课程名称︰普通生物学乙上 课程性质︰必修 课程教师︰陈俊宏 开课学院：医学院 开课系所︰医学系 考试日期（年月日）︰2008／10／27 考试时限（分钟）：110min 是否需发放奖励金：是 （如未明确表示，则不予发放） 21. Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon dioxide (CO2) from one molecule of pyruvate? A. alcohol. B. lactate. C. glyceraldehydes-3-phosphate. D. acetyl-CoA. E. citrate. 22. During aerobic respiration, electrons travel downhill in which sequence? A. food → NADH → electron transport chain → oxygen. B. food → citric acid cycle → ATP → NAD+. C. glucose → pyruvate → ATP → oxygen. D. food →glycolysis → citric acid cycle → NADH → ATP. E. glucose → ATP → electron transport chain → NADH. 23. What is proton-motive force? A. The force required to remove an electron from hydrogen. B. Movement of hydrogen into the mitochondrion. C. The transmembrane proton concentration gradient. D. The addition of hydrogen to NAD+. E. The transmembrane proton concentration gradient. (the same as C) 24. Which of the following describes ubiquinone? A. A small hydrophobic electron carrier. B. A protein in the electron transport chain. C. A substrate for synthesis of FADH2. D. An essential amino acid. E. A vitamin needed for efficient glycolysis. 25. In alcohol fermentation, NAD+ is regenerated from NADH during which of the following? A. reduction of pyruvate to form lactate. B. oxidation of NAD+ in the citric acid cycle. C. phosphorylation of ADP to form ATP. D. reduction of pyruvate to PEP. E. reduction of acetaldehyde to ethanol. (ethyl alcohol) 26. Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements describes a function of phosphofructokinase? A. It is an allosteric enzyme. B. It is activated by ATP. C. It is inhibited by AMP. D. It catalyzes the conversion of fructose-1,6-bisphosphate to fructose-6-phosphate, an early step of glycolysis. E. It is inhibited by citrate, an intermediate of the citric acid cycle. 27. In vertebrate animals, brwon fat tissue's color is due to abundant contains relatively few mitochondria. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function fo the brown fat tissue? A. to increase the production of ATP synthase. B. to increase the rate of oxidative phosphorylation from its few mitochondria. C. to allow the animals to regulate their metabolic rate when it is especially hot. D. to regulate temperature by converting energy from NADH oxidation to heat. E. to allow other membranes of the cell to perform mitochondrial function. 28. Which of the following are directly associated with photosystem Ⅰ? A. P680 reaction-center chlorophyll. B. harvesting of light energy by ATP. C. passing electrons to plastoquinone. D. receiving electrons from plastocyanin. E. extraction of hydrogen electrons from the splitting of water. 29. In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chmiosmosis translocates protons from A. the stroma to the thylakoid space. B. the matrix to the stroma. C. the stroma to the photosystem Ⅱ. D. the intermembrane space to the matrix. E. ATP synthase to NADP+ reductase. 30. Why are C4 plants able to photosynthesize with no apparent photorespiration? A. They do not participate in the Calvin cycle. B. They use PEP carboxylase to initially fix CO2. C. They are adapted to cold, wet climates. D. They conserve water more efficiently. E. They exclude oxygen from their tissues. 31. CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they A. fix CO2 into pyruvate in the mesophyll cells. B. fix CO2 into sugars in the bundle-sheath cells. C. fix CO2 into organic acids during the night. D. use the enzyme phosphofructokinase, which outcompetes rubisco for CO2. E. use photosystems Ⅰ and Ⅱ at night. 32. Vinblastine is a standard chmotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to A. disruption of mitotic spindle formation. B. inhibition of regulaorty protein phosphorylation. C. myosin denaturation and inhibition of cleavage furrow formation. D. inhibition of DNA synthesis. E. suppression of cyclin production. 33. Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur? A. Chromosomally abnormal cells still have normal metabolism. B. Transformation introduces new chromosomes into cells. C. Cancer cells are no longer density dependent. D. Cancer cells are no longer anchorage dependent. E. Chromosomally abnormal cells can still go through cell cycle checkpoints. 34. Which of the following describe(s) cyclin-dependent kinase (Cdk) ? A. Cdk is present throughout the cell cycle. B. Cdk is inactive, or "turned off," in the presence of cyclin. C. Cdk is an enzyme that attaches phosphate groups to other proteins. D. Both A and C are true. E. Both B and C are true. 35. The MPF protein complex turns itself off by A. activating a process that destroys cyclin component. B. activating an enzyme that stimulates cyclin. C. binding to chromatin. D. exiting the cell. E. activating the anaphase-promoting complex. 36. Which phase of the cell cycle is shortest? A. G0. B. G1. C. S. D. G2. E. M. --

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