AP Bio Chapter 8
induced fit
caused by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate.
thermodynamics
The study of energy transformations that occur in a collection of matter.
catalyst
a chemical agent that selectively increases the rate of a reaction without being consumed by the reaction.
cooperativity
a kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating bindings of additional substrate molecules to those subunits.
enzyme
a macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. most enzymes are proteins.
entropy
a measure of disorder, or randomness
anabolic pathway
a metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules.
catabolic pathway
a metabolic pathway that releases energy by breaking down complex molecules to simpler molecules.
endergonic reaction
a nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings.
spontaneous process
a process that occurs without an overall input of energy; a process that is energetically favorable.
noncompetitive inhibitors
a substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme's shape so that the active site no longer effectively catalyzes the conversion of substrate to product.
competitive inhibitor
a substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics.
enzyme-substrate complex
a temporary complex formed when an enzyme binds to its substrate molecule(s).
If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously? a) Energy input into the organism must be occurring to drive the decrease in entropy. b) In this situation, the second law of thermodynamics must not apply. c) The entropy of the organism's environment must also be decreasing. d) Heat is being used by the organism as a source of energy. e) The first law of thermodynamics is being violated.
a) Energy input into the organism must be occurring to drive the decrease in entropy.
Which of the following statements about enzymes is true? a) Enzymes speed up the rate of the reaction without changing the DG for the reaction. b) The more heat that is added to a reaction, the faster the enzymes will function. c) Enzymes react with their substrate (form chemical bonds), forming an enzyme-substrate complex, which irreversibly alters the enzyme. d) Enzymes increase the rate of a reaction by raising the activation energy for reactions. e) All of the listed responses are correct
a) Enzymes speed up the rate of the reaction without changing the DG for the reaction.
Under most conditions, the supply of energy by catabolic pathways is regulated by the demand for energy by anabolic pathways. Considering the role of ATP formation and hydrolysis in energy coupling of anabolic and catabolic pathways, which of the following statements is most likely to be true? a) High levels of ADP act as an allosteric activator of catabolic pathways b) High levels of ATP act as an allosteric activator of catabolic pathways. c) High levels of ADP act as an allosteric inhibitor of anabolic pathways. d) High levels of ATP act as an allosteric activator of anabolic pathways. e) High levels of ADP act as an allosteric inhibitor of catabolic pathways.
a) High levels of ADP act as an allosteric activator of catabolic pathways
What is the fate of the phosphate group that is removed when ATP is converted to ADP? a) It is acquired by a reactant in an endergonic reaction. b) It is acquired by a reactant in a spontaneous reaction. c) It is broken down into one phosphorus and four oxygen atoms. d) It is acquired by a reactant in an exergonic reaction. e) It is used to convert an ATP into an AQP
a) It is acquired by a reactant in an endergonic reaction
Organisms are described as thermodynamically open systems. Which of the following statements is consistent with this description? a) Organisms acquire energy from, and lose energy to, their surroundings. b) Heat produced by the organism is conserved in the organism and not lost to the environment. c) The metabolism of an organism is isolated from its surroundings. d) Because energy must be conserved, organisms constantly recycle energy and thus need no input of energy. e) All of the listed responses are correct.
a) Organisms acquire energy from, and lose energy to, their surroundings.
Which of the following is an example of the second law of thermodynamics as it applies to biological reactions? a) The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water. b) All types of cellular respiration produce ATP. c) Cellular respiration releases some energy as heat. d) The first and second choices are correct. e) The first, second, and third choices are correct.
a) The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water.
What best characterizes the role of ATP in cellular metabolism? a) The free energy released by ATP hydrolysis may be coupled to an endergonic process via the formation of a phosphorylated intermediate. b) It is catabolized to carbon dioxide and water. c) The charge on the phosphate group of ATP tends to make the molecule very water-soluble. d) The release of free energy during the hydrolysis of ATP heats the surrounding environment. e) The DG associated with its hydrolysis is positive.
a) The free energy released by ATP hydrolysis may be coupled to an endergonic process via the formation of a phosphorylated intermediate.
Consider the growth of a farmer's crop over a season. Which of the following correctly states a limitation imposed by the first or second law of thermodynamics? a) To obey the first law, the crops must represent an open system. b) The entropy of the universe must decrease to account for the increased entropy associated with plant growth. c) Growth of the crops must occur spontaneously. d) The process of photosynthesis produces energy that the plant uses to grow. e) All of the listed responses are correct.
a) To obey the first law, the crops must represent an open system.
