Osmosis in Cells

Some fab real time osmosis videos to set the mood!

Group Starter ActivityMr 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

Water, H2O

A membrane that only lets small molecules through it

The cells become ‘full’ of water and are called turgid

The cytoplasm comes away from the cell wall and the cells are called plasmolysed.

Animals cells which have lost water become shrunken and are called haemolysed.

Now try your osmosis practice problems!