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

INVESTIGATING OSMOSIS AND WATER POTENTIAL IN POTATO CORES

Extracts from this document...

Introduction

INVESTIGATING OSMOSIS AND WATER POTENTIAL IN POTATO CORES WRITTEN BY SARA KHAN AIM: The aim of the experiment is to investigate osmosis and water potential of potato cores using different concentrations of sucrose solutions. INTRODUCTION: Plant cells contain a cell wall and a cell membrane. The cell wall is a permeable layer whilst the membrane is a selectively permeable membrane, this means that it will only allow certain molecules to pass through it and keep out others. An example of this is water and sucrose; water is a small molecule that can pass through the selectively permeable membrane, whilst larger molecules such as sucrose are unable to. Root hairs of plants contain within them many different substances. The way in which plant root cells take up water is by using this selectively permeable membrane to allow 'osmosis' to take place. Osmosis is a specific type of diffusion concerning only water molecules; it is the net movement of water molecules from a region of high concentration to a region of low concentration. When plant root cells take up water, water from the soil is passed across the selectively permeable they move from a high concentration in the soil to a region of low concentration inside the cell. The effect of dissolving solute molecules in pure water is to reduce the concentration of water molecules and hence to lower the water potential. All solutions therefore have lower water potentials than pure water. How much lower the solution is than pure water is known as solute potential. ...read more.

Middle

3. Distilled water- the pure water is needed because pure water is required to make up each concentration of sucrose and also for the control experiment. 4. Water bath- water bath is required to regulate the temperature. 5. Sucrose solution- the solution will be 30 cm3 for every set of potato tubes. 6. Syringe - this will allow equal volumes of each solution to be put in each test tube. 7. 15-test tubes- these will provide the container in which the solution and potato tissues are to be placed in. METHOD: 1. Label the test tubes with the concentration of the sucrose solution that will be placed in them. (Each concentration will be done three times including the control). 2. Set bath water to 25 degrees Celsius. 3. Take the syringe and extract 30cm3 of distilled water and place it in the test tube. (Make sure the syringe is clean). 4. Take a potato borer and a potato and use the potato to obtain a cylindrical piece of potato. 5. Weigh the potato cores using a top pan balance and record this weight. All cores should have the same mass. 6. Measure the diameter and length using the 15cm ruler. 7. Now place the potato tissues in the test tubes and leave in test tube rack for 3 hours. After this take out the potato tissue and measure its mass, length and diameter. 8. Record these results. 9. Repeat the experiment twice more and then record an average to have reliable results. ...read more.

Conclusion

Errors such as those mentioned would have made the conclusion reached invalid and therefore they could not be used as preliminary work for another experiment or as a basis for another investigation. The effect of these errors can be said to be minimal and thus resulting in a reliable experiment. The experiment that was carried out was reliable. This is mainly because of the steps that were taken whilst carrying out the investigation. These include the use of precision instruments, which meant the results were accurate and also reliable. The repeated readings are very close together and this shows that no large errors took place because this would have been noticed like the one anomalous result was seen on the graph. The apparatus used were to a high degree of accuracy but there are modifications, which could have been made to improve the experiment. These are all listed below: MODIFICATIONS: 1. Further test can be done for higher concentrations such as 50% sucrose solution. By having at least 10 different sucrose solutions this would give a more accurate graph from which more deductions can be made. 2. The use of a digital balance accurate to 0.001g could be used to gain increasingly more accurate results. 3. The readings can be repeated more than three times to increase the accuracy. 4. More precise instruments could be used to get all the potato cores to be of exactly the same length before placing them in the experiment to make it a fairer test. The modifications listed above would help in eliminating sources of error and also increase the reliability of the results. The modifications also suggest further work that can be done. ...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

    An Experiment to determine Water Potential in Potato Tissue.

    4 star(s)

    Volume of Water (cm3) Volume of Sucrose (cm3) 0.0 20 0 0.2 16 4 0.4 12 8 0.6 8 12 0.8 4 16 1.0 0 20 In this experiment the only variable that I change was the different concentrations. The variables that were all kept the same, were the length of the potato, the

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

    As it is soluble, it affects the osmotic balance of the cell by lowering the water potential. A potato, unlike an apple, is not a fruit - it is a tuba and its primary job is to produce runners so the plant can expand and produce more plants.

  1. Investigating the cellular water potential of potato cells.

    There was a choice of using Petri dishes, boiling tubes or glass beakers. I decided that Petri dishes were unsuitable as a lot of solution is needed in order to submerge the potato samples, also it would be very difficult to ensure that the potato samples did not come into contact with the surface of the Petri dishes.

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

    potato pieces, and making a record of the length to the nearest millimetre. And we will be using a very sensitive balance so that we can get the best readings possible. But I believe one of the most important step in the fair testing is to make sure that the potato is fully covered by the solution.

  1. To find out the effect of changing the concentration of different solutions in which ...

    As water has moved into the potato it will now have a larger mass. As the vacuole size will increase, the cytoplasm will push against the cell wall causing the potato to increase in height as well as feeling firmer.

  2. Investigating the Water Potential of Potato Cells

    I then put this potato piece into some sucrose solution. I found that a high water potential solution meant the potato was more firm so drooped less. It was therefore higher up the scale. When the water potential of the solution was low then the potato would become droopier and was therefore lower on the scale.

  1. Invetigation on osmosis in potato cores.

    The net (overall) result is that water enters the potato core. The potato core is likely to swell up and increase in mass. If the liquid is exactly the same water concentration as the cells in the potato core there will be no net movement of water across the cell membrane and no change in mass.

  2. An Investigation to determine the Water potential of Potato cells.

    Pressure potential is the amount added to water potential by pressure. By increasing the pressure in a cell its water potential is increased as the force of the water molecules on the plasma membrane is increased, making it more likely for them to travel out of the cell.

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