What factors affect osmosis?

In my investigation I am going to attempt to discover if osmosis is affected by a certain factor. Osmosis is the movement of water from an area of high water concentration through a semi-permeable membrane to an area of low water concentration. Osmosis is affected by water potential which is the term used to

describe the movement of a concentration of water, and as a general rule water always falls from an area of high water concentration to an area of low water concentration in a similar way to gravitation or electrical potential. In simple terms, it is sometimes referred to as the diffusion of water. I am going to find out how the concentration of a solution affects osmosis in an investigation using potatoes and sucrose solution. Osmosis depends upon a semi-permeable membrane because this allows water to pass both ways through the membrane but not other solutions with larger molecules, for example sucrose solution (see diagram to the right). A number of factors could affect osmosis such as; type of plant material, temperature, type of solution or concentration of solution. I could have chosen to investigate any of these factors effect on osmosis but instead I chose to investigate the concentration of solution, as I believe it will have the greatest effect on osmosis and will allow me to show a higher level of scientific knowledge and I chose it as opposed to other factors as I believe that the other acts would have changed the investigation too greatly. Changing the temperature would have given the water particles greater energy, which would mean they would have greater energy to move around. If I were to change the type of plant material this could have affected the semi-permeable membrane, which without it is near impossible for osmosis to take place.

Osmotic pressure is a term which means that the more concentrated as solution is, the higher the osmotic pressure will be and is the opposite to water potential as water moves from a low to a high osmotic pressure. The osmotic pressure that surrounds a cell will affect the state of the cell and there are three possible concentrations of solution to consider;

1. Hypotonic – a solution of higher osmotic pressure to the cell.

2. Isotonic - a solution of equal osmotic pressure to the cell.

3. Hypertonic – a solution of lover osmotic pressure than the cell.

The equipment I will use for my investigation is as follows:

Borer – to extract the potato cylinders;
Measuring cylinders;
Beaker - to hold the solutions;
Electronic Balance – to take the mass of the potato cylinder;
Scalpel;
Safety Glasses;
Sucrose solution & distilled water – to create the different solutions;
Timer;
2 Potato’s;

I will use a borer to take the cylinder of potato from one of the potatoes and I will the measure it to ensure all the cylinders are of ...

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Teacher Reviews

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Ross Robertson

10th of May 2013

This account of an investigation into the effect of varying sucrose solution concentration on the passage of water into and out of potato tissue by osmosis is generally well written and covers most of the required sections in an experimental report. The writer makes a determined effort to fully explain the process of osmosis, although a number of out-dated terms are used. A detailed method is followed by some 'interesting' data which the writer makes a good effort to analyse. To gain the higher grades at GCSE, the following issues need to be addressed: [1] A clearly expressed hypothesis is needed from the outset, one which links the IV and DV, together with detailed biological evidence to support it. This evidence should be obtained, at least in part, from the work of other scientists who have carried out similar investigations. [2] The language of osmosis should be updated. [3] Control variables should be listed in table form and their potential effect on the DV discussed. [4] The reliability of the results needs careful examination by comparing them with data from other scientists. Despite these shortcomings, this is a good attempt at a difficult topic. 4 stars

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