.1
-Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products in Figure 8.1?
A) a
B) b
C) c
D) d
E) e

Accepted Answer

The answer of The following questions are based on the...

Question 15

-How do cells use the ATP cycle shown in the figure?
A) Cells use the cycle to recycle ADP and phosphate.
B) Cells use the cycle to recycle energy released by ATP hydrolysis.
C) Cells use the cycle to recycle ADP, phosphate, and the energy released by ATP hydrolysis.
D) Cells use the cycle to generate or consume water molecules as needed.
E) Cells use the cycle primarily to generate heat.

Accepted Answer

Cells use the ATP cycle to recycle ADP and phosphate, which are combined to regenerate ATP, the primary energy carrier in cells.

Question 16

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook.
-If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?
A) Additional product will be formed.
B) Additional substrate will be formed.
C) The reaction will change from endergonic to exergonic.
D) The free energy of the system will change.
E) Nothing; the reaction will stay at equilibrium.

Accepted Answer

Enzymes do not change the thermodynamics of a reaction, they only increase the rate of reaction. Therefore, adding an enzyme to a solution where its substrate and product are in equilibrium will not change the equilibrium position of the reaction. The reaction will continue to stay at equilibrium.

Question 17

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.
-With respect to the enzyme that converts X to Y, substance A functions as
A) a coenzyme.
B) an allosteric inhibitor.
C) the substrate.
D) an intermediate.
E) a competitive inhibitor.

Accepted Answer

Substance A binds to the enzyme at a site remote from the active site, causing a conformational change that decreases the enzyme's activity. This behavior is characteristic of an allosteric inhibitor. A coenzyme is a small molecule that binds near the active site and is required for enzyme activity. The substrate is the molecule that the enzyme acts upon, and intermediate is a molecule formed during the reaction but is not a final product. A competitive inhibitor binds to the active site and competes with the substrate for binding.

Question 18

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook.
-If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to
A) add more of the enzyme.
B) heat the solution to 90°C.
C) add more substrate.
D) add an allosteric inhibitor.
E) add a noncompetitive inhibitor.

Accepted Answer

Adding more enzyme increases the number of active sites available for the substrate, thus increasing the rate of reaction when the substrate concentration is already at a saturating level. Heating the solution excessively or adding inhibitors would not increase the yield of products and could potentially denature the enzyme or further inhibit the reaction.

Question 19

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.
-What is substance X?
A) a coenzyme
B) an allosteric inhibitor
C) a substrate
D) an intermediate
E) the product

Accepted Answer

Substance X is the substrate that is converted to Y by the enzyme.

Answer: B
 Product A binding to the enzyme at a position remote from its active site indicates that it is an allosteric inhibitor, as it is affecting the enzyme's activity through an allosteric site rather than directly at the active site.

Question 20

-Which of the following is the most correct interpretation of the figure?
A) Inorganic phosphate is created from organic phosphate.
B) Energy from catabolism can be used directly for performing cellular work.
C) ADP +  ᵢ are a set of molecules that store energy for catabolism.
D) ATP is a molecule that acts as an intermediary to store energy for cellular work.
E)  ᵢ acts as a shuttle molecule to move energy from ATP to ADP.

Accepted Answer

The answer of 
-Which of the following is the most...

Quiz 8: An Introduction to Metabolism

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as is to .

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Most cells cannot harness heat to perform work because

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following in Figure 8.1 would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the ΔG of the reaction in Figure 8.1?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D → A + B, in Figure 8.1?

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Some bacteria are metabolically active in hot springs because

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy needed for the noncatalyzed reverse reaction, C + D → A + B, in Figure 8.1?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy required for a noncatalyzed reaction in Figure 8.1?

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Which of the following metabolic processes can occur without a net influx of energy from some other process?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Assume that the reaction in Figure 8.1 has a ΔG of -5.6 kcal/mol. Which of the following would be true?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 8.1?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products in Figure 8.1?

-How do cells use the ATP cycle shown in the figure?

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. -With respect to the enzyme that converts X to Y, substance A functions as

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. -What is substance X?

-Which of the following is the most correct interpretation of the figure?

Quiz 8: An Introduction to Metabolism

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Most cells cannot harness heat to perform work because

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following in Figure 8.1 would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the ΔG of the reaction in Figure 8.1?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D → A + B, in Figure 8.1?

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Some bacteria are metabolically active in hot springs because

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy needed for the noncatalyzed reverse reaction, C + D → A + B, in Figure 8.1?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy required for a noncatalyzed reaction in Figure 8.1?

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Which of the following metabolic processes can occur without a net influx of energy from some other process?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Assume that the reaction in Figure 8.1 has a ΔG of -5.6 kcal/mol. Which of the following would be true?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 8.1?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 8.1. Figure 8.1 -Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products in Figure 8.1?

-How do cells use the ATP cycle shown in the figure?

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. -With respect to the enzyme that converts X to Y, substance A functions as

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. -What is substance X?

-Which of the following is the most correct interpretation of the figure?

The following questions are from the end-of-chapter "Test Your Understanding" section in Chapter 8 of the textbook. -Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as is to .