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

Potato coursework

Extracts from this document...


How does the concentration of a solution affect the osmosis rate of a potato Aim: The aim of my experiment is to see if the concentration of sugar solution I use will affect the rate of osmosis in potato cells. I will do this by recording data collected on the potatoes placed in different concentrations of sucrose. Research: Osmosis is a special kind of diffusion that only concerns the movement of water. If two solutions are separated by a semi-permeable membrane, which only allows certain sized molecules through there will be a net movement of the water molecules, from the less concentrated solution (the one with more water molecules), to the solution which is more concentrated (has more solute molecules). This is because as in ordinary diffusion the molecules move to even-out any difference in concentration. However, because of the semi-permeable membrane, which does not allow the larger solute molecules to cross; only the water molecules can move. The water molecules will continue to cross the semi-permeable membrane until equilibrium is reached, where the two solutions are of equal concentration. The greater the difference in the number of water molecules on either side of the membrane, the greater the water potential. Water potential is represented by the Greek letter ?. pure water has a water potential of 0kPa. As substances dissolve in the water, the water potential drops and becomes negative. ...read more.


spend in the sugar solution * Measuring cylinder - I will use a 2ml measuring cylinder so I can accurately measure different concentrations of the sugar solution * Paper towels -I will use these to dry the potatoes before they are weighed Preliminary The aim of my preliminary is to see which are the most suitable time and length to use in my main experiment. I will do the experiment as stated and use my results to come up with the suitable measurements. Results 5 minutes Length Weight before Weight after Difference 1cm 0.43 0.41 -0.02 2cm 0.81 0.78 -0.03 3cm 1.24 1.21 -0.03 4cm 1.55 1.51 -0.04 5cm 2.05 2.00 -0.05 10 minutes Length Weight before Weight after Difference 1cm 0.47 0.45 -0.02 2cm 0.86 0.82 -0.04 3cm 1.26 1.23 -0.03 4cm 1.66 1.57 -0.09 5cm 2.15 1.73 -0.42 15 minutes Length Weight before Weight after Difference 1cm 0.46 0.44 -0.02 2cm 0.92 0.87 -0.05 3cm 1.31 1.25 -0.06 4cm 1.83 1.77 -0.06 5cm 2.35 2.29 -0.06 20 minutes Length Weight before Weight after Difference 1cm 0.52 0.45 -0.07 2cm 0.84 0.81 -0.03 3cm 1.23 1.17 -0.06 4cm 1.61 1.55 -0.06 5cm 2.06 2.02 -0.04 From my results I have decided to use15 minutes to soak the potato in the sugar solution. I feel this is best as it produced consistent results and gave me enough time to set up the next experiment whilst the potato was in the solution. ...read more.


This could be down to any number of reasons including an inaccuracy when measuring out the solution. It could also be possible that the amount of time sI patted each potato piece to dry it could affect the end result. Although I can no be accurate when saying what affected my experiment I can guess at some of the factors that may have affected it. If I was to do the experiment again there would be a few things I would alter so I could increase the reliability of the results. Firstly I would put a lid on the test tubes. This is because water could evaporate out of the test tube causing the concentration to change. Another thing I would change is I would dry the potatoes in exactly the same way for the same amount of time for every experiment as a little bit of water left on the potato piece can affect its weight. The last thing I would change is the ruler I used. I would make sure the ruler had millimetres on it so I could make sure that each potato piece is exactly the same length. I think the results my graph produced are very reliable. They helped me come to a valid conclusion which I had predicted. To further my experiment I could vary the vegetables I use to see if the effect of concentration is the same on them. Examples of vegetables I could use are swede or parsnip, as these vegetables have similar properties to the potato. Clair Kidd-Stanton, 2107 Page 1 The George Ward School ...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

    Sand Dune Succession Coursework

    5 star(s)

    Marram grass, when covered by sand, has stems which can elongate allowing the grass to re-emerge. The long roots that spread deep into the ground help search for water. Preliminary work: I carried out a preliminary investigation at Winterton sand dunes.

  2. Marked by a teacher

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

    5 star(s)

    of each cress seed in all three petri dishes. This is done using a ruler. The results of the experiment are shown below. Once again the average length of shoot of cress seeds was calculated using the previous method - see appendix.

  1. Marked by a teacher

    Investigate the water potential of celeriac.

    5 star(s)

    Cut each cylindrical celeriac piece to a length of 5cm with the razor. Using the scales, measure the mass of each cylindrical piece of celeriac and record the mass in a table. Place one piece of celeriac into each test tube and start the stopwatch.

  2. Peer reviewed

    The comparison of antibacterial properties of herbal products and standard antibiotics

    5 star(s)

    * Oven- to dry the herbal soaked filter discs. Set at 180?, leave the discs in for 15minutes. * Baking tray- to place the herbal discs on. Method: (The highlighted steps are the alterations) 1. Wash your hands prior to the experiment and using cotton wool and disinfectant wipe down the surface area you are using.

  1. Peer reviewed

    Effect of Caffeine on the Heart Rate of Daphnia

    3 star(s)

    Excess water is removed by using filter paper from the cavity slide as too much solution will result in vigorous movement of Daphnia. Counting of heart beat or beatings of the legs would then be more difficult. 8. There is an alternative in counting the heart beat or beating of legs of Daphnia, if no scientific calculator is available.

  2. Investigating Water Potential Of Potatoes.

    solution they swell and may even burst, this phenomenon is known as haemolysis which literally means blood- splitting. Diagram 2 (Letts Study Guide, Biology, Chapter 7, Pg. 72, Julian Ford- Robinson) It follows that if a cell is to maintain its normal size and shape it must either exist

  1. Osmosis in Potato cells

    in mm Final Length in mm Change in Length in mm % Change in length Abdulla 100% water 3.44 3.61 0.17 4.94 40.00 40.00 0.00 0.00 Abdulla 5% Sucrose 3.30 3.34 0.04 1.21 40.00 40.00 0.00 0.00 Abdulla 10% Sucrose 3.45 3.35 -0.10 -2.90 40.00 40.00 0.00 0.00 Abdulla 15%

  2. Investigation on Osmosis using a potato.

    I will have 6 sets because we will have to test the potatoes in 6 different types of solutions; 0 Molar, 0.2 Molar, 1/3 Molar, 0.8 Molar sucrose solution, 1.0 molar solutions of sucrose, 0 molar sucrose solution will be distilled water..

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