Osmosis

Objectives Describe osmosis as passive transport. Define isotonic, hypertonic and hypotonic. Describe what happens to an animal and

plant cell in isotonic, hypertonic and hypotonic solutions.

Textbook pages 185-186

Think! Think!! Think!!!A Google search for “water drinking deaths” returns over 18 million

results! This is a common story in the news. How can someone die from drinking too much water?

Diffusion

Osmosis

Osmosis – the diffusion of water through a selectively permeable membrane from an area of high concentration to an area of low concentration

Osmosis only happens when the membrane is NOT permeable to a solute, but is permeable to water.

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Osmosis – pg 185

Membrane is permeable to water but not to sugar More sugar on the left than on the right. Less water on the left than on the right. Over time, the water passes through the membrane from where there was more to

where there was less. The water level changes.

Osmosis

Concentration – the amount of dissolved substance in a volume of water

Hypertonic – “above strength” left side of the membrane where solute is more concentrated !!!!!

Hypotonic – “below strength” right side of the solution where solute is less concentrated !!!!!!

Isotonic – “same strength” the second beaker where both sides are equally concentrated !!!!!!

Osmosis

Osmosis is passive transport, like diffusion, because it occurs spontaneously without requiring energy.

!!!!!

Osmosis

Animation

How Osmosis Works in Cells

http://www.phschool.com/atschool/phbio/active_art/osmosis/index.html

How Osmosis Works on Animal Cells Page 186 animation http://www.linkpublishing

.com/video-transport.htm#OSMOSIS

How Osmosis Works on Plant Cells http://www.linkpublishing

.com/video-transport.htm#OSMOSIS

Drinking Water Deaths

When you drink too much water, are your cells being placed in a hypotonic, hypertonic or isotonic solution?

Will your cells, shrink, burst or stay the same?