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

Water Potential of Potato Tuber Cells: The Density Method

Extracts from this document...


Valentina Zunarelli IB Biology Practical Water Potential of Potato Tuber Cells: The Density Method Introduction Aim To find out the water potential of potato tuber cells by testing whether a drop of coloured solution sinks or floats in test tubes containing solutions of different densities. This is called the density method. Hypothesis My hypothesis is that the drop of coloured solution will rise if the tissue gained water from the solution, making it denser. However, if the water potential is the same as the solution's, the drop will neither fall nor rise. Method Firstly label seven test tubes: 0.10, 0.15, 0.20, 0.25, 0.30, 0.50, 1.00 mol dm-3. Then, using a separate graduated syringe in each case, place 5cm3 of the appropriate solution in each test tube. ...read more.


This test tube of decanted solution should be placed in the test tube rack in the position of previously occupied by the tube containing the potato discs immersed in 0.1mol dm-3 sucrose. Do this with all the solutions. *Using a teat pipette to collect a small amount of blue sucrose solution from the 0.1 mol dm-3 sucrose tube. Now with great care, introduce a single drop of this blue fluid into the tube with the same concentration but without the methylene blue that was decanted from the potato slices. The drop should be released carefully into the centre of the liquid about 5 mm below the surface. Watch the drop and note whether it remains in the same place, sinks, or rises. ...read more.


At 0.3 mol dm-3 the speed at which the drop rose was extremely slow. When the solution is more concentrated than drop of blue sucrose solution the sucrose solution rises and vice versa when the sucrose is more concentrated than the solution. We have found the isotonic point (when the drop of blue sucrose solution remains still, does not rise nor fall); this is at about 0.5 Mol dm-3. Evaluation This experiment was rather successful since the isotonic point was found. However, it could have been repeated more times in order to have more fair results. Then an average could have been found and it would have been more accurate. Another factor is that the potato from which the cylinders are taken could be abnormal - this could be prevented by amalgamating sets of results, for example of a whole class, where each experimenter used a different potato. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction 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 AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Investigate the water potential of celeriac.

    5 star(s)

    The cell is now plasmolysed 5. When water potential outside of the cell is equal to the water potential inside of the cell, it is in a state of equilibrium. From previous experiments, I know that carrots have more sucrose dissolved in them than celeriac and potatoes.

  2. Marked by a teacher

    Osmosis. Aim: To find the molarity of potato tubers cell sap. BIOLOGICAL ...

    4 star(s)

    This will result in inaccuracy. This can be done be cutting the potato strips using a cork borer to get a smooth surface and then resizing it to a similar length. This will result the potatoes to have the same surface area.

  1. Peer reviewed

    Osmosis. Finding the water potential of potato tuber cells

    3 star(s)

    Measure x5 amount of distilled water into homogeniser using the other glass pipette 3. Ensure that the pipettes are kept away from each other 4. Mix the liquid thoroughly with homogeniser 5. Pour solution into the glass beaker 6. Label the molarity of the solution 7.

  2. Investigating Water Potential Of Potatoes.

    Besides this the other results seemed to be just right according to the line of best fit. The first result we received was for the solution with a concentration of 0 molar at 26.15%. The second was at 18.6% for the solution with a concentration of 0.1molar.

  1. Osmosis in Potato cells

    The experiment on the chips was performed at the same time of day on the same day so that the temperature changes that occurred throughout the experiment affected all chips simultaneously. Obtaining the evidence Equipment: * One potato cut into five equal sized chips.

  2. Investigation on Osmosis using a potato.

    -2.127659574 1.30 1.24 24 6 -4.615384615 1.38 1.22 27 3 -11.5942029 1.34 1.15 30 0 -14.17910448 The end result here is very much the same as the end results in the past two tests. The only small difference I can see is that the 30 ml sucrose solution + 0

  1. Investigating the stomata density in Hedera up a wall?

    plant, but to do this is must lose water, so if the plant was to lose more water at the top then at the bass, then more water and other compounds will be pulled up the plant, and they plant can the carry on its life processes.

  2. Aim: To find out the water potential of potato cells using different concentrations of ...

    The diagram above can be used to describe Osmosis. If two solutions of different concentration are separated by a semi-permeable membrane which is permeable to the smaller solvent molecules (water molecules) but not to the larger solute molecules (sucrose molecules), then the solvent will tend to diffuse across the membrane from the less concentrated to the more concentrated solution.

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