Osmosis, I predict the mass of potato will first increase then start decreasing as the concentration of salt increases. I think this because at first water will enter the potato

OSMOSIS COURSEWORK

OSMOSIS

Aim:

To investigate the effect of different concentrations of salt solutions on the mass of potato tissue.

Background Information:

Osmosis

Some membranes allow some particles to pass through them and not others, they are partially permeable. Osmosis is a special type of diffusion - diffusion of water molecules through a partially permeable membrane. More water molecules pass from the water into the dilute solution than pass back the other way, because there is a higher concentration of water molecules in the pure water than there is in the solution. Eventually the level on the more concentrated side of the membrane will rise, while that on the less concentrated side falls. When the concentration of water is the same on both sides of the membrane, the movement of water will be the same in both directions.

Osmosis in plants Plant cells have a strong cell wall surrounding them. When they take up water by osmosis they start to swell, but the cell wall prevents them from bursting. Plant cells become "turgid" when they are put in dilute solutions. Turgidity is very important to plants because this is what makes stand up into the sunlight. When plant cells are placed in concentrated sugar solutions they lose water by osmosis and they become "flaccid.

Prediction: I predict the mass of potato will first increase then start decreasing as the concentration of salt increases. I think this because at first water will enter the potato, because the water outside will have a higher concentration then water in the potato. This means that outside water will start moving into the potato tissue because of osmosis increasing the mass of the potato. Then when the outside salt solution reaches a certain concentration, water from the potato will go out side decreasing the mass of the potato. In a graph showing the percentage change of potato mass cylinders in different concentrations of salt solutions, I think the graph will show that the mass will be high then slope down as the concentrations of salt solution get higher.

Apparatus:

Method:

First of all I will cut 6 pieces of potato using a potato borer. I will use a ruler to make sure that they will all have a diameter of 5 millimetres and will have a length of 3 cm if they were not I would use a knife and cut it to the length needed on a tile. Then I will measure the mass of all of them using a scale and record it.