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

Investigate the effect of the concentration of the enzyme catalase on the decomposition of hydrogen peroxide.

Extracts from this document...


Helen Bewick 10C Investigate the effect of the concentration of the enzyme catalase on the decomposition of hydrogen peroxide. During my investigation I hope to find out if the concentration of the enzyme catalase will have an effect on the decomposition of hydrogen peroxide. I will do this by changing the surface area of a potato cube and reacting it with hydrogen peroxide. What are enzymes? Enzymes are proteins that are involved in every chemical reaction in living cells. Enzymes are biological catalysts that speed up reactions but do not get used up in the reaction. An enzyme has an active site that is specific to its substrate. The substrate fits into the active site where it is broken down. The lock and key diagram shown below illustrates this. Substrate fits into enzyme's specific active site. Enzyme breaks down substrate. In my investigation I will be using the enzyme catalase in a potato cube. Hydrogen peroxide is decomposed by the enzyme catalse into oxygen and water. The equation for the reaction is: Catalyses Hydrogen peroxide water + oxygen 2H2O2 (aq) 2H2O (I) + O2 (Equation source - Chemistry for You written by Lawrie Ryan) Prediction I predict that as the surface area increases, thereby increasing the concentration of catalase, oxygen will be produced more quickly as the rate of reaction will increase. As the concentration of catalase is increased the rate of reaction will increase because the collision theory states that in a higher concentration there is a larger number of particles in the same volume. For the particles to react with each other they need to collide. So in a higher concentration there will be more collisions, therefore there will be more successful collisions, which increases the rate of reaction. This means that in a higher concentration the number of enzymes will increase thereby increasing the number of active sites causing the hydrogen peroxide to be decomposed more quickly and produce oxygen more quickly. ...read more.


Equipment I will need to perform my investigation Equipment Reason for use Graduated test tube Enables me to measure the amount of oxygen released accurately. I could have used a measuring cylinder but it would be harder to turn it upside down because the entrance isn't thumb sized. I could have used a burette but it would be difficult to hold it upright because it is long. Delivery tube Collects all oxygen that is released. Measuring cylinder and pipette Accurately measures amount of hydrogen peroxide to the nearest cm3 Conical flask and bung Prevents any oxygen being lost during the reaction Scalpel and tile Enables me to increase the surface area of the potato without contaminating the potato. Stopwatch Allows me to accurately measure the time to a hundredth of a second. Water trough Allows me to use downward displacement of water to collect the oxygen produced during the experiment. Method When I am measuring the hydrogen peroxide I will make sure the measuring cylinder is on a flat level surface and measure to the bottom of the meniscus. The different surface areas I will be investigating will be 24cm2, 32cm2, 40cm2, 48cm2, 56cm2 and 64cm2. I have chosen to use 6 different concentrations of the enzyme catalase because I think that I will gain a range of results so that I can make a reliable conclusion. 1- I will ensure that all the apparatus is airtight and then I will set up the apparatus as shown below. 2- I will measure out 60cm3 of hydrogen peroxide into the conical flask. 3- I will fill the graduated test tube with water then turn it upside down with my thumb placed over the entrance whilst it is still emerged in water thus ensuring that no air bubbles are let into the graduated test tube. 4- I will place a 2cm3 potato cube into the conical flask. ...read more.


To prevent this I could use a wider conical flask so I could spread the potato out more so the pieces wouldn't stick together. * It was also difficult to cut a 2cm3 cube of potato 5 times so if I was to redo the investigation I would start with a larger cube maybe a 4cm cube. * One of the variables that affect enzymes is pH. Every enzyme has an optimum pH level at which it can bond best with its substrate. Any change in the pH level will denature the enzyme and change the shape of the enzyme's active site so it cannot bond as well with the substrate, which in this case is the hydrogen peroxide. A change in the pH could have reduced the rate of reaction and make my results unfair. I could improve the investigation by maintaining a constant pH using a pH buffer of pH 7. I would use a pH 7 buffer because this is equal to the natural environment of the enzyme in the potato tissue. I could extend my investigation by using higher concentrations of the enzyme catalase by increasing the surface area of the potato even more. If I did this I could find out at what concentration the rate of reaction is quick enough to decompose all the hydrogen peroxide. If I did this I could draw a graph more like my predicted graph. I could also extend my investigation by using a larger number of concentrations between those I have already recorded so I could draw a more accurate line of best fit. I used a potato as my source of catalase. The concentration of catalase could have changed in the different potatoes which would have made my results unfair. To make my investigation a lot more accurate I could use a 1 molar solution of the enzyme catalase instead of the potato cubes. I could have diluted the enzyme to create different concentrations. This way I could have measured the concentrations far more accurately and greatly reduce the chances of error in my investigation. ...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. To investigate the effect of enzyme concentration on the activity of catalase in potato ...

    because the amount of substrate is limiting the rate of the reaction. The substrate is the limiting factor but this did not occur in my experiment. The substrate was not a limiting factor. Another important trend that I analysed is that as the surface area increases so does the rate.

  2. A investigation into the effect of inhibitor concentration on the enzyme catalase.

    +3.48 330 +3.3 +3.96 360 +3.8 +4.56 390 +4.3 +5.16 420 +4.8 +5.76 450 +5.2 +6.24 480 +5.6 +6.72 510 +5.9 +7.08 540 +6.2 +7.44 570 +6.4 +7.68 600 +6.6 +7.92 Total Increase =+6.6 Total Increase =+7.92 0cm of Distilled Water 10cm of Lead Nitrate Solution TIME FROTH LEVEL VOLUME

  1. The aim of this experiment is to demonstrate that the substrate Hydrogen Peroxide will ...

    27.056965 6.5 1.5 5 x 1 27.056965 6.2 2.0 5 x 1 27.056965 6.0 2.5 5 x 1 27.056965 5.2 3.0 From these results, a graph can then be plotted with time (in 30-second intervals) on the x-axis and the volume of oxygen gas released on the y-axis (in cm3)

  2. Investigating the effect of enzyme catalase concentration on hydrogen peroxide.

    However, also I was worried about the fact that maybe as more and more potato strips were put in, maybe they would begin to obstruct each other and prevent bubbles from being released. Obtaining Evidence. Method: The first part of the experiment was to measure 10 ml of water, which

  1. Investigate the effect of enzyme concentration on the activity of catalase in potato tuber ...

    This should be changed to the nearest 0.1ml. Evaluating evidence: - Form doing my experiment I can conclude that I have no anomalous results. I think that the overall accuracy of the measurements was quite accurate. The volume of hydrogen peroxide was measured using a measuring cylinder to the nearest 1ml.

  2. Inhibition of the decomposition of hydrogen peroxide by the catalase enzyme using copper sulphate.

    The substrate no longer fits the active site and so is unable to be catalysed by the enzyme. Another situation that can arise from extreme pHs is the active site can become flooded with hydrogen or hydroxyl ions and this can prevent the substrate from fitting the active site.

  1. An Investigation into the effect of surface area on the activity of catalase in ...

    Other problems which I encountered, though not as dramatic or major, included reducing my volume of hydrogen peroxide used to 20ml from 100ml, because of the transaction from a conical flask to a boiling tube. However, after this adjustment I readjusted the measurement again to 15ml from 20ml, due to

  2. Investigating the Effect of Substrate Concentration on Catalase

    Control variables What they are Why they must be controlled In order to keep the temperature constant, the conical flask always will be kept on the table rather than the wooden part of the clamp (as the wood will have a higher temperature).

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