1. Water movement through membranes Plant Physiology UNI 2009

2. Pressure difference Pipe #1 Pressure Potential = +1 bar Solute Potential = -2 bars Membrane passes water only Pipe #2 Pressure Potential = +3 bars Solute Potential = -2 bars Which way does the water move?

3. Pressure difference Pipe #1 Pressure Potential = +1 bar Solute Potential = -2 bars Membrane passes water only Pipe #2 Pressure Potential = +3 bars Solute Potential = -2 bars Water (only) moves from higher to lower potential.

4. Solute difference Pipe #1 Pressure Potential = +1 bar Solute Potential = -2 bars Membrane passes water only Pipe #2 Pressure Potential = +1 bar Solute Potential = -4 bars Which way does the water move?

5. Solute difference Pipe #1 Pressure Potential = +1 bar Solute Potential = -2 bars Membrane passes water only Pipe #2 Pressure Potential = +1 bar Solute Potential = -4 bars Water (only) moves from higher to lower potential.

6. Pressure and solute differences--I Pipe #1 Pressure Potential = +1 bar Solute Potential = -1 bars Membrane passes water only Pipe #2 Pressure Potential = +3 bars Solute Potential = -4 bars Which way does the water move?

7. Pressure and solute differences--I Pipe #1 Pressure Potential = +1 bar Solute Potential = -1 bars Membrane passes water only Pipe #2 Pressure Potential = +3 bars Solute Potential = -4 bars Water (only) moves from higher to lower water potential.

8. Pressure and solute differences--II Pipe #1 Pressure Potential = -4 bars Solute Potential = -1 bars Membrane passes water only Pipe #2 Pressure Potential = +2 bars Solute Potential = -8 bars Which way does the water move?

9. Pressure and solute differences--II Pipe #1 Pressure Potential = -4 bars Solute Potential = -1 bar Membrane passes water only Pipe #2 Pressure Potential = +2 bars Solute Potential = -8 bars Water (only) moves from higher to lower water potential.

10. Pressure and solute differences--III Pipe #1 Pressure Potential = -4 bars Solute Potential = -1 bars Membrane passes water only Pipe #2 Pressure Potential = +2 bars Solute Potential = -7 bars Which way does the water move?

11. Pressure and solute differences--III Pipe #1 Pressure Potential = -4 bars Solute Potential = -1 bar Membrane passes water only Pipe #2 Pressure Potential = +2 bars Solute Potential = -7 bars No NET water movement: Pipes at equilibrium for water potential.