osmosis 1
TRANSCRIPT
Osmosis in Cells
Some fab real time osmosis videos to set the mood!
Group Starter Activity
Mr and Mrs Martinez went on holiday to Acapulco for a few days.
When they came back their favourite plant looked like this!
Explain the changes in terms of water movement
5 days ago Today
Plants rely on the movement of water through them:
Root hairs take in water from the soil by osmosis.
Water always moves to areas of lower water concentration.
Why is osmosis important?
We say that the cell is turgid.
Water moves into a plant cell.
The cell wall stops the cell from bursting.
Turgid cell.
Vacuole is filling all the space and pushing against cell wall
This is useful as it gives plant stems support
Plants- Water moving in
Cell turgor pressure
If a lot of water leaves the cell, the cytoplasm starts to peel away from the cell wall and we say the cell has undergone plasmolysis.
When water moves out of the plant cell vacuole, by osmosis, it becomes flaccid
Flaccid cell.
Vacuole is much smaller and taking up less space
Plants- Water moving out
Plasmolysis
Osmosis in Plant CellsLow water concentration outside the cell
(ie concentrated solution outside)
High water concentration outside the cell
(ie pure water or dilute solution outside)
Equal water concentrations inside & out
(ie equal solute concentrations inside & out)
Animal cells have no cell wall to stop the swelling, just a flexible cell membrane.
Animals- Water moving in
haemolysed turgid then burst
If an animal cells are put in pure water (HWC) they take in water by osmosis until they burst.
normal
haemolysed
Animals- Water moving outIf an animal cells are put in a concentrated solution (LWC) they lose water by osmosis until they become shrunken or haemolysed.
http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/Osmosis_Animation.htm
normal
1. What is a partially permeable membrane?
2. Which substance moves by osmosis?
3. What happens to plant cells that take up water by osmosis, and what do you call the cell?
4. What happens to plant cells that lose water by osmosis, and what do you call the cell?
5. What does ‘haemolysed’ mean? How does it happen?
Quick Quiz- Osmosis
Now try your osmosis practice problems!