2. Fill in the blanks on your sheet as we go through the ppt Diffusion Diffusion is the movement of molecules from an area of high concentration to an area of low concentration, until evenly spread out.
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4. Respiration- gas exchange In breathing you exchange carbon dioxide (CO 2 ) and oxygen (O 2 ) between alveoli in the lungs and the blood. This is an example of diffusion . SEM photos of lung alveoli
8. Osmosis Osmosis is a special case of diffusion. It is the net movement of water across a selectively permeable membrane from a high concentration to a low concentration . The cell membrane has very small holes in it. Small molecules can pass through, but larger ones cant. We say it is selectively permeable . Selectively permeable membrane ???
9. Water concentration gradient In osmosis water moves both ways to balance up the concentrations. The overall (net) movement is to the area of low water concentration. High Water Concentration, few molecules of solute. Dilute solution Low Water Concentration, many molecules of solute. Concentrated solution Water molecule Solute molecule Key: Water movement
10. Osmosis in action http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html Have a look at this video and answer the questions on the next slide:
