Bsc 1010L Ch6

Front 1

Why do we have storage macromolecules, such as fats, in our bodies?
A. We can break down these macromolecules to provide energy for the endergonic reactions in our bodies.
B. Human cells can directly capture the energy of sunlight through photosynthesis and store it as macromolecules such as fats.
C. Macromolecules, such as fats, are a convenient way to store kinetic energy.
D. Breaking down macromolecules, such as fats, is an endergonic process.

Back 1

A. We can break down these macromolecules to provide energy for the endergonic reactions in our bodies.

Front 2

2. Energy is defined as:
A. heat.
B. the capacity to do work.
C. change.
D. movement.

Back 2

B. the capacity to do work.

Front 3

3. The amount of energy available to do work is called:
A. activation energy

B. free energy
C. kinetic energy
D. potential energy

Back 3

B. free energy

Front 4

4. The energy needed to destabilize existing chemical bonds and start a chemical reaction is called:
A. activation energy
B. free energy
C. kinetic energy
D. potential energy

Back 4

A. activation energy

Front 5

Based on the graph, what are the optimal temperatures for the human enzyme and hotsprings prokaryote enzyme?

A. The optimal temperature for the human enzyme is 30 degrees C. The optimal temperature for the hotsprings prokaryote enzyme is 60 degrees C.
B. The optimal temperature for the human enzyme is 40 degrees C. The optimal temperature for the hotsprings prokaryote enzyme is 72 degrees C.
C. The optimal temperature for the human enzyme is 46 degrees C. The optimal temperature for the hotsprings prokaryote enzyme is 79 degrees C.
D. The optimal temperature for the human enzyme is 35 degrees C. The optimal temperature for the hotsprings prokaryote enzyme is 65 degrees C.

Back 5

B. The optimal temperature for the human enzyme is 40 degrees C. The optimal temperature for the hotsprings prokaryote enzyme is 72 degrees C.

Front 6

6. A drug binds to the active site of an enzyme. If it is bound to the active site of the enzyme, it prevents substrate binding. This drug would be considered a:
A. noncompetitive inhibitor
B. allosteric inhibitor
C. allosteric activator
D. competitive inhibitor

Back 6

D. competitive inhibitor

Front 7

7. A particular reaction has a negative delta G. However, this reaction takes many years to proceed in the absence of enzyme. Why is this the case?
A. This reaction does not obey the second law of thermodynamics
B. This reaction does not proceed spontaneously
C. The initial free energy of the reactants is much less than the final free energy of the products
D. A certain amount of activation energy is required for the reaction to proceed

Back 7

D. A certain amount of activation energy is required for the reaction to proceed

Front 8

8. A molecule that closely resembles the shape of a substrate for an enzyme would most likely serve as a:
A. noncompetitive inhibitor
B. allosteric inhibitor
C. competitive inhibitor
D. allosteric activator

Back 8

C. competitive inhibitor

Front 9

9. Oxidation and reduction reactions are chemical processes that result in a gain or loss of:
A. atoms.
B. neutrons.
C. electrons.
D. molecules.
E. protons.

Back 9

C. electrons.

Front 10

10. The synthesis of sugar molecules through the process of photosynthesis requires energy absorbed from sunlight. Bearing this in mind, what kind of reaction is photosynthesis?
A. exergonic
B. endergonic
C. catabolic
D. feedback

Back 10

B. endergonic

Front 11

11. A particular chemical reaction is exergonic. What can you say about the relationship between the reactants and the products in this exergonic reaction?
A. The reactants have more free energy than the products
B. The reactants are likely more disordered and the products are likely more ordered
C. The reactants cannot spontaneously react to generate the products
D. The reactants likely have lower enthalpy than the products

Back 11

A. The reactants have more free energy than the products

Front 12

12. Kinases are enzymes that can phosphorylate (transfer phosphate groups onto) macromolecules such as proteins. A particular kinase, Kinase 1 is known to promote cell division. It promotes cell division by phosphorylating Protein X. Phosphorylation of Protein X activates Protein X. Once activated, Protein X stimulates the production of other proteins such as Protein Y and Z that directly promote cell division. In order to function, Kinase 1 requires the presence of Metal A. However, in the presence of Protein A, Kinase 1 is nonfunctional. From the description, what is considered the substrate of Kinase 1?
A. Protein X
B. Protein Y
C. Protein Z
D. Metal A
E. Protein A

Back 12

A. Protein X

Front 13

13. Kinases are enzymes that can phosphorylate (transfer phosphate groups onto) macromolecules such as proteins. A particular kinase, Kinase 1 is known to promote cell division. It promotes cell division by phosphorylating Protein X. Phosphorylation of Protein X activates Protein X. Once activated, Protein X stimulates the production of other proteins such as Protein Y and Z that directly promote cell division. In order to function, Kinase 1 requires the presence of Metal A. However, in the presence of Protein A, Kinase 1 is nonfunctional. From the description, what is considered a cofactor of Kinase 1?
A. Protein X
B. Protein Y
C. Protein Z
D. Metal A
E. Protein A

Back 13

D. Metal A

Front 14

14. Hexokinase is an enzyme that binds specifically to glucose and converts it into glucose 6-phosphate. The activity of hexokinase is suppressed by glucose 6-phosphate, which binds to hexokinase at a location that is distinct from the active site. This is an example of what?
A. Feedback inhibition
B. Competitive inhibition
C. Cofactor binding
D. Allosteric activation

Back 14

A. Feedback inhibition

Front 15

15. The organic non-protein components that aid in enzyme functioning are called:
A. reactants.
B. cofactors.
C. coenzymes.
D. substrates.
E. products.

Back 15

C. coenzymes.

Front 16

16. The inorganic non-protein components that participate in enzyme catalysis are known as:
A. coenzymes.
B. cofactors.
C. products.
D. substrates.
E. reactants.

Back 16

B. cofactors.

Front 17

17. Many metabolic pathways are ultimately concerned with ATP; either with the generation of ATP, or with the requirement of ATP for that pathway to function. Why is ATP so important to metabolism?
A. Hydrolysis of ATP is used to drive exergonic reactions
B. Hydrolysis of the bond between adenine and ribose in ATP is commonly used to release energy that can be used to drive other cellular reactions
C. The phosphate groups of ATP are held together by unstable bonds that can be broken to release energy
D. ATP is a protein that serves as the energy currency of cells

Back 17

C. The phosphate groups of ATP are held together by unstable bonds that can be broken to release energy

Front 18

18. The chemistry of living systems representing all chemical reactions is called
A. catabolism.
B. anabolism.
C. metabolism.
D. enzymology.
E. thermodynamics.

Back 18

C. metabolism.

Front 19

19. A calorie is the commonly used unit of chemical energy. It is also the unit of:
A. light.
B. magnetism.
C. sound.
D. heat.
E. radioactivity.

Back 19

D. heat.

Front 20

20. The term oxidation is derived from the name of the element oxygen. This is reasonable, because oxygen:
A. attracts electrons very strongly.
B. can be oxidized by accepting electrons.
C. contains more electrons than are needed.
D. passes electrons to many other types of molecules.

Back 20

A. attracts electrons very strongly.

Front 21

21. When an atom or molecule gains one or more electrons, it is said to be:
A. energized.
B. oxidized.
C. polarized.
D. reduced.

Back 21

D. reduced.

Front 22

22. The ultimate source of energy for humans comes from what source?
A. The sun
B. Plants
C. Water
D. Air
E. Animals

Back 22

A. The sun

Front 23

23. Glucose is broken down through cellular respiration, which involves a large number of chemical reactions. At the end of the cellular respiration process, a large number of ATP molecules are generated, but yet, not all of the possible energy that is contained in a molecule of glucose can be harnessed through these chemical reactions to generate ATP. In other words, during cellular respiration, not all of the energy that is contained in a molecule of glucose is converted into the energy stored in ATP. What happened to the remaining energy?
A. It is destroyed
B. It is used to drive exergonic reactions
C. It is donated to molecules in the cellular respiration process to reduce them
D. It is lost as heat

Back 23

D. It is lost as heat

Front 24

24. The Law of Thermodynamics that states that energy cannot be created or destroyed is:
A. The First Law of Thermodynamics
B. The Second Law of Thermodynamics
C. The Third Law of Thermodynamics
D. The Fourth Law of Thermodynamics

Back 24

A. The First Law of Thermodynamics

Front 25

25. The Law of Thermodynamics that states that increases in entropy are favored is:
A. The First Law of Thermodynamics
B. The Second Law of Thermodynamics
C. The Third Law of Thermodynamics
D. The Fourth Law of Thermodynamics

Back 25

B. The Second Law of Thermodynamics

Front 26

26. A current problem in modern medicine is the development of drug resistance mutations. This occurs when a mutation arises in a patient making him/her resistant to a drug and thus rendering the drug useless in treating a specific disease. Many useful drugs are competitive inhibitors of specific enzymes, and the drug-resistance mutations prevent the binding of the drug. These types of mutations, in addition to preventing competitive inhibitor binding, can also sometimes reduce the activity of the enzyme. Why is that the case?
A. Binding to the competitive inhibitor is essential for the function of the enzyme
B. These mutations most likely affect an allosteric site on the enzyme
C. These mutations lower the activation energy of the reaction catalyzed by the enzyme
D. These mutations most likely change the shape of the active site of the enzyme

