3.2.2 Types of Solution – Isotonic

What is Isotonic Solution?

In isotonic solutions, both solutions have equal water potential.

Water Concentration and Solute Concentration of a Cell in a Isotonic Solution

Water concentration and solute concentration are equal in both solutions.

Effect of Isotonic Solution on Animal Cell

  1. If an animal cell such as red blood cell is placed into a isotonic solution, amount of water molecules is transported into the red blood cells by osmosis is equal to the amount of water molecules transported out from the cell (as shown in the diagram above).
  2. Therefore the amount of water in the cell remain unchanged.
  3. The red blood cells maintain their shape.

The Youtube video above shows the effects of isotonic solution on red blood cells. All the cells remain unchanged in isotonic solution.

Effect of Isotonic Solution on Plant Cell

  1. When a plant cell is placed in an isotonic solution, solute concentration in the external solution is equal to the solute concentration i the cell sap.
  2. Therefore the rate of diffusion of water into the cell is equal to the rate of diffusion of water out from the cell.
  3. As a result, the shape of the cell remain unchanged.

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