To investigate the affects of a potato in different molar solution of sucrose and water. Ultimately, I would like to find the molarity inside a potato cell.

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Biology Coursework

Helen Wilkinson

11 CHW 11set1

Aim

The aim of this experiment is to investigate the affects of a potato in different molar solution of sucrose and water. Ultimately, I would like to find the molarity inside a potato cell.

Diagram

Hypothesis

I have researched the topic of osmosis and have found out osmosis is the diffusion of water particles from a high concentration to a low concentration of water particles. This movement of water particles occurs through a partially permeable membrane. A partially permeable membrane have very small gaps which only the smaller water molecules can fit through therefore pass in and out of the object, the large sucrose molecules are unable to fit through at all.  In the experiment I wish to complete, the small holes in the potato membrane will allow water to pass either into the potato tissue or into the solution around the tissue. If the solution around the potato were a weak solution (lots of water particles) I would expect the water particles from around the potato to diffuse into the potato cell by osmosis, because the water molecules are moving from a weak sugar solution to a strong sugar solution. I would expect this to continue until equilibrium is reached, this means the concentration is the same in both the tissue and the solution therefore the water molecules can pass through the membrane on both sides at a steady rate. I would expect the potato to change in two different ways, it would get heavier and bigger in size. I would expect this to happen because there is more water in the potato.

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OSMOSIS – MOVEMENT OF WATER PARTICLES

        Sucrose

        Water

        THE POTATO CELL

Pilot test

I have decided to conduct a pilot test to check, my hypothesis is correct and to ensure I have placed a safe experiment. For my pilot test I have put three pieces of potato in three different concentration so sucrose. I have recorded their weight before and then again after a set time in the solution. I have used a formula to work out the change in weight

The formula is; Change in mass

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