Back 26

D. These mutations most likely change the shape of the active site of the enzyme

Front 27

27. Tacrolimus (FK-506) is a drug that inhibits an enzyme called calcineurin. Calcineurin is a protein phosphatase. This is an enzyme that dephosphorylates (removes phosphate groups from) proteins. When added to cells, tacrolimus can inhibit the dephosphorylation of a protein called NFAT, but it cannot prevent the dephosphorylation of a protein called CDK1. What is the most likely explanation for this finding?
A. Calcineurin requires an additional cofactor to dephosphorylate NFAT
B. NFAT is a substrate of calcineurin, but CDK1 is not
C. Tacrolimus is a competitive inhibitor of calcineurin for NFAT, but not for CDK1
D. Tacrolimus changes the optimum pH for calcineurin

Back 27

B. NFAT is a substrate of calcineurin, but CDK1 is not

Front 28

28. RNA molecules that also act as enzymes are given the name:
A. ribozymes
B. cofactors
C. coenzymes
D. allosteric enzymes

Back 28

A. ribozymes

Front 29

29. In an enzyme-catalyzed reaction, the reactant is called the:
A. coenzyme
B. catalyst
C. substrate
D. product

Back 29

C. substrate

Front 30

30. When the substrate is bound to the enzyme, the shape of the enzyme may change slightly, leading to:
A. an induced fit
B. a great range of possible catalytic activities
C. a greater supply of activation energy
D. more permanent binding through intimate total contact
E. more possible products of the reaction

Back 30

A. an induced fit

Front 31

31. In order to reuse an enzyme after the conclusion of an enzyme catalyzed reaction, what must occur?
A. the enzyme has to be resynthesized
B. the enzyme has to separate itself from the product
C. changes into an active form
D. the enzyme has to decrease entropy

Back 31

B. the enzyme has to separate itself from the product

Front 32

32. You are working with a specific enzyme-catalyzed reaction in the lab. You are a very careful experimentalist, and as a result, at the beginning of each of your experiments, you measure the temperature in the lab. On days 1 through 5, the temperature in the lab was 20oC. Today is day 6 of your experiment, and the temperature in the lab is 30oC. How do you predict that this will alter the rate of your enzyme-catalyzed reaction?
A. It will decrease the rate
B. It will increase the rate
C. It could possibly increase or decrease the rate
D. it will not affect the rate

Back 32

C. It could possibly increase or decrease the rate

Front 33

33. Metabolic reactions fall under two general categories: anabolic and catabolic. What type of chemical reactions are these two classes of metabolic reactions?
A. Anabolic reactions are exergonic reactions, whereas catabolic reactions are endergonic.
B. Both anabolic and catabolic reactions are exergonic.
C. Both anabolic and catabolic reactions are endergonic.
D. Anabolic reactions are endergonic reactions, whereas catabolic reactions are exergonic.

Back 33

D. Anabolic reactions are endergonic reactions, whereas catabolic reactions are exergonic.

Front 34

34. Under standard conditions, ATP can release for every molecule converted to ADP
A. less than 1 cal of energy.
B. 1 to 2 cal of energy.
C. 7.3 Kcal of energy.
D. different amounts of energy depending on the cell.

Back 34

C. 7.3 Kcal of energy.

Front 35

35. Glucose is converted into glucose 6-phosphate by hexokinase. Glucose 6-phosphate then serves as the substrate for the enzyme phosphoglucose isomerase, which converts this reactant into fructose 6-phosphate. Fructose 6-phosphate serves as the substrate for phosphofructokinase, which converts fructose 6-phosphate into fructose 1,6-bisphosphate. Based on the information provided, this is an example of what?
A. Feedback inhibition
B. Allosteric regulation
C. A metabolic pathway
D. Enzyme inhibition

Back 35

C. A metabolic pathway

Front 36

36. In an experiment described in a chemistry lab book, the directions state that after mixing two chemicals (A and B) and waiting 5 minutes that A will be oxidized. This means that:
A. chemical A has lost electrons to chemical B.
B. chemical A has gained electrons from chemical B.
C. chemical A has gained energy in the form of heat from chemical B.
D. chemical A has lost energy in the form of heat to chemical B.
E. chemical A has reacted with oxygen.

