Investigating the Water Potential of Celery Cells

Investigating the Water Potential of Celery Cells

Aim

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I will be investigating the water potential of celery and to find out

which solution will be isotonic with the celery cells, in other words

equilibrium between the two no water will leave the cell, or enter. I

will do this by following this method.

Method

1. Cut a 5 cm length of celery stem

2. Cut through the grooves to divide the stem into thin strips

3. Dry the cell sap from the strips using a paper towel

4. Record and note the mass of each strip

5. Collect 6 test tubes, and put 10 cm³ of solutions 0.0, 0.1, 0.2,

0.3, 0.5, 0.7, 0.8. In separate test tubes

6. Cut each celery piece into 5 cm cubes and place into test tubes

7. Leave for 30 mins at room temperature

8. And collect the strips out of the test tubes, dry them and record

the mass of each strip

Prediction

I predict that as the concentration of sucrose increases, The cell

will firstly become turgid, as since the concentration is low the

water potential outside the cell will be higher than inside to water

will diffuse in. Then as the concentration gets higher the water

potential outside will become lower than inside the cell so water will

diffuse out and the cell will become plasmolysed.

I also predict that solution concentration 0.3 will be isotonic

because of the pressure potential. As the water moves into the cell it

pushes up against the cell wall this is called the pressure potential

and it increases the water potential until an equilibrium is reached,

and because the cell is so inelastic it takes very little water to

achieve this. That's why I believe in-between 0.3 and 0.4 will be

isotonic as it is very close to pure water.

Background Information

Osmosis - The net movement of water molecules from a region of high

water potential to a low water potential, through a selectively