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Osmosis In Plant Tissue.

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Osmosis In Plant Tissue. Introduction. Osmosis only happens if there is a membrane present. It does not require energy to take place. It is the movement of water particles from a dilute solution to a more concentrated solution through a selectively permeable membrane. If a plant cell is placed into a solution of water and the concentration outside of the cell is much more dilute than inside then water moves into the cell. The cell will get slightly bigger but will not "pop". If a plant cell is placed into a salt solution of about 0.3% (the same concentration as the cell contents) then water freely moves in and out at the same rate and the cell stays constant. This is called the isotonic point. If a plant cell is placed into a solution where the water moves out faster than it moves in the vacuole will shrink, as water is lost. The cell then becomes plasmolysed and 'floppy'. This shows that osmosis occurs until the concentrations of both solutions are equal. Further Research Using visking tubing, you can recreate osmosis in a semi permeable membrane. Fill the visking tubing with a sugar solution and put it in pure water. The water rises up the tube because the water enters through osmosis. The glucose molecules are too big to diffuse out into the water. This following information is taken from the National-Louis University web-page http://faculty.nl.edu/jste/osmosis.htm In an hypotonic solution, the cell will swell, but will not burst because of the rigid cell wall. ...read more.


When the experiment is finished, after 24 hours, take out the potato chips in exactly the same order they were put in. As long as all parts of the experiment are carried out on the same bench at the same time then the temperature level should be the same. Control Of Variables. There are two types of variable. There is the independent variable and a dependent variable. An independent variable is something you can change and a dependent variable is something you measure. The independent variable in the experiment is the concentration of the sugar solution. The dependant variable in the experiment is the change in mass of the potato cell. All other variables, which might affect the results, must be kept the same to keep the test fair. Two examples of controlled variables are: * Surface area of the potato chip. If the surface area is bigger on some than the others then the rate of osmosis would differ. To solve this problem use a cork borer (the same one each time) and cut to 5cm to give precise chips and control the variable. * Safety Procedures. * Do not leave the potato in the solution for longer than 24 hours as there is a chance of bacteria growing. * Be careful when cutting with the scalpel so you do not cut yourself * If you spill any water immediately clean it up so no-one slips on it * Do not run in the laboratory * Be careful of the sharp edges of the cork borer Results Table For Average Mass Of Potato Chips. ...read more.


Water will rush out of the cell thus causing the cell to shrink. This shrinking process is scientifically termed crenation. The information above is taken from the Georgia Perimeter College website. I would organise my investigation as follows: I would take samples of blood on microscope slides and add different concentrations of sailine solution with a pipette in measured amounts. Then I would observe and record any changes by using a microscope and a notebook. To carry out this experiment I would need: * 4 test tubes * Test tube rack * Dropper bottle of sheep blood * Dropper bottle of 0.9% NaCl solution * Dropper bottle of 10% NaCl solution * Wash bottle of distilled H2O * Marker pen * 6" vinyl ruler * Rubber Stoppers for test tubes * Four clean microscope slides * Four cover slips I predict that as the concentration gets stronger, the paler the colour of liquid. As the concentrations get weaker, the liquid will go a very deep red colour. This is because as the concentration gets weaker there is more H20 than salt and the blood cell absorbs more water through osmosis. Eventually there will be no space left in the cell to absorb any more water and it will pop. The weaker solutions of saline will be a red colour because of the haemoglobin leaking out. This is known as haemolysis. The picture above is of red blood cells bursting when the skin us burnt. From this picture you can see that it is very difficult to tell the difference between the burst and un-burst cells. This experiment would need a very strong microscope to see the blood cells and would need an expert to tell which are burst and which are not. ...read more.

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