Chapter 3 Flashcards
1
Q
What is Kinetic Energy?
A
The energy of motion.
2
Q
What is potential energy?
A
Stored energy.
3
Q
What is thermodynamics?
A
The study of the energy flow during chemical and physical reactions.
4
Q
What is the first law of thermodynamics?
A
The principle that energy can be transferred and transformed but cannot be created or destroyed.
5
Q
What is entropy?
A
Disorder, in thermodynamics.
6
Q
What is the second law of thermodynamics?
A
Principle that for any process in which a system changes from an initial to a final state, the total disorder of the system and its surroundings always increases.
7
Q
What is enthalpy?
A
Potential energy in a system.
8
Q
What is endothermic?
A
Refers to reactions that absorb energy.
9
Q
What is exothermic?
A
Refers to processes that release energy.
10
Q
What is a spontaneous reaction?
A
Chemical or physical reaction that occurs without outside help.
11
Q
What is an exergonic process?
A
Reaction that has a negative ΔG because it releases free energy.
12
Q
What is an endergonic process?
A
Reaction that can proceed only if free energy is supplied.
13
Q
What is metabolism?
A
The biochemical reactions that allow a cell or organism to extract energy from its surroundings and use that energy to maintain itself, grow, and reproduce.
14
Q
What is a catabolic pathway?
A
Type of metabolic pathway in which energy is released by the breakdown of complex molecules to simpler compounds.
15
Q
What is an anabolic pathway?
A
Type of metabolic pathway in which energy is consumed to build complicated molecules from simpler ones; often called a biosynthetic pathway.
16
Q
What is energy coupling?
A
The process by which ATP is brought in close contact with a reactant molecule involved in an endergonic reaction, and when the ATP is hydrolyzed, the terminal phosphate group is transferred to the reactant molecule.
17
Q
What is a coupled reaction?
A
Reaction that occurs when an exergonic reaction is joined to an consumer?An organism that consumes other organisms in a community or ecosystem.
18
Q
What is an ATP cycle?
A
Continued breakdown and resynthesis of ATP.
19
Q
What are monosaccharides?
A
The smallest carbohydrates, containing three to seven carbon atoms.
20
Q
What is activation energy?
A
The initial input of energy required to start a reaction.
21
Q
What is meant by a transition state?
A
An intermediate arrangement of atoms and bonds that both the reactants and the products of a reaction can assume.
22
Q
What is a catalyst?
A
Substance with the ability to accelerate a spontaneous reaction without being changed by the reaction.
23
Q
What are enzymes?
A
Protein that accelerates the rate of a cellular reaction.
24
Q
What is an active site?
A
The region of an enzyme that recognizes and combines with a substrate molecule.
25
What is meant by conformation?
The overall three-dimensional shape of a protein.
26
What is a cofactor?
An inorganic or organic nonprotein group that is necessary for catalysis to take place.
27
What are coenzymes?
Organic cofactors that include complex chemical groups of various kinds.
28
What is competitive inhibition?
Inhibition of an enzyme reaction by an inhibitor molecule that resembles the normal substrate closely enough that it fits into the active site of the enzyme.
29
What is an allosteric site?
A regulatory site outside the active site.
30
What is an allosteric inhibitor?
Molecule that converts an enzyme with an allosteric site, a regulatory site outside the active site, from the active form to the inactive form.
31
What is an allosteric activator?
Molecule that converts an enzyme with an allosteric site, a regulatory site outside the active site, from the inactive form to the active form.
32
What is feedback inhibition?
In enzyme reactions, regulation in which the product of a reaction acts as a regulator of the reaction. Also referred to as end-product inhibition.
33
What is pepsin?
An enzyme made in the stomach that breaks down proteins.
34
What is free energy?
The energy in a system that is available to do work.
35
Which of the following represents a form of potential energy?
a. light
b. electricity
c. glucose
d. heat
c. glucose
36
Which statement is true?
a. A hydroelectric plant is an example of an open system.
b. A hydroelectric plant converts the potential energy of falling water to the kinetic energy of electricity.
c. Earth is an open system.
d. A greenhouse is an isolated system.
a. A hydroelectric plant is an example of an open system.
37
Which of these statements best describes the branch of science known as thermodynamics?
a. It concerns energy.
b. It concerns energy and how it changes during only physical and not chemical transformations.
c. It concerns energy and how it changes during only chemical and not physical transformations.
d. It concerns energy and how it changes during chemical and physical transformations.
d. It concerns energy and how it changes during chemical and physical transformations.
38
Which of the following best describes an open system?
a. It exchanges only matter but not energy with its surroundings.
b. It exchanges only energy but not matter with its surroundings.
c. It does not exchange energy or matter with its surroundings.
d. It exchanges both energy and matter with its surroundings.
d. It exchanges both energy and matter with its surroundings.
