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

Plan and carry out an experiment to investigate Osmosis in Potato tissue

Extracts from this document...

Introduction

Plan and carry out an experiment to investigate Osmosis in Potato tissue Planning Aim: To investigate osmosis in Potato tissue and find its water potential, using eight different molarities of sucrose Hypothesis Osmosis is defined as the net movement of water or any other solutions molecules from a region in which they are highly concentrated to a region in which they are less concentrated. This movement must take place across a partially permeable membrane such as a cell wall, which lets smaller molecules such as water through but does not allow bigger molecules to pass through. The molecules will continue to diffuse until the area in which the molecules are found reaches a state of equilibrium, meaning that the molecules are randomly distributed throughout an object, with no area having a higher or lower concentration than any other. Apparatus Test tube Label Sucrose solution Potato tissue 8 x test tubes 8 x potato chips 8 different sucrose solutions labels top pan balance test tube rack Method In each test tube, put 30cm� of each solution of sucrose, and label it with the molarity of the sucrose that is in that tube, this is needed because otherwise you would not be able to plot the graph at the end showing how the molarity of the sucrose directly effects osmosis, or if the different molarities become mixed, anomalies will appear in your results. ...read more.

Middle

% change for 1st set of data % change for 2nd set of data average % change 0 6 9.3 7.7 0.0625 5 8.4 6.7 0.125 3 3.5 3.3 0.25 0 0.9 0.5 0.5 -12 -9.1 -10.6 0.75 -17 -12.9 -15 1 -21 -19 -20 1.25 -22 -15.9 -19 Analysing and considering evidence The graph shows the line of best fit for the average percentage change in mass of the potato chip over two experiments, each being forty five minutes in length. The graph is a curve that slopes downwards and does not go through the origin. Because the line is not straight and does not pass through the origin, it means that the percentage gain and loss in mass and concentration are not directly proportional. However, there is a pattern on my graph, and this is, as the concentration of the solution increases, the percentage change in mass decreases. Although the last solution being 1.25 molar sucrose, has a higher average than that of the 1 molar sucrose solution. This suggests an anomaly in my results, that either the other chips were not blot-dried to the same extent or that there was water on the chip and that it contaminated the sucrose and diluted the solution making it weaker, or that the chip cell has completely plasmolysed and that there can be no more water loss. ...read more.

Conclusion

The cutting of the potatoes was the most difficult part of the experiment as although I was recording my results by mass, it could well have affected the surface area and so the overall rate of osmosis. If I were to repeat the experiment I would have possibly found a machine to cut the potato as it would ensure that all potatoes would be the same weight and dimensions. As well as the potato I could have found a more accurate way to measure out the solutions and to determine the molar concentrations. Perhaps I could have used a burette. This would ensure that I have an accurate amount of fluid in each test tube. I could also weigh each chip on a more accurate scale, e.g. not to 0.00g but to 0.0000g There were not any out of the ordinary results, but some were not as close to the line as others. This is possible a human error. When the potato chips were removed from the test tubes and dried I may well have dried some potatoes more thoroughly than others and so some would have more excess water, which would add to the mass. If the experiment was repeated I could find another way to dry the potatoes that would ensure that all were dried in the same way for the same time. However with all this said I think that the experiment was truly successful and I was very pleased with the complete comparison of my results with my initial prediction Simon Herbert 8001 ...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)

    Therefore, the test tube that had celeriac discs placed in it first was immersed in the solution for a longer period of time, which would have affected the results. A final error I found was when blotting the celeriac discs of excess solution.

  2. Marked by a teacher

    Biology coursework planning - the effect of lead chloride on the growth of cress ...

    5 star(s)

    This is because during the preliminary work, 15ml was found to correspond well with the size of the petri dish and the cotton pads. The capacity of the cotton pads to soak up water was moderate - the seeds were neither flooded nor deprived of the solution.

  1. Marked by a teacher

    Determining the Water Potential of Sweet Potato Tissue

    4 star(s)

    This will increase the water potential of the cell until it reaches equilibrium. The cell wall is so inelastic that it takes very little water to enter the cell to achieve this. Solution with ? more negative (lower) than the cell, water will leave the cell causing the protoplast to

  2. Marked by a teacher

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

    4 star(s)

    of molecules that can pass at one go, as more area of the semi-permeable membrane is exposed to the solution. So, when the surface area is less, the rate of osmosis decreases because only a few can pass at one time.

  1. Peer reviewed

    The comparison of antibacterial properties of herbal products and standard antibiotics

    5 star(s)

    From knowledge it can be established that the higher the concentration the faster the reaction occurs, this can be related to the herbal products only as both penicillin and streptomycin were used as dry discs mass produced with the same concentration per disc.

  2. Investigating Water Potential Of Potatoes.

    more and more negative. The component of the water potential, which is due to the presence of solute molecules, is called the osmotic potential or solute potential. (So solute molecules can be a variable according to which direction osmosis occurs in) Plant cells (including potatoes)

  1. Investigation on Osmosis using a potato.

    this is because when using it make sure that the potato is firmly on a surface if not the cork borer may go into ones hand and damage skin tissues. But other than that, there were not any bigger matters to be cautious or concerned of.

  2. Osmosis In Potatoes.

    As concentration increases, the length decreases. In this graph, I had many negative results. This shows that length is very strongly affected by osmosis. � Graph 3 'Average change in weight' is quite confusing. For example, the result I obtained for 0.1 molar concentration does not follow the pattern of the other results.

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