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Osmosis, diffusion presentation

  3. Group - 6 (Blue birds) Ourselves • Md. Aminul Haque - 15309039 • Md. Mahmud Hasan - 15309010 • Mahabub Rahman Sajib - 16209018 02
  5. Molecules are always moving Molecules move randomly and bump into each other and other barriers 04
  6. Movement of molecules from higher concentration to lower concentration slowly spread apart over time. This is diffusion. T1 T2 T3 Diffusion 05
  7. Diffusion • Movement of molecules from an area of high concentration to an area of lower concentration. • Factors that affect the rate of diffusion: size of molecules, size of pores in membrane, temperature, pressure, and concentration. 06
  8. Diffusion [High] [Low] concentrated, high energy molecules diffuse, low energy molecules 07
  9. Diffusion will continue until equilibrium is reached. This means there will be an equal distribution of molecules throughout the space. This is why food coloring moves throughout a beaker of water; why odors smell strong at first and then disappear over time. Equilibrium, a result of diffusion, shows the uniform distribution of molecules of different substances over time as indicated in the above diagram. 08
  10. Significances of Diffusion • It is an essential process in exchange of gases during respiration and photosynthesis. • Uptake of minerals is also affected by the process of diffusion. • It helps in removal of excess water by the process of transpiration. 09
  11. Osmosis • Osmosis is the movement of water through a semi-permeable membrane • At first the concentration of solute is very high on the left. • But over time, the water moves across the semi- permeable membrane and dilutes the particles. 10
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  13. Osmosis – A Special kind of Diffusion Diffusion of water across a selectively permeable membrane (a barrier that allows some substances to pass but not others). The cell membrane is such a barrier. Small molecules pass through – ex: water Large molecules can’t pass through – ex: proteins and complex carbohydrates 12
  14. Hypotonic – The solution on one side of a membrane where the solute concentration is less than on the other side. Hypotonic Solutions contain a low concentration of solute relative to another solution. Hypertonic – The solution on one side of a membrane where the solute concentration is greater than on the other side. Hypertonic Solutions contain a high concentration of solute relative to another solution. 13
  15. Over time molecules will move across the membrane until the concentration of solutes is equal on both sides. This type of solution is called isotonic . 14
  16. Turgor Pressure builds in the cell and causes osmosis to stop because of the rigid cell wall. Plants will wilt when cells lose water through osmosis. Hypotonic Solution Hypertonic Solution PLANT CELLS 15
  17. ELODEA CELLS As viewed under the microscope 16
  18. Significances of osmosis  It is an essential step in the exchange of gases during respiration and photosynthesis.  During passive Salt uptake, the irons are absorbed by simple process of diffusion.  Last step in stomata transpiration is the diffusion of water vapors from the intercellular spaces into the outer atmosphere through open stomata. 17
  19. PASSIVE TRANSPORT Passive transport occurs without expenditure of energy. Molecules move using their own kinetic energy . Diffusion and osmosis are examples of passive transport. Passive transport allows cells to get water, oxygen and other small molecules that they need. It also allows the cell to get rid of waste such as carbon dioxide. DIFFUSION OSMOSIS 18
  20. THE END 19
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