In active transport, the affinity of any given binding site for the molecule to be transported changes as the site goes from facing one side of the membrane to facing the other side.
Indicate whether the statement is true or false.
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Question 2) The component of the plasma membrane that acts as a selective barrier to diffusion of polar molecules is the integral proteins.
Indicate whether the statement is true or false.
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Question 3) In general, polar molecules diffuse more rapidly across cell membranes than do nonpolar molecules.
Indicate whether the statement is true or false.
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Question 4) Molecules increase their rate of diffusion as temperature increases.
Indicate whether the statement is true or false.
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Question 5) All other factors being equal, the rate of diffusion across a permeable surface will be greater for small molecules than for larger ones.
Indicate whether the statement is true or false.
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Question 6) Although permeability to mineral ions does not vary much from one cell to another, different cells vary considerably in their permeability to nonpolar molecules.
Indicate whether the statement is true or false.
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Question 7) Specific proteins in the membranes mediate movement of lipid-soluble molecules into cells.
Indicate whether the statement is true or false.
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Question 8) Which lists the epithelial cell barrier compartments in the order of the typical Na+ concentrations, from highest to lowest?
A. intracellular, lumen side, blood side
B. blood side, lumen side, intracellular
C. blood side, intracellular, lumen side
D. lumen side, intracellular, blood side
E. lumen side, blood side, intracellular
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Question 9) The greater the concentration difference of a substance between two volumes separated by a permeable membrane, the lesser the magnitude of the net flux of the substance.
Indicate whether the statement is true or false.
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Question 10) What is the most common transport mechanism by which glucose and other organic solutes cross the luminal membrane of an epithelial cell layer?
A. secondary active cotransport with Na+
B. glucose ATPase pump
C. facilitated diffusion
D. simple diffusion through the paracellular pathway
E. through an ion channel
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