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

To observe the effect of varying salt concentrations outside plant tissue and how water movement by Osmosis is affected.

Extracts from this document...

Introduction

Aim: To observe the effect of varying salt concentrations outside plant tissue and how water movement by Osmosis is affected. Theory: Diffusion occurs from an area of high concentration to an area of low concentration. This results in a homogeneous distribution. This can be related to Osmosis in plants, as water will move from a less concentrated area to a more concentrated area. This occurs through a semi-permeable selective membrane. All plants have a Semi-permeable membrane and it is normally called the cell membrane. This means that the membrane surrounding the plant will let water through either way to balance the ratio of, e.g. salt. But nothing else can pass through the membrane apart from water because other molecules are too large to pass through. This process will continue as long as there is an imbalance in the concentration of the substance, e.g. salt. In plants, the wall of cellulose surrounds the cell membrane. The cellulose has no osmotic properties. It is freely permeable to all liquid and dissolved substances but the fact that it stretches very little limits the size to which plants cells can swell when they take in water by osmosis. If you have a solution A that is stronger than B that means A is hypertonic to B, B is hypertonic to A and if they are equal in strength they are isotonic. ...read more.

Middle

I will then use a knife/blade to cut the potato cylinders to exactly 20mm using a mm ruler. I will then mix the solutions up. To do this I will get the 20% salt solution (already mixed up) and put it into a measuring cylinder of 20cm3. I will then measure it up to 10cm3 and add water to the 20cm3 mark. This will make a 10% salt solution. I will keep doing this until I get a 5,10,15 and 20% solutions. These will be held in beakers and the solution at 20cm3. I will then put the potato cylinders into the different solutions and leave them for 2 hours. After 2 hours I will take the potato cylinders out of the solution, dry the surface with a paper towel and use the mm ruler to measure the lengths. I will do this three times with two batches of 20mm potato cylinders and one batch of 30mm potato cylinders. To plot the graph I will need the differences of weights/lengths. So, I will add the three values up for the start weight/length and divide by three. I will do that for the end weight/length as well. I will then subtract the average start weight/length from the end weight/length. Obtaining evidence: Table for the weight of potato core: Weight at start (g) ...read more.

Conclusion

I could extend the experiment to a more exact level by looking at the potato cylinders under a microscope, and then I would be able to see the cells in greater detail and draw some more observational results. If I were to find out more about osmosis I would do a demonstration of how +osmosis works more clearly. I would use Visking tubing to replace the plant cell wall and fill it with a sugar solution - Glucose. This is because the Visking tubing has tiny little holes in like a semi-permeable membrane. I will then place the tube in a beaker containing pure water. Diagram: Pure water Visking tubing containing Glucose Because there are more glucose molecules in the Visking tube, the water molecules pass through the semi-permeable membrane to 'dilute' the sugar concentration. There is a net flow of water molecules into the Visking tubing. The water molecules can travel both ways through the membrane. The Glucose cannot diffuse into the water because the molecules are too big to fit through the semi-permeable membrane. This causes the Visking tubing to fill up with water. Eventually the tubing will become so full up that it will burst. Graphs for the two experiments A graph to show the how the changing concentration of salt solution affects its mass in g A graph to show the how the changing concentration of salt solution affects its length in mm ...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)

    * In the preliminary the experiment was not repeated so if something had gone wrong there was nothing for it to be compared to. This made it difficult to point of anomalous points. Therefore in this experiment I will repeat it so that it is a reliable experiment.

  2. Marked by a teacher

    An experiment to investigate how the effect of varying concentrations of salt solutions play ...

    4 star(s)

    After twenty-four hours the results will be recorded and the apparatus would be washed and cleared METHOD > A range of salt solutions will be prepared from 0 MOLAR to 2 MOLAR > Using a cork borer I shall cut out potato tissue from the potato itself, five potato cylinders are required so the experiment can proceed.

  1. Marked by a teacher

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

    4 star(s)

    Using potato tubes is also very useful because they are solid and visible cells that won't dissolve or fall apart in water. I also feel that the method is very safe, though wearing safety glasses and hand protection will be a safety precaution when using the scalpel as it is very sharp and could easily jerk when cutting the potato.

  2. Factors Affecting Osmosis In Plant Tissue

    The PH can be kept constant easily by using the same neutral solutions throughout. Finally time of the experiment will for as long as possible, bearing in mind on the schedule of lessons. The time of the experiment needs to be as close to twenty-four hours as possible for an outlook of osmosis in a day.

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

    However, as water moves out of the cell (i.e. in solutions with a lower water potential) the cell wall ensure that the cell does not completely shrivel up. We can therefore say that water potential in a plant cell = solute potential + pressure potential.

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

    Even if this was happening, drying to the same extent made sure that the same thing happened to all the other chunks too. These 'possible errors' were discovered in a previous experiment done in class, therefore allowing modifications in the method to be made to get fair and true results.

  1. Lab Research Paper. Just a Pinch of Salt and a Dash of Bacteria: the ...

    This leads us to the question, which bacteria, E. coli 101 or Bacillus subtilis, can withstand higher concentrations of salt? A probable answer to this question would be that if there is a very high concentration of salt, then instead of inhibiting bacterial growth, it will help the bacteria, specifically E.

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

    4. Leave for 24 hours. 5. Remove samples; wipe off excess water on dry tissue paper. 6. Immediately re-weigh the samples and record the results. Number and Range: There will be 7 different molarity levels 0, 0.5, 0.1.15, 0.2, 0.25, and 0.3. The results will also be taken five times per molarity level and an average taken this will help reduce anomalous results.

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