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 Distinguish between diffusion and osmosis
 Know how particles move in and out of cells

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The movement of particles from areas of higher concentration to areas of lower concentration is diffusion.
Diffusion is one way that materials are exchanged between a cell and its environment

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Water is very important to the cells of organisms. The diffusion of water across cell membranes is called osmosis.
The concentration of particles important to cell functions are kept in balance by osmosis.

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 With your group come up with 4 examples of osmosis or diffusion (total of 4)
 One stray
 Stayers – list your examples
 Strayer – pick your favorite example from the group you visit

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 Static equilibrium: no change in the system is occurring.
 For example, a bucket of water is in equilibrium because there is no change occurring to it.

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Dynamic equilibrium: changes in the system are occurring, but at the same rate as one another.
 For example, a bucket of water with a hole in it is releasing water. At the same time more water is being poured in the bucket at the same rate it is pouring out.

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 Suppose you have a balloon filled with helium. As you know this balloon will not float forever and after a day or so will eventually shrink and remain on the ground.
 This is an example of diffusion. The helium slowly escapes the balloon across the surface until the concentration is equal on both sides.
 Why is it some balloons float for longer periods of time than others? (answer the question in your notebook)

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 Diffusion is an important concept for humans because our very existence depends on it.
 The cells of the human body utilize diffusion every day!
 Can you think of where in the human body diffusion might be important?

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The movement of particles across a cell membrane by diffusion or osmosis pHet

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The movement of particles across a cell membrane that g oes against diffusion
Requires the cell to use energy

 Red blood cells are surrounded by plasma
 Plasma is made of water, salts, sugars and other particles
 If placed in pure water, the red blood cells would burst
 In a salty solution, the red blood cells shrivel

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 Has this ever happened to you?
 With the information you just learned, and your previous experience, form a hypothesis of why you think that is…

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 Are your fingers swelling or shrinking?
 What do you know about your skin?