Osmosis

Experiment showing osmosis What is osmosis? What is water potential? Water potential of sucrose solution Water movement across a differentially permeable membrane Osmosis and plant cells Osmosis and red blood cells

Experiment showing osmosis 30 minutes later

What is osmosis? The net movement of water molecules across a differentially permeable membrane from a less concentrated solution to a more concentrated solution The net movement of water molecules across a differentially permeable membrane from a region of higher water potential to a region of lower water potential

What is water potential? The probability of water molecules moving through a membrane from each side of the differentially permeable membrane Value  as the concentration of solutes  (i.e. as the concentration of water molecules ) Distilled water: water potential = 0 greatest water potential Solutions: water potential < 0 (-ve value)

- Water potential of sucrose solution + + - Water potential (arbitrary unit) Concentration of sucrose solution (M)

Water movement across a differentially permeable membrane low water potential high water potential net movement of water molecules water molecule sucrose molecule

Osmosis and plant cells When young plant cells are immersed in distilled water  they become turgid, bigger and heavier

Osmosis and plant cells When young plant cells are immersed in concentrated sucrose solution  they become soft, smaller and lighter

Osmosis and red blood cells When red blood cells are immersed in distilled water they burst and release red pigments

concentrated sucrose solution Osmosis and red blood cells When red blood cells are immersed in concentrated sucrose solution they shrink

Summary Osmosis: the net movement of water molecules across a differentially permeable membrane down a water potential gradient Effect of osmosis