39
Suppose you are studying about energy. Which of these forms of energy are found in an apple as it grows on a tree, then falls and is digested by an animal?
a. kinetic - thermal - potential
b. potential - potential - thermal
c. potential - kinetic - thermal
d. thermal - kinetic - potential
c. potential - kinetic - thermal
40
Which term refers to the disorder in a system?
a. enthalpy
b. anabolism
c. free energy
d. entropy
d. entropy
41
Which of these statements best describes free energy?
a. energy available to do work
b. energy required for a reaction to begin
c. energy that is in the universe
d. energy that is in people
a. energy available to do work
42
Which of these statements best describes enthalpy?
a. the total kinetic energy of a system
b. the total potential energy of a system
c. energy required for a reaction to begin
d. energy required for a reaction to stop
b. the total potential energy of a system
43
Which of the following is a difference between reactants and products in endergonic and exergonic reactions?
a. Products have less free energy than reactants in exergonic reactions, while products have more free energy than reactants in endergonic reactions.
b. Products have more free energy than reactants in both exergonic and endergonic reactions.
c. Products have more free energy than reactants in exergonic reactions, while products have less free energy than reactants in endergonic reactions.
d. Products have less free energy than reactants in both exergonic and endergonic reactions.
a. Products have less free energy than reactants in exergonic reactions, while products have more free energy than reactants in endergonic reactions.
44
Which statement is true?
a. Methane has low enthalpy.
b. Ice has high enthalpy.
c. Ice has high entropy.
d. Steam has higher entropy than liquid water.
d. Steam has higher entropy than liquid water.
45
Which statement would be true for a chemical reaction that has a negative ΔG?
a. The reaction would be spontaneous.
b. The reaction would absorb free energy.
c. The reaction would be endergonic.
d. In an open system, the reaction would run to equilibrium.
a. The reaction would be spontaneous.
46
Which statement is true regarding spontaneous reactions?
a. They have a positive ΔG.
b. They tend to happen if the reaction increases disorder.
c. They tend to happen if the reaction increases enthalpy.
d. They are endergonic.
b. They tend to happen if the reaction increases disorder.
47
Which of the following accurately describes the relationship between melting of ice and entropy?
a. The melting of ice is an exothermic process, but still endergonic because of the large increase of entropy as ice changes to liquid.
b. The melting of ice is an endothermic process, but still endergonic because of the large increase of entropy as ice changes to liquid.
c. The melting of ice is an exothermic process, but still exergonic because of the large increase of entropy as ice changes to liquid.
d. The melting of ice is an endothermic process, but still exergonic because of the large increase of entropy as ice changes to liquid.
d. The melting of ice is an endothermic process, but still exergonic because of the large increase of entropy as ice changes to liquid.
48
Which statement is true?
a. A living cell has high entropy but its surroundings have low entropy.
b. A living cell obeys the second law of thermodynamics.
c. After a cell dies, its entropy decreases.
d. A living cell is a closed system.
b. A living cell obeys the second law of thermodynamics.
49
Suppose a friend asks you why we need to eat. Which of these statements might be your answer?
a. A significant amount of the ingested food provides energy needed to maintain the high entropy state in your cells.
b. A significant amount of the ingested food provides energy needed to maintain the low entropy state in your cells.
c. A significant amount of the ingested food provides energy needed to maintain the low enthalpy state in your cells.
d. A significant amount of the ingested food provides energy needed to maintain the high enthalpy state in your cells.
b. A significant amount of the ingested food provides energy needed to maintain the low entropy state in your cells.
50
Which statement about cellular metabolism is true?
a. Anabolism refers to the breakdown of organic (food) molecules.
b. Catabolic pathways only have endergonic reactions.
c. The sum of the free energy changes arising from anabolism has a negative ΔG.
d. Overall, catabolism releases free energy.
d. Overall, catabolism releases free energy.
51
Which of the following is true of ATP?
a. Its hydrolysis reduces intramolecular repulsion.
b. Its hydrolysis requires a large amount of free energy.
c. Its hydrolysis in aqueous solution is kinetically fast.
d. Release of the Pi upon hydrolysis decreases the entropy of the system.
a. Its hydrolysis reduces intramolecular repulsion.
52
Which statement is true of a coupled reaction?
a. It has an overall positive ΔG.
b. It links exergonic and endergonic reactions.
c. It is nonspontaneous.
d. It absorbs free energy.
b. It links exergonic and endergonic reactions.
53
What is the importance of the energy coupling for a cell?
a. An endergonic reaction in a cell provides energy for any endergonic reaction in the cell.
b. An exergonic reaction in a cell provides energy for any exergonic reaction in the cell.
c. An endergonic reaction in a cell provides energy for any exergonic reaction in the cell.
d. An exergonic reaction in a cell provides energy for any endergonic reaction in the cell.
d. An exergonic reaction in a cell provides energy for any endergonic reaction in the cell.
