Water Potential of Potato Tuber Cells

Water Potential of Potato Tuber Cells

AIM:

To find the water potential of potato tuber cells.

HYPOTHESIS:

When cells are put in a solution with a different water potential than

inside of them, cells will gain or loose water. If concentration of

solution is the same, there will be no change in mass.

THEORETICAL BACKGROUND:

If a sample of tissues immersed in solution of varying water potential

(concentration of water molecules), the cells will loose or gain water

by osmosis. If the cell is put into solution of higher water potential

(hypotonic solution), water will go inside the cell. As the pressure

potential rises inside the cell it becomes turgid. In the plant cells

turgidity is rising up the moment when cell can't take more water

because of cell wall. Animal cells don't have cell wall so water is

constantly going inside the cell until it lyses.

If the cell is put into solution of lower water potential (hypertonic

solution) the water will go out of cell and cell will be plasmolysed.

In both ways cell will gain or loose mass.

APPARATUS AND MATERIALS:

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¨ Cork borer

¨ Scalpel

¨ Syringe

¨ Digital balance

¨ Filter paper

¨ Forceps

¨ Blue ink

EXPERIMENT 1:

METHOD:

1. In 6 test tubes labelled: distilled water, 0.1, 0.2, 0.3, 0.4, 0.5

mol dm3; place10 ml of appropriate solution.

2. Using a cork borer and scalpel cut 6 cylinders of 10mm diameter and

1,2 cm length. All cylinders should be cut into six discs of

approximately equal thickness (2mm). When they are cut place each

group on a separate filter paper.

3. Weight each group of discs accurately with filter paper and then

only weight filter paper. Calculate mass of potato.

4. Put each group of potato discs in one of the 6 test tubes and watch

out that all discs are immersed in a solution. Stopper the test tubes

firmly and leave them still for 24 hours.