Download Osmosis in Cells

Osmosis in Cells
Some fab real time osmosis videos to
set the mood!
Osmosis in Cells
•To be able to
describe Osmosis
in plants
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
Why is osmosis important?
Plants rely on the movement of water through
them:  Water always moves to areas of lower
water concentration.
 Root hairs take in water from the soil
by osmosis.
Plants- Water moving in
Water moves into a plant cell.
The cell wall stops the cell from bursting.
We say that the cell is turgid.
Turgid cell.
Vacuole is filling all the space
and pushing against cell wall
This is useful as it gives plant
stems support
Cell turgor pressure
Plants- Water moving out
When water moves out of the plant cell
vacuole, by osmosis, it becomes flaccid
Vacuole is much smaller
and taking up less space
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.
Osmosis in Plant Cells
Low water
concentration
outside the cell
(ie concentrated
solution outside)
Equal water
concentrations inside
& out
High water
concentration
outside the cell
(ie equal solute
(ie pure water or
concentrations inside & dilute solution
out)
outside)
Animals- Water moving in
Animal cells have no cell wall to stop the swelling, just a flexible
cell membrane.
If an animal cells are put in pure water (HWC) they take in water by
osmosis until they burst.
haemolysed
normal
turgid then burst
Animals- Water moving out
If an animal cells are put in a concentrated solution
(LWC) they lose water by osmosis until they become
shrunken or haemolysed.
haemolysed
normal
http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/Osmosis_Anima
tion.htm
Quick Quiz- Osmosis
What is a partially permeable membrane?
A membrane that only lets small molecules through it
Which substance moves by osmosis?
Water, H2O
What happens to plant cells that take up water by osmosis, and what
do you call the cell?
The cells become ‘full’ of water and are called turgid
What happens to plant cells that lose water by osmosis, and what do
you call the cell?
The cytoplasm comes away from the cell wall and the cells are called
plasmolysed.
What does ‘haemolysed’ mean? How does it happen?
Animals cells which have lost water become shrunken and are
called haemolysed.
Now try your osmosis practice
problems!