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

"Osmosis" - The Potato Experiment.

Extracts from this document...


GCSE Biology Coursework "Osmosis": - The Potato Experiment Background Information Osmosis can be defined as the movement of water across a semi-permeable membrane from a region of high water concentration to a region of low water concentration. The semi-permeable membrane allows small particles through it but does not allow large particles such as sodium chloride. Osmosis will continue until a state of equilibrium is reached i.e. there is no area with a higher or lower concentration than another area. To land plants, water and osmosis are vital as they play leading roles in the structural support of a plant. Lack of water will lead to a plant wilting (becoming flaccid) and possibly dieing. Osmotic pressure. If a plant was placed in a waterlogged area, where the external solute to the cell (being less concentrated (or hypertonic) to the cell vacuole contents) the cell will not continue to take in water via osmosis for ever. The cell wall made of cellulose acts as a firm barrier to any more expansion. Once the cell is full of water, it is said to be turgid. This means that the inward force is equal to that of the outward force. The inward pressure is called turgor pressure and the outward force is called osmotic pressure. ...read more.


Salt Solution For the solution. Distilled Water To be mixed with NaCl to make the correct molarity solutions. Test Tube Rack To Keep the test tubes in. Beakers For measuring the solutions. Plan 1. Bore 12 tubes of potato out of the same potato(being careful not to cross them) 2. Cut the ends of the pieces (as there is an impermeable skin layer, which if not removed could prevent osmosis and therefore make the experiment and unfair test) and cut them to the correct length. 3. Weigh each and record the weight in a results table. 4. using some sort of marking system mark one pair of each of the potato sticks as there will be two per test tube. 5. Mark each of the test tubes so you know which test tube holds what concentration of solution. 6. Make the sodium chloride solutions by adding varying amounts of sodium chloride to varying amounts of distilled water. The mounts are shown in the table below. Moles Distilled water /ml Sodium Chloride (NaCl) solution /ml 0 25 0 0.2 20 5 0.4 15 10 0.6 10 15 0.8 5 20 1.0 0 25 7. Place 2 pieces of potato in each test tube. ...read more.


This means that the potato. This means that the potato was turgid after the experiment. o Point B is the point of equilibrium meaning that there is no net movement in or out of the cell. This also means that the concentration of salt inside is equal to the concentration outside of the potato cells. o Between points B and C, there is net movement of water out of the potato as it has decreased in mass. Between the C and D and it is an almost horizontal line. This means that this is the point where all the water in the cells of the potato have moved out of the cell and there is no solute left to leave. The actual graph show the percentage gain and loss in mass plotted against the molar concentration of sodium chloride (NaCl). I have drawn a line of best fit onto the graph. The line is a negatively slopping curve. It doesn't pass through the origin, which means that the percentage gain and loss in mass and the concentration are not directly proportional to each other. However, there is a pattern on the graph. It shows the percentage gain and loss in mass is inversely proportional to the concentration i.e. as the concentration increases the percentage gain and loss in mass decreases. ...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

Here's what a teacher thought of this essay

4 star(s)

A sound investigation which could be improved with some simple scientific experimental procedure alterations.
1. Be clear of the aim of the investigation. It is clear that water will move in and out of the potato cell by osmosis, the aim of the experiment was to determine the solute concentration of the potato cell, which
was achieved. The conclusion should have focussed on this.
2. Try to avoid talking in first person throughout the paper instead of saying "I did this, then I did this..." write in third person i.e "Firstly the potato cylinders were added to the sodium chloride solution, they were then left for 24 hours..."
3. Be consistent with terminology. If you refer to the potato cylinders as cylinders at the start of the paper call it this throughout the paper.

Marked by teacher Jon Borrell 08/01/2013

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)

    This could have been affected by at what length they were cut. If they had a larger or smaller weight or length chances are that their surface area could have been larger or smaller as well. This means that osmosis would be able to occur more quickly in one potato piece compared to another as the surface area affects osmosis.

  2. Marked by a teacher

    Biology Coursework - Osmosis

    5 star(s)

    When plant cells are placed in a solution which has exactly the same osmotic strength as the cells they are in a state between turgidity and flaccidity. We call this incipient plasmolysis. "Incipient" means "about to be". When I forget to water the potted plants in my study you will see their leaves droop.

  1. Marked by a teacher

    An Experiment to determine Water Potential in Potato Tissue.

    4 star(s)

    Therefore as solute potential is the same as water potential when the pressure potential is zero the water potential also equals -540 Kpa. Evaluation As I mentioned in conclusion, the actual water potential of potato cell and my result was very different. I think this is caused by experimental errors.

  2. What is the difference in Vitamin C content between orange juice and orange squash?

    The results were taken 3 times for each liquid, in order to obtain the average amount of each liquid needed to decolourise the DCPIP solution. In doing this, I was able to conduct an accurate and fair experiment, in order for the experiment to be as accurate as possible, and for the results to be 'truthful', and fair.

  1. An experiment to investigate osmosis in plant tissue.

    0mls 16mls 1.0M Controlling Variables When conducting the experiment you must be very careful as to keep certain factors as constant as possible. In this experiment we are only intending to vary the concentrations of the solutions. To make the experiment as fair and as accurate as possible make sure you do the following: i.

  2. Estimate the concentration of the cytoplasm of potato cells.

    I predicted that there will be an increase in length of the potato chips in the salt solutions of lower concentration, as the concentration of the solution rises the change in length of the potato chips will decrease. Preliminary Results Concentration (Molar) Length at End (cm) Change in Length (cm)

  1. Efeects of Osmosis in Plant Cells

    Percentage Change in Mass (+ or -) 0.0 1 10.81 11.57 + 0.76 + 9.6% 2 10.84 13.04 + 2.16 3 9.82 11.08 + 1.26 4 10.82 10.62 - 0.15 Average 10.57 11.58 + 1.01 0.2 1 11.07 11.20 + 0.13 + 0.5% 2 10.00 9.81 - 0.19 3 10.65 10.80 + 0.15 4 10.79 10.92 +

  2. To investigate the factors that effect osmosis in living tissue.

    to which the membrane is impermeable or less permeable. As we are discussing osmosis with regards to plants, I believe it is necessary that we consider the structure of plant cells. A simplified drawing of a leaf palisade cell3 is illustrated below: Within the cell there are two selectively permeable membranes, "one lining the outer surface of the cytoplasm

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