1. 1.3 Diffusion, Osmosis, and the Cell Membrane
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.
Concentration is the amount of substance in a given space.
The smell of fresh baked bread “spreading” throughout the room is an example of diffusion.
The diffusion of ink in water.
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3. diffusion
DYE
WATER

5. Diffusion and the Cell Membrane
The cell membrane is a selectively permeable membrane.
This means that it has many small openings that let some substances pass through it but not others.
One way that substances can move through the cell membrane is by diffusion.
When the concentration on both sides of the membrane is the same, it is called equilibrium.
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6. Diffusion and the Cell Membrane
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7. Osmosis
Osmosis is the diffusion of water through a selectively permeable membrane.
Osmosis occurs when water particles move from a higher concentration to a lower concentration.
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8. ANIMATION of Osmosis: http://auth. mhhe

9. Osmosis and the Cell
Cells contain water and need this water to survive.
Osmosis is how the cell gains and loses its needed water.
Explain how placing this wilted flower in water will cause the flower to “straighten up”.
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10. Examples of Osmosis
Example 1: Equal movement of water in and out of cells
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11. OSMOSIS TERMS 1 - ISOTONIC the cell stays the same
When there is an equal amount of water on both sides of the membrane.
the cell stays
the same

12. Examples of Osmosis
Example 2: More water moving into cells than is moving out
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13. 2 - HYPOTONIC the cell expands or bursts
When there is more salt inside the cell (and more water outside).
the cell expands
or bursts

14. Examples of Osmosis
Example 3: More water moving out of cells than is moving in
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15. 3 - HYPERTONIC the cell shrinks
When there is more water inside the cell (and more salt outside).
the cell
shrinks

16. hypotonic sol'n isotonic sol'n hypertonic sol'n
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