General, Organic & Biological Chemistry, 5e (Timberlake) Chapter 23 Metabolism and Energy Production 23.1 Multiple-Choice Questions 1) When combined with electron transport, one turn of the citric acid cycle produces ATP A) 24 B) 12 C) 10 D) 14 E) Answer: C Objective: 23.1 Global Outcomes: GO2 2) Which coenzyme is the electron acceptor in the following reaction? H | - C| H | C| → - C =C | | A) FAD B) NAD+ C) FMN D) NADH E) FADH2 Answer: A Objective: 23.1 Global Outcomes: GO2 3) Which coenzyme is the electron acceptor in the following reaction? OH O | - C- → - C| H A) FAD B) NAD+ C) FMN D) NADH E) FADH2 Answer: B Objective: 23.1 Global Outcomes: GO2 4) NAD+ participates in reactions that produce A) a CH2 group B) a C=O bond C) phosphorylation D) ADP from ATP Copyright © 2016 Pearson Education, Inc E) a C-C bond Answer: B Objective: 23.1 Global Outcomes: GO2 5) FAD is a coenzyme which usually participates in A) oxidation of alcohols to aldehydes B) formation of carbon-carbon double bonds C) decarboxylation reactions D) phosphorylation reactions E) β-oxidation reactions Answer: B Objective: 23.1 Global Outcomes: GO2 6) In order to enter the citric acid cycle, pyruvate is first converted to A) ate B) acetaldehyde C) citrate D) acetyl CoA E) ethanol Answer: D Objective: 23.1 Global Outcomes: GO2 7) The citric acid cycle is used in the oxidation of A) glucose only B) glucose and fatty acids only C) fatty acids only D) glucose, fatty acids, and proteins E) proteins only Answer: D Objective: 23.1 Global Outcomes: GO2 8) What electron acceptor(s) is(are) used in the citric acid cycle? A) FAD only B) NAD+ only C) NADH + FADH2 + HS - CoA D) FMN E) NAD+ + FAD Answer: E Objective: 23.1 Global Outcomes: GO2 9) Which of the following compounds in the citric acid cycle undergoes oxidative decarboxylation? A) citrate B) isocitrate C) succinate D) fumarate E) succinyl CoA Answer: B Objective: 23.1 Global Outcomes: GO2 10) Which of the following is the net reaction for one turn of the citric acid cycle? Copyright © 2016 Pearson Education, Inc A) Acetyl CoA + NAD+ + FAD + GDP + Pi + 2H2O → 2CO2 + NADH + H+ + FADH2 + HS - CoA + GTP B) Pyruvate + NAD+ + FAD + GDP + Pi + 2H2O → CO2 + NADH + H+ + FADH2 + GTP C) Acetyl CoA + NAD+ + FAD + GDP + Pi → CO2 + NADH + H+ + FADH2 + HS - CoA + GTP D) Glucose + NAD+ + 2GDP + Pi + 2H2O → 2Pyruvate + NADH + H+ + GTP E) Glucose + 2GDP + Pi → 2Lactate + 2GTP Answer: A Objective: 23.1 Global Outcomes: GO2 11) The citric acid cycle operates only under aerobic conditions because A) oxygen is a reactant in the citric acid cycle B) oxygen is a product of the citric acid cycle C) CO2 is a product of the citric acid cycle D) the NADH and FADH2 produced by the citric acid cycle can only be reoxidized by the electron transport chain E) the NAD+ and FAD produced by the citric acid cycle can only be reduced by the electron transport chain Answer: D Objective: 23.1 Global Outcomes: GO2 12) When oxygen is in plentiful supply in the cell, pyruvate is converted to A) CoA B) acetyl CoA C) glucose D) lactate E) fructose Answer: B Objective: 23.1 Global Outcomes: GO2 Copyright © 2016 Pearson Education, Inc 13) Which of the three major stages of metabolism includes the citric acid cycle? A) Stage one B) Stage two C) Stage three Answer: C Objective: 23.1 Global Outcomes: GO2 14) The citric acid cycle takes