Which is the most abundant form of energy in a cell? a) chemical energy b) kinetic energy c)electrochemical gradients d) mechanical energy e) heat
a) chemical energy
Select the incorrect association. a) exergonic...uphill b) enzyme...protein c) potential energy...positional energy d) exergonic...spontaneous e) kinetic energy...motion
a) exergonic...uphill exergonic reactions release energy
Which of the following reactions would be endergonic? a) glucose + fructose → sucrose b) ATP → ADP + Pi c) HCl → H+ + Cl- d) C6H12O6 + 6 O2 → 6 CO2 + 6 H2O e) All of the listed responses are correct.
a) glucose + fructose → sucrose
Enzyme activity is affected by pH because _____. a) high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site b) low pH will denature all enzymes c) changes in pH can cause loss of cofactors from the enzyme d) most substrates don't function well at high or low pH e) the binding of hydrogen ions to the enzyme absorbs energy and thus there may not be enough energy to overcome the activation energy barrier
a) high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site
The electronic arrangement in which of the following molecules means that this (these) molecule(s) has/have greater free energy than the others? a) methane b) carbon dioxide c) water d) The first two molecules listed are roughly equal in the energy they contain. e) The first three molecules listed are roughly equal in the energy they contain.
a) methane
An exergonic (spontaneous) reaction is a chemical reaction that _____. a) releases energy when proceeding in the forward direction b) cannot occur outside of a living cell c) is common in anabolic pathways d) leads to a decrease in the entropy of the universe e) occurs only when an enzyme or other catalyst is present
a) releases energy when proceeding in the forward direction
A chemical reaction is designated as exergonic rather than endergonic when _____. a) the potential energy of the products is less than the potential energy of the reactants b) activation energy exceeds net energy release c) the products are less complex than the reactants d) it absorbs more energy e) activation energy is required
a) the potential energy of the products is less than the potential energy of the reactants
Which part of the equation ΔG = ΔH - TΔS tells you if a process is spontaneous? a) ΔG b) ΔS c) ΔH d) TΔS e) All of these values reveal the direction in which a reaction will go.
a) ΔG
When one molecule is broken down into six component molecules, which of the following will always be true? a) ΔS is positive. b) ΔG is positive. c) ΔH is negative. d) An input of free energy is needed. e) ΔS is negative.
a) ΔS is positive.
Which of the following statements about ATP (adenosine triphosphate) is correct? a) The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways. b) The hydrolysis of ATP can supply energy needed for catabolic pathways. c) The energy release on hydrolysis of ATP is the result of breaking a high-energy bond. d) Almost all of the free energy released on the hydrolysis of ATP is released as heat. e) The hydrolysis of ATP is an endergonic process.
a)The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.
cofactor
any nonprotein molecule or ion that is required for the proper functioning of an enzyme. cofactors can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate, during catalysis.
Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reaction? a) α-phosphate (the phosphate closest to ribose) b) β-phosphate (the middle phosphate) c) γ-phosphate (the terminal phosphate) d) adenine group e) ribose sugar
c) γ-phosphate (the terminal phosphate)
In cells, what is usually the immediate source of energy for an endergonic reaction? a) ADP b) ATP c) glucose d) sugar e) as spontaneous reactions, endergonic reactions do not need an addition of energy
b) ATP
Which of the following statements about enzymes is incorrect? a) Most enzymes are proteins. b) An enzyme is consumed during the reaction it catalyzes. c) Enzymes can be used to accelerate both anabolic and catabolic reactions. d) An enzyme lowers the activation energy of a chemical reaction. e) An enzyme is very specific in terms of which substrate it binds to.
b) An enzyme is consumed during the reaction it catalyzes.
When 1 mole of ATP is hydrolyzed in a test tube without an enzyme, about twice as much heat is given off as when 1 mole of ATP is hydrolyzed in a cell. Which of the following best explains these observations? a) Cells are less efficient at energy metabolism than reactions that are optimized in a test tube. b) In the cell, the hydrolysis of ATP is coupled to other endergonic reactions. c) Cells have the ability to store heat; this cannot happen in a test tube. d) The amount of heat released by a reaction has nothing to do with the free energy change of the reaction. e) In cells, ATP is hydrolyzed to ADP and Pi, but in the test tube it is hydrolyzed to carbon dioxide and water.
b) In the cell, the hydrolysis of ATP is coupled to other endergonic reactions.
