This document discusses the differences and similarities between diffusion and osmosis. It begins by introducing the group members working on the topic. Then, it provides examples and comparisons of diffusion and osmosis. The main differences are that diffusion involves transport across no membrane, while osmosis requires a semi-permeable membrane. Osmosis also involves the movement of water, while diffusion can involve any molecules or ions. Their similarities are that both involve the passive transport of substances from an area of higher concentration to lower concentration. The document then discusses misconceptions students may have and provides activities to help overcome them, such as using demonstrations involving semi-permeable membranes.
21. 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
22. 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
23. 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
24. 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
25. 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
29. 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
30. 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
31. 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)
37. ATP ENERGY Water ATP energy Gas Molecules Ink drop in solution Blood cell Isotonic drink Colour gas Liquid molecules Grape jus Fish in hypotonic
38. Movement of substance Tonicity Movement of molecules Semi-permeable membrane Syrup drink SEMI-PERMEABLE MEMBRANE Perfume No semi-permeable membrane Solid molecules
