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A blood cell is placed into a salt-water mixture (70% salt). What is likely to result if the red blood cell’s membrane is permeable to water?

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Correct Answer: B. The cell will shrivel
For cells with a selectively permeable membrane, water will move from higher water concentrations to lower water concentrations. In this problem, the salt is too large to cross the membrane, so the salt concentration will remain the same. Since red blood cells have more water than the salt-water mixture, the water in the cell would leave to try to make the two environments isotonic. If water leaves the cell, the cell will eventually shrink.
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