If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur? a) Additional substrate will be formed. b) Nothing; the reaction will stay at equilibrium. c) Additional product will be formed. d) The free energy of the system will change. e) The reaction will change from endergonic to exergonic.
b) Nothing; the reaction will stay at equilibrium
Molecules A and B contain 110 kcal/mol of free energy and molecules B and C contain 150 kcal/mol of energy. A and B are converted to C and D. What can be concluded? a) The conversion of A and B to C and D is exergonic; the products are less organized than the reactants. b) The reaction that proceeds to convert A and B to C and D is endergonic; the products are more organized than the reactants. c) A and B will be converted to C and D with a net release of energy. d) The conversion of A and B to C and D is spontaneous. e) The entropy in the products, C and D, is higher than in the reactants, A and B.
b) The reaction that proceeds to convert A and B to C and D is endergonic; the products are more organized than the reactants.
Which of the following statements correctly describes some aspect of ATP hydrolysis being used to drive the active transport of an ion into the cell against the ion's concentration gradient? a) Both ATP hydrolysis and active transport are spontaneous because they result in an increase in entropy of the system. b) This is an example of energy coupling. c) The hydrolysis of ATP is endergonic, and the active transport is exergonic. d) Neither ATP hydrolysis nor active transport is spontaneous. e) ATP is acting as a transport protein to facilitate the movement of the ion across the plasma membrane.
b) This is an example of energy coupling
Which of these is exhibiting kinetic energy? a) a person sitting on a couch while watching TV b) a space station orbiting Earth c) an archer with a flexed bow d) the high-energy phosphate bonds of a molecule of ATP e) a rock on a mountain ledge
b) a space station orbiting Earth
The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example of _______. a) an endergonic pathway b) a catabolic pathway c) a pathway that occurs in animal cells but not plant cells d) a pathway in which the entropy of the system decreases e) a pathway that converts organic matter into energy
b) catabolic pathway
Which of these reactions requires a net input of energy from its surroundings? a) hydrolysis b) endergonic c) exergonic d) ATP--> ADP + P e) catabolic
b) endergonic
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______. a) exergonic; spontaneous b) exergonic; endergonic c) entropy; enthalpy d) work; energy e) free energy; entropy
b) exergonic; endergonic
Most cells cannot harness heat to perform work because a) heat must remain constant during work. b) temperature is usually uniform throughout a cell. c) heat is not a form of energy. d) cells do not have much heat; they are relatively cool. e) heat can never be used to do work.
b) temperature is usually uniform throughout a cell.
Some bacteria are metabolically active in hot springs because a) they are able to maintain a lower internal temperature. b) their enzymes have high optimal temperatures. c) high temperatures make catalysis unnecessary. d) their enzymes are completely insensitive to temperature. e) they use molecules other than proteins or RNAs as their main catalysts.
b) their enzymes have high optimal temperatures
A plot of reaction rate (velocity) against temperature for an enzyme indicates little activity at 10°C and 45°C, with peak activity at 35°C. The most reasonable explanation for the low velocity at 10°C is that _____. a) the hydrogen bonds that define the structure of the enzyme's active site are unstable b) there is too little activation energy available c) the cofactors required by the enzyme system lack the thermal energy required to activate the enzyme d) the enzyme was denatured e) the substrate becomes a competitive inhibitor at lower temperature
b) there is too little activation energy available
"Conservation of energy" refers to the fact that ______. a) the entropy of the universe is always increasing b) the net amount of disorder is always increasing c) energy cannot be created or destroyed but can be converted from one form to another d) no chemical reaction is 100 percent efficient e) if you conserve energy you will not be as tired
c)energy cannot be created or destroyed but can be converted from one form to another
Which of the following metabolic processes can occur without a net influx of energy from some other process? a) 6 CO2 + 6 H2O → C6H12O6 + 6 O2 b) glucose + fructose → sucrose c) C6H12O6 + 6 O2 → 6 CO2 + 6 H2O d) ADP + i → ATP + H20 e) amino acids → protein
c) C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
Which of the following statements about enzyme function is correct? a) Enzymes can greatly speed up reactions, but they cannot change the activation energy because they cannot change the net energy output. b) Enzymes can change the equilibrium point of reactions, but they cannot speed up reactions because they cannot change the net energy output. c) Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output. d) Enzymes can greatly speed up reactions, but they cannot change the net energy output because they cannot change the activation energy. e) None of the listed responses is correct.
c) Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.
