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Final Exam Fall 2004 corrected

Final Exam Fall 2004 corrected - BME 499 “Biophysical...

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BME 499 “Biophysical Chemistry” Name: ______________________________ Final Exam, Dec. 17, 2004 1) Assume you are swimming in a polluted lake and the toxic molecule in that lake cannot enter your body through the skin. While you swim, however, you are remembering your Biophysical Chemistry course and start wondering if the toxic molecule (diffusion coefficient D = 70 10 -9 m 2 s -1 ) may be able to diffuse into your body along the urinary tract. The typical length of the urethra of women is 4 cm and men 20 cm. Assuming the urethra (diameter 2.6 mm) would be filled with enough residual urine that the toxic substance could diffuse into the bladder, a) how long could a woman stay in the lake (6 P) and b) how long a man (4 P) before significant amounts of the toxin would arrive in the bladder? Assume the residual urine in the urethra to be stagnant. (Note: Urinary tract infections are usually caused by motile bacteria not by diffusion of toxic substances along the urethra!) 2) a) Explain in thermodynamic terms why a perfume will spread throughout a room even in the absence of air flow (2 P) . b) Why is this process spontaneous (2 P) ? c) Which fundamental Law of Thermodynamics “governs” this process (1 P) ? d) Do you think this process would be faster or slower in a sauna (temp = 95 degrees Celsius) compared to a cold room (temp = 4 degrees Celsius) (1 P) ? e) Why (2 P) ? f) In which room, sauna or cold room would the change in Gibbs free energy be larger (2 P) ? Assume absence of air flow for all questions.
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3) a) What are the benefits for living organisms to couple reactions in metabolism (4 P) ? b) List three biochemical processes that are accomplished by coupling reactions (3 P) and c) give a short explanation of which reaction is coupled to do what (3 P) .
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