• 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

Biology Coursework-Osmosis

Extracts from this document...

Introduction

Biology Coursework-Osmosis Aim To find out what effect altering the concentration of sucrose solution would have on the occurrence of osmosis in a potato. Prediction I predict that as the concentration of the sugar solution around the potato decreases, the size of the potato will increase. I have come to this conclusion due to the previous work we have done on osmosis. So, if we put a potato in a 2M concentration of sucrose it would decrease in size, whereas if we were to put it in a 1.5 M concentration it would not decrease as much in size as the one in 2M concentration. Essentially what I am saying is that as the concentration increases, so will the amount of mass lost by the potato. I feel that nearer the extremes of concentration the results will be more closely grouped. Reason Osmosis is a process in which water moves through a partially permeable membrane. It will move from a higher concentration of water to a lower concentration. For example:- if there was one side of a partially permeable solution with 8/10 parts water and the other side was 4/10 parts water, the side with 8/10 would flow from its higher concentration to the lower concentration in an attempt to even out the concentration on both sides. The reason the water molecules are able to pass through and even out the concentration is that they are small enough to fit through the membrane whereas the sucrose molecules are too large to fit through. Below is a diagram to show osmosis across a partially permeable membrane: Due to the water molecules being smaller than the sugar molecules, they are able to fit through into the cell. ...read more.

Middle

Evidence I measured 5 different concentrations of solutions to make sure that I got a meaningful set of results. I feel that taking 5 different concentrations was varied enough to get a fair set of results due to my preliminary work. Also testing it three times allowed me to identify any anomalies that may have occurred and consequently take them in to account. Accuracy The way I have ensured maximum accuracy is to use 25ml measuring cylinders and made sure not to contaminate all the equipment. Also, and most crucially, I am repeating the experiment 3 times so as to obtain maximum accuracy and then taking an average figure. Recording Evidence I think that a clear and concise way would be to put them in a table such as the one shown below:- SEE TABLE ON NEXT PAGE m Volume (ml) Volume of water (ml) Volume of sucrose (ml) Initial mass (g) After mass (g) Change in mass (g) Average change in mass (g) % difference average % difference 2 20 0 20 1.90 0.91 -0.99 -52% 2 20 0 20 1.89 0.82 -1.07 -1.02 -56% -54% 2 20 0 20 1.87 0.865 -1.01 -54% 1.5 20 5 15 1.90 1.13 -0.77 -40% 1.5 20 5 15 1.922 1.11 -0.81 -0.79 -42% -41% 1.5 20 5 15 1.93 1.14 -0.79 -40% 1 20 10 10 1.94 1.58 -0.36 -18% 1 20 10 10 1.87 1.49 -0.38 -0.36 -20% -19% 1 20 10 10 1.90 1.56 -0.34 -18% 0.5 20 15 5 1.94 1.99 0.05 0.02% 0.5 20 15 5 1.87 1.97 0.10 0.08 0.05% 0.04% 0.5 20 15 5 1.90 2.01 0.11 0.05% 0 20 20 0 1.86 2.20 0.34 18% 0 20 20 0 1.88 2.29 0.41 0.36 21% 19% 0 20 ...read more.

Conclusion

One way to avoid this would be to use complicated machinery to weigh and cut the potato; although beneficial, this wasn't practical. So just taking extra time and care with the cutting would make it more accurate. I could have done more work. I could have done the experiment more times to gain a more accurate result . Also I could test more of a range of concentrations - again to obtain a more accurate result. Also I could experiment with exposing the same weight pieces , but with different surface areas. This would be interesting to do. The results were perhaps a bit undetermined here and there. I think this could have been from one, if not more of the above factors. If I was to repeat the experiment again then I would go to a higher concentration to see what happens in relation to the cell wall. And exactly how much osmosis is able to occur and what would happen to the cell and its wall when it reached the limit. The reason I would do this as I think it would be both interesting and beneficial to see what the capabilities of the cell and its cell walls were. Also if I were to do it again I would test more values of concentration. For example I tested 0,0.5,1,1.5,2. Then I would go in to more values like 0,0.25,0.5,0 .75,1, 1.25.....etc. The reason for this is I feel it would provide me with more accurate results to base my graph and theories on. Also I would like to see how the surface area would affect osmosis. This is because I feel that it would be interesting to know what affect it has and to compare it to the other set of results I obtained. ?? ?? ?? ?? ANDREW DUNCAN 10P BIOLOGY MRS HUGHES OSMOSIS COURSEWORK ...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)

    this one was left on the side longer or maybe the solution was contaminated by a slightly stronger one. However, I do not believe that one anomaly is significant, so long as you have done plenty of retests to expose any outliers so you do not include them in graphs.

  2. Marked by a teacher

    Photosynthesis Coursework

    4 star(s)

    and the boundaries for the measurements, this experiment was not in itself in my opinion accurate enough to be the basis of my main experiment. This lack of accuracy was mainly due to the fact that by simply counting the bubbles, I was relying on each bubble being exactly the same size, which they clearly were not.

  1. Marked by a teacher

    Biology Coursework

    3 star(s)

    Cells in the body have 23 pairs of chromosomes. Half inherited from each parent. The structure of DNA is double helix (too long) and it is made up of bases, phosphates and pentose sugar. Bases are units of genetic code, they pair with complimentary base pairs (held together by base pairs: Cytosine (Casey)

  2. Marked by a teacher

    Biology Coursework - Osmosis

    3 star(s)

    The 0.6 molar solution of sodium chloride, I think, should make a big difference now, noting that it should be a large difference between the two concentration gradients. And therefore the weight should decrease by not too much, but still noticeably.

  1. Marked by a teacher

    Osmosis Coursework

    3 star(s)

    It can move out because the plant's cell membrane is permeable to water, and will continue to do so until the concentration of water inside and outside the cells are equal. The plant loses some of the water, which was in it, and the cell contents shrink away from the cell wall.

  2. Osmosis Coursework

    This can be seen in living cells. The cell membrane in cells is semi-permeable and the vacuole contains a sucrose solution. So when a cell is placed in high water concentration water will move across the membrane into the cell where it's in a lower concentration by osmosis, making the cell swell.

  1. Free essay

    Osmosis Coursework

    Surface Area - The surface area is the area of surface around the potato chip. The larger the surface area the faster the rate of osmosis. This is because there are more molecules that are exposed to diffuse in comparison to the molecules in a smaller surface area.

  2. Osmosis Coursework

    of the solute potential and the pressure potential.* Turgidity If you put a plant cell into a weak solution (sometimes called a hypotonic solution)* the water potential inside the cell will be smaller than the water potential in the solution.

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