Plan On Osmosis Experiment

Plan On Osmosis Experiment

Introduction

Knowing that osmosis (a diffusion of water) will occur across a

semi-permeable membrane whenever there is a difference between the

water concentration on the two sides of the membrane. And knowing that

when this happens to all they will either become turgid if water flows

into them, or plasmolysed if the water flows out of them, and

therefore change their volume, we are going to test the hypothesis

that:

"If the concentration of a solution into which a cylinder of potato

cylinders are placed is greater than a certain level the cylinder will

contract, and if the concentration is less than that it will expand."

Aim

1. To investigate the effect of increasing the concentration of

sucrose solution on the rate of osmosis in potato cells.

2. To investigate the internal concentration of potato cells in

terms of sucrose solution.

Hypothesis

For this investigation I think that the lower the concentration of the

sugar solution in the test tube the larger the mass of the potato will

be. This is because the water molecules pass from a high

concentration, i.e. in the water itself, to allow concentration, i.e.

in the potato cylinder.

Therefore the cylinders in higher water concentration will have a

larger mass than in the higher sugar concentration.

Variables

To create a fair test certain aspects of the experiment will have to

be kept the same whilst one key variable is changed. I have chosen to

vary the concentration of the sugar solution. This will give me a

varied set of results from which I hope to make my conclusion. If any

of the non-variables are not kept constant however it would mean that

it would not be a fair test. For instance if one of the potato

cylinders was 1cm longer than the rest the surface area of the

cylinder would be greater and therefore would have more "space" for

the osmosis to occur.