• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13

Investigating how varying the concentration of substrate (hydrogen peroxide) affects the rate of reaction with the enzyme catalase.

Extracts from this document...


AS Level Biology Coursework Investigating how varying the concentration of substrate (hydrogen peroxide) affects the rate of reaction with the enzyme catalase. * Abstract of experiment I carried out the following experiment to investigate how varying the concentrations of hydrogen peroxide affects the rate of reaction with catalase in the form celery. I tested the rate of reaction at 5 different concentrations of hydrogen peroxide and found that the higher the concentration the faster the rate of reaction goes. The following write up explains my experiment in detail: * Aim In this experiment I want to look at how the concentration of hydrogen peroxide affects the rate of reaction with catalase. Here hydrogen peroxide is the substrate and catalase is the enzyme. * Introduction REFERENCES: Biology 1 Advanced Sciences http://gened.emc.maricopa.edu/bio/bio181/BioBk/BioBookEnzym.html. Enzymes are protein molecules that can be called biological catalysts. A catalyst is a molecule that speeds up a chemical reaction, the catalyst will remain unchanged at the end of the reaction. Metabolic reactions that occur in living organisms are catalysed by enzymes. Enzymes are globular proteins. The molecules are coiled into a precise three-dimensional shape, with hydrophilic R-groups on the outside of the molecules ensuring that they are soluble. The enzyme I will use in this experiment is catalase, it is found in food such as potato, celery and liver. Catalase works to remove hydrogen peroxide from cells. Catalase increases the speed of reaction that decomposes hydrogen peroxide and produces water and oxygen. Formula: Catalase Hydrogen peroxide Water + Oxygen 2H2O2 2H2O O2 The way catalase works to decompose hydrogen peroxide can be explained by the lock and key theory, like all enzymes, catalase has an active site. The active site of an enzyme is an area to which another molecule can bind. This molecule is called the substrate. It has a lock and key structure because the active site's shape allows the substrate to fit perfectly. ...read more.


At this point I needed to consider whether the amount of juice produced when the celery is mashed would affect the reaction rate. I found it difficult to measure the amount of juice the celery produced so to keep the experiment fair I will only use the solid mush not the juice. As my aim is to investigate how the concentration of substrate affects the rate of reaction I needed to chose the different concentrations of hydrogen peroxide that I would test. I carried out my preliminary experiment at different concentrations and have decided to use five concentrations of hydrogen peroxide. This will give me a wide range of results. I will use concentrations of 100%, 70%, 40%, 10% and 0%. In each case I will use distilled water to dilute the hydrogen peroxide. My 0% will be the control, it will be 5ml of distilled water. I am not expecting to see a reaction here. See table below to see amounts of hydrogen peroxide and distilled water to be used: Amount of hydrogen Amount of distilled peroxide (ml) water (ml) 100% 5 0 70% 3.5 1.5 40% 2 3 10% 0.5 4.5 0% 0 5 I will also carry out the experiment with 100% hydrogen peroxide on celery that has been in boiling water to see if that affects the rate of reaction. Here I would expect to see no reaction, as the celery would have been denatured by temperature. Another consideration I have taken into account is whether to use fresh celery each time or if it was all right to use frozen celery. I thought maybe freezing the celery would denature the enzymes but when I tested this, frozen celery produced a reaction, so I have decided to use the frozen celery and defrost it. This means I won't have to worry about getting fresh celery. After carrying out my preliminary experiment I have decided to do my experiment as follows: * Plan I will first set up the apparatus (listed before) ...read more.


Also the readings could be affected by my speed of reaction of reading off the measuring cylinder. > The precision of measuring the amounts of hydrogen peroxide, celery and water I used each time could have also affected my results, as it was difficult to be completely accurate. To make the measurements more accurate I could have used pipettes rather than pouring the hydrogen peroxide and water. I could also improve this experiment in the following ways: If I had the time I would do more repeats at each of the concentrations of hydrogen peroxide. This would make the average I took more accurate as it would mean errors, which could have been made in one experiment, would not affect the over all result so much. To improve the accuracy of reading the amount of oxygen given off at timed intervals, I could ask someone to start and stop the stop-clock and call out time intervals while I recorded the amount of oxygen given off at each time interval. This would mean my readings might be more accurate. Also to improve this experiment I should extend it to include more time intervals. I think if I had continued to take readings every 10 seconds for another minute it would have produced a better graph as my curve would have flattened off more as the solution became saturated. I could repeat this experiment for more concentrations of hydrogen peroxide so I could have more rates of reaction to compare. This would make my results more reliable. I conclude that my final conclusion is valid because the evidence shows that my prediction was correct. This is seen in my results, on the graph it shows that the 100% concentration of hydrogen peroxide has the fastest rate of reaction. I feel that any uncertainties play little affect in making my conclusion any less valid as they can be justified by the inaccuracies I stated at the start of this evaluation. December 2001 Elanor Parsons 1 1 ...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 Patterns of Behaviour 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 Patterns of Behaviour essays

  1. Factors Affecting the Rate of Catalytic Decomposition of Hydrogen Peroxide.

    particles - hence twice as many should occur. This should result in roughly double the rate of reaction. The relationship should be linear, and the line of best fit should go through the origin (0,0) as the hydrogen peroxide does not decompose when it is just sitting in a beaker with no catalyst.

  2. Effect Of Substrate Concentration On The Activity Of Catalase

    The reason that the number is less than two times could be put down to the fact that at 16% the Enzyme's active sites may already be close to being saturated with Hydrogen Peroxide. There may also be some experