When Plant Cells Lose Water Plant Physiology UNI
- Slides: 9
When Plant Cells Lose Water Plant Physiology UNI 2009
Fully turgid cell WP = 0 SP = -15 PP = +15 • In equilibrium with pure water • Solutes in cell “pull” water in • Pressure positive • Membrane pushed up against wall • Wall stretched slightly (most cells) • Leaf feels really stiff
Slight water loss (few %) WP = -10 SP = -15 PP = +5 • Slight water loss • Almost no change in water volume • Pressure changes significantly (still +) • Solute potential does not change significantly • Membrane still pushed up against wall • Wall still stretched slightly (most cells) • Leaf feels quite stiff
More water loss (few more %) WP = -14 SP = -15 PP = +1 • Slight further water loss • Almost no change in water volume • Pressure changes significantly (still +) • Solute potential does not change significantly • Membrane still pushed up against wall • Leaf not very stiff
More water loss (wilting) WP = -15 SP = -15 PP = 0 • Slight further water loss • Almost no change in water volume • Pressure now just at zero • Solute potential still about the same • Membrane just touching wall • Leaf wilted
Even more water loss (cell plasmolyzing) WP = -20 SP = -20 PP = 0 • Slight further water loss • More membrane pulling away from wall (not attached) • Pressure still zero (= atmosphere) • Significant change in water volume • Solute becomes more concentrated • Solute potential lower • Leaf still wilted, but alive
Yet more water loss (further plasmolysis) WP = -25 SP = -25 PP = 0 • Slight further water loss • More membrane pulling away from wall (not attached) • Pressure still zero (= atmosphere) • Significant change in water volume • Solute becomes more concentrated • Solute potential lower • Leaf still wilted, but alive
Lethal water loss WP = -40 SP = -40 PP = 0 • More further water loss • More membrane pulling away from wall (not attached) • Pressure still zero (= atmosphere) • Solute becomes more concentrated, solute potential lower • Irreversible loss of membrane & protein function
The End • Plants can lose turgor (pressure) and not be harmed • Cells can plasmolyze a bit and not be harmed • If cells become sufficiently dehydrated, metabolic functions are reduced • If they be come too dehydrated, they die
