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Cell Membranes Problem Set

Problem 4: Osmosis

Tutorial to help answer the question

A sample of cells is placed in a salt solution. The cells shrink and the membrane is distorted. Relative to the cell, the solution is probably:

A. isotonic.
B. hypotonic.
C. osmotic.
D. hypertonic.


Cells in aqueous solutions

The figures show what can happen when animal or plant cells are placed in an aqueous solution. Water can move across membranes, but polar solutes dissolved in water cannot. The net movement of water (osmosis) is in the direction of increased solute concentrations. An easy way to visualize this rule is simply that the net water movement is from an area of high water concentration (little dissolved solute) to an area of low water concentration (high levels of solute).

Animal cells
Plant cells
Isotonic animal cells
If the solution is isotonic relative to the cell, then the solute concentrations are the same on both sides of the membrane and water moves equally in both directions
Isotonic Plant Cell
Hypertonic Animal Cells A hypertonic solution has increased solute, and a net movement of water outside causing the cell to shrink. Hypertonic Plant Cell
Hypotonic Animal Cells
A hypotonic solution has decreased solute concentration, and a net movement of water inside the cell, causing swelling or breakage.
Hypotonic Plant Cell
Problem 4 | Answer | Problem 5

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