AP Lovrien - Enzymes And Energy
(95).webp "AP Lovrien - Enzymes And Energy - Quiz")
- 1.
The active site of an enzyme is the region that
- A.
Binds allosteric regulators of the enzyme.
- B.
Is involved in the catalytic reaction of the enzyme.
- C.
Digests the products of the catalytic reaction.
- D.
Is inhibited by the presence of a coenzyme or a cofactor.
Correct Answer
B. Is involved in the catalytic reaction of the enzyme.Explanation
The active site of an enzyme is the region that is involved in the catalytic reaction of the enzyme. This means that it is the specific location where the enzyme binds to its substrate and facilitates the conversion of the substrate into a product. The active site provides a precise environment for the reaction to occur, including the necessary amino acid residues and functional groups that participate in the catalysis. It is at the active site that the enzyme and substrate interact and form an enzyme-substrate complex, allowing the reaction to proceed efficiently.Rate this question:
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- 2.
During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the for the new reaction?
- A.
-40
- B.
-20
- C.
0
- D.
20
- E.
40
Correct Answer
B. -20Explanation
If the ΔG of the enzyme-catalyzed reaction is -20 kcal/mol, it means that the reaction is exergonic and releases energy. Doubling the amount of enzyme in the reaction does not affect the ΔG value, as it is a measure of the energy difference between the reactants and products. Therefore, the ΔG for the new reaction will still be -20 kcal/mol.Rate this question:
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- 3.
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
- A.
Some enzymes change their structure when activators bind to the enzyme.
- B.
A competitive inhibitor can outcompete the substrate for the active site.
- C.
The binding of the substrate changes the shape of th enzyme's active site.
- D.
The active site creates a microenvironment ideal for the reaction.
Correct Answer
C. The binding of the substrate changes the shape of th enzyme's active site.Explanation
According to the induced fit hypothesis of enzyme catalysis, the correct statement is that the binding of the substrate changes the shape of the enzyme's active site. This hypothesis proposes that the active site of an enzyme is not a rigid structure, but rather it can undergo conformational changes upon substrate binding. The enzyme's active site can adjust its shape to better accommodate and interact with the substrate, leading to a more efficient catalytic reaction. This concept highlights the dynamic nature of enzyme-substrate interactions and the importance of the induced fit in enzyme catalysis.Rate this question:
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- 4.
A chemical reaction that has a positive increase in G is correctly described as
- A.
Endergonic
- B.
Endothermic
- C.
Enthalpic
- D.
Spontaneous
- E.
Exothermic
Correct Answer
A. EndergonicExplanation
An endergonic reaction is a chemical reaction that requires an input of energy in order to proceed. In this type of reaction, the Gibbs free energy (G) increases, indicating that the products have a higher energy state than the reactants. This means that the reaction is not spontaneous and will not occur without the addition of energy. Therefore, the correct answer is endergonic.Rate this question:
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- 5.
Which of the following is true of enzymes?
- A.
Enzymes that require a cofactor or ion for catalysis speed up more appreciably than if the enzymes act alone.
- B.
Enzyme function is increased if the three-dimensional structure or conformation of an enzyme is altered.
- C.
Enzyme function is independent of physical and chemical environmental factors such as pH and temperature.
- D.
Enzymes increase the rate of chemical reactions by lowering activition energy barriers.
Correct Answer
D. Enzymes increase the rate of chemical reactions by lowering activition energy barriers.Explanation
Enzymes increase the rate of chemical reactions by lowering activation energy barriers. Activation energy is the energy required to start a chemical reaction. Enzymes act as catalysts, facilitating the reaction by reducing the amount of energy needed to initiate it. They achieve this by binding to the reactant molecules and bringing them closer together, allowing them to interact more easily and forming a transition state with lower energy requirements. This lowers the activation energy barrier, making the reaction proceed faster. Therefore, enzymes play a crucial role in accelerating biochemical reactions in living organisms.Rate this question:
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- 6.
When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows:
- A.
+ change in G, + change in H, + change in S
- B.
+ change in G, + change in H, - change in S
- C.
- change in G, - change in H, - change in S
- D.
+ change in G, - change in H, - change in S
- E.
- change in G, - change in H, + change in S
Correct Answer
B. + change in G, + change in H, - change in SExplanation
When glucose monomers are joined together to form a cellulose polymer, the process requires energy and is not spontaneous, resulting in a positive change in Gibbs free energy (+ change in G). Additionally, the formation of the glycosidic linkages involves bond formation, which requires energy, leading to a positive change in enthalpy (+ change in H). However, the formation of a polymer from monomers typically results in a decrease in disorder, leading to a negative change in entropy (- change in S). Therefore, the correct answer is + change in G, + change in H, - change in S.Rate this question:
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- 7.
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.
Correct Answer
C. Succinate is the substrate, and fumarate is the product.Explanation
The given information states that succinate dehydrogenase catalyzes the conversion of succinate to fumarate. This implies that succinate is the substrate, as it is the molecule being acted upon by the enzyme, and fumarate is the product, as it is the molecule formed as a result of the reaction.Rate this question:
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- 8.
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, what is the purpose of using malonic acid in this experiment?
- A.
It is a competitive inhibitor
- B.
It blocks the binding of fumarate.
- C.
It is an allosteric inhibitor.
- D.
It is able to bind to succinate.
- E.
It replaces the usual enzyme.
Correct Answer
A. It is a competitive inhibitorExplanation
Malonic acid is used in this experiment as a competitive inhibitor. This means that it competes with succinate for the active site of succinate dehydrogenase. By binding to the active site, malonic acid prevents succinate from binding and inhibits the conversion of succinate to fumarate. The fact that malonic acid resembles succinate but cannot be acted upon by succinate dehydrogenase allows it to effectively compete with succinate for the enzyme's active site. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid, indicating its competitive nature.Rate this question:
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- 9.
Which of the following is likely to lead to an increase in the concentration of ATP in a cell?
- A.
An increase in a cell's anabolic activity.
- B.
An increase in a cell's catabolic activity.
- C.
An increased influx of cofactor molecules.
- D.
An increased amino acid concentration.
- E.
The cell's inceased transport of materials to the environment.
Correct Answer
B. An increase in a cell's catabolic activity.Explanation
An increase in a cell's catabolic activity is likely to lead to an increase in the concentration of ATP in a cell. Catabolic activity involves the breakdown of molecules, such as glucose, to release energy. This energy is used to synthesize ATP through cellular respiration. Therefore, an increase in catabolic activity would result in more molecules being broken down, leading to a higher production of ATP.Rate this question:
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- 10.
Which of the following is true for anabolic pathways?
- A.
They do not depend on enzymes.
- B.
They are usually highly spontaneous chemical reactions.
- C.
They consume energy to build up polymers from monomers.
- D.
They release energy as they degrade polymers to monomers.
Correct Answer
C. They consume energy to build up polymers from monomers.Explanation
Anabolic pathways involve the synthesis of complex molecules from simpler ones, such as building polymers from monomers. This process requires energy input, usually in the form of ATP, to drive the chemical reactions and build up larger molecules. Enzymes play a crucial role in facilitating these reactions, but they are not mentioned as being independent of enzymes in the question. Therefore, the correct answer is that anabolic pathways consume energy to build up polymers from monomers.Rate this question:
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- 11.
Whenever energy is transformed, there is always an increase in the
- A.
Free energy of the system.
- B.
Free energy of the universe.
- C.
Entropy of the system.
- D.
Entropy of the universe.
- E.
Enthalpy of the universe.
Correct Answer
D. Entropy of the universe.Explanation
Whenever energy is transformed, there is always an increase in the entropy of the universe. This is because the second law of thermodynamics states that in any energy transformation, the total entropy of the system and its surroundings will always increase. Entropy is a measure of the disorder or randomness in a system, and energy transformations tend to increase the overall disorder of the universe. Therefore, the correct answer is entropy of the universe.Rate this question:
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- 12.
Which of the following types of reactions would decrease the entropy within a cell?
- A.
Dehydration reactions
- B.
Hydrolysis
- C.
Respiration
- D.
Digestion
- E.
Catabolism
Correct Answer
A. Dehydration reactionsExplanation
Dehydration reactions involve the removal of water molecules to form larger molecules. This process leads to a decrease in the number of possible arrangements of molecules, resulting in a decrease in entropy within a cell. As a result, dehydration reactions would decrease the entropy within a cell.Rate this question:
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Jan 18, 2024Quiz Edited by
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Oct 23, 2014Quiz Created by
Justin Lovrien
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