AP Biology Chapter 8

Choose the pair of terms that correctly completes this sentence:Catabolism is to anabolism as ____ is to ____. a. exergonic; spontaneous b. exergonic; endergonic c. free energy; entropy d. work; energy e. entropy; enthalpy

Which of the following statements regarding enzymes is true? a. Enzymes decrease the free energy change of a reaction. b. Enzymes increase the rate of a reaction. c. Enzymes change the direction of chemical reactions. d. Enzymes are permanently altered by the reactions they catalyze. e. Enzymes prevent changes in substrate concentrations.

A chemical reaction that has a positive Δ G is correctly described as a. endergonic. b. endothermic. c. enthalpic. d. spontaneous. e. exothermic

Which of these statements regarding enzymes is false? a. Enzymes are proteins that function as catalysts. b. Enzymes display specificity for certain molecules with which they interact. c. Enzymes provide activation energy for the reactions they catalyze. d. The activity of enzymes can be regulated by other molecules. e. An enzyme may be used many times over for a specific reaction

What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways? a. feedback regulation b. bioenergetics c. energy coupling d. entropy e. cooperativity

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as a. metabolic inhibition. b. feedback inhibition. c. allosteric inhibition d. noncooperative inhibition e. reversible inhibition.

Which of the following types of reactions would decrease the entropy within a cell? a. dehydration reactions b. hydrolysis c. respiration d. digestion e. catabolism

If an enzyme has been inhibited noncompetitively, a. the Δ G for the reaction it catalyzes will always be negative. b. the active site will be occupied by the inhibitor molecule. c. raising substrate concentration will increase the inhibition. d. more energy will be necessary to initiate the reaction. e. the inhibitor molecule may be chemically unrelated to the substrate

If an enzyme is added to a solution where its substrates and products are in equilibrium, what would occur? a. Additional product would be formed. b. Additional substrate would be formed. c. The reaction would change from endergonic to exergonic. d. The free energy of the system would change. e. Nothing; the reaction would stay at equilibrium.

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(n) a. competitive inhibitor of the enzyme. b. noncompetitive inhibitor of the enzyme. c. allosteric activator of the enzyme. d. cofactor necessary for enzyme activity. e. coenzyme derived from a vitamin

How does a non-competitive inhibitor decrease the rate of an enzyme reaction? a. by binding at the active site of the enzyme b. by changing the structure of the enzyme c. by changing the free energy change of the reaction d. by acting as a coenzyme for the reaction e. by decreasing the activation energy of the reactio

What is a nonprotein "helper" of an enzyme molecule called? a. accessory enzyme b. allosteric group c. coenzyme d. functional group e. enzyme activator

Which of the following represents the activation energy required for the enzyme-catalyzed reaction? a. a b. b c. c d. d e. e

Which of the following represents the Δ G of the reaction? a. a b. b c. c d. d e. e

Which of the following terms best describes the reaction? a. endergonic b. exergonic c. anabolic d. allosteric e. nonspontaneous

Which of the following represents the activation energy required for a noncatalyzed reaction? a. a b. b c. c d. d e. e

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 the products of the catalytic reaction. d. is inhibited by the presence of a coenzyme or a cofactor. e. both A and B

Which of the following describe(s) some aspect of metabolism? a. synthesis of macromolecules b. breakdown of macromolecules c. control of enzyme activity d. A and B only e. A, B, and C

Which of the following is most similar in structure to ATP? a. an anabolic steroid b. a DNA helix c. RNA nucleotides d. an amino acid with three phosphate groups attached e. a phospholipid

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. Some reactants will be converted to products. d. A net input of energy from the surroundings is required for the reactions to proceed. e. The reactions are nonspontaneous

Which of the following characteristics is not associated with allosteric regulation of an enzyme's activity? a. A mimic of the substrate competes for the active site. b. A naturally occurring molecule stabilizes a catalytically active conformation. c. Regulatory molecules bind to a site remote from the active site. d. Inhibitors and activators may compete with one another. e. The enzyme usually has a quaternary structure.

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? a. catalysis b. metabolism c. anabolism d. dehydration e. catabolism

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? a. denaturization of the enzyme b. allosteric inhibition c. competitive inhibition d. saturation of the enzyme activity e. insufficient cofactors

How can one increase the rate of a chemical reaction? a. Increase the activation energy needed. b. Cool the reactants. c. Decrease the concentration of the reactants. d. Add a catalyst. e. Increase the entropy of the reactants

ATP generally energizes a cellular process by a. releasing heat upon hydrolysis. b. acting as a catalyst. c. coupling free energy released by ATP hydrolysis to free energy needed by other reactions. d. breaking a high-energy bond. e. binding directly to the substrate(s) of the enzyme

Which curve was most likely generated from an enzyme that requires a cofactor? a. curve 1 b. curve 2 c. curve 4 d. curve 5 e. It is not possible to determine whether an enzyme requires a cofactor from these data

Which curve represents the behavior of an enzyme taken from a bacterium that lives in hot springs at temperatures of 70°C or higher? a. curve 1 b. curve 2 c. curve 3 d. curve 4 e. curve 5

Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid? a. curve 1 b. curve 2 c. curve 3 d. curve 4 e. curve 5

According to the induced fit hypothesis of enzyme catalysis, which of the following is CORRECT? 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. A competitive inhibitor can outcompete the substrate for the active site. d. The binding of the substrate changes the shape of the enzyme's active site. e. The active site creates a microenvironment ideal for the reaction