Back 36

A. chemical A has lost electrons to chemical B.

Front 37

37. In a chemical reaction, glyceraldehyde-3-phosphate + NAD+ yields 1,3-bisphosphoglycerate + NADH. In this reaction, what happened to NAD+?
A. It was oxidized to form NADH
B. It was reduced to form NADH
C. It was activated to form NADH
D. it served as an enzyme to catalyze the reaction, and at the end of the reaction formed NADH

Back 37

B. It was reduced to form NADH

Front 38

38. In a chemical reaction, 1,3-bisphosphoglycerate + ADP yields 3-phosphoglycerate plus ATP. What is the delta G for this reaction?
A. Greater than zero.
B. Less than zero.
C. Equal to zero.
D. Cannot be determined

Back 38

B. Less than zero.

Front 39

39. For a particular chemical reaction, the enthalpy of the reactants is -400 kJ. The enthalpy of the products is -390 kJ. The entropy of the reactants is 0.2 kJ/K. The entropy of the products is 0.3 kJ/K. The temperature of the reaction is 25oC. What can you conclude about this reaction?
A. It is exergonic
B. It is endergonic
C. it is a redox reaction
D. It is being catalyzed by an enzyme

Back 39

A. It is exergonic

Front 40

40. Does ADP contain the capacity to provide energy for the cell?
A. No. ADP does not contain any bonds that can be broken to provide energy for the cell.
B. Yes. ADP has the same capacity to provide energy for the cell as ATP.
C. Yes. Cleaving the bond between the ribose sugar and the two phosphate groups can provide energy for the cell.
D. Yes. Cleaving the bond between the terminal phosphate and the phosphate attached to the ribose sugar can provide energy for the cell.

Back 40

D. Yes. Cleaving the bond between the terminal phosphate and the phosphate attached to the ribose sugar can provide energy for the cell.

Front 41

41. AMP-activated protein kinase (AMPK) is an enzyme that is activated by high levels of AMP in cells. If levels of AMP are high in cells, that means that levels of ATP are low. Once active, AMPK activates catabolic pathways and inhibits anabolic pathways in the cell. Why do you think that is the case? Choose the answer that best explains the role of AMPK.
A. High levels of AMP indicate that there is a high amount of energy stored in the cell, thus activating catabolic pathways and inhibiting anabolic pathways are mechanisms to use stored energy.
B. By inhibiting anabolic pathways, AMPK provides a mechanism to generate heat for the cell, which is important if AMP levels are high in the cell.
C. By activating catabolic pathways, AMPK provides a mechanism to activate exergonic pathways, which is important if AMP levels are high in the cell.
D. Activating catabolic pathways and inhibiting anabolic pathways will ultimately lead to higher consumption of ATP, which is important if AMP levels are high in the cell.

Back 41

C. By activating catabolic pathways, AMPK provides a mechanism to activate exergonic pathways, which is important if AMP levels are high in the cell.

Front 42

42. You are studying an enzyme-catalyzed reaction that induces a particular cellular activity in the lab. If you wanted to slow down that particular cellular activity by controlling the enzyme, what could you do?
A. Decrease the temperature of the incubator where the cells are growing
B. Increase the pH of the media the cells are growing in to the optimum pH
C. Add cofactors to the media the cells are growing in
D. Add an allosteric activator to the cells

Back 42

A. Decrease the temperature of the incubator where the cells are growing

Front 43

43. A new antibiotic has been developed that inhibits the activity of an enzyme by competitive inhibition. What effect will this have on the activation energy of the enzyme-catalyzed reaction?
A. The activation energy required for the reaction in the presence of the antibiotic would be greater than the activation energy required in the absence of the antibiotic
B. The activation energy required for the reaction in the presence of the antibiotic would be less than the activation energy required in the absence of the antibiotic
C. The activation energy required for the reaction in the presence of the antibiotic will be the same as the activation energy required in the absence of the antibiotic

Back 43

C. The activation energy required for the reaction in the presence of the antibiotic will be the same as the activation energy required in the absence of the antibiotic

Front 44

44. A new antibiotic has been developed. It acts as a noncompetitive inhibitor. How will this antibiotic affect delta G for the enzyme-catalyzed reaction?
A. Delta G will increase
B. Delta G will decrease
C. Delta G will be unaffected

Back 44

C. Delta G will be unaffected

Front 45

45. Glycolysis is a metabolic process that is done by all cells. However, not all cells make use of another metabolic process called the Krebs cycle. What does this tell you about the evolution of these processes?
A. As a metabolic process, glycolysis likely evolved prior to the Krebs cycle
B. As a metabolic process, the Krebs cycle likely evolved prior to glycolysis
C. Both the Krebs cycle and glycolysis likely evolved at the same time

Back 45

A. As a metabolic process, glycolysis likely evolved prior to the Krebs cycle

Front 46

46. Enzyme 1 converts substrate A into product B. Is this an example of a metabolic pathway?
A. Yes. This is a metabolic pathway that includes feedback inhibition.
B. No. This only describes one chemical reaction. A metabolic pathway includes multiple chemical reactions.
C. Yes. This is a simple metabolic pathway.
D. No. A metabolic pathway must include an inhibitory step.

Back 46

B. No. This only describes one chemical reaction. A metabolic pathway includes multiple chemical reactions.

Front 47

47. It is summer, and you are excited about going to your local amusement park, and specifically about riding the new roller coaster that was just built. You imagine waiting at the top of the stairs for the roller coaster to pull into the station, climbing into the car, strapping yourself into the seatbelt, and pulling down the harness. You can imagine the cars slowly chugging up to the top of the first hill, coming down on the other side, and the excitement you expect to feel as you go along for the ride. Of all of the things that you have imagined, which is an example of potential energy?
A. Waiting at the top of the stairs for the roller coaster to pull into the station
B. Climbing into the car
C. Pulling down the harness
D. The roller coaster car going up the first hill

Back 47

A. Waiting at the top of the stairs for the roller coaster to pull into the station

Front 48

48. Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group. This is the first committed step of the metabolic pathway of glycolysis, and thus it is very tightly regulated. AMP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1,6-bisphosphate. ATP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1,6-bisphosphate. There are other regulators of this enzyme as well. What is the role of AMP in this example?
A. Competitive inhibitor
B. Noncompetitive inhibitor
C. Allosteric inhibitor
D. Allosteric activator
E. Catalyst

Back 48

D. Allosteric activator

Front 49

49. You eat a bowl of beans as part of your dinner. As you digest the beans, the proteins that are present get broken down to their component amino acids. As your body destroys the macromolecules that were present in the beans, is the energy present in those molecules destroyed?
A. Yes. By breaking down these macromolecules, some of the energy they contained is destroyed.
B. No. While the vast majority of the energy contained in these macromolecules is converted to heat, it is not actually destroyed.
C. No. The energy contained within these macromolecules is converted into other forms of chemical energy and kinetic energy, though some is lost as heat.
D. No. Breaking down molecules does not lead to the release of energy.

Back 49

C. No. The energy contained within these macromolecules is converted into other forms of chemical energy and kinetic energy, though some is lost as heat.

Front 50

50. While standing at the top of the stairs, you have a potential energy of 40 Joules. If you walk all the way down the stairs, what would your potential energy be at the bottom of the stairs?
A. 0 Joules
B. 20 Joules
C. 40 Joules
D. 80 Joules

Back 50

A. 0 Joules

Front 51

51. If you were able to increase the kinetic energy of the molecules inside your body, how would this affect your body temperature?
A. It would increase
B. It would decrease
C. It would remain the same

Back 51

A. It would increase

Front 52

52. You return home to find that your baby brother has scattered his toy trains and trucks all over the floor of your room. As you begin to pick up the toys and put them away, you realize that even though he is just a baby, he has clearly mastered:
A. the first law of thermodynamics.
B. the second law of thermodynamics.
C. potential energy.
D. free energy.

Back 52

B. the second law of thermodynamics.

Front 53

53. If the G of a reaction was -31.45 kJoules, you would know that:
A. the products have more free energy than the reactants.
B. the reaction requires an energy input of 31.45 kJoules to proceed.
C. the reaction most likely leads to development of a more ordered system.
D. the reaction is spontaneous.

Back 53

D. the reaction is spontaneous.

Front 54

54. In the hypothetical biochemical pathway, P Q + R S T, which step is likely to have evolved first?
A. P Q
B. Q + R
C. R S
D. S T

Back 54

D. S T

Front 55

55. While conducting an experiment, you realize that a competitive inhibitor was interfering with your reaction. How could you overcome this problem?
A. Add a non-competitive inhibitor to the reaction.
B. Add a cofactor to the reaction.
C. Increase the concentration of the correct substrate in the reaction.
D. Add an allosteric activator to the reaction.

Back 55

C. Increase the concentration of the correct substrate in the reaction.

Front 56

56. A ribozyme catalyzes a reaction on itself and actually changes shape. This is an example of what?
A. Intra-enzyme reactions
B. Inter-enzyme reactions
C. Intramolecular catalysis
D. Intermolecular catalysis

Back 56

C. Intramolecular catalysis