Practice_Exam_I_ans

# Practice_Exam_I_ans - Spring 2004 BCHS 3304 Practice Exam...

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Spring 2004 BCHS 3304 Practice Exam I- 1). An enzyme (protein catalyst) catalyzes the reaction: A B once per microsecond. How many times does the enzyme catalyze the reaction in one minute? a). 1 X 10 8 min -1 b). 6 X 10 8 min -1 c). 1 X 10 7 min -1 d). 6 X 10 7 min -1 e). 6 X 10 9 min -1 (d), 1 X 10 6 X 60 = 6 X 10 7 min -1 . 2). A DNA helix is 2 nanometers in diameter. How many DNA helices can you fit side-by-side in 1 decimeter? a). 5 X 10 8 helices b). 2 X 10 7 helices c). 5 X 10 -7 helices d). 2 X 10 9 helices e). 5 X 107 helices (e), 0.1 meters / 2 X 10 -9 meters per helix = 5 X 10 7 helices. 3). When 1 mole of crystalline sucrose is placed in 1 L pure water, the reaction vessel gets cool to the touch, and it takes many minutes for all of the sucrose to dissolve at room temperature. Given what you know of thermodynamics, what are the signs of the values of the change in enthalpy and entropy of the system? a). H +; S - b). H +; S + c). H -; S - d). H -; S + (b), H +; S +. 4). A chemical reaction occurs in a beaker of water. The internal energy of the system did not change throughout the course of the reaction, but the system lost 4 kJ of heat to the surroundings. What does this imply about the work done by/on the system? a). The surroundings did 4 kJ of work on the system. b). The system did 4 kJ of work on the surroundings. c). This is not possible as it violates the 1 st law of Thermodynamics. d). This is not possible as it violates the 2 nd law of Thermodynamics. e). Cannot calculate due to insufficient information. (a), the surroundings did 4 kJ of work on the system. 5). A process has the following thermodynamic parameters: H ° ’ is “-“ and S ° ’ is “-“. At what temperatures will this process be spontaneous? a). Spontaneous at temperatures below T = H ° ’/ S ° ’. b). Spontaneous at temperatures above T = H ° ’/ S ° ’. c). Spontaneous at all temperatures. d). Not spontaneous at any temperature. (a), spontaneous at temperatures below T = H ° ’/ S ° ’.

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6). The hydrolysis of phosphoenolpyruvate to pyruvate and inorganic phosphate (Pi) is represented by the following reaction and has the indicated G ° ’: H 2 O + phosphoenolpyruvate pyruvate + Pi + H + G ° ’ = -61.9 kJ mol -1 The hydrolysis of ATP is represented by the following reaction and has the indicated G ° ’: H 2 O + ATP ADP + Pi + H + G ° ’ = -30.5 kJ mol -1 Write the net chemical equation for the synthesis of ATP from ADP and inorganic phosphate using the hydrolysis of phosphoenolpyruvate to drive the reaction. Calculate the net G ° ’ for the overall reaction and indicate whether the overall reaction would be spontaneous or non-spontaneous. H
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Practice_Exam_I_ans - Spring 2004 BCHS 3304 Practice Exam...

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