place in the A) mitochondria B) cytosol C) cytoplasm D) Golgi apparatus E) endoplasmic reticulum Answer: A Objective: 23.1 Global Outcomes: GO7 15) Most of the energy released in the citric acid cycle is used to produce A) glucose B) acetyl CoA C) NADH and FADH2 D) carbon dioxide and water E) citric acid Answer: C Objective: 23.1 Global Outcomes: GO2 16) Another name for the citric acid cycle is A) electron transport B) glycolysis C) the tricarboxylic acid (TCA) cycle D) glucolysis E) the transamination pathway Answer: C Objective: 23.1 Global Outcomes: GO7 17) Another name for the citric acid cycle is A) the Krebs cycle B) gluconeogenesis C) glucose hydrolysis D) oxidative phosphorylation E) the chemiosmotic pump Answer: A Objective: 23.1 Global Outcomes: GO7 Copyright © 2016 Pearson Education, Inc 18) In the first reaction of the citric acid cycle A) glucose becomes pyruvate B) ATP is produced C) NADH is produced D) acetyl CoA reacts with oxaloacetate to give citrate E) pyruvate becomes CO2 and H2O Answer: D Objective: 23.1 Global Outcomes: GO2 19) During the first reaction in the citric acid cycle, A) HS- CoA is released B) acetyl CoA is made C) a decarboxylation occurs D) a decomposition occurs E) ATP is synthesized Answer: A Objective: 23.1 Global Outcomes: GO2 20) The transformation of citrate to isocitrate in the citric acid cycle requires two reactions A) oxidation B) reduction C) hydrolysis D) decarboxylation E) dehydration-hydration Answer: E Objective: 23.1 Global Outcomes: GO2 21) The citric acid cycle step that removes the first CO2 molecule is a(n) A) oxidative decarboxylation B) reduction C) carbonylation D) hydrolysis E) combination Answer: A Objective: 23.1 Global Outcomes: GO2 22) In the third major step of the citric acid cycle, NAD + is converted to A) NAS- B) NAD2+ C) NADH2 D) NAD E) NADH Answer: E Objective: 23.1 Global Outcomes: GO2 23) Step of the citric acid cycle is the hydrolysis of succinyl CoA In this reaction A) the energy released is used to make GTP B) the energy released is used to make ATP C) carbon dioxide is released D) α-ketoglutarate is released Copyright © 2016 Pearson Education, Inc E) the enzyme aconitase is needed Answer: A Objective: 23.1 Global Outcomes: GO2 24) In the hydrolysis of succinyl CoA in step of the citric acid cycle, CoA is released as A) HS-CoA B) HO-CoA C) CoA-O- D) CoA-S- E) CoA-COO- Answer: A Objective: 23.1 Global Outcomes: GO2 25) The GTP formed in step of the citric acid cycle is used to make A) carbon dioxide B) oxygen C) water D) CoA E) ATP Answer: E Objective: 23.1 Global Outcomes: GO2 26) In the dehydration of succinate to fumarate in the citric acid cycle, the coenzyme used is A) CoA B) acetyl CoA C) NAD+ D) NADH E) FAD Answer: E Objective: 23.1 Global Outcomes: GO2 27) In step of the citric acid cycle, fumarate is converted to malate by a reaction A) hydrolysis B) dehydrogenation C) hydrogenation D) hydration E) dehydration Answer: D Objective: 23.1 Global Outcomes: GO2 28) The last step in the citric acid cycle converts malate to A) citrate B) isocitrate C) succinate D) fumarate E) oxaloacetate Answer: E Objective: 23.1 Global Outcomes: GO2 29) One method of regulation of the citric acid cycle is A) allosteric control Copyright © 2016 Pearson Education, Inc B) osmosis C) temperature control D) carbon dioxide production E) water