Which of the following is (are) true for anabolic pathways?

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.

e. They consume energy to build up polymers from monomers.
Which of the following is a statement of the first law of thermodynamics?

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.

c. Energy cannot be created or destroyed.
Whenever energy is transformed, there is always an increase in the

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. entropy of the universe.
Which of the following is true for all exergonic reactions?

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.

b. The reaction proceeds with a net release of free energy.
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

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.

c. It is lost to the environment.
Enzymes are described as catalysts, which means that they _____.

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

e. increase the rate of a reaction without being consumed by the reaction
Which of the following is NOT a way in which an enzyme can speed up the reaction that it catalyzes?

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.

b. The active site can provide heat from the environment that raises the energy content of the substrate.

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.

Some bacteria are metabolically active in hot springs because

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.

c. their enzymes have high optimal temperatures.
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to

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. add more of the enzyme.
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______.

a. exergonic; spontaneous
b. entropy; enthalpy
c. exergonic; endergonic
d. free energy; entropy
e. work; energy

c. exergonic; endergonic
Which of the following statements about feedback regulation of a metabolic pathway is correct?

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.

c. The final product of a metabolic pathway is usually the compound that regulates the pathway.

It is quite common that the end product of the pathway controls the overall rate of the pathway

Which of the following statements describes enzyme cooperativity?

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.

b. A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits.
Which of the following statements is true about enzyme-catalyzed reactions?

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.

e. The reaction is faster than the same reaction in the absence of the enzyme.
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction’s

a. endothermic level.
b. free-energy content.
c. entropy.
d. equilibrium point.
e. activation energy.

e. activation energy.
A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because

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.

c. the activation energy barrier for this reaction cannot easily be surmounted at room temperature.
Which of the following statements regarding enzymes is true?

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.

b. Enzymes increase the rate of a reaction by lowering the activation energy barrier.
The active site of an enzyme is the region that

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.

c. is involved in the catalytic reaction of the enzyme.
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?

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.

b. The binding of the substrate changes the shape of the enzyme’s active site.
Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?

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

c. curves 1 and 4
The following question is based on the reaction A + B – C + D shown in the figure.

Which of the following represents the activation energy required for a noncatalyzed reaction in the figure?

a. a
b. b
c. c
d. d
e. e

c. c
The following question is based on the reaction A + B – C + D shown 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

c. exergonic, ? G ; 0
The following question is based on the reaction A + B – C + D shown in the figure.

Which of the following represents the ?G of the reaction in the figure?

a. a
b. b
c. c
d. d
e. e

d. d
The following question is based on the reaction A + B – C + D shown in the figure.

Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

a. a
b. b
c. c
d. d
e. e

d. d
The following question is based on the reaction A + B – C + D shown in the figure.

Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D > A + B, in the figure?

a. a
b. b
c. c
d. d
e. e

a. a
The following question is based on the reaction A + B – C + D shown 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?

a. a
b. b
c. c
d. d
e. e

d. d
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