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Thursday, April 7, 2011

Study Guide, Ch.8 (?) Metabolism

1)Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? 1) ___E____
A)catalysis B)anabolism C)dehydration D)metabolism E)catabolism

 (E is the correct answer for #1, given by  ___E____ . The rest of the questions do this as well)


2)Which of the following is a statement of the first law of thermodynamics? 2) __A_____
A)Energy cannot be transferred or transformed. B)The entropy of the universe is constant. C)Energy cannot be created or destroyed. D)The entropy of the universe is decreasing. E)Kinetic energy is stored energy that results from the specific arrangement of matter.

3)Whenever energy is transformed, there is always an increase in the 3) ___E____ A)free energy of the system. B)entropy of the system. C)enthalpy of the universe. D)free energy of the universe. E)entropy of the universe. 4)Which of the following is considered an open system? 4) ____A___ A)an organism B)a sealed terrarium C)liquid in a corked bottle D)food cooking in a pressure cooker 5)Why is ATP an important molecule in metabolism? 5) ____B___ A)Its terminal phosphate group contains a strong covalent bond that when hydrolyzed releases free energy. B)It provides energy coupling between exergonic and endergonic reactions. C)Its hydrolysis provides an input of free energy for exergonic reactions. D)Its terminal phosphate bond has higher energy than the other two. E)A, B, C, and D 6)Which of the following statements is (are) true about enzyme-catalyzed reactions? 6) ___B____ A)The free energy change of the reaction is opposite from the reaction in the absence of the enzyme. B)The reaction is faster than the same 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 7)How can one increase the rate of a chemical reaction? 7) ____B__ A)Decrease the concentration of the reactants. B)Add a catalyst. C)Increase the entropy of the reactants. D)Increase the activation energy needed. E)Cool the reactants. 8)Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in 8) ___ A ___ A)breaking the bond between glucose and fructose and forming new bonds from the atoms of water. B)bringing glucose and fructose together to form sucrose. C)utilization of water as a covalent bond is formed between glucose and fructose to form sucrase. D)the release of water from sucrose as the bond between glucose and fructose is broken. E)production of water from the sugar as bonds are broken between the glucose monomers. 9)Which of the following statements regarding enzymes is true? 9) __A_____ A)Enzymes decrease the free energy change of a reaction. B)Enzymes prevent changes in substrate concentrations. C)Enzymes change the direction of chemical reactions. D)Enzymes increase the rate of a reaction. E)Enzymes are permanently altered by the reactions they catalyze.
Refer to Figure 8.1 to answer the following questions. graphic(Fig0801.bmp) Figure 8.1 10)Which curve represents the behavior of an enzyme taken from a bacterium that lives in hot springs at temperatures of 70°C or higher? 10) ____C__ A)curve 1 B)curve 2 C)curve 3 D)curve 4 E)curve 5 11)Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid? 11) ___D___ A)curve 1 B)curve 2 C)curve 3 D)curve 4 E)curve 5 12)Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? 12) ____B__ A)allosteric inhibition B)competitive inhibition C)denaturization of the enzyme D)insufficient cofactors E)saturation of the enzyme activity 13)Which of the following is true of enzymes? 13) _A_____ A)Enzymes increase the rate of chemical reaction by lowering activation energy barriers. B)Enzymes may require a nonprotein cofactor or ion for catalysis to take speed up more appreciably than if the enzymes act alone. C)Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. D)Enzyme function is increased if the three-dimensional structure or conformation of an enzyme is altered. The following questions are based on the reaction A + B → C + D shown in Figure 8.2. graphic(Fig0802.bmp) Figure 8.2 14)Which of the following terms best describes the reaction? 14) __A____ A)exergonic B)endergonic C)allosteric D)anabolic E)nonspontaneous 15)Competitive inhibitors block the entry of substrate into the active site of an enzyme. On which of the following properties of an active site does this primarily depend? 