Investigate the Water Potential of Potato Cells Essay -- GCSE Biology

Investigate the Water Potential of Potato Cells Introduction In my investigation, I hope to determine the water potential of potato cells. The plant material I will use in my investigation will be potato chips, which I will cut myself prior to the investigation. I hope to find the concentration of a solution where the chip stays the same mass and length, which will tell me that the water potential inside the cells is the same as the water potential outside the cells. Background Osmosis is defined as the movement of water through a semi-permeable membrane. Semi - permeable membranes are permeable to water but impermeable to certain dissolved substances. In the case of this experiment, the sucrose molecules cannot diffuse through the cell membrane because the sucrose molecules are much bigger than water molecules. The water potential of a solution is a measure how dilute the solution is, and therefore of how readily water will diffuse from this solution, through a semi-permeable membrane, into another solution. Pure distilled water has a water potential of zero: the water potential becomes more negative as more substances are dissolved in it. When two solutions are separated by a semi-permeable membrane, water moves from the side with high water potential to the side with low water potential: If we dissolve substances in water we lower the water potential of the solution:- High water potential Some water potential Low Water Potential Chip grows Chip stays the same Chip shrinks Key Variables o Mass of the chip - I think that the larger the mass of the chip then the bigger the difference in results will be, therefore I think that to make experiment more easy it would be best to u... ...ive balance to measure the mass, and I could have used a burette or pipette for volumes of liquids. I also could have used a sharper knife to cut the lengths of the chips. All of these things would have made my experiment more accurate. I also could have done a few more averages and repeats, to decrease the margin of error in my experiment, making my results more reliable. For further work, I would like to see if in my experiment I could actually get the result in my experiment where chip does not change at all, by putting it in the correct Molarity of sucrose solution. I would do this by putting it in different concentrations, ranging from 0.1M to 0.4M, and see what happened. I would also like to do the original experiment again, but using the improvements I listed above, and see how much of a difference there was in the results with the improvements.