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Does the concentration of a solution affect osmosis? -- A* - page 2
Keywords: Biology Osmosis Concentration Sucrose solution
By georgie1 on 31/12/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 2 of 10 pages: 1 2 3 4 5 6 7 8 9 10the membrane may become denatured, and become fully permeable, vastly increasing the rate of osmosis. As a result, I will control this element of my experiment at room temperature (approximately 26˚).
• Volume of sucrose. Each potato needs to be left to stand in the same amount of sucrose in order to keep the investigation fair. If one experiment had less solution than another, it would result in a difference in the osmosis because there would be fewer molecules to act on the potato.
• Size of potato cutting/Surface area. The larger the surface area of the potato cutting, the more places the water molecules have to pass through the potato membrane by osmosis. For this reason, I have chosen to keep all of my potato cuttings to the same size of 1cm³.
• Type of tissue (potato). The skin of a potato is partially permeable; however, if I was to use different kinds of potato then they might have differences in how permeable they are. Consequently, I will consistently use the same kind of potato.
• Blotting. If each potato cutting is differently, then some will already contain more water molecules than ever. Therefore, I shall ensure that I blot all potato cuttings in the same way.
To ensure that my investigation is thoroughly reliable, I am going to be collecting my own
results, and then compiling a class set of results and calculating averages. Effectively, this means I will be collecting approximately 14 results each time, providing me with strong evidence to base conclusions upon. I am also using accurate measuring devices such as a measuring cylinder [for precise volumes of sucrose solution], a ruler that measures in millimetres (mm) [for exact lengths of potato cutting], and weighing scales that measure to two decimal places [for exact weights of potato]. These methods allow precision and definite accuracy.
The apparatus that I will require for this experiment are as follows:
- 7 different concentrations of sucrose solution. As the aim of my investigation is to see how the rate of osmosis is affected by the concentration of the sucrose solution, I need a sufficient number of concentrations. This is so that I can easily depict anomalies and trends in my results, in order to draw an accurate conclusion.
- Weighing scales. This is in order to accurately measure the weight of the potato cutting before and after the experiment, and therefore calculate reliable percentage differences in mass.
- White tile. This is so that I
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