Which of the following statements about the active site of an enzyme is correct? a) Coenzymes are rarely found in the active site of an enzyme. b) The structure of the active site is not affected by changes in temperature. c) The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits. d) The active site has a fixed structure (shape). e) The active site allows the reaction to occur under the same environmental conditions as the reaction without the enzyme.
c) The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.
The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. Which of the following best explains why this decrease occurs? a) The allosteric inhibitor causes free energy change of the reaction to increase. b) The allosteric inhibitor binds to the substrate and prevents it from binding at the active site. c) The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site. d) The allosteric inhibitor binds to the active site, preventing the substrate from binding. e) The allosteric inhibitor lowers the temperature of the active site.
c) The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site.
What is meant by the "induced fit" of an enzyme? a) The presence of the substrate in solution induces the enzyme to slightly change its structure. b) The substrate can be altered so that it is induced to fit into the enzyme's active site. c) The enzyme changes its shape slightly as the substrate binds to it. d) The shape of the active site is nearly perfect for specifically binding the enzyme's substrate(s). e) The enzyme structure is altered so that it can be induced to fit many different types of substrate.
c) The enzyme changes its shape slightly as the substrate binds to it.
How do enzymes lower activation energy? a) by increasing reactivity of products b) The second and third choices above are correct. c) by locally concentrating the reactants d) by harnessing heat energy to drive the breakage of bonds between atoms e) The first two responses above are correct.
c) by locally concentrating the reactants
The energy for an endergonic reaction comes from a(n) ______ reaction. a) ADP + P --> ATP b) anabolic c) exergonic d) glucose + glucose --> maltose e) synthesis
c) exergonic
The following reaction A--> B + C + heat is a(n) _______ reaction. a) dehydration synthesis b) anabolic c) exergonic d) exchange e) endergonic
c) exergonic
Which of the following is changed by the presence of an enzyme in a reaction? a) The sign of ΔG b) the G value for the reactants c) the activation energy d) the G value for the products e) the magnitude of ΔG.
c) the activation energy
The formation of glucose-6-phosphate from glucose is an endergonic reaction and is coupled to which of the following reactions or pathways? a) the formation of ATP from ADP + Pi b) the conversion of glucose + fructose to make sucrose c) the hydrolysis of ATP d) the contraction of a muscle cell e) the active transport of a phosphate ion into the cell
c) the hydrolysis of ATP
What is energy coupling? a) the hydrolysis of ATP to ADP + P b) a barrier to the initiation of a reaction c) the use of energy released from an exergonic reaction to drive an endergonic reaction d) a description of the energetic relationship between the reactants and products in an exergonic reaction e) the use of an enzyme to reduce EA
c) the use of energy released from an exergonic reaction to drive an endergonic reaction
Which of the following statements about allosteric proteins is/are true? a) They are sensitive to environmental conditions. b) They exist in active and inactive conformations. c) They are acted on by inhibitors. d) All of the first three listed responses are correct. e) None of the three listed responses is correct.
d) All of the first three listed responses are correct.
Which of the following correctly states the relationship between anabolic and catabolic pathways? a) The flow of energy between catabolic and anabolic pathways is reversible. b) Energy derived from catabolic pathways is used to drive the breakdown of organic molecules in anabolic pathways. c) Catabolic pathways produce usable cellular energy by synthesizing more complex organic molecules. d) Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways. e) Degradation of organic molecules by anabolic pathways provides the energy to drive catabolic pathways.
d) Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.
According to the second law of thermodynamics, which of the following is true? a) All reactions produce some heat. b) The total amount of energy in the universe is constant. c) The entropy of the universe is constantly decreasing. d) The decrease in entropy associated with life must be compensated for by increased entropy in the environment in which life exists. e) Energy conversions increase the order in the universe.
d) The decrease in entropy associated with life must be compensated for by increased entropy in the environment in which life exists.
Which of the following statements correctly describe(s) the role(s) of heat in biological reactions? a) Heat from the environment is necessary for substrates to get over the activation energy barrier. b) The kinetic energy of the substrates is increased as the amount of heat in the system is increased. c) Increasing the amount of heat in a system will increase the rate of enzyme-catalyzed reactions. d) The first and second choices are correct. e) The second and third choices are correct.
d) The first and second choices are correct
Above a certain substrate concentration, the rate of an enzyme-catalyzed reaction drops as the enzymes become saturated. Which of the following would lead to a faster conversion of substrate into product under these saturated conditions? a) an increase in concentration of enzyme b) increasing the temperature by a few degrees c) increasing the substrate concentration d) The first and second listed responses are correct. e) The first, second, and third listed responses are correct.
d) The first and second listed responses are correct.
