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

To determine the concentration of the cell sap in potato storage tissue. By using Osmosis, determine what the sugar concentration of cell sap is.

Extracts from this document...


Biology Coursework Emmeline Hastings Aim: To determine the concentration of the cell sap in potato storage tissue. By using Osmosis, determine what the sugar concentration of cell sap is. Prediction I predict that the potato segment in the distilled water will definitely gain in weight because the solution outside it has a much higher concentration of water then in the cell sap meaning Osmosis will occur and the potato segment take in water. I predict that 0.2M sugar solution will also gain weight because it still has quite a high concentration of water outside the potato. The potato in the 0.4M solution will gain weight but the potato in the 0.6M and 0.8M solutions will lose weight. The glucose concentration of the cell sap will be between 0.4M and 0.5M. Scientific Knowledge This experiment is based on the concept of Osmosis. Osmosis is the diffusion of water molecules from a region of high water concentration to a low water concentration through a semi permeable membrane (in this case, the cell potato cell membrane). The cell walls of the potato cells are semi permeable meaning that water molecules (which are small) can fit through but other bigger molecules such as glucose cannot pass through. The water molecules can flow both ways through the membrane, letting molecules both in and out. The Kinetic theory states that all molecules of every substance have energy which causes them to move about for example a chemical reaction can be accelerated through heating because the molecules gain more energy efficiently causing harder and more effective collisions of the molecules. ...read more.


Surface area would affect the rate of Osmosis by allowing more area for the water to enter or exit. The weight of the potato will effect the results because if one potato piece is larger then another it will have more water inside it. * Each sugar solution will be measured to the same amount for each boiling tube (30 ml). * All boiling tubes will be kept in the same area so that no effects are made by differentiating environments. * All water used in the experiment will be distilled and without any impurities that may effect the rate of Osmosis. * I will repeat the experiment twice and use 5 different sugar solutions to achieve a good set of results that with facilitate my analysis. Variables * The range of sugar solutions used i.e. 0.2M, 0.4M etc. Constants * Temperature * Start mass of Potato segments * Measurement of sugar solution potato segments are put in (30 ml). Safety This experiment is not very dangerous, but the sugar solutions are sticky and messy. I must be careful using the cork borer and the Scalpel, as they are a potential hazard. Results Test One Test Two Solution (M) Start mass (g) Finish mass (g) Difference (g) Start Mass (g) Finish Mass (g) Difference (g) Average Difference (g) 0.0M 1.40 1.81 0.41 1.40 1.77 0.30 0.39 0.2M 1.40 1.48 0.08 1.40 1.50 0.10 0.09 0.4M 1.40 1.37 -0.03 1.40 1.37 -0.03 -0.03 0.6M 1.40 1.10 -0.30 1.40 1.06 -0.34 -0.32 0.8M 1.40 0.88 -0.52 1.40 0.92 -0.48 -0.5 Graphs of Results Analysis From ...read more.


This alters my found Glucose concentration of the cell sap but still leaves me with a fairly accurate result. Improvements could be made to obtain a far more reliable result. In order to have made my investigation more accurate I could have spent more time on making the potato segments more equal in weight, I could also have used a larger and more informative set of glucose solutions: 0.25M, 0.35M, 0.45M, 0.55M. By using a closer and narrower range of solutions, the concentration of the cell sap could be found more accurately. I could have monitored room temperature and any other environmental changes that could also affect the experiment such as light intensity. I could have done this by keeping the light intensity constant by using an electric lamp. By repeating the experiment a greater number of times my averages would be made that little but more precise. Also to extend the experiment, because the Glucose concentration of the cell sap that I found is not entirely accurate, I could repeat the experiment but this time using a range of glucose solutions that the concentration may be. For example 0.32M, 0.34M, 0.36M, and so on. This would offer me a more accurate and reliable result to the experiment. I also hypothesise that the experiment is still accurate if all constants are kept constant, and that if an environmental change occurs, as long as it occurs to all of the solutions in equal amounts, the results would not be altered. I could extend the experiment by proving this hypothesis. ...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)

    Final mass (g) Change in mass (g) Mean change in mass (g) Mean % change in mass 1st run 2nd run 1st run 2nd run 1st run 2nd run 0.00 Distilled Water 0.20 0.40 0.60 0.80 1.00 Method * First of all of the safety measures should take place. Clean tidy environment, hair tied back and goggles.

  2. Marked by a teacher

    An Experiment to determine Water Potential in Potato Tissue.

    4 star(s)

    They were 0.0 moldm-3, 0.1 moldm-3, 0.2 moldm-3, 0.4 moldm-3, 0.8 moldm-3, and 1.0 moldm-3. All the potatoes were 3 cm long and the thickness of all the potatoes were kept same by using same sized cork borer. This was to make sure that they all had similar mass.

  1. Marked by a teacher

    Science Coursework: Investigating Osmosis in potato tissue

    4 star(s)

    Why has this happened? Maybe the 2 spatulas worth of salt and sugar weren't enough and we needed a more concentrated solution - maybe 3 or4 spatulas worth was needed. Maybe we needed to leave it in there for longer as 10 minutes might not have been enough (although in our last pre test it proved my prediction and only 5 minutes was needed).

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

    By looking at my line graph, I have also found that equilibrium would have been reached at a concentration of 0.36M if I had used that particular concentration. I also found some information by not looking at the line graph, but by looking at the potato cylinders after the experiment.

  1. Find the concentration of Potato Cell Sap.

    5 5.0 45.0 44.0 -1.0 My lack of conclusive results was due to 3 factors; -Length of time that the potato was left for; I only left the original pieces of potato in solution for 30 minutes. They do however need to be left for a lot longer.

  2. The Effect of Glucose Concentration on Osmosis through Potato Tissue

    molecules compared to the cells in the potato cord, so there is a net movement of water molecules in the potato cells. This causes the cells to swell and become turgid. Diagram showing the set-up of apparatus: Method: The different concentrations of sugar solutions were already measured out.

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

    Here are the results: Mass at 0 hours (g) Mass at 2hours (g) Mass at 3.5 hours (g) Potato in 0M 1.86 2.35 2.26 Potato in 1M 1.90 1.65 1.46 Apple in 0M 1.44 1.45 1.61 Apple in 1M 1.43 1.57 1.37 There are two anomalous results (in bold)

  2. Investigating the Effect of Concentration on the Rate of Osmosis in Potato Tissue.

    Method: Firstly, having chosen the concentration as the input variable, the other possible variable must be kept constant to ensure that the results are caused by the concentration and nothing else. To make sure we keep the temperature constant, we will leave the potato pieces in the same environment and under the same conditions (i.e.

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