Osmosis in Potatoes

Osmosis in Potatoes

Planning

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Introduction:

Osmosis is the special name used to describe the diffusion of water

across a membrane, from a dilute solution to a more concentrated

solution. In biology, this usually means the diffusion of water in and

out of cells. Osmosis is just one special kind of diffusion because it

is only water molecules we are considering.

Molecules will diffuse from where there is a lot of them to a region

where they are fewer in number; that is, front a region of highly

concentrated molecules to a region of lower concentration (below).

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In a plant cell, when water molecules enter it, the vacuole will fill

and push against the cell wall. The cell will become very firm, or

turgid.

If a plant is in an environment where there is not much water, water

will leave the plant cells and move into the cells with less water.

The vacuole will shrink and the plant will wilt. When even more water

leaves the cell, the cell membrane tears away from the cell wall. This

is called plasmolysis.

To prove this, I will be performing an experiment in which I will

place potato cylinders into various sugar/water solutions for 24 and

observing the effect this has on the potatoes.

Method:

1) Use the boring rod to cut out 15 cylinder shaped pieces of potato

of equal volume, cut them into 5cm strips.

2) Dry the chips with a paper towel, and record their weight.

3) Put three pieces of potato each into 5 tubes.

4) Label each tube with 0.0m, 0.25m, 0.5m, 0.75m and 1.0m.

5) Pour the correct solution into the corresponding tube, just

covering the potato.

6) Leave the tubes for 24 hours. After 24 hours is up, dry the chips

with a paper towel, then weigh each potato chip and record the weight.

7) Also record the texture of the chips.

8) Work out the change in weight (M2-M1 / M1 x 100)