110_sampleQ_03_answers

110_sampleQ_03_answe - SAMPLE EXAM QUESTIONS FOR FIRST MID-TERM(WITH ANSWERS 1 A membrane that is selectively permeable to only chloride ions

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SAMPLE EXAM QUESTIONS FOR FIRST MID-TERM (WITH ANSWERS) 1. A membrane that is selectively permeable to only chloride ions separates two solutions of potassium chloride, with concentrations of 1 M and 10 M. What will be the voltage of the concentrated solution relative to the more dilute solution? A. -116 mV. B. ** +58 mV C. +116 mV D. -29 mV E. -58 mV Note that the membrane is permeable only to chloride ions. The concentration difference is 10-fold, and the ion is monovalent, so from the Nernst equation we predict a voltage 0f 58mV. Chloride ions will move down their concentration gradient from the side with high concentration – negative ions leaving that side will thus make it positive with regard to the side with lower concentration. 2. At the peak of the action potential the current through sodium channels is small because; A. all sodium channels have inactivated. B. the sodium conductance reduces to almost zero at +50 mV. C. ** the movement of Na + ions down their concentration gradient is balanced by the electrical field across the axon membrane. D. it is exactly counterbalanced by flow of K + ions through potassium channels. E.
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This note was uploaded on 04/14/2010 for the course BIO SCI BIO N110 taught by Professor Leon,chance&parker during the Spring '09 term at UC Irvine.

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110_sampleQ_03_answe - SAMPLE EXAM QUESTIONS FOR FIRST MID-TERM(WITH ANSWERS 1 A membrane that is selectively permeable to only chloride ions

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