Metabolic pathways in cells are typically far from equilibrium. Which of the following processes tend(s) to keep these pathways away from equilibrium? a) the continuous removal of the products of a pathway to be used in other reactions b) an input of free energy from outside the pathway c) an input of heat from the environment d) The first and second listed responses are correct. e) The first, second, and third listed responses are correct.
d) The first and second listed responses are correct.
The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of _____. a) cooperativity b) noncompetitive inhibition c) feedback inhibition d) allosteric regulation e) competitive inhibition
d) allosteric regulation
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP? a) anabolism b) potentiation c) digestion d) cellular respiration e) redox
d) cellular respiration
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP? a) anabolism b) potentiation c) digestion d) cellular respiration e) redox
d) cellular respiration
The reaction ADP + P--> ATP is a(n) _______ reaction. a) hydrolysis b) spontaneous c) chemical d) endergonic e) exergonic
d) endergonic
Chemical energy is a form of _______ energy. a) heat b) motion c) kinetic d) potential e) entropic
d) potential
Which of the following is an example of the cellular work accomplished with the free energy derived from the hydrolysis of ATP, involved in the production of electrochemical gradients? a) facilitated diffusion b) chromosome movement on microtubules c) the beating of cilia d) proton movement against a gradient of protons e) the chemical synthesis of ATP
d) proton movement against a gradient of protons
In general, the hydrolysis of ATP drives cellular work by _____. a) lowering the free energy of the reaction b) releasing heat c) changing to ADP and phosphate d) releasing free energy that can be coupled to other reactions e) acting as a catalyst
d) releasing free energy that can be coupled to other reactions
Which of the following determines the sign of ΔG for a reaction? a) the enzyme catalyzing the reaction having a low affinity for the products b) the free energy of the products c) the enzyme catalyzing the reaction having a high affinity (strength of binding) for the reactants d) the free energy of the reactants and the free energy of the products e) the free energy of the reactants
d) the free energy of the reactants and the free energy of the products
Which of the following statements about equilibrium of chemical reaction is correct? a) The equilibrium point is where the system has the highest free energy b) Most reactions in a living cell are close to equilibrium. c) Reactions can only go in the direction toward equilibrium. d) The equilibirum point of a reaction represents the least stable configuration for that reaction. e) A reaction that is at equilibrium is not capable of doing any work.
e) A reaction that is at equilibrium is not capable of doing any work.
Which of the following states the relevance of the first law of thermodynamics to biology? a) Energy is destroyed as glucose is broken down during cellular respiration b) The total energy taken in by an organism must be greater than the total energy stored or released by the organism. c) Living organisms must increase the entropy of their surroundings. d) Photosynthetic organisms produce energy in sugars from sunlight. e) Energy can be freely transformed among different forms as long as the total energy is conserved.
e) Energy can be freely transformed among different forms as long as the total energy is conserved.
What do the sign and magnitude of the ΔG of a reaction tell us about the speed of the reaction? a) The more negative the ΔG, the faster the reaction is. b) The sign does not matter, but the larger the magnitude of ΔG, the faster the reaction. c) The sign does not matter, but the smaller the magnitude of ΔG, the faster the reaction. d) The sign determines whether the reaction is spontaneous, and the magnitude determines the speed. e) Neither the sign nor the magnitude of ΔG have anything to do with the speed of a reaction.
e) Neither the sign nor the magnitude of ΔG have anything to do with the speed of a reaction.
Which of the following environments or actions would not affect the rate of an enzyme reaction? a) pH b) substrate concentration c) cooling the enzyme d) heating the enzyme e) None of the listed responses is correct.
e) None of the listed responses is correct.
Succinylcholine is structurally almost identical to acetylcholine. If succinylcholine is added to a mixture that contains acetylcholine and the enzyme that hydrolyzes acetylcholine (but not succinylcholine), the rate of acetylcholine hydrolysis is decreased. Subsequent addition of more acetylcholine restores the original rate of acetylcholine hydrolysis. Which of the following correctly explains this observation? a) Succinylcholine must be an allosteric regulator for this enzyme. b) Succinylcholine must be a noncompetitive inhibitor. c) The active site must have the wrong configuration to permit succinylcholine binding. d) The activation energy barrier for succinylcholine hydrolysis is higher than for acetylcholine hydrolysis. e) Succinylcholine must be a competitive inhibitor with acetylcholine.
e) Succinylcholine must be a competitive inhibitor with acetylcholine.
