Energy drives movement

1. Energy drives movement Plant Physiology UNI 2006

2. 2 connecting rooms Low energy kids High energy kids

3. Energy difference Low energy kids High energy kids

4. Energy difference drives movement NET movement from high energy side to low energy side

5. Water potential, water movement and cells

6. WP WP 2 cells—look at water in cells P P Low water potential(high solutes, = pressure) High water potential (low solutes, = pressure)

7. P Solutes can’t move across membrane so solute concentration doesn’t change But water can but walls prevent major volume change WP WP Membranes select what movesWalls determine volume P High solute concentration Low solute concentration

8. P P WP WP Water moves--start Low water potential (high solutes, low pressure) High water potential (low solutes, high pressure)

9. P P WE WE WE WE Water moves--middle(all at the same time) P P Pressure increases Pressure decreases Water potential increases Water potential decreases

10. P P P P WP WP WP WP Water moves--end Pressure increases Pressure decreases WATER POTENTIAL EQUILIBRIUMIS ESTABLISHED Water potential increases Water potential decreases

11. P P WP WP WP WP At water potential equilibrium Pressures NOT equal Pressures NOT equal No NET water movement(water movement equal in both directions) Concentrations NOT equal Water potentials are equal Water potentials are equal

12. Substances will move • From higher to lower energy • Each substance has own independent energy • Until equilibrium is reached • Both sides now have = energies for substance • Only if there is a route for them to move • Water goes through membranes easily • Solutes cannot (they don’t go to equilibrium) • Water potential equilibrium • Solute and pressure forces counterbalance