Investigating Osmosis

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Investigating Osmosis Aim - In this experiment, I am going to try to find what the concentration of sucrose inside the vacuole of a potato is. Introduction - Osmosis is a special kind of diffusion, and can be defined as the movement of water molecules through a semi-permeable membrane from a region of high water concentration to a region of low water concentration, until both are the same strength. But, osmosis is the diffusion of water only and not of substances dissolved in water. Diffusion occurs because there is a vast amount of empty space between the molecules of all substances. This space is largest in gases and much smaller in liquids and solids. Molecules constantly collide and intermingle with each other, and are always at a state of random movement. Due to the spaces between molecules, this movement is much greater in gases and liquids than in solids. Diffusion is a result of the random movement of molecules and leads to an equal distribution of particles in the space they occupy. The diagram above is an example where osmosis has taken place. The weak sugar solution is separated from the strong sugar solution by a semi-permeable membrane, with the water diffusing from the weak solution until both solutions are of equal strength. However, as only water can move through the semi-permeable membrane, equal concentrations of solutions can not always be reached. Examples of everyday diffusion include : * Oxygen diffusing from airsacs in the lungs into blood capillaries around the airsacs, while carbon dioxide diffuses from the blood into the airsacs. * In the gut wall, digested food, e.g. glucose, ... ... middle of paper ... ...ge to be sure that the concentration is around 0.2M, as there is too much weight loss at values below this for it to be a higher value than 1M. Before doing the experiment, I used text books to find out more about osmosis and so this gave me a better idea of what should happen. To extend the investigation, I could experiment with concentrations of sucrose between 0.2M and 0.4M, in small intervals to find the exact amount of sucrose inside the vacuole of the potato. I could also do the experiment with different plants or fruits, to see if the concentration varies with each different thing, or is similar. I think that I do have enough evidence to support a firm conclusion that the concentration of sucrose inside the vacuole of a potato is between 0M and 1M, but an extension in the experiment would make it more precise.

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