concentration Answer: A Objective: 23.1 Global Outcomes: GO2 30) The process which requires oxygen to produce carbon dioxide and water is called A) fermentation B) reduction C) decomposition D) oxidation E) respiration Answer: E Objective: 23.2 Global Outcomes: GO2 31) Which of the following metabolic pathways can occur in the absence of oxygen? A) electron transport B) oxidative phosphorylation C) citric acid cycle D) glycolysis E) β-oxidation Answer: D Objective: 23.2 Global Outcomes: GO2 32) Under anaerobic conditions, there is a net production of ATP during glycolysis A) zero B) two C) four D) six E) eight Answer: B Objective: 23.2 Global Outcomes: GO4 33) Cyanide ion and carbon monoxide inhibit A) cytochrome c oxidase B) ATP production C) antibiotic activity D) CoQ formation E) CoA formation Answer: A Objective: 23.2 Global Outcomes: GO2 34) In the chemiosmotic model, protons circulate through a protein complex called A) Cyt c B) FMN C) Complex III D) CoQ E) ATP synthase Answer: E Objective: 23.2 Global Outcomes: GO2 Copyright © 2016 Pearson Education, Inc 35) The components of the electron transport chain NOT include A) oxygen (O2) B) Cyt c C) Complex III D) CoQ E) acetyl CoA Answer: E Objective: 23.2 Global Outcomes: GO2 36) In the chemiosmotic model of oxidative phosphorylation, ATP is synthesized as A) OH- flows through ATP synthase B) electrons flow through ATP synthase C) Ca2+ flows through ATP synthase D) H+ flows through ATP synthase E) Na+ flows through ATP synthase Answer: D Objective: 23.2 Global Outcomes: GO2 37) In electron transport, the synthesis of ATP from ADP + P i is called A) glycolysis B) fermentation C) oxidative phosphorylation D) isomerization E) hydrolysis Answer: C Objective: 23.2 Global Outcomes: GO2 38) In electron transport, the three protein complexes (I, III, and IV) A) act as proton pumps, which generate a proton gradient B) transfer electrons from NAD+ to O2 C) transfer electrons from FAD to O2 D) act as electron pumps, which generate an electron gradient E) act as Ca2+ pumps, which generate a Ca2+ gradient Answer: A Objective: 23.2 Global Outcomes: GO2 39) In electron transport, the oxidized product from the reaction of CoQ + NADH + H + is A) CoQ B) CoQH2 C) FADH D) FAD E) NAD+ Answer: E Objective: 23.2 Global Outcomes: GO2 40) The electron carrier provides 1.5 ATP via electron transport A) FADH2 B) NADH C) NADPH Copyright © 2016 Pearson Education, Inc D) HS-CoA E) acetyl CoA Answer: A Objective: 23.2 Global Outcomes: GO2 41) Electron transport is also called A) the citric acid cycle B) β-oxidation C) transamination D) the respiratory chain E) fermentation Answer: D Objective: 23.2 Global Outcomes: GO2 Copyright © 2016 Pearson Education, Inc 42) In electron transport, NADH and FADH2 are used to provide A) oxygen B) electrons and hydrogen ions C) carbon atoms D) water and carbon dioxide E) thiol groups Answer: B Objective: 23.2 Global Outcomes: GO2 43) The energy released during electron transport is used to produce A) glucose B) citric acid C) carbon dioxide D) ATP E) NADH Answer: D Objective: 23.2 Global Outcomes: GO2 44) The compounds in the respiratory chain that remove hydrogen ions and electrons from NADH are classified as A) oxidative transporters B) osmotic carriers C) electron carriers D) phosphorylators E) citrates Answer: C Objective: 23.2 Global Outcomes: GO2 45) One example of an electron carrier in the respiratory chain is A) ATP B) GTP C) coenzyme Q D) citrate E) water Answer: C Objective: 23.2 Global Outcomes: GO2 10 Copyright © 2016 Pearson Education, Inc 46) Which is the best choice for the box labeled "Answer" in the illustration below? A) oxidized carrier B B) carbon dioxide C) OHD) reduced carrier BH2 E) energy Answer: D Objective: 23.2 Global Outcomes: GO2 47) What is the correct coefficient for ATP in the complete combustion of glucose? C6H12O6 + 6O2 → 6CO2 + ATP + 6H2O A) B) 12 C) 18 D) 24 E) 32 Answer: E Objective: 23.3 Global Outcomes: GO4 48) Which of the following is NOT a possible product of pyruvate under anaerobic conditions? A) lactate B) acetaldehyde C) fumarate D) ethanol E) CO2 Answer: C Objective: 23.3 Global Outcomes: GO2 49) In stage three of metabolism, the overall result is to release A) glucose and water B) lactate and acetyl CoA C) lactate and glucose D) glycogen and water E) carbon dioxide and energy Answer: E Objective: 23.3 Global Outcomes: GO2 50) Overall, one turn of the citric acid cycle produces A) three CO2 molecules B) three NADH molecules C) two FADH2 molecules D) ATP 11 Copyright © 2016 Pearson Education, Inc E) GTP Answer: B Objective: 23.3 Global Outcomes: GO2 51) In glycolysis, glucose produces pyruvate ions and a total of ATP molecules A) B) C) D) E) 12 Answer: C Objective: 23.3 Global Outcomes: GO4 52) The complete oxidation of glucose produces ATP molecules A) B) C) 12 D) 24 E) 32 Answer: E Objective: 23.3 Global Outcomes: GO4 12 Copyright © 2016 Pearson Education, Inc 23.2 Short Answer Questions In this figure depicting the Stages of Metabolism taken from your text, identify the metabolic substance numbered 1) Substance Answer: proteins Objective: 23.1 Global Outcomes: GO2 2) Substance Answer: carbohydrates or polysaccharides Objective: 23.1 Global Outcomes: GO2 3) Substance Answer: lipids Objective: 23.1 Global Outcomes: GO2 13 Copyright © 2016 Pearson Education, Inc 4) Substance Answer: pyruvate Objective: 23.1 Global Outcomes: GO2 5) Substance Answer: acetyl CoA Objective: 23.1 Global Outcomes: GO2 6) Substance Answer: carbon dioxide Objective: 23.1 Global Outcomes: GO2 7) Substance Answer: ATP Objective: 23.1 Global Outcomes: GO2 8) Substance Answer: oxygen Objective: 23.1 Global Outcomes: GO2 9) Process Answer: citric acid cycle or Krebs cycle or tricarboxylic acid cycle Objective: 23.1 Global Outcomes: GO2 10) Process 10 Answer: electron transport Objective: 23.1 Global Outcomes: GO2 11) Process 11 Answer: oxidative phosphorylation Objective: 23.1 Global Outcomes: GO2 14 Copyright © 2016 Pearson Education, Inc In this figure, depicting part of the Citric Acid Cycle, taken from your text, identify the substances numbered 12) Substance 12 Answer: acetyl CoA Objective: 23.1 Global Outcomes: GO2 13) Substance 13 Answer: citrate Objective: 23.1 Global Outcomes: GO2 14) Substance 14 Answer: carbon dioxide Objective: 23.1 Global Outcomes: GO2 15) Substance 15 Answer: α-ketoglutarate Objective: 23.1 Global Outcomes: GO2 16) Substance 16 Answer: carbon dioxide Objective: 23.1 Global Outcomes: GO2 15 Copyright © 2016 Pearson Education, Inc 17) Substance 17 Answer: succinyl CoA Objective: 23.1 Global Outcomes: GO2 18) Substance 18 Answer: oxaloacetate Objective: 23.1 Global Outcomes: GO2 23.3 True/False Questions 1) In reaction of the citric acid cycle, α-ketoglutarase, a five-carbon keto acid, is decarboxylated Answer: TRUE Objective: 23.1 Global Outcomes: GO2 2) In reaction of the citric acid cycle, acetyl CoA reacts with oxaloacetate Answer: TRUE Objective: 23.1 Global Outcomes: GO2 3) Citrate is one of the products of the citric acid cycle Answer: FALSE Objective: 23.1 Global Outcomes: GO2 4) NAD+ acts as a hydrogen acceptor in metabolic reactions Answer: TRUE Objective: 23.1 Global Outcomes: GO2 5) FADH2 is the oxidized form of FAD Answer: FALSE Objective: 23.1 Global Outcomes: GO2 6) Cyt c is a component of complex IV Answer: FALSE Objective: 23.2 Global Outcomes: GO2 7) The energy levels of complexes decrease as electron transport progresses Answer: TRUE Objective: 23.2 Global Outcomes: GO2 16 Copyright © 2016 Pearson Education, Inc 8) 12 ATP are produced when glucose is oxidized to CO and H2O Answer: FALSE Objective: 23.3 Global Outcomes: GO4 9) The conversion of ATP to ADP and inorganic phosphate produces 7.3 kcal/mole of energy Answer: TRUE Objective: 23.3 Global Outcomes: GO4 10) The oxidation of NADH yields 2.5 ATP Answer: TRUE Objective: 23.3 Global Outcomes: GO4 11) The oxidation of FADH2 yields 1.5 ATP Answer: TRUE Objective: 23.3 Global Outcomes: GO4 17 Copyright © 2016 Pearson Education, Inc 23.4 Matching Questions Indicate the amount of ATP produced when each of the following reactions occurs A) ATP B) ATP C) 32 ATP D) 2.5 ATP E) 10 ATP 1) complete oxidation of glucose Objective: 23.3 Global Outcomes: GO4 2) acetyl CoA → 2CO2 Objective: 23.3 Global Outcomes: GO4 3) glucose → pyruvate under aerobic conditions Objective: 23.3 Global Outcomes: GO4 4) glucose → lactate Objective: 23.3 Global Outcomes: GO4 5) pyruvate → acetyl CoA + CO2 Objective: 23.3 Global Outcomes: GO4 Answers: 1) C 2) E 3) A 4) B 5) D Match the terms with the following descriptions A) oxidative phosphorylation B) coenzyme A 6) the process that makes ATP using energy from the electron transport chain Objective: 23.3 Global Outcomes: GO2 7) the carrier of acetyl (two-carbon) groups Objective: 23.1 Global Outcomes: GO2 Answers: 6) A 7) B 18 Copyright © 2016 Pearson Education, Inc Identify each of the following metabolic pathways A) glycolysis B) electron transport C) citric acid cycle 8) the conversion of glucose to pyruvic acid Objective: 23.1 Global Outcomes: GO2 9) the series of reactions that converts acetyl CoA to carbon dioxide and water Objective: 23.1 Global Outcomes: GO2 10) the series of reactions that produces water Objective: 23.2 Global Outcomes: GO2 11) the series of reactions that uses electron carriers Objective: 23.2 Global Outcomes: GO2 Answers: 8) A 9) C 10) B 11) B 19 Copyright © 2016 Pearson Education, Inc ... 23. 1 Global Outcomes: GO2 22) In the third major step of the citric acid cycle, NAD + is converted to A) NAS- B) NAD2+ C) NADH2 D) NAD E) NADH Answer: E Objective: 23. 1 Global Outcomes: GO2 23) ... proteins Objective: 23. 1 Global Outcomes: GO2 2) Substance Answer: carbohydrates or polysaccharides Objective: 23. 1 Global Outcomes: GO2 3) Substance Answer: lipids Objective: 23. 1 Global Outcomes:... Answer: pyruvate Objective: 23. 1 Global Outcomes: GO2 5) Substance Answer: acetyl CoA Objective: 23. 1 Global Outcomes: GO2 6) Substance Answer: carbon dioxide Objective: 23. 1 Global Outcomes: GO2