• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Investigate the water potential of potato.

Extracts from this document...

Introduction

Aim: to investigate the water potential of potato. Research: Osmosis in plant cells Osmosis is the net movement of water molecules from a region of their higher concentration to a region of their lower concentration through a partially permeable membrane. If the concentration of water molecules is the same in the plant cell and the surrounding liquid, there will be no net movement of water into or out of the cell; and if the concentration of water molecules is greater in the cell than the surrounding liquid, there will be a net movement of water from the plant cell to the surrounding solution. Osmosis will occur whenever a partially permeable membrane separates two solutions containing different concentrations of water molecules. If the cell is surrounded by pure water, or by a solution whose solute concentration is lower, and water potential higher, than that of the cell's contents, water flows into the cell by osmosis and swells up. The external solution is said to be hypotonic to the solution in the cell. This means the solute concentration is lower than that of the cell. If the cell is surrounded by a solution whose solute concentration is higher and water potential lower than that of the cell, then water will flow out of the cell causing the cell to shrink. ...read more.

Middle

This part of the preparation must be done very accurately as a change in the surface area may allow more or less osmosis to occur. I will then use an electric balance to weigh the potato tubers, once a tuber has been weighed the mass will be recorded as well as the test tube it has been placed into. The potato is going to be left in solution for 24 hours to allow the processes to occur and to allow the water movement to settle. After 24 hours I will return to the experiment and take each piece of potato out of the test tube with tweezers, dry them off by dabbing them with tissue on by one and weighing them on the electric balance and record their final mass. Apparatus: * 18 test tubes and bungs * Test tube rack * White tile * Scalpel * Potato corer * Thermometer * Tissue paper * Electronic balance * Sucrose solutions * Distilled water * Ruler * Measuring cylinder * Tweezers Variables: To create a fair test certain aspects of the experiment will have to be kept the same whilst one key variable will change. I have chosen to vary the concentration of the sucrose solution. ...read more.

Conclusion

This anomalous result could be explained by numerous errors, for example the balance may not have been very precise; water from previous potatoes may still have been on the balance. Also it may have been measured in accurately from the other cuttings of potato. The precision of measuring the concentration of the solution may also have changed for this result. However there were a few areas where there could be improvement. Firstly, when I dried off the excess water on the potato cylinders after the experiment and before I weighed them, I used a paper towel. This might have either taken some water out of the potato or it might of left some excess water on the potato. This part of the experiment is difficult to come up with an accurate and fair method, as other ways would also lead to some slight mistakes. Also the potato itself was not from the same potato and was not exactly the same size, although I did try to cut them to 1.5cm each, this could have effected the amount of water gained or lost. Finally, I could extend the experiment to a more exact level by looking at the potato cylinders under a microscope, then I would be able to see the cells in greater detail and draw some more observational results. ?? ?? ?? ?? Isabel Murtough Biology coursework MR ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Life Processes & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Life Processes & Cells essays

  1. Marked by a teacher

    To determine the water potential of a potato tuber cell using varying salt solution.

    5 star(s)

    Potato 1 This is the cell of which we are determining the water potential. Weighing scale 0.01g divisions 1 To measure the change in mass of the potato cell hence to calculate the water potential. Ruler 15cm 1 To accurately measure out the exact size of potato cells required Cork

  2. Marked by a teacher

    An Experiment to determine Water Potential in Potato Tissue.

    4 star(s)

    This will make the mass of the potato decrease. My reason for saying this would happen is that water always moves from a region of high concentration to a region of low concentration and in the case of osmosis the molecules go through a partially permeable membrane.

  1. Aim To determine the water potential of a potato tuber cell

    I predict that the water potential will be within the range of minus 1280 kPa and minus 260 kPa for a normal potato tuber cell. I think this because minus 1280 kPa is the suggested water potential, (for a quantity of 0.45 molar sucrose)

  2. Investigate the water potential of potato tissue and compare this with the water potential ...

    To cut the plant samples on. Electronic Balance (measuring to 1 decimal place) To measure the mass of the plant samples before and after the experiment with a suitable degree of accuracy. 1 Brae burn apple 1 red potato Paper towels (damp)

  1. Water potential of potato tuber cells - the weighing method.

    Record the mass of each of these groups into your table. 9) Then place one set of discs into the distilled, one set into the 0.1M and so on. 10) After 24 hours remove the discs from each test tube.

  2. Investigating the cellular water potential of potato cells.

    The glass beakers were also unsuitable as to fully submerge the potato samples, there would once again be a need for large amounts of solution. I decided to use boiling tubes as it is possible to fully submerge all of the samples and keep them from touching the sides of the boiling tube.

  1. An Investigation to determine the Water potential of Potato cells.

    I realised that after leaving the potato pieces in the solutions for only 20 minutes the mass of the potato tissues did not change more than 5.61% from the original, therefore to attain accurate results which show the change in mass of the potatoes once they have reached equilibrium I

  2. To determine the water potential of potato tuber tissue

    * Weigh all of the cores and record the weight. * Start the stop-clock and add a core to a solution at five second intervals (don't forget to record which core went in which solution). * When the time = 30 min take the cores out at 5 second intervals, and place them on a labelled piece of paper towel.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work