The aim of this experiment is to work out if potatoes lose or gain mass in different sugar solutions due to osmosis and to solve where the water concentration outside the cell is equal to the concentration inside the cell;

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Afolabi Adebayo                                                                                        10A

The Aim: The aim of this experiment is to work out if potatoes lose or gain mass in different sugar solutions due to osmosis and to solve where the water concentration outside the cell is equal to the concentration inside the cell; this is known as the isotonic point. In the investigation I would have to be as precise and accurate as I possibly can in order to have a reliable set of results for a good conclusion.

Introduction: I am going to perform an investigation on osmosis in potato cells. Osmosis is the movement of water molecules through a semi permeable membrane, separating solutions of different concentrations. The water molecules pass from a region of high concentration to a region of low concentration. The molecules will continue to diffuse until the area in which the molecules are found reaches a state of equilibrium, meaning that the molecules are randomly distributed throughout an object, with no area having a higher or lower concentration than any other.

Many cell membranes behave as semi permeable membranes, and osmosis is a vital mechanism in the transport of fluids in living organisms, for example, in the transport of water from the soil to the roots in plants.

If a cell is in contact with a solution of lower water concentration than its own contents, then water leaves the cell by osmosis, through the cell membrane. Water is lost first from the cytoplasm, then the vacuole through the tonoplast. The living contents of the cell contracts and eventually pulls away from the cell wall and shrinks, this is known as a plasmolysed cell.

           If you put a plant cell in water, water enters by Osmosis, and then swells up. However, the cell will not burst. This is due to the fact that the cell walls are made from cellulose, which is extremely strong. Eventually, the cell stops swelling, and when this point is reached, we say the cell is turgid. This is important, because it makes the stem of plants strong.

        In our investigation we are using potatoes to demonstrate the activity of osmosis; we will do this by placing the potatoes in different sucrose concentrations.

At the end of the investigation we will take readings of the weight and analyze them carefully.

Equipment: During this experiment I will use the following equipment:

.4 boiling tubes

.Boiling tube rack

.1 potato

.1 table knife

.100ml measuring tube

.Paper towels

.1 ruler (cm)

.An electronic scale (g)

.Distilled water

.Sucrose

.Pipette

Prediction: I have done some preliminary work into osmosis in potato cells. I weighed three potato cores, and then put one into sucrose solution one into distilled water and one in a weak solution. After 25 minutes, I removed the potato cores from the solutions and re-weighed them.

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Preliminary results

I discovered that the potato in distilled water had increased in mass and the one in sucrose had decreased in mass. This decrease was due to the flow of water out of the vacuole making the vacuole pull inwards, away from the cell wall meaning the cell was plasmolysed (flaccid). Thus the increase was due to the flow of water into the vacuole and the vacuole had begun to push against the cell wall, this is known as a turgid cell. Turgor pressure is caused by the uptake of water by the ...

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