Osmosis
- Created by: N1ntendo-Sw1tch
- Created on: 25-02-23 20:24
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- Osmosis
- osmosis is the diffusion of water molecules down a water potential gradient (high to low) through a selectively permeable membrane
- Water Potential (psi- ?)
- measure of the ability of water molecules to move and is measured in kilopascals (KPa)
- plant: ? = solute potential + pressure potential (? s+ ? p) animal: ? = solute potential (?=?s)
- All solutions have a negative ? because polar molecules attract the water molecules so they cannot move elswhere
- pure water has 0KPa
- Pressure Potential
- the solutes in vacuole draw water in by osmosis, this causes the vacuole to expand and push on the cell wall. cell wall = inelastic so exerts an outward pressure
- managing water balance
- Hypotonic
- solution has a lower solute conc than the cell. so cell has lower ? than solution
- animal cell: water will diffuse into the cell and possibly cause it to burst because they have no cell wall
- Plant cell: water will diffuse into cell causing it to become turgid as water entering causes the vacuole expands and pushes on the cell wall creating pressure
- Isotonic
- solution has an equal conc of solute and water potential as cell
- Animal cell: the cell will be a normal size and not gain or lose any water (no net movement)
- Plant cell: cytoplasm is begining to pull away from cell wall (incipient plasmolysis) because there's not enough water to push the cell contents against the wall
- hypertonic
- solution has higher solute conc than the cell. so cell has higher water potential than solution
- Animal cell: water will diffuse out of the cell and shrivel up
- plant cell: water will diffuse out of cell and will become floppy as there's no pressure on the cell wall. it does retain its shape though
- Hypotonic
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