Which of the following statements is true regarding enzyme cooperativity? a. A multi-enzyme complex contains all the enzymes of a metabolic pathway. b. A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway. c. A substrate molecule bound to an active site affects the active site of several subunits. d. Several substrate molecules can be catalyzed by the same enzyme. e. A substrate binds to an active site and inhibits cooperation between enzymes in a pathway

Which of the following is not true of enzymes? a. Enzyme catalysis is dependent on the pH and temperature of the reaction environment. b. Enzyme catalysis is dependent on the three-dimensional structure or conformation of the enzyme. c. Enzymes provide activation energy for the reaction they catalyze. d. Enzymes are composed primarily of protein, but they may bind nonprotein cofactors. e. Enzyme activity can be inhibited if the enzyme's allosteric site is bound with a noncompetitive inhibitor

Whenever energy is transformed, there is always an increase in the a. free energy of the system b. free energy of the universe c. entropy of the system d. entropy of the universe e. enthalpy of the universe

Which of the following statements regarding ATP is (are) correct? a. ATP serves as a main energy shuttle inside cells. b. ATP drives endergonic reactions in the cell by the enzymatic transfer of the phosphate group to specific reactants. c. The regeneration of ATP from ADP and phosphate is an endergonic reaction. d. A and B only e. A, B, and C

Which of the following statements correctly describe(s) catabolic pathways? a. They do not depend on enzymes. b. They consume energy to build up polymers from monomers. c. They release energy as they degrade polymers to monomers. d. They lead to the synthesis of catabolic compounds. e. both A and B

Which of the following statements correctly describe(s) some aspect of energy in living organisms? a. Living organisms can convert energy among several different forms. b. Living organisms can use energy to do work. c. Organisms expend energy in order to decrease their entropy d. A and B only e. A, B, and C

The first law of thermodynamics states that energy can be neither created nor destroyed. For living organisms, which of the following is an important consequence of the first law? a. The energy content of an organism is constant. b. The organism ultimately must obtain all of the necessary energy for life from its environment. c. The entropy of an organism decreases with time as the organism grows in complexity. d. Organisms are unable to transform energy. e. Life does not obey the first law of thermodynamics.

Which of the following is true of enzymes? a. Enzymes may require a nonprotein cofactor or ion for catalysis to take place. b. Enzyme function is reduced if the three-dimensional structure or conformation of an enzyme is altered. c. Enzyme function is influenced by physical and chemical environmental factors such as pHand temperature. d. Enzymes increase the rate of chemical reaction by lowering activation energy barriers. e. All of the above are true of enzymes.

Which of the following is a statement of 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. Kinetic energy is stored energy that results from the specific arrangement of matter. e. Energy cannot be transferred or transformed.

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics? a. Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time. b. Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is balanced by an increase in the entropy of the universe. c. Living organisms do not follow the laws of thermodynamics. d. As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth. e. Living organisms are able to transform energy into entropy.

Which of the following statements about metabolism is incorrect? a. Metabolism is an emergent property of life at the level of organisms. b. Metabolism manages the utilization of materials and energy resources. c. The uptake of water associated with the hydrolysis of biological polymers is part of metabolism. d. Metabolism depends on a constant supply of energy. e. None of these statements about metabolism is incorrect.

If an enzyme solution is saturated with substrate, the most effective way to obtain an even 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 an allosteric inhibitor e. add a noncompetitive inhibitor.

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because a. the starch solution has less free energy than the sugar solution. b. the hydrolysis of starch to sugar is endergonic. c. the activation energy barrier for this reaction cannot be surmounted. d. starch cannot be hydrolyzed in the presence of so much water. e. starch hydrolysis is nonspontaneous.

43. The regulation of enzyme function is an important aspect of cell metabolism. Which of the following is least likely to be a mechanism for enzyme regulation? a. allosteric regulation b. cooperativity c. feedback inhibition d. removing cofactors e. reversible inhibition

Which of the following statements is true concerning catabolic pathways? a. They combine molecules into more energy-rich molecules. b. They are usually coupled with anabolic pathways to which they supply energy in the form of ATP. c. They are endergonic. d. They are spontaneous and do not need enzyme catalysis. e. They build up complex molecules such as protein from simpler compounds.

What is the change in free energy of a system at chemical equilibrium? a. slightly increasing b. greatly increasing d. greatly decreasing c. slightly decreasing e. no net change

Which of the following statements is (are) true about enzyme-catalyzed reactions? a. The reaction is faster than the same reaction in the absence of the enzyme. b. The free energy change of the reaction is the same as the reaction in the absence of the enzyme. c. The reaction always goes in the direction toward chemical equilibrium. d. A and B only e. A, B, and C

Which of the following is (are) true for anabolic pathways? a. They do not depend on enzymes. b. They are highly regulated sequences of chemical reactions. c. They consume energy to build up polymers from monomers. d. They release energy as they degrade polymers to monomers. e. both B and C

An enzyme catalyzes a reaction by a. supplying the energy to speed up a reaction. b. lowering the energy of activation of a reaction. c. lowering the G of a reaction. d. changing the equilibrium of a spontaneous reaction. e. increasing the amount of free energy of a reaction.

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. d. heat content. c. endothermic level. e. free-energy content.