Which of these statements about enzyme inhibitors is true? a) A competitive inhibitor binds to the enzyme at a place that is separate from the active site. b) When the product of an enzyme or an enzyme sequence acts as its inhibitor, this is known as positive feedback. c) Inhibition of enzyme function by compounds that are not substrates is something that only occurs under controlled conditions in the laboratory. d) A noncompetitive inhibitor does not change the shape of the active site. e) The action of competitive inhibitors may be reversible or irreversible.
e) The action of competitive inhibitors may be reversible or irreversible.
From the equation ΔG = ΔH - TΔS it is clear that _____. a) a decrease in the system's total energy will increase the probability of spontaneous change b) increasing the entropy of a system will increase the probability of spontaneous change c) increasing the temperature of a system will increase the probability of spontaneous change d) The first and second choices are correct. e) The first three choices are correct.
e) The first three choices are correct.
Which of the following has the most free energy per molecule? a) an amino acid molecule b) a cholesterol molecule c) a fatty acid molecule d) a sugar molecule e) a starch molecule
e) a starch molecule
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to a) heat the solution to 90°C. b) add an allosteric inhibitor. c) add more substrate. d) add a noncompetitive inhibitor. e) add more of the enzyme.
e) add more of the enzyme
A(n) ________ reaction occurs spontaneously. a) endergonic b) chemical c) kinetic d) anabolic e) exergonic
e) exergonic
Which of these are by-products of cellular respiration? a) ATP, carbon dioxide, and water b) glucose, carbon dioxide, and water c) carbon dioxide and water d) ATP and carbon dioxide e) heat, carbon dioxide, and water
e) heat, carbon dioxide, and water
Which of the following situations does not represent an energy transformation? a) the production of sugars from carbon dioxide and water during photosynthesis b) the release of carbon dioxide as glucose is broken down during cellular respiration c) the production of ATP using phosphate from the breakdown of glucose e) the coupling of ATP hydrolysis to the production of a proton gradient across a membrane by a proton pump d) All of the listed responses represent energy transformations.
e) the coupling of ATP hydrolysis to the production of a proton gradient across a membrane by a proton pump
Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide (C6H12O6 + 6 O2 -> 6 CO2 + H2O) is correct? a) The free energy lost in this combustion is less than the energy that appears as heat. b) the entropy of the universe decreases as the result of this reaction. c) The reverse reaction, making glucose from water and carbon dioxide, must be an exergonic reaction. d) This is the process of cellular respiration, an anabolic pathway that releases free energy. e) The entropy of the products is greater than the entropy of the reactants.
e) the entropy of the products is greater than the entropy of the reactants
Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because _____. a) the phosphate groups are polar and are attracted to the water in the cell's interior b) they are hydrogen bonds, which are only about 10% as strong as covalent bonds c) the valence electrons in the phosphorus atom have less energy on average than those of other atoms d) the bonds between the phosphate groups are unusually strong and breaking them releases free energy e) the negatively charged phosphate groups vigorously repel one another and the terminal phosphate group is more stable in water than it is in ATP
e) the negatively charged phosphate groups vigorously repel one another and the terminal phosphate group is more stable in water than it is in ATP
If, during a process, the system becomes more ordered, then _____. a) ΔG is positive b) ΔH is positive c) ΔH is negative d) ΔG is negative e) ΔS is negative
e) ΔS is negative
chemical energy
energy available in molecules for release in a chemical reaction; a form of potential energy
thermal energy
heat
activation energy
the amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation
allosteric regulation
the binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.
energy
the capacity to cause change, especially to do work ( to move matter against an opposing force).
kinetic energy
the energy associated with the relative motion of objects. moving matter can perform work by imparting motion to other matter.
bioenergetics
the overall flow and transformation of energy in an organism. the study of how energy flows through organisms.
free energy
the portion of biological system's energy that can perform work when temperature and pressure are uniform throughout the system. the change in free energy of a system (DG) is calculated by the equation DG=DH - TDS, where DH is the change in enthalpy ( in biological systems, equivalent to total energy), T is the absolute temperature, and DS is the change in entropy
second law of thermodynamics
the principle stating that every energy transfer or transformation increases the entropy of the universe. usable forms of energy are at least partly converted to heat.
substrate
the reactant on which an enzyme works
active site
the specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs.
heat
the total amount of kinetic energy due to the random motion of atoms or molecules in a body of matter; also called thermal energy. heat is energy in its most random form
metabolism
the totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism