Osmosis Investigation

Essay by tamzenHigh School, 10th grade March 2004

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Osmosis Investigation


In this investigation I aim to find concentration of a potato cell. I will do this buy putting slices of potato in to different concentrations of sugar seclusions so we may find the concentration that is isotonic with potato cell sap. A piece of potato in such a solution will neither gain nor lose any weight.


My hypothesis is that the isotonic point will be between the 80 and 120g/l. I predict this because I have done a preliminary experiment that suggested this is where the isotonic point lay. I presume that the potato chip in the 50g/l will become turgid and gain in weight because the chip will have a lower concentration than the water and it will take in the water to make the water molecules the same inside as the outside of the chip. The potato chip in the 90g/l will become flaccid and lose weight because outside the chip there is a high concentration of sugar and the chip will give out water to make the water concentration outside equal to that on the inside of the chip.

Scientific background

This information is from web.ukonline.co.uk

Osmosis is a special form of diffusion:


from a dilute solution to a more concentrated one


This type of membrane (also called semi-permeable) allows only water, but not other (dissolved) substances to pass through.

All cells are surrounded by a cell membrane, which is partially permeable, and the cytoplasm contains dissolved substances (solutes), e.g. sugars, salts, proteins. Whether or not water enters or leaves the cell depends on the relative concentrations of the cytoplasm and the fluid surrounding them.


I have conducted a previous experiment of this but it was not accurate, but I found that...