19. Osmosis Concept 1. Water molecules are always moving about 2. Net movement of WATER MOLECULES (Solvent) from a solution of [higher] of water to one with [lower] of water 3. Movement of WATER MOLCULES must be through a PARTIALLY PERMEABLE MEMBRANE
20. Water Potential ‘High’ Water Potential Instead of using the word concentration for water… We use WATER POTENTIAL - Water potential is the measure of tendency for water to move from one place to another - Water moves from High Water Potential to Low Water Potential ‘Low’ Water Potential
21. Osmosis Concept (revised) 1. Net movement of WATER MOLECULES (Solvent) from a solution of higher concentration of water to one with lower concentration of water 2. Movement of WATER MOLCULES must be through a PARITALLY PERMEABLE MEMBRANE water potential water potential
22. Container A (Concentrated Solute Solution) 20% Water Concentration 80% Solute Concentration Container B (Diluted Solute Solution) 66.6% Water Concentration 33.33% Solute Concentration Remember Diffusion? Net Movement of particles down a concentration gradient from an area of higher concentration to an area of lower concentration! Legend Water molecule Partially Permeable Membrane Solute molecule
23. It’s about the Word Play A B 80% sucrose 20% water 20% sucrose 80% water Net Concentrated Solution (Sucrose for example) Low Water Potential Low concentration of Solvent High concentration of Solute Hypertonic compared to B Dilute Solution High Water Potential High Concentration of Solvent Low Concentration of Solute Hypotonic compared to A
27. POE Spot the errors! Semi-Permeable Membrane A 10% sucrose solution B 20% sucrose solution “Osmosis taking place via the uni-direction movement of water molecules from A to B” Solution A is hypertonic solution Solution B is hypotonic solution
28. Spot the errors! Semi-Permeable Membrane A 10% sucrose solution “Osmosis taking place via the uni-direction movement of water molecules from A to B” A 10% sucrose solution B 20% sucrose solution Solution A is hypertonic Solution B is hypotonic V V
29. Misconceptions 1. Semi-permeable membrane (Partially) 2. This is a hypertonic solution (need to be relative to something) 3. Molecules only move from high water potential to low water potential (It’s the net movement, molecules do not stop moving anyway)
35. ATP ENERGY Water ATP energy Gas Molecules Ink drop in solution Blood cell Isotonic drink Colour gas Liquid molecules Grape jus Fish in hypotonic
36. Movement of substance Tonicity Movement of molecules Semi-permeable membrane Syrup drink SEMI-PERMEABLE MEMBRANE Perfume No semi-permeable membrane Solid molecules