• 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
  14. 14
  15. 15
  16. 16

Osmosis Investigation

Extracts from this document...


Skill Area P: Planning and Experimental Procedures Aim The aim of this experiment is to demonstrate the process of osmosis in potato tissue. To do this I will cut strips of potato, immerse them in various concentrations of sucrose solution and examine the change in length of the strips, if any. Preliminary Study To set up a range and interval for my experiment I carried out some preliminary work to give me an indication of what the change in length would be like. I used three concentrations, 0, 0.5 and 1.0 molar (1M) and immersed three 50mm strips in each solution for 15 minutes. The results are shown in the following table: - Molarity Length after immersion Average length after immersion Change in length Percentage change 1st strip 2nd strip 3rd strip 0 53mm 50mm 47mm 52mm 2mm 4% 0.5 51mm 49mm 49mm 50mm 0mm 0% 1.0 52mm 51mm 48mm 48mm -2mm -4% In this preliminary study, the equilibrium concentration, that is where there is no change in length, is approximately 0.5M. A range of concentrations either side of this value should therefore give me a satisfactory set of results. Apparatus/Materials 6 test tubes Test tube rack Scalpel Cutting board Vernier 20cm3 Graduated pipette Stopwatch Various sucrose solutions Potato Distilled water Planned method I will first obtain 5 sucrose solutions - 0M, 0.2M, 0.4M, 0.6M, 0.8M and 1.0M. (These are all available from stock and made up by science technicians). ...read more.


As the difference between the water potential is less however, I think less water will be taken in than in the 0M solution and the increase in length will be smaller. In solutions stronger than 0.4M, I predict the potato strips will decrease in length. This is because above 0.4M the external solution will be of a higher concentration than the cell sap. The sucrose solution will have a more negative water potential than the cell. This means that water will leave the cell by ex-osmosis and give a plasmolysed state to the cell. A plasmolysed cell is one where the protoplast is completely pulled away from the cell wall (see diagram below). As the concentrations increase, the difference between the two water potentials of the cell and the solution will increase so I predict more water will leave the cell. Skill Area O: Obtaining Evidence I followed my original plan and did not make any changes to the proposed method. I used all the apparatus listed in the planning section. All safety procedures were carried out and no-one was injured during the experiment. All results obtained are shown in the table below. Results Molarity Length at end of experiment (mm) Average length after immersion (mm) Trial 1 Trial 2 Trial 3 0 53.46 53.24 52.40 53.03 0.2 51.52 52.63 52.24 52.13 0.4 49.96 50.71 49.68 50.12 0.6 48.64 48.13 48.84 48.54 0.8 48.45 48.39 48.15 48.33 1.0 47.80 48.09 48.23 48.04 Skill Area A: Analysing Evidence and Drawing Conclusions In the table below, ...read more.


If I were to redo this investigation I would suggest the following changes: * I would make sure a number of people were placing the strips in the solutions reducing the risk of one set of strips having more time for osmosis to occur. * I would use a cork borer as this would give me a uniform shape and keep the surface area constant. * To improve the reliability of my results, I could increase the number of concentrations by going up in intervals 0.1M not 0.2M (i.e. 0M, 0.1M, 0.2M, 0.3M...). This would give me more points to plot to improve my line of best fit. * If I didn't have time restrictions, I would leave the potato strips in the solutions for 24 hours, as this would give more time for osmosis to occur and stabilise. * Finally I would put strips in separate test tubes, as this would prevent the risk of strips touching and reducing the surface area for osmosis. To provide additional evidence for conclusions, I could repeat this investigation measuring the mass of the potato strips because this would mean that all over change was taken into account (change in all 3 dimensions). I could also investigate the effect of various concentrations of sucrose solution on different types of potatoes (e.g. sweet potato, new potato). Also I could compare the effect of various concentrations of sucrose solution on different types of vegetables (e.g. swede, parsnip, and carrot) and also see if the dynamic equilibrium varies with different tissues. ...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

    Find the rate of osmosis in different vegetables (Carrot, Potato, Swede, Parsnip and Sweet ...

    3 star(s)

    This was because osmosis is water moving through partially permeable membranes, and the more sucrose in the solution, the less water will diffuse and less % change will occur. The past experiment inspired me to do an osmosis experiment, but with completely different variables.

  2. Osmosis is defined as 'the movement of water molecules from an area of high ...

    As for the experiment that we carried out, no changes were made in the experiment. Obtaining evidence After the experiment, I had to dry the potatoes first, so that the water outside the tissue of the potatoes won�t alter the weight of what it is supposed to be.

  1. Osmosis Coursework. Investigation Of The Effect of Different Concentrations of Sucrose Solution on Potato ...

    The cell will have decreased in volume and mass because of the decrease in water. If the potato tissue is placed in a solution with the same water concentration of that inside the cell, water will move out of the cell at the same rate as it enters the cell.

  2. Osmosis Investigation

    When analyzing the results, I noticed that there is an obvious pattern that falls into my predictions. I have noticed that when the potato tubors were placed in a concentrated sucrose solution, they decreased in mass and length. In fact, when the sucrose solution was more concentrated, the decrease in mass and length was greater.

  1. Osmosis investigation

    At the 0.4 Molar solution, there was 12ml3 of sucrose solution and 18ml3 of water so there was a dramatically smaller mass increase, only 1.04%, this shows that equilibrium was nearly reached, or an isotonic. This makes sense, as there is only a 6ml3 difference between the two solutions the

  2. Determination of molarity of cell sap in potato tubers.

    Once again it is important that the substance that is added to the water is soluble in water. Osmosis is also used industrially, mainly in the process of agriculture. Sometimes in industry, quite different from agriculture, osmosis may also be used.

  1. The endeavour of this investigation is to ascertain if there is any effect of ...

    The trends were as expected from the background knowledge and were similar to the secondary source tables results in the Appendix Advantages: - The main advantage was that the experiment showed a very brief result of what is expected when varying the sucrose concentration - The experiment proved to a

  2. An Investigation To Demonstrate The Affect Of Different Sucrose Concentration On Osmosis In Plant ...

    As the potato cells took in or gave out the water depending on the concentration of the tissue and the concentration of the solution it is surrounded by. Variables Independent Variable Controlled Variables Solution concentration Surface area Solution volume Duration of experiment Temperature Weighing scales During my experiment I am

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