Biology Exam 3 chapter 8
28. Which of the following is the most correct interpretation of the figure? Which of the following is the most correct interpretation of the figure?
ATP is a molecule that acts as an intermediary to store energy for cellular work.
21. Which of the following statements describes a central role that ATP plays in cellular metabolism?
ATP provides energy coupling between exergonic and endergonic reactions.
12. Which of the following types of reactions would decrease the entropy within a cell?
Anabolic reactions
3. Most cells cannot harness heat to perform work because _____.
Temperature is usually uniform throughout a cell heat is not a form of energy
34. What is the name of the thermodynamic barrier that must be overcome before products are formed in a spontaneous reaction?
activation energy
23. Which of the following molecules is most similar in structure to ATP?
an RNA nucleotide
58. Which of the following statements describes an example of cooperativity associated with enzyme regulation?
binding a substrate to one subunit of a tetramer stimulates faster binding of substrate to each of the other three subunits
40. How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?
by binding to an allosteric site, thus changing the shape of the active site of the enzyme
38. Which of the following conditions may be overcome by increasing the substrate concentration in an enzymatic reaction with a fixed amount of enzyme?
competitive inhibition
53. HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?
competitive inhibition
35. During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?
-20 kcal/mol
54. A series of enzymes catalyze the reactions in the metabolic pathway 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 substrate
37. Which of the following statements describes a key component of the induced fit hypothesis of enzyme catalysis?
Binding of substrate to the active site changes the shape of the active site of an enzyme.
48. Use the following information to answer the question below. Graph of Progress of the Reaction on x-axis versus free energy on y-axis. Four horizontal dotted lines are shown; three about equally spaced in the top third of the y-axis to split with one line peaking at the topmost line and one peaking at the second line; they rejoin above the lowest upper line and fall to The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?
D
4. A decrease in entropy is associated with which type of reaction?
Dehydration
17. A chemical reaction that has a positive ΔG is best described as _____.
Endergonic
7. Which of the following statements describes the first law of thermodynamics?
Energy cannot be created or destroyed.
30. Which of the following statements about enzyme function is true?
Enzymes increase the rate of chemical reactions by lowering activation energy barriers.
19. The relationship between catabolism and anabolism is most similar to the relationship between which of the following pairs of terms?
Exergonic; Endergonic
1. Which of the following statements is true of metabolism in its entirety in all organisms?
Metabolism consists of all the energy transformation reactions in an organism.
44. Use the following information to answer the question below. X-axis shows concentration of reactants, micromolar, from 0 to positive 10; y-axis shows rate of product formation from 0 to positive 10. Line starts at origin, curves upward sharply to the right to about 4.0, 8.0, and levels out gradually. Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant In the figure, why does the reaction rate plateau at higher reactant concentrations?
Most enzyme molecules are occupied by substrate at high reactant concentrations.
15. Which of the following statements is true for a system at chemical equilibrium?
The system can do no work.
24. Which of the following statements describes a common characteristic of catabolic pathways?
They are exergonic and provide energy that can be used to produce ATP from ADP and i.
6. Which of the following statements about anabolic pathways is true?
They consume energy to build up polymers from monomers.
47. Use the following information to answer the question below. Graph of Progress of the Reaction on x-axis versus free energy on y-axis. Four horizontal dotted lines are shown; three about equally spaced in the top third of the y-axis and one near the bottom of the y-axis. Distance a is from the bottom line to the middle of the three upper lines. . The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following terms best describes the forward reaction in the figure?
exergonic, G < 0
32. Which of the following aspects of enzyme structure is best described by a clasping handshake analogy?
the specific manner in which an enzyme binds substrate
14. The mathematical expression for the change in free energy of a system is ΔG = ΔH - T ΔS. Which of the following statements is correct?
ΔG is the change in free energy.