15) ____B__ A)the enzyme becoming too saturated because of the concentration of substrate B)the ability of an enzyme to form a template for holding and joining molecules C)the enzyme providing an appropriate microenvironment conducive to a reaction's occurrence D)the enzyme's ability to stretch reactants and move them toward a transition state E)the enzyme forming covalent bonds with the reactants 16)How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? 16) __A____ A)by changing the shape of a reactant B)by changing the free energy change of the reaction C)by acting as a coenzyme for the reaction D)by decreasing the activation energy of the reaction E)by binding at the active site of the enzyme The next questions are based on the following information.
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. 17)What is substance X? 17) ___E___ A)a coenzyme B)the product C)an allosteric inhibitor D)an intermediate E)a substrate 18)Substance A functions as 18) __D____ A)the substrate. B)an intermediate. C)a competitive inhibitor. D)an allosteric inhibitor. E)a coenzyme. 19)Some enzymatic regulation is allosteric. In such cases, which of the following would usually be found? 19) ___E___ A)feedback inhibition B)the need for cofactors C)an enzyme with more than one subunit D)cooperativity E)both activating and inhibitory activity 20)Among enzymes, kinases catalyze phosphorylation, while phosphatases catalyze removal of phosphate(s). A cell's use of these enzymes can therefore function as an on-off switch for various processes. Which of the following is probably involved? 20) ______ A)a change in the optimal temperature at which a reaction will occur B)a change in the optimal pH at which a reaction will occur C)the change in a protein's charge leading to cleavage D)the change in a protein's charge leading to a conformational change E)the excision of one or more peptides 21)When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes 21) _D_____ A)reduced. B)dehydrogenated. C)hydrogenated. D)oxidized. E)an oxidizing agent. 22)Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy 22) __B____ A)CO2 is reduced and O2 is oxidized. B)C6H12O6 is oxidized and O2 is reduced. C)O2 is oxidized and H2O is reduced. D)O2 is reduced and CO2 is oxidized. E)C6H12O6 is reduced and CO2 is oxidized. 23)Starting with one molecule of glucose, the "net" products of glycolysis are 23) _A_____ A)2 NADH, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O. B)6 CO2, 6 H2O, 2 ATP, and 2 pyruvate. C)2 NAD+, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O. D)6 CO2, 6 H2O, 36 ATP, and 2 citrate. E)2 FADH2, 2 pyruvate, 4 ATP, and 2 H2O. 24)In glycolysis, for each molecule of glucose oxidized to pyruvate 24) __C____ A)4 molecules of ATP are used and 2 molecules of ATP are produced. B)2 molecules of ATP are used and 6 molecules of ATP are produced. C)2 molecules of ATP are used and 4 molecules of ATP are produced. D)2 molecules of ATP are used and 2 molecules of ATP are produced. E)6 molecules of ATP are used and 6 molecules of ATP are produced. Use the following information to answer the next questions.
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate 1) loses a carbon, which is given off as a molecule of CO2, 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A. 25)These three steps result in the formation of 25) ____A__ A)acetyl CoA, NADH, H+, and CO2. B)acetyl CoA, O2, and ATP. C)acetyl CoA, NAD+, ATP, and CO2. D)acetyl CoA, FADH2, and CO2. E)acetyl CoA, FAD, H2, and CO2. 26)How does pyruvate enter the mitochondrion? 26) _E_____ A)diffusion B)through a pore C)through a channel D)facilitated diffusion E)active transport 27)During cellular respiration, acetyl CoA accumulates in which location? 27) ___E___ A)mitochondrial outer membrane B)mitochondrial inner membrane C)cytosol D)mitochondrial intermembrane space E)mitochondrial matrix 28)How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? 28) ____B__ A)8 B) 2 C) 4 D) 6 E) 10 Refer to Figure 9.2, showing the citric acid cycle, as a guide to answer the following questions. graphic(Figure9-2.bmp) Figure 9.2 29)How many molecules of carbon dioxide (CO2) would be produced by five turns of the citric acid cycle? 29) ___C___ A)60 B) 5 C) 10 D) 12 E) 2 30)Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through substrate-level phosphorylation? 30) ___E___ A)24 B) 11 C) 12 D) 2 E) 1 31)How many reduced dinucleotides would be produced with four turns of the citric acid cycle? 