• 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

To Investigate the Rate of Osmosis In Potatoes and Find Out the Sucrose Concentration of the Potato.

Extracts from this document...

Introduction

INTRODUCTION Aim: To investigate the rate of osmosis in potatoes and find out the sucrose concentration of the potato. Osmosis is the movement of water molecules from a solution of high water potential to a solution of low water potential across a partially permeable membrane. Water potential is the ability at a solution to lose water. A concentrated solution has a low water potential and a dilute solution has a high water potential. The diagram below illustrates the concept of osmosis. The diagram above shows a concentrated sucrose solution and a dilute sugar solution separated by a partially permeable membrane. This membrane allows small molecules, such as water, to pass through it but it does not allow larger molecules like sucrose through it. The water moves from the right to the left so that the sucrose concentration on the left is decreased. The concentrated solution becomes more dilute due to the extra water molecules entering it. In plant cells the cell changes when the concentration around it changes. A plant cell can become turgid or flaccid. When the concentration of water is higher outside the cell than inside the cell, water will move by osmosis down its concentration gradient, through the cell membrane and into the cell. As water goes in the vacuole and cytoplasm will swell. As the cell has cell wall, which is fully permeable, it will not burst. The cell's volume and mass will increase. The cell will expand to its maximum size and it is then said to be in a turgid state. When the concentration of water outside the cell is lower than inside the cell, the opposite happens. ...read more.

Middle

When the solution is 0.35 it is higher than the potato so water diffuses out of the potato by osmosis and the concentration of the solution is reduced. As the cells lose water they become flaccid. There is no water movement when the concentration is the same of the potato. From the preliminary I predict that the concentration of the cell sap is 0.3 M. However this may not be exactly correct but only approximate as a wide range of concentrations was used in the preliminary. The diagram below demonstrates this: 0.25 M 0.3 M 0.35 MAIN EXPERIMENT Aim: To find out the concentration of the cell sap in a potato by investigating the movement of water within a potato. Apparatus: - Potato x 1 - Pair of borers - Knife - White tile - Test tubes x 15 - Test tube rack x 3 - 1 molar sucrose solution - Water - Syringe (10ml) x 2 - Forceps - Filter paper - Electronic weighing scales - Sticky labels x 15 Method: 1. Using the knife the potato was cut into three pieces. 2. 15 cylinders were cut from the potato using the pair of borers. (3 cylinders per piece of potato) 3. The 15 potato cylinders were all cut to a length of 4cm using the knife. This meant that all 15 had the same surface area. 4. All 15 potato cylinders were weighed and their masses were noted. 5. The concentrations of 0.25, 0.275, 0.3, 0.325 and 0.35 molar were written on to the sticky labels. Each concentration had three labels and these were stuck on to the 15 test tubes. ...read more.

Conclusion

As I had done three tests for each concentration the results were more accurate as averages of the three tests were used to plot the graph. The third test for when the concentration was 0.275 M was anomalous as it was much lower than the other values (tests 1 and 2). Also, the average % mass change for when the concentration was 0.325 M was quite high and it was the furthest point from the line of best fit. These anomalous results were most probably caused by human error i.e. inaccurate measurement. Improvements 1. Instead of using potato cylinders I would use smaller discs. The cylinders would be cut into equally sized smaller discs, which would increase the potato's surface area. This would mean that the mass change of the potato would be more substantial and the results would how a clearer trend. 2. The variables would be kept constant in order to keep it a fairer test. This means that the concentrations, amount of solution, size of discs, time would all be measured more accurately. The temperature and pressure would also be monitored. 3. The potatoes would be dried using the filter paper evenly so that the results would not be largely affected. Extending the investigation The investigation could be extending in a number of ways b8ut still based around osmosis. In my investigation I investigated how the concentration of sucrose solution affected the movement of water into and out of the potato. Instead of the concentration of a sucrose solution, other variables such as temperature, pressure and humidity could be varied to see how they affected the rate of osmosis. Different vegetables could be used to see how they compare to how the potato was affected. Various root vegetables could be used such as carrots, onions, potatoes. ...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

    How does the concentration of a sucrose solution affect the rate of Osmosis in ...

    5 star(s)

    others, so this may be, along with the different boiling times, the reason for the increase and decrease in mass in the two control experiments. I chose to draw a line graph with four different lines on it to show the percentage change in the three different experiments, and then the averages.

  2. Marked by a teacher

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

    4 star(s)

    larger changes than the 2M solution (0.3cm to 0.2cm and 0.05g to 0.04g). I can conclude that my prediction was correct: "I predict that the potato tubes in the solution of distilled water will increase the most in weight and length and that the potato tubes in the 3M solution will decrease the most in weight and length.

  1. Marked by a teacher

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

    3 star(s)

    LENGTH: 4.50cm AVERAGE FINAL LENGTH: 4.18cm AVERAGE INITIAL MASS: 0.69g AVERAGE FINAL MASS: 0.52g The average change in length was a decrease of 4.50-4.18=0.32cm (-0.32cm gain) The average change in mass was a loss of 0.69-0.52=0.17g (-0.17g gain) Results: The prior test showed that water does move from places with high water concentration to places with low water concentration.

  2. Find the concentration of Potato Cell Sap.

    This was due to the timings of lessons. * Instead of using a measuring cylinder, I used a 10cm� Syringe. I found this easier, quicker and more accurate. * I also set up the apparatus the day before I conducted my experiment.

  1. To find out the concentration of cell sap

    gm After mass in gm Total gain or loss in gm 1st attempt 1.7 1.8 0.1 2nd attempt 1.7 1.8 0.1 Average 0.1 0 m Solution Molarity Before mass in gm After mass in gm Total gain or loss in gm 1st attempt 1.7 2.1 0.4 2nd attempt 1.7 2.0

  2. Osmosis, What is the effect of sucrose concentration on the rate of osmosis in ...

    They move faster through the partially permeable membrane and therefore the rate of osmosis speeds up. To solve this problem I will conduct my experiment within one hour on the same day. Therefore, temperature will not fluctuate significantly to ruin the results 5)

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

    But other than that, there weren�t any bigger matters to be cautious of. Method I believe this task is very simple and should be very easy to carry out the experiment.

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

    Plasmolysis is the shrinkage of the cytoplasm of a plant cell, so that the call membrane begins to tear away from the cell wall; caused by loss of water. This means that if the cell loses too much water it will become damaged beyond repair.

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