• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13

Investigation Of Water Potential

Extracts from this document...


Planning Title: Investigating the water potential of root vegetables. Aim: The aim of the experiment is to find the water potential of potato tuber cells. Background: This investigation is based largely on water potential. Plant cells behave in certain ways when subjected to certain conditions. If a plant cell is immersed in a solution with the same water potential as the plant cell the mass will remain the same. If the plant cell is immersed in a solution with a higher water potential than the cell then the mass will increase. Finally in the plant cell is immersed in a solution with a water potential lower than that of the cell it will decrease in mass. This is due to the rule of water potential. Water will diffuse through a partially permeable membrane down its concentration gradient from a region of high water potential to a region of low water potential. Thus we can find out the approximate water potential of potato tuber cells using this method and getting a more accurate reading from the graph. I found this diagram on a website. Identified in the references section. Prediction: Based on my background information I predict that at a low concentration of sucrose the potato tuber cells will increase in mass. In potato tuber samples immersed in a solution with high concentration of sucrose will decrease in mass. I believe this because in solutions of low sucrose concentration there is a high water potential. This means water will move from the solution to the potato tuber cells. In solutions of high sucrose concentration the water potential is low, therefore the water will move from the potato tuber cell to the sucrose solution. Meaning it will decrease in mass in solutions of high sucrose concentration. Preliminary Experiment: Introduction: In this experiment the lengths of potato tuber cells will be examined after being immersed in sucrose solutions of different concentrations. ...read more.


Results: Results Table Showing Concentration, Mass at the start and end, Average masses at the start and end. Sucrose Concentration/ (M) Mass at Start (g) Average Mass at Start (g) Mass at End (g) Average Mass at End (g) 0.00 2.60 2.69 0.00 2.60 2.57 2.70 2.73 0.00 2.50 2.80 0.10 2.40 2.53 0.10 2.70 2.53 2.70 2.65 0.10 2.50 2.72 0.20 2.50 2.48 0.20 2.40 2.43 2.51 2.48 0.20 2.40 2.45 0.30 2.70 2.53 0.30 2.30 2.46 2.51 2.46 0.30 2.40 2.40 0.40 2.38 2.38 0.40 2.41 2.43 2.35 2.41 0.40 2.35 2.41 0.50 2.38 2.28 0.50 2.32 2.35 2.22 2.23 0.50 2.20 2.19 0.60 2.20 2.05 0.60 2.20 2.27 2.13 2.11 0.60 2.40 2.15 Fig. 6 Results: To be able to plot these points accurately on a graph the results must be used to calculate the change in mass per gram. Change in mass per gram = Change in mass/ Mass at Start The average mass at the beginning and end of the experiment will be used to calculate the change in mass per gram. Also this will produce only one result allowing the graph to be produced using one point. After calculating the average change in mass per gram the percentage change in mass per gram can be calculated. Change in mass per gram X 100 = Percentage change in mass per gram Table Showing Calculations and Change in mass per gram for each Sucrose concentration and the Percentage Change in mass per gram for each sucrose concentration Fig. 7 Sucrose Concentration (M) Calculation (g) Change in mass per gram (g) Percentage change in mass per gram (%) 0 (2.73 - 2.57) / 2.57 0.06 6 0.1 (2.65 - 2.53) / 2.53 0.04 4 0.2 (2.48 - 2.43) / 2.43 0.02 2 0.3 (2.46 - 2.46) / 2.46 0 0 0.4 (2.38 - 2.43) / 2.43 -0.02 -2 0.5 (2.23 - 2.35) ...read more.


Improvements: Table showing possible Improvements in the Experiment Limitation Improvement How improvement increases reliability? Identifying particular potato cell (3 potato cylinders per boiling tube) Use 2 different colour water proof pens Each potato tuber cell can be identified when in solution removing chance of misleading inaccurate results Inaccurate concentration made by using sucrose and water to create an approximate concentration Making solutions using sucrose powder More accurate technique means results more likely to be a true representation of that concentration Removing excess water Leave cells out of solution for a set time before weighing Allows all cells to lose the same amount of water Reliability of Evidence: The reliability of the evidence is very good. The results show that the net movement of water molecules are from a region of high water potential to a region of low water potential. This is the same conclusions made by other published studies, for example the Biology 1 book. Published by the press syndicate of the university of Cambridge and endorsed by OCR. Validity of Conclusions: My conclusion states: After analysing the experiment I conclude that it was a success. The tables show no particularly anomalous results. Also the results followed the basic principles of osmosis. When the concentration of sucrose was low the results showed an increase in mass of the potato tuber cells, they then levelled off at a medium concentration. Finally when the concentration of sucrose was high the results showed a decrease in mass of the potato tuber cells. Although the limitations may have affected results I believe this would have been very slight. Even the main source of error being the ability to remove excess water would have had little significance on the overall results. I believe this because precautions and improvements were made after the preliminary stage to make results more accurate. Making the limitations less relevant. The results coincide with other published studies and predictions made. For these reasons I believe the conclusions are valid and the investigation was a success. ...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 Molecules & 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 AS and A Level Molecules & Cells essays


    We call this incipient plasmolysis. "Incipient" means "about to be". When I forget to water the potted plants in my study you will see their leaves droop. Although their cells are not plasmolsysed, they are not turgid and so they do not hold the leaves up into the sunlight WATER

  2. Affect of sucrose concentration on the rate of respiration.

    But another cause of the problem could have been the activation time, as I noticed that after 20 minutes large amounts of froth had been produced by the yeast. From my preliminary work I can conclude that the mass of yeast that I should use in my experiment should be 3grams.

  1. An experiment investigating the concentration of sucrose in cells of carrot and potato

    can be seen by noting the point at which the line of best fit crosses the x-axis. Plasmolysed cell (Flaccid Cell) Cell wall Cell membrane Vacuole Tonoplast Nucleus Outside solution has entered cell A plasmolysed cell is the opposite of a turgid cell.

  2. An experiment to find of the isotonic point of root vegetables cells in contents ...

    * Two 10 ml pipettes- one will be used to measure out distilled water and the other will be used to measure the 1 molar sucrose solution. Two different pipettes will be used to prevent cross contamination and this will reduce the chance of getting less reliable results.

  1. Experiment to investigate the water potential of potato tissues when immersed in various sucrose ...

    = ?s + ?p This equation therefore enables the net movement of water molecules between different systems with varying water potential to be established. Plant cells such as the potato tissue used in the experiment contain a variety of solutes, largely dissolved in the water of the large cell vacuole that each possesses.

  2. To find out how different concentrations of sucrose solution affect the incipient plasmolysis of ...

    Furthermore the carrot has the second highest percentage mass decrease which was 18.75% meaning it should have the second lowest water potential, also the swede has the second smallest mass decrease which was -6.67%. Depending on the different types of root vegetables used they all will have different water potentials

  1. Catalyse Investigation

    Prepare boiling tubes, each with 25 ml of hydrogen peroxide in them (only prepare as many as will be used on that day). Prepare solutions of 20%, 17.5 %, 15%, 12.5%, 10%, 7.5%, 5%, 2.5% and 0%. There should be three test tubes of each concentration for the repeats.

  2. Investigating Osmosis.

    The cell membrane acts somewhat like a balloon, and if too much water enters the cell, the cell can burst, which kills the cell. So cells usually have some kind of mechanism for preventing too much water from entering or pumping the water out or simply making a tough outer coat that will not rupture.

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