54
Suppose that you are studying about metabolism. Which of the following statements about a catabolic pathway would you most likely read in your chapter?
a. It releases the kinetic energy of a molecule in breaking it down to a simpler molecule.
b. It requires the potential energy of a molecule to synthesize a more complex molecule.
c. It releases the potential energy of a molecule in breaking it down to a simpler molecule.
d. It requires the potential energy of a molecule to break it down to a simpler molecule.
c. It releases the potential energy of a molecule in breaking it down to a simpler molecule.
55
Which of the following statements about activation energy is true?
a. It is a kinetic barrier to spontaneous reactions.
b. It is provided by enzymes.
c. It is provided by hydrolysis of ATP.
d. It increases as a system becomes more thermodynamically stable.
a. It is a kinetic barrier to spontaneous reactions.
56
Which statement correctly describes a catalyst?
a. It increases the change in free energy of a reaction.
b. It undergoes a chemical change during a reaction.
c. It is always an inorganic molecule.
d. It speeds up a chemical reaction.
d. It speeds up a chemical reaction.
57
Which of the following is characteristic of enzymes?
a. They raise the activation energy in any reactions, even if not a part of them.
b. They lower the activation energy in any reactions, even if not a part of them.
c. They lower the activation energy in a reaction in which they take part.
d. They raise the activation energy in a reaction in which they take part.
c. They lower the activation energy in a reaction in which they take part.
58
Which of the following is most likely an active site?
a. a very small region of the cell where enzymes reside
b. a whole enzyme, since enzymes help catalysis take place
c. a very large region of an enzyme where catalysis takes place
d. a very small region of an enzyme where catalysis takes place
d. a very small region of an enzyme where catalysis takes place
59
Which of these statements describes the relationship between an enzyme and its substrate?
a. A substrate binds to the active site of an enzyme.
b. A substrate binds to the reactive site of an enzyme.
c. An enzyme binds to the active site of a substrate.
d. An enzyme binds to the reactive site of a substrate.
a. A substrate binds to the active site of an enzyme.
60
Burning sugar is a spontaneous reaction. Why is it then that a spoonful of sugar doesn't burst into flames on its own?
a. It requires an enzyme to do so.
b. It requires an activation energy to do so.
c. It requires a cofactor to do so.
d. It requires a substrate to do so.
b. It requires an activation energy to do so.
61
Which statement is true for enzymes?
a. They catalyze a specific reaction.
b. They are changed by the reaction.
c. They permanently combine with the substrate.
d. They make an endergonic reaction proceed spontaneously.
a. They catalyze a specific reaction.
62
Which of the following is an inorganic enzyme helper?
a. a coenzyme
b. an activator
c. a cofactor
d. an allosteric activator
c. a cofactor
63
Which of the following is an organic enzyme helper?
a. a coenzyme
b. an inhibitor
c. a cofactor
d. an allosteric activator
a. a coenzyme
64
Which of the following statements describes the enzyme cycle?
a. Enzymes cycle between one conformation and another.
b. After catalysis, enzymes are released unchanged to bind another substrate.
c. Enzymes are continuously cycling energy between exergonic and endergonic reactions.
d. Enzyme active sites cycle between high affinity and low affinity.
b. After catalysis, enzymes are released unchanged to bind another substrate.
65
Which statement is true of an enzyme-catalyzed reaction?
a. The enzyme helps the product(s) reach the transition state.
b. An enzyme catalyst is necessary because the reaction is not spontaneous.
c. The enzyme accelerates the reaction by lowering the activation energy.
d. At transition state, the product has high enthalpy.
c. The enzyme accelerates the reaction by lowering the activation energy.
66
Suppose that you are studying about enzymes. Which of the following would you learn?
a. Enzymes are not rigid objects but are flexible enough to change their shape just before binding to the substrate.
b. Enzymes are rigid objects and are not flexible enough to change their shape just before binding to the substrate.
c. Enzymes are rigid objects but are flexible enough to change their shape just before binding to the substrate.
d. Enzymes are not rigid objects and are not flexible enough to change their shape just before binding to the substrate.
a. Enzymes are not rigid objects but are flexible enough to change their shape just before binding to the substrate.
67
Which of the following has a shape similar to an enzyme's substrate?
a. a competitive inhibitor
b. an allosteric inhibitor
c. a noncompetitive inhibitor
d. a coenzyme inhibitor
a. a competitive inhibitor
68
What are allosteric inhibitors?
a. molecules that bind in the enzyme's active site, causing a change in shape of the enzyme
b. molecules that bind in the enzyme's active site, but do not change the shape of the enzyme
c. molecules that bind on the enzyme but not in the active site, causing a change in shape of the enzyme.
d. molecules that bind on the enzyme but not in the active site, and do not change the shape of the enzyme.
c. molecules that bind on the enzyme but not in the active site, causing a change in shape of the enzyme.
69
During feedback inhibition, the ________ of the pathway is an allosteric regulator.
a. reactant
b. intermediate
c. end-product
d. enzyme
c. end-product
70
Irreversible inhibition can be overcome by making more enzyme.
a. True
b. False
a. True
