BIOL 121 Chapter 8

Which of the following is consistent with the first law of thermodynamics? A. Energy cannot be created or destroyed. B. The entropy of the universe is decreasing. C. The entropy of the universe is constant. D. Energy cannot be transferred or transformed.

A. Energy cannot be created or destroyed.

Which of the following types of reactions would decrease the entropy within a cell? A. anabolicreactions B. hydrolysis C. digestion D. catabolic reactions

A. anabolic reactions

A chemical reaction that has a positive ΔG is best described as _____. A. endergonic B. enthalpic C. spontaneous D. exergonic

A. endergonic

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction? A. -40kcal/mol B. -20 kcal/mol C. 0 kcal/mol D. +20 kcal/mol

B. -20 kcal/mol

Why is ATP an important molecule in metabolism? A. Its hydrolysis provides an input of free energy for exergonic reactions. B. It provides energy coupling between exergonic and endergonic reactions. C. Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. D. Its terminal phosphate bond has higher energy than the other two phosphate bonds.

B. It provides energy coupling between exergonic and endergonic reactions.

Which of the following is true when comparing an uncatalyzed reaction to the same reaction with a catalyst? A. The catalyzed reaction will be slower. B. The catalyzed reaction will have the same ∆G. C. The catalyzed reaction will have higher activation energy. D. The catalyzed reaction will consume all of the catalyst.

B. The catalyzed reaction will have the same ∆G.

Which of the following is true for all exergonic reactions? A. The products have more total energy than the reactants. B. The reaction proceeds with a net release of free energy. C. The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. D. A net input of energy from the surroundings is required for the reactions to proceed.

B. The reaction proceeds with a net release of free energy.

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's _____. A. entropy B. activation energy C. equilibrium point D. free-energy content

B. activation energy

Anabolic pathways _____. A. are usually highly spontaneous chemical reactions B. consume energy to build up polymers from monomers C. release energy as they degrade polymers to monomers D. consume energy to decrease the entropy of the organism and its environment

B. consume energy to build up polymers from monomers

The active site of an enzyme is the region that _____. A. binds allosteric regulators of the enzyme B. is involved in the catalytic reaction of the enzyme C. binds noncompetitive inhibitors of the enzyme D. is inhibited by the presence of a coenzyme or a cofactor

B. is involved in the catalytic reaction of the enzyme

Anabolic reactions are usually ______. A. spontaneous B. non-spontaneous C. exergonic D. enthalpic E. increasingentropy

B. non-spontaneous

Identify the substrate(s) in the following reaction: sucrose —-[sucrase]-—> glucose + fructose A. fructose B. sucrose C. glucose D. A and B

B. sucrose

Which of the following is true of metabolism in its entirety in all organisms? A. Metabolism depends on a constant supply of energy from food. B. Metabolism uses all of an organism's resources. C. Metabolism consists of all the energy transforming reactions in an organism. D. Metabolism manages the increase of entropy in an organism.

C. Metabolism consists of all the energy transforming reactions in an organism.

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as _____. A. a noncompetitive inhibitor of the enzyme B. an allosteric activator of the enzyme C. a cofactor necessary for enzyme activity D. a coenzyme derived from a vitamin

C. a cofactor necessary for enzyme activity

Allosteric enzyme regulation is usually associated with _____. A. feedback inhibition B. activating activity C. an enzyme with more than one subunit D. the need for cofactors

C. an enzyme with more than one subunit

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? A. the need for a coenzyme B. allosteric inhibition C. competitive inhibition D. insufficient cofactors

C. competitive inhibition

According to the induced fit hypothesis of enzyme catalysis, _____. A. the binding of the substrate depends on the shape of the active site B. some enzymes change their structure when activators bind to the enzyme C. the binding of the substrate changes the shape of the enzyme's active site D. the active site creates a microenvironment ideal for the reaction

C. the binding of the substrate changes the shape of the enzyme's active site

A system at chemical equilibrium _____. A. consumes energy at a steady rate B. releases energy at a steady rate C. has zero kinetic energy D. can do no work

D. can do no work

Enzymes increase the rate of a reaction by ________. A. lowering the specific heat of the reaction B. lowering the index of a fraction of the reaction C. lowering the isotopes of the reaction D. lowering the activation energy of the reaction E. None of the above

D. lowering the activation energy of the reaction

Most enzymes are proteins that _______. A. are consumed during cellular respiration B. are consumed during mitosis C. are consumed during meiosis D. regulate chemical reactions E. regulate nuclear fission

D. regulate chemical reactions

True or False: A noncompetitive inhibitor's effect is eliminated by adding an excess amount of substrate to the reaction.

False. An excess amount of a substrate can NOT overcome the inhibitory effects of a NONCOMPETITIVE inhibitor. It can with competitive inhibitors, however.

True or False: All catalysts are consumed by the chemical reaction in which they participate.

False. Not all catalysts are consumed by the chemical reaction in which they participate.

True or False: In thermodynamics, spontaneous processes occur quickly.

False. Spontaneous processes can occur QUICKLY OR SLOWLY.

True or False: When an enzyme is in its the induced-fit stage, it can accept other substrates for processing.

False. When an enzyme is in its the induced-fit stage, binding of the substrate changes the shape of the enzyme, so it can only accept that particular substrate.

True or False: A chemical reaction with a negative △G will release heat.

True

True or False: A non-spontaneous chemical reaction will require energy to complete it.

True

True or False: A reaction at equilibrium has zero free energy.

True

True or False: A spark is needed to get over the activation energy barrier of a chemical reaction.

True

True or False: Exergonic reactions generally tend to release heat.

True

True or False: The phosphorylated intermediate is one of the products of an ATP-mediated energy coupling reaction.

True