Osmosis in red onion's cells

Experiment

What is osmosis?

Osmosis is a process in which a fluid moves through a semipermeable membrane so that each side has equal amounts

What are we going to do?

We are going to do an experiment to show how osmosis takes place in red onion's cells.

We need:

-A microscope

-Salt water

-Distilled water

-A red onion

Steps that we have to follow to do the experiment

1 We extract a thin layer from the red onion

2 We place it into the microscope

3 We add salt water to the layer and we observe that the cells get smaller

4 We add distilled water to the layer and we observe that the cells get bigger

Why do the cells get smaller with salt water and get bigger with distilled water?

When we add salt water to the layer, the osmotic pressure is lower and the solution is very concentrated. The cells loose water, dehydrate and shrink.

When we add distilled water to the layer, the osmotic pressure is higher and the solution isn't concentrated. The cells get water and explode (plasmolisis)

What can we see in the microscope?

Big image