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A chip off the old block - Biology Investigation

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A chip off the old block Problem: Mr. Haddock the fish shop owner has a problem. He has cut a large number of potatoes into chips to cook the next day but his fridge has broken down and he needs to keep the chips fresh and firm until the next day, until he can use them. Solution: Mr. Haddock must keep the chips in an environment that is such that it will inhibit osmosis and stop the chips from increasing or decreasing in mass. As osmosis is the movement of water molecules across a partially permeable membrane from a region of high concentration to a region of lower concentration he must place the potatoes into an environment in which the water concentration is the same in the inside of the potato cells and in the environment they are in, in other words he must find an equilibrium. To create this equilibrium, or isotonic solution to put the potato chips into he must make sure that there are the same number of dissolved particles in the water environment as there are in the potato itself. ...read more.


I intend to use varying concentrations of salt to the intervals of 0.1 molar. I will start at full water concentration and no salt, concentration 0.0 molar. I will then increase this by 0.1 each time and have potato in solutions of concentrations 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and full salt concentration 1.0 molar. For the sample of potato in the 1.0 molar solution I predict that after a set time period of one night exosmosis, or water loss from the potato shall occur. Hence, plasmolysis or the withdrawal of the vacuole from the cell membrane shall take place and 0the cell will become flaccid or limp. All this means that the potato shall decrease in mass and they will, in the morning be useless to Mr. Haddock as they will be shrivelled. I believe that the same will be true for the potatoes placed into solutions of 0.9 molar, 0.8 molar and 0.7 molar. However although I believe that exosmosis will occur in these samples of potato I also believe that the cells shall remain more and more turgid as the concentration of salt decreases. ...read more.


the vacuoles will gain water and place more pressure on the walls of the potato cells causing them to become firm. I believe the same to be true for the potato samples place in concentrations of 0.1molar, 0.2 molar, and 0.3 molar. However although I think that endosmosis shall occur in the samples of potato in these environments I think that it will occur in varying intensities and that the potato sample in the 0.3 molar concentration will see hardly any change at all. The reason that I have not stated a prediction for the samples of potatoes in concentrations of 0.4, 0.5 and 0.6 molar is that they are my effective grey area as in this region it is difficult to predict if endosmosis or exosmosis shall occur or if an isotonic environment, or close to it has been formed. However if forced to state a prediction for potato samples in 0.4 molar solutions I would say endosmosis would occur and that for potato samples in 0.6 molar solutions exosmosis shall occur. ...read more.

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