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Can anyone please explain how to identify the solutions in 2A?

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brandih | eNotes Employee

Posted September 26, 2013 at 9:15 PM via web

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Can anyone please explain how to identify the solutions in 2A?

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Tagged with biology, science, solution, tonicity

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ncchemist | eNotes Employee

Posted September 26, 2013 at 11:02 PM (Answer #1)

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It looks like you are dealing with the concept of tonicity.  Tonicity deals with osmotic pressure and the flow of water via osmosis from one solution to another separated via a semi permeable membrane.  In the pictures shown on your paper, you are looking at cells immersed in different aqueous solutions.  These three pictures illustrate the three different types of tonicity encountered by cells.

The first picture has the cell in a hypertonic solution.  This means that the concentration of solutes is greater in the solution outside the cell than inside the cell.  This means that water will flow out of the cell to try and balance the concentration of the overall system.  This causes the cell to shrink in size.  Remember that in nature, particles will diffuse from areas of high concentration to low concentration.  Since the solute particles cannot pass through the cell membrane, the water will pass through the membrane instead to try to even out the concentrations.

The middle picture demonstrates an isotonic solution.  This is where the concentration of solutes is equal both inside and outside the cell.  So water flows evenly in both directions, resulting on no net change.

The third picture shows a hypotonic solution.  This is where the concentration of solutes is greater inside the cell, so the net water flow is from the outside to the inside of the cell.  As a result, the cell swells up in size and can possibly rupture.

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