31) __A____ A)4 FADH2 and 12 NADH B)4 FAD+ and 12 NAD+ C)2 FADH2 and 8 NADH D)1 FADH2 and 4 NADH E)1 FAD and 4 NAD+ 32)For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle, what is the total number of NADH + FADH2 molecules produced? 32) ___B___ A)10 B) 12 C) 4 D) 5 E) 6 33)During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level? 33) __D____ A)NAD+ B)ADP + Pi C)ATP D)FADH2 E)NADH 34)Inside an active mitochondrion, most electrons follow which pathway? 34) __C____ A)citric acid cycle → FADH2 → electron transport chain → ATP B)electron transport chain → citric acid cycle → ATP → oxygen C)citric acid cycle → NADH → electron transport chain → oxygen D)pyruvate → citric acid cycle → ATP → NADH → oxygen E)glycolysis → NADH → oxidative phosphorylation → ATP → oxygen
35)Energy released by the electron transport chain is used to pump H+ ions into which location? 35) __B__ A)mitochondrial inner membrane B)mitochondrial intermembrane space C)mitochondrial outer membrane D)cytosol E)mitochondrial matrix 36)In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP? 36) ___E___ A)energy released from substrate-level phosphorylation B)No external source of energy is required because the reaction is exergonic. C)energy released as electrons flow through the electron transport system D)energy released from ATP synthase pumping hydrogen ions from the mitochondrial matrix E)energy released from movement of protons through ATP synthase 37)When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the 37) ___D___ A)reduction of NAD+. B)restoration of the Na+/K+ balance across the membrane. C)lowering of pH in the mitochondrial matrix. D)creation of a proton gradient. E)formation of ATP. 38)Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration, how many oxygen molecules (O2) are required? 38) ____C__ A)1 B) 12 C) 6 D) 2 E) 38 39)Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in cellular respiration? 39) ___B___ A)4 B) 76 C) 38 D) 15 E) 2 40)In liver cells, the inner mitochondrial membranes are about 5 X the area of the outer mitochondrial membranes, and about 17 X that of the cell's plasma membrane. What purpose must this serve? 40) ______ A)It allows for increased rate of glycolysis. B)It increases the surface for oxidative phosphoryation. C)It allows the liver cell to have fewer mitochondria. D)It allows for increased rate of the citric acid cycle. E)It increases the surface for substrate-level phosphorylation. graphic(Fig0903.bmp) Figure 9.3 41)The accompanying figure shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain? 41) ____A__ A)NADH, FADH2, and electrons B)oxygen, carbon dioxide, and water C)Oxygen and electrons D)NAD+ , FAD, and electrons E)NADH, FADH2, and protons 42)Which of the following most accurately describes what is happening along this chain? 42) ____C__ A)Energy of the electrons increases at each step. B)Molecules in the chain give up some of their potential energy. C)Each electron carrier alternates between being reduced and being oxidized. D)Chemiosmosis is coupled with electron transfer. E)ATP is generated at each step. 43)In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of 43) ___A___ A)ATP, CO2, and ethanol (ethyl alcohol). B)ATP, pyruvate, and acetyl CoA. C)ATP, pyruvate, and oxygen. D)ATP, CO2, and lactate. E)ATP, NADH, and pyruvate.
44)When muscle cells are oxygen deprived, the heart still pumps. What must the heart cells be able to do? 44) ______ A)continue aerobic metabolism when skeletal muscle cannot B)remove oxygen from lactate C)remove lactate from the blood D)transform lactate to pyruvate again E)derive sufficient energy from fermentation 45)Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements describes a function of phosphofructokinase? 45) ___C___ A)It catalyzes the conversion of fructose-1,6-bisphosphate to fructose-6-phosphate, an early step of glycolysis. B)It is activated by AMP (derived from ADP). C)It is an allosteric enzyme. D)It is activated by ATP. E)It is inhibited by citrate, an intermediate of the citric acid cycle. 46)Which of the following statements describes NAD+? 46) __B____ A)NAD+ has more chemical energy than NADH. B)NAD+ is reduced to NADH during both glycolysis and the citric acid cycle. C)NAD+ can donate electrons for use in oxidative phosphorylation. D)NAD+ is reduced by the action of hydrogenases. E)In the absence of NAD+, glycolysis can still function.

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