NPB 101 Sample Midterm I

NPB 101 Sample Midterm I - NPB Sample Midterm 1 Identify...

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NPB Sample Midterm 1 Identify the letter of the choice that best completes the statement or answers the question. 1. Positive feedback operates to maintain a controlled factor in a relatively steady state, whereas negative feedback moves a controlled variable even further from a steady state. a. true. b. false. 2. Glycolysis a. yields 2 molecules of ATP for each molecule of glucose processed. b. requires oxygen c. takes place in the mitochondrial matrix. d. Both (b) and (c) above. e. All of these answers. 3. Which of the following is not a function of membrane proteins? a. they serve as channels. b. they determine the fluidity of the membrane. c. they serve as carriers. d. they serve as receptor sites. e. they serve as membrane-bound enzymes. 4. Osmosis occurs when water diffuses down its concentration gradient. Given that the plasma membrane of cells is permeable to water (because there are water channels in the membrane), what would be the effect of decreasing the extracellular concentration of a non-permeable sugar such as sucrose? a. cell volume would decrease. b. cell volume would increase. c. the membrane potential would hyperpolarize. d. there would be no effect on the cell. e. Both (a) and (c) above. 5. According to Fick's law of diffusion, which of the following changes would decrease the rate of net diffusion of a substance across a membrane? a. an increase in the substance's concentration gradient b. an increase in the permeability of the membrane to the substance c. an increase in the surface area of the membrane d. an increase in the thickness of the membrane e. None of these answers. 6. Which protein(s) is/are responsible for development of the resting membrane potential? a. leak channels. b. gated channels. c. pumps. d. Both (a) and (b) above. e. Both (a) and (c) above.
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7. The Na+/K+ ATPase is a transmembrane protein that transports Na+ and K+ ions against their concentration gradients. The conformation of the protein and its binding affinities for Na+ and K+ are determined by the state of intracellular phosphorylation. Which effect of phosphorylation or dephosphory- lation can best account for the active transport of Na+ and K+ ions across the PM? a. with the binding sites of both ions exposed to the intracellular fluid, phosphorylation increases the binding affinity to Na+ and decreases the binding affinity to K+. b. with the binding sites of both ions exposed to the extracellular fluid, dephosphorylation decreases the binding affinity to both ions. c. with the binding sites of both ions exposed to the extracellular fluid, dephosphorylation increases the binding affinity to both ions. d. with the binding sites of both ions exposed to the intracellular fluid, phosphorylation decreases the binding affinity to Na+ and increases the binding affinity to K+. 8.
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This note was uploaded on 04/03/2010 for the course NPB 53422 taught by Professor Usrey during the Winter '10 term at UC Davis.

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NPB 101 Sample Midterm I - NPB Sample Midterm 1 Identify...

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