Intro to Osmoregulation Flashcards
Osmoregulation
- Regulation of solute concentrations and water balance by a cell or organism
- Balances the uptake and loss of water and solutes
Solute
A substance that is dissolved in a solution (usually water)
Addition of sucrose
Reduces water potential
Lower water potential
Induces water uptake from xylem
Guard cell turgor pressure is controlled by
Regulation of K+ movement
What changes the stoma size
Changes in turgor pressure(inflates or deflates guard cells)
What creates solute gradients
Movement of salts out of the ascending limb
In kidney: descending limb is only permeable to
Water
In kidney: Ascending limb is only permeable to
Na+ and Cl- (may leave nephron by passive or active transport)
Osmosis
The diffusion of (free) water across a selectively permeable membrane, in this case, the plasma membrane
Water potential equation
Water potential = solute potential + pressure potential
Water Potential
Water always moves from the system with a higher water potential to the system with a lower water potential (lower to higher solute concentration)
Solute potential and concentration
Solute potential decreases with increasing solute concentration
Osmotic forces
Drive the movement of water into and out of cells
Do animal cells or plant cells burst
- Animal cells can burst
- Plant cells do not because of the cell wall
Cells vs pure water osmotic potential
Cells have a lower osmotic potential than pure water because of the salts and proteins in them, so water moves in them
Salt water vs cells osmotic potential
Salt water has a lower osmotic potential than cells, so water flows outwards
What solution do animal cells do the best in
isotonic solution
What solution do plant cells do the best in
Hypotonic solution
Plant cells, water, and turgor pressure
Water moves into plant cell and increases turgor pressure; the cell wall pushes back and keeps the cells rigid and the plant from wilting
Does water move up or down water potential gradient?
Down
How do plants extract water from the soil
To extract water from the soil, a plant root must establish a water potential gradient so that water flows toward the cells of the root from the soil. The water potential must be lower in the root than in the surrounding soil
