An Investigation into the Factors which Affect Osmosis

An Investigation into the Factors which Affect Osmosis

Osmosis is defined as the movement of water molecules from a higher

concentration to a lower concentration through a partially permable

membrane. Osmosis occurs with molecule moving in and out, these

molecules move across the plant’s cell membrane. The plant’s cell

membrane is partially permable and therefore it has small holes in it

which allow for small water molecules to pass through it however

larger molecules such as glucose through.

However on the out side of the plant cells there is a cell wall of

cellulose that has larger holes that let anything pass through it.

This cell wall is totally permeable and therefore will allow larger

molecules such as glucose through it, but the larger molecules can

still not pass the cell membrane. When these cells are in a solution

which has a higher concentration of water than the cells concentration

of water the water will diffuse into the cell as the water moves from

a higher concentration (the solution) to the lower concentration (the

cells.) As more and more water enters the cell the cell wall starts to

expand and the cell starts to become turgid.

Even is a plant cell is placed in a solution where there is a high

water concentration and a weak sugar solution (say a 0.1 d/mol3 strong)

there will still be more water outside the cell than inside the cell

therefore there will still be an increase in volume and weight. This

means that when the plant cells are placed in a strong sugar solution

(where there is more sugar than water.) there will be a decrease in

weight and volume. This process is defined as plasmolysis. This is

where the cell membrane pulls away from the cell wall, this is because

a lot of water has been moved from the cell as the plant cell has the

strong concentration of water and the solution has a weak

concentration the water will move from the plant top the water.

Sometimes the cell will shrivel up completely and it becomes flaccid.

This is represented in the diagram below

With osmosis occurring there will eventually be a point where the

concentration of water will be equal to the concentration inside the

cell. This means that with the water still diffusing in and out there

will be equal amounts going in and out. This means that osmosis is

still occurring but the plant or the solution is either gaining o...

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...ainst the cell

wall, the tugor pressure will reach it’s maximum and the cells will

not be able to take in any more water. At the other end of the line, I

would expect the line to eventually curve off horizontally. Once the

cell becomes flaccid and the cell membrane collapses, no more water

would be able to escape.

I did predict that the stronger the solution the more the potato chips

would lose weight. I believe my results have proven this.

Evaluation

I am pleased with the way my experiment has gone, I did not come

across too many problems and most of my points on the graph were close

to the line of best fit. Therefore I am happy with the accuracy of my

results.

I think my method was adequate for producing accurate results I could

still improve it. I could’ve also tried to measure the potato chips

more accurately when cutting them.

I feel my investigation on the whole was a sucsess. I achieved

reliable and accurate results. however I could increase my confidence

in my conclusions by repeating the experiment with another carrot to

back it up. But on the whole my experiment matched my prediction and I

am happy about my results and the way I conducted it.