a. They release energy as they degrade polymers to monomers.
b. They consume energy to decrease the entropy of the organism and its environment.
c. They are usually highly spontaneous chemical reactions.
d. They do not depend on enzymes.
e. They consume energy to build up polymers from monomers.
a. Kinetic energy is stored energy that results from the specific arrangement of matter.
b. Energy cannot be transferred or transformed.
c. Energy cannot be created or destroyed.
d. The entropy of the universe is constant.
e. The entropy of the universe is decreasing.
a. entropy of the universe.
b. enthalpy of the universe.
c. entropy of the system.
d. free energy of the system.
e. free energy of the universe.
a. The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.
b. The reaction proceeds with a net release of free energy.
c. A net input of energy from the surroundings is required for the reactions to proceed.
d. The products have more total energy than the reactants.
e. The reactions are rapid.
a. It is used to store energy as more ATP.
b. It is transported to specific organs such as the brain.
c. It is lost to the environment.
d. It is used to power yet more cellular work.
e. It is used to generate ADP from nucleotide precursors.
a. can alter the free energy change (?G) for a chemical reaction
b. are proteins
c. increase the free energy of the reactants to make the reaction go faster
d. provide activation energy for the reactions they facilitate
e. increase the rate of a reaction without being consumed by the reaction
a. The active site of the enzyme can provide a microenvironment with a different pH that facilitates the reaction.
b. The active site can provide heat from the environment that raises the energy content of the substrate.
c. Binding of the substrate to the active site can stretch bonds in the substrate that need to be broken.
d. The enzyme binds a cofactor that interacts with the substrate to facilitate the reaction.
e. The binding of two substrates in the active site provides the correct orientation for them to react to form a product.
An enzyme cannot extract heat from the environment to speed a reaction. It can only lower the activation energy barrier so that more substrates have the energy to react.
a. they are able to maintain a lower internal temperature.
b. they use molecules other than proteins or RNAs as their main catalysts.
c. their enzymes have high optimal temperatures.
d. high temperatures make catalysis unnecessary.
e. their enzymes are completely insensitive to temperature.
a. add more of the enzyme.
b. heat the solution to 90°C.
c. add more substrate.
d. add a noncompetitive inhibitor.
e. add an allosteric inhibitor.
a. exergonic; spontaneous
b. entropy; enthalpy
c. exergonic; endergonic
d. free energy; entropy
e. work; energy
a. The enzyme that is regulated by feedback inhibition is usually the last enzyme in the metabolic pathway.
b. The products of the pathway become the reactants for a different reaction, and thus products are unable to accumulate.
c. The final product of a metabolic pathway is usually the compound that regulates the pathway.
d. The compound that regulates the pathway acts as a competitive inhibitor or a positive allosteric regulator.
e. Accumulation of the product of the pathway increases further formation of that product.
It is quite common that the end product of the pathway controls the overall rate of the pathway
a. Several substrate molecules can be catalyzed by the same enzyme.
b. A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits.
c. A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway.
d. A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.
e. A multienzyme complex contains all the enzymes of a metabolic pathway.
a. Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions.
b. The free energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme.
c. Enzyme-catalyzed reactions require energy to activate the enzyme.
d. The reaction always goes in the direction toward chemical equilibrium.
e. The reaction is faster than the same reaction in the absence of the enzyme.
a. endothermic level.
b. free-energy content.
d. equilibrium point.
e. activation energy.
a. the hydrolysis of starch to sugar is endergonic.
b. the starch solution has less free energy than the sugar solution.
c. the activation energy barrier for this reaction cannot easily be surmounted at room temperature.
d. starch hydrolysis is nonspontaneous.
e. starch cannot be hydrolyzed in the presence of so much water.
a. Enzymes increase the rate of a reaction by making the reaction more exergonic.
b. Enzymes increase the rate of a reaction by lowering the activation energy barrier.
c. Enzymes change the equilibrium point of the reactions they catalyze.
d. Enzymes make the rate of a reaction independent of substrate concentrations.
e. Enzymes increase the rate of a reaction by reducing the rate of reverse reactions.
a. binds noncompetitive inhibitors of the enzyme.
b. binds allosteric regulators of the enzyme.
c. is involved in the catalytic reaction of the enzyme.
d. is inhibited by the presence of a coenzyme or a cofactor.
a. A competitive inhibitor can outcompete the substrate for the active site.
b. The binding of the substrate changes the shape of the enzyme’s active site.
c. Some enzymes change their structure when activators bind to the enzyme.
d. The active site creates a microenvironment ideal for the reaction.
e. The binding of the substrate depends on the shape of the active site.
a. curves 1 and 5
b. curves 3 and 4
c. curves 1 and 4
d. curves 2 and 4
e. curves 2 and 5
Which of the following represents the activation energy required for a noncatalyzed reaction in the figure?
Which of the following terms best describes the forward reaction in the figure?
a. endergonic,?G ; 0
b. chemical equilibrium,?G = 0
c. exergonic, ? G ; 0
d. exergonic,?G ; 0
e. endergonic,?G ; 0
Which of the following represents the ?G of the reaction in the figure?
Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?
Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D > A + B, in the figure?
Which of the following represents the difference between the free-energy content of the reactants and the free-energy content of the products in the figure?