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

An Investigation into Osmosis.

Extracts from this document...


Year 11 Biology Coursework: An Investigation into Osmosis Introduction In this investigation, I am trying to find the answer to these two key questions below: 1 What are the factors that determine whether water moves in or out of the potato? 2 How does the concentration of a solution surrounding a cell affect movement in and out of cell across its semi- permeable membrane? In order to do this I will need to consider what osmosis is and make some experiments to help me investigate and find answers for the key questions. Background Information Osmosis is diffusion of water molecules moving from a particularly permeable membrane from a high concentration to a lower concentration. The water molecules can pass both ways through the membrane in two- way traffic, but there is a steady net flow of water molecules into the lower concentration of water. In figure 1 is a diagram showing how osmosis takes place. Figure 1 - What happens in Osmosis Osmosis is important for living things such as plant and animal cells. For animal cells they can easily burst if they take in too much water by osmosis as they do not have a cell all to contain it. However, for plant cells, osmosis makes them swell up when they are surrounded by weak solution and makes the flaccid cells to become turgid cells, this means that it gives the cells support to open the stomatal porb guard cells and to support the plant tissues. Leaves from plants are supported by the turgar pressure, without this, the plant will wilt and the leaves will droop, and plasmolysis will take place in the plant cells. Another plant cell that osmosis can affect is the root hair cell. The root cells are responsible to absorb minerals such as water from the soil fro growth. The concentration of minerals is higher in the root cell than in the soil, meaning osmosis of diffusion will not take place for the root to absorb the minerals. ...read more.


I will then mix into a test tube, thus keeping the same total volume of 10cm� in the mixture but changing its concentration. I chose to do 6 different concentrations as this will give me a more accurate result to compare with my prediction and the outcome of the investigation. The length of potato will be the same as I am not investigating the different length of potato and its effects on rate of osmosis, but I will need to keep in the same so that only the concentration is affecting the rate of osmosis, I will keep the potato at maximum of 2cm long, and the size of it will always be at whatever potato borer I use, so that only concentration and its effects on rate of osmosis is investigated and that all my tests are fair. In this experiment I will need to leave the potato for approximately 10 minutes so that osmosis can take place for fair amount of time, giving me an accurate and correct result. I will need to keep every reactions occurring in each test tube starting and ending at the same time, so that the rate of osmosis can be accurately recorded and are not anomalous and so that it will be a fair test. To calculate the change in mass, I will measure the mass of potato using an electronic balance before and after the osmosis reaction, the difference between them will help me to determine whether rate of osmosis in the potato with different concentrations, which also shows how much the potato, is saturated or unsaturated. To make the test fair I will try and keep the weight of the potato the same or very similar throughout the experiments, so that all conditions are the same except for concentration, so that I can investigate and analyse its effects on osmosis successfully. Another major issue that I need to take care of its keeping it a fair test by repeating the experiment more than once, ...read more.


should all be negative numbers as mass of potato should have decreased due to the osmosis theory, I found out that in experiment 2, the change in mass was +0.02 when it should have been a minus, there is no wrong calculations done, which means that there has been an error in concentration of the solutions used for 15% solution. In order to improve my overall results and make my results more reliable for my investigation, I will need to do the following: 1 Keep the temperature same throughout the experiment, as temperature increases it can give kinetic energy and cause an increase in rate of osmosis 2 How out the age of potatoes used and use the same potato throughout the experiment- the age of potato can affect the permeability of the membrane, thus affecting the rate of osmosis when water molecules passes through. 3 Do more number of the same experiments, this gives more results chance to ignore anomalous data when drawing a graph. 4 Make sure the volumes of the solution are exact and accurate from the cylinder before pouring it into a mixture; otherwise there may be different concentrations of solutions for a specific concentration, thus giving anomalous data and results. 5 The star and end time for osmosis should be exactly the same as best as possible in all experiments, therefore osmosis does not take place longer than needed 6 Weight the potatoes all together at the same time on individual electronic balance, so that osmosis does not take place to one potato while another potato is being weighed I might also investigate all the factors that will affect the rate of osmosis rather than just the concentration of the solutions, so I am able to contrast this data with other experiments, enabling to link different concepts and results together and give me a clear idea how much does each factor affects rate of osmosis, (i.e. investigating length of potatoes with different concentrations of solutions of at different temperature). ...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

    Biology Coursework - Osmosis

    5 star(s)

    Results: Table These tables show the results I got from my experiment: D/W Mass (g) Start Mass (g) End Total Change (g) Percentage Change(to 2dp) Observations Test 1 1.65 1.77 +0.12 +7.26 Turgid Does Not Float Test 2 1.52 1.64 +0.12 +7.89 Turgid Does Not Float Test 3 1.58 1.69 +0.11 +6.96 Turgid Does Not Float 0.25M Mass (g)

  2. Marked by a teacher

    An investigation into the factors affecting osmosis

    4 star(s)

    And that is why I am predicting that the weight of the potato in this experiment should be decreased by only a fraction. The 0.28 molar solution of sucrose, I think, should make a slight difference now, noting that it should be a small difference between the two concentration gradients.

  1. Marked by a teacher

    Science Coursework: Investigating Osmosis in potato tissue

    4 star(s)

    Then we added the salt to one of the solutions (2 spatulas worth) and sugar to another (2 spatulas worth). We then placed the potato in their respective solutions, and started the timer. After 10 minutes we took the pieces of potato out of the solution and weighed and measured them.

  2. Marked by a teacher

    What factors affect osmosis in potato cylinders?

    4 star(s)

    This is because there is a higher concentration of water in the boiling tube and a lower concentration of water in the visking tubing. The visking tubing then expanded because it was gaining water and turned turgid. In boiling tube B the water in the visking tubing will diffuse into the boiling tube containing sugar solution.

  1. Marked by a teacher

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

    3 star(s)

    IN MASS %CHANGE IN MASS 0.89g 0.91g 0.76g 0.74g -0.17g -18.68% 0.93g 0.75g 0.92g 0.75g 0.90g 0.71g 0.92g 0.73g INITIAL LENGTH AVERAGE INITIALLENGTH FINAL LENGTH AVERAGE FINAL LENGTH CHANGE IN LENGTH % CHANGE IN LENGTH 5.00cm 5.00cm 4.50cm 4.58cm -0.42cm -8.40cm 5.00cm 4.60cm 5.00cm 4.50cm 5.00cm 4.60cm 5.00cm 4.70cm Analyzing

  2. Experiment to Investigate Osmosis in Potatoes

    As it would be impossible to measure with any degree of accuracy the expansion or contraction of cells on an individual basis I have decided to look at gain or loss of water in terms of increase or decrease in mass.

  1. Osmosis investigation

    I had a choice between using boiling tubes or test tubes. I chose to use boiling tubes, as they are larger and allowed the 3 chips to have most of their surface area available for osmosis to take place, unlike test tubes, which are smaller. Precise and reliable measurements: 1.

  2. GCSE Biology What effects the rate of Osmosis

    - Although because there are more on one side than the other, there's a steady net flow into the region with fewer water molecules. This is how you take the Percentage increase = increase/ decrease in mass * 100 or decrease in mass of initial mass the potato chip Prediction

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