Chapter 19 Testbank - Chapter 19 Oxidative Phosphorylation...

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Chapter 19 Oxidative Phosphorylation and Photophosphorylation Multiple Choice Questions i. Electron-transfer reactions in mitochondria Page: 707 Difficulty: 1 Ans: E Almost all of the oxygen (O 2 ) one consumes in breathing is converted to: A) acetyl-CoA. B) carbon dioxide (CO 2 ). C) carbon monoxide and then to carbon dioxide. D) none of the above. E) water. 2. Electron-transfer reactions in mitochondria Pages: 710-713 Difficulty: 3 Ans: E A new compound isolated from mitochondria is claimed to represent a previously unrecognized carrier in the electron transfer chain. It is given the name coenzyme Z. Which line of evidence do you feel is the least conclusive in assigning this compound a position in the electron transfer chain? A) Alternate oxidation and reduction of the mitochondrion-bound coenzyme Z can be readily demonstrated. B) Removal of coenzyme Z from the mitochondria results in a decreased rate of oxygen consumption. C) The rate of oxidation and reduction of mitochondrion-bound coenzyme is of the same order of magnitude as the overall rate of electron transfer in mitochondria as measured by oxygen consumption. D) The reduction potential of Z is between that of two compounds known to participate in the electron transport chain E) When added to a mitochondrial suspension, coenzyme Z is taken up very rapidly and specifically by the mitochondria. 3. Electron-transfer reactions in mitochondria Pages: 712-713 Difficulty: 2 Ans: B Antimycin A blocks electron transfer between cytochromes b and c 1 . If intact mitochondria were incubated with antimycin A, excess NADH, and an adequate supply of O 2 , which of the following would be found in the oxidized state? A) Coenzyme Q B) Cytochrome a 3 C) Cytochrome b D) Cytochrome e E) Cytochrome f
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Chapter 19 Oxidative Phosphorylation and Photophosphorylation 4. Electron-transfer reactions in mitochondria Page: 714 Difficulty: 2 Ans: B Cyanide, oligomycin, and 2,4-dinitrophenol (DNP) are inhibitors of mitochondrial aerobic phosphorylation. Which of the following statements correctly describes the mode of action of the three inhibitors? A) Cyanide and 2,4-dinitrophenol inhibit the respiratory chain, and oligomycin inhibits the synthesis of ATP. B) Cyanide inhibits the respiratory chain, whereas oligomycin and 2,4-dinitrophenol inhibit the synthesis of ATP. C) Cyanide, oligomycin, and 2,4-dinitrophenol compete with O 2 for cytochrome oxidase (Complex IV). D) Oligomycin and cyanide inhibit synthesis of ATP; 2,4-dinitrophenol inhibits the respiratory chain. E) Oligomycin inhibits the respiratory chain, whereas cyanide and 2,4-dinitrophenol prevent the synthesis of ATP. 5. Electron-transfer reactions in mitochondria Pages: 715-716 Difficulty: 2 Ans: B In the reoxidation of QH 2 by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH 2 because: A) cytochrome c is a one-electron acceptor, whereas QH 2 is a two-electron donor. B)
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This note was uploaded on 04/14/2010 for the course BHC 3023 taught by Professor Harmen during the Spring '10 term at University of South Florida - Tampa.

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Chapter 19 Testbank - Chapter 19 Oxidative Phosphorylation...

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