An Investigation To Demonstrate The Affect Of Different Sucrose Concentration On Osmosis In Plant Tissue

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Mihir Desai

A.M.F.

Biology Coursework on Osmosis Preliminary Experiment An Investigation To Demonstrate The Affect Of Different Sucrose Concentration On Osmosis In Plant Tissue

Planning

What I am investigating

My aim in this experiment is to investigate the effect of varying concentration of a certain sugar solution on the amount of osmotic activity between the solution and a potato chip of a given size

Preliminary Experiment

Hypothesis: Osmosis is the movement of water molecules from a region in which they are highly concentrated to a region in which they are less concentrated. This movement must take place across a partially permeable membrane such as a cell membrane, which lets smaller molecules such as water through but does not allow bigger molecules to pass through. 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 diffuse throughout an object, with no area having a higher or lower concentration than any other.

Apparatus:

  •  6 boiling tubes
  • 3 potato chips of 2cm
  • electronic lab scales
  • 0M-1M of sucrose solution
  • scalpel
  •   clay tile
  • measuring cylinder
  • stop watch
  • beaker
  • tissue paper
  • ruler

Method: A range of sucrose sugar solutions were prepared with concentrations 0 molar (distilled water), 0.5 molar, and 1 molar.  Three sections of potato were cut using a scalpel and will be measured using a ruler to both 2cm and 3cm. The mass of each chip was measured to find the mass change. The chips were placed in each test tube, using 10 cm of each concentration of sugar solution and once in the test tubes they each were labelled. The potato pieces were then be placed in the different test tubes and then left overnight, as I felt this was enough time for Osmosis to occur. Then the potato pieces were removed, the surface solution was removed using paper towels and then they were re-weighed. In this way, the chips were blotted by the tissue to ensure no excess water would be left, that could potentially affect the conclusion.

Results:

Conclusion: From my results I can say that all the potato chips have lost mass apart from the potato chips which went into the test tube filled with distilled water or 0M, which gained mass. This proved my hypothesis to be correct, as bigger molecules were unable to pass through the potato. As the potato cells took in or gave out the water depending on the concentration of the tissue and the concentration of the solution it is surrounded by.

Variables

During my experiment I am going to do all the experiments at room temperature so the process of Osmosis may not be increased or decreased whilst the experiment is taking place. As Osmosis, would occur at different rates in different temperatures. For the purpose of the experiment I would use potatoes which have all been treated in the same way, for example, I will use potatoes which have all been cut to the same size and are washed and peeled, in this way allow the same surface area for Osmosis to occur on each chip. The mass of the potato is a dependent variable, and this means that it will be measured throughout the experiment. I will measure the mass in grams. The potato chip will be measured before it is put in the solution, and after. This will allow us to see whether osmosis has taken place, and to what extent by looking at whether the mass of the chip has altered. Therefore I will be able to calculate a percentage change and compare the results to others, checking if the percentage change has varied or not. The volume of the solution that the potato chips are kept in must be fair, the potatoes will all be totally submersed in the solution, and the amount of solution will be kept the same because all the potato chips are the same size. I am also going to use the same balance to weigh my potato chips. This is because the measurements may slightly vary between scales. By doing this I cut on the percentage of error at the end of my experiment.

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How I will make the data reliable

To create a fair test certain aspects of the experiment will have to be kept the same whilst one key variable is changed the sugar solution (measured in molars). This will give me a varied set of results from which I hope to make an accurate conclusion. If any of the controlled variables below are not kept constant it would mean it would not be a fair test, in that way giving me false results and an inexact conclusion; for example if the surface area of one chip was greater than ...

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