• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14

Investigation to see how Concentration affects the rate of Osmosis on Potatoes.

Extracts from this document...

Introduction

Investigation to see how Concentration affects the rate of Osmosis on Potatoes Planning The aim of this investigation is see how altering the rate the concentration of water and salt solution affects the rate of osmosis of potatoes. Osmosis is the diffusion of water from a high concentration of water (a dilute solution) to a low concentration of water (a concentrated solution) through a semi-permeable membrane. A semi-permeable membrane is porous but allows water to pass through it more rapidly than dissolved substances. The diagram shows how water molecules have diffused from a dilute solution to a concentrated across a semi permeable membrane. As a result, the level of liquid on the left will rise, and fall on the right. The rate of osmosis is dependant on a few things. It depends on * The thickness of the membrane * The concentration inside and outside the membrane - Concentration gradient * The size of the ions * The Surface Area. Using potato cylinders and 1M Salt Solution (NaCl Solution). I will look at the rate of osmosis on the potato cylinders in different concentrations of salt solution. I will dilute the solutions using distilled water. Hypothesis I predict that when the potato tubes are in a higher concentration of the salt solution than the concentration of water, i.e. the solution is concentrated, then the potato tubes will lose mass and become smaller. This is because the concentration of water outside the potato cylinders is concentrated, and there is not much water. Due to osmosis the water inside the potato cylinders will move out. This will decrease the mass of the potato, make it smaller and make it flaccid due to the loss of water. The potato cells lose turgor and become flaccid. I predict that when the potato tubes are in a lower concentration of the salt solution than the concentration of water, i.e. ...read more.

Middle

because there were not enough test tube racks * I did repeat the experiment but the second time the results had to be taken at a different time period - only after 2-3 hours due to time. The first experiment results were taken after about 18 hours, which is why the results in Experiment 2 may be anomalous. * The same apparatus could not be used as the experiment was done after a few days. * The same temperature could not be kept as the room temperature differed from experiment 1 to 2. Precautions These are the safety precautions that were carried out to ensure that the experiment was safe: * The scalpel and cork borer was used to cut the potato on the white tile, so nothing is damaged * The tubes were kept in a beaker so that the tubes could not be tampered with * They were left untouched so the results would not be affected * The beaker of test tubes was put near the wall, on the desk so that the tubes would not fall of the desk. Here are the results tables for Experiment 1: Results Mass of Potato cylinders / g Tube 1 2 3 Averages 1 0.73 0.71 0.68 0.71 2 0.68 0.67 0.69 0.68 3 0.74 0.73 0.83 0.76 4 0.77 0.82 0.73 0.77 5 0.96 0.93 0.96 0.95 6 0.88 0.92 0.96 0.92 Before After Mass of Potato cylinders / g Tube 1 2 3 Averages 1 0.90 0.86 0.84 0.86 2 0.95 0.83 0.91 0.89 3 0.92 0.95 0.92 0.93 4 0.90 0.86 0.93 0.90 5 0.91 0.97 0.84 0.91 6 0.83 0.85 0.89 0.86 Gain or Loss Tube Change in Mass / g 1 -0.15 2 -0.21 3 -0.17 4 -0.13 5 0.04 6 0.06 (A negative number indicates loss) Here is the results table for Experiment 2: Before After Mass of Potato cylinders / g Tube 1 2 3 Averages 1 0.65 0.82 0.72 0.73 2 0.83 0.73 0.79 0.78 3 ...read more.

Conclusion

If the temperature were kept constant then the experiment would be fairer and give better results. This could have been done by doing the experiment in a temperature-controlled room, to ensure that the temperature remains constant. The experiment could also have given better results if I had used more accurate weighing scales, to give better weight readings. If I were to repeat the experiment I could have possibly found a machine to cut the potatoes. This would ensure that all potatoes would be the same weight and dimensions and make the experiment fairer and give better results. To find better results, I could also have measured the volume of the solution left when re weighing the potatoes. If this was done, then I could have seen if the volume changes match the mass changes. It would also have provided extra evidence for the accuracy of the results. In these ways I could have improved my current experiment I carried out. To extend my experiment I could test how concentration affects the rate of osmosis on different vegetables. I could have used different vegetables, like a cucumber. Then I could find out whether osmosis occurs with the same trends with any vegetable. I could also have done the experiment with another solution instead of salt solution. I could have used sugar solution, and then compared the two sets of results to see if it makes a difference and why it makes a difference. I could also have extended this experiment by testing more solutions with the potato cylinders. I could have used more different concentrations of salt solution to give better results in this experiment. By doing this I could have found the isotonic point, which is where osmosis is balanced so there is water movement, as the water concentration is the same on both sides of the semi permeable membrane. I cold also have tested how the osmosis rate changes with different potato cylinder sizes. From this I would be able to see if the size of the potato affects the rate of osmosis. Ricky Patel ...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

    The aim of this investigation is to find out how the concentration of the ...

    4 star(s)

    This is quite simply because the longer the water is able to pass through from one solution to the next, the more water will be able to pass through, because it is a gradual process. Although if no other variables are changed the rate of osmosis will stay the same, the amount of osmosis will increase.

  2. Marked by a teacher

    To investigate how varying the concentration of sucrose solutions affects the rate of osmosis ...

    3 star(s)

    LENGTH CHANGE IN LENGTH % CHANGE IN LENGTH 5.00cm 5.00cm 4.80cm 4.76cm -0.24cm -4.8% 5.00cm 4.70cm 5.00cm 4.70cm 5.00cm 4.80cm 5.00cm 4.80cm Solution concentration: 0.75M INITIAL MASS AVERAGE INITIAL MASS FINAL MASS AVERAGE FINAL MASS CHANGE IN MASS % CHANGE IN MASS 0.92g 0.92g 0.82g 0.78g -0.14g -15.22% 0.95g 0.80g

  1. Osmosis. Aim ...

    Type of potato I will use the potato chips from the same potato spud to ensure that the potato chips have the same genetic make and have the same semi-permeable membrane. Also I cut the potato chips to the same dimensions so that the surface area of the potato chips

  2. Find the concentration of cell sap in potato and to investigate the behaviour of ...

    the water molecules in different experiments will have more energy provided by the temperature. To keep this a fair test I will keep the experiments at room temperature and will use the same water and salt solution that has been left at room temperature.

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

    having several molarity all the way up to 1% I could be more accurate and pin point at around what position exactly I would do the experiment. This also helped establish that if the potato sunk then it would probably lose weight and if it floated then it would gain

  2. Investigating how concentration of salt solution affects osmosis in potato

    The mass of the potato is a dependent variable, and this means that it will be measured throughout the experiment. I will measure the mass in grams. The potato chip will be measured before it is put in the solution, and after.

  1. Osmosis Investigation

    From my experiment, I have also obtained data on the change of mass in the potato tubors when placed in the different concentrations of solution. In order to present this information clearly, I have shown this on a bar graph, which indicates the initial and final mass for the tubors placed in each of these different solutions.

  2. Biology-2 QWC Practice Questions & Answers

    Also, there is a thin cuticle of wax on the surface of the leaf to protect it without blocking the essential sunlight. Internally, the leaf is carefully structured to make sure the plant can photosynthesize as much as possible; found in the upper portion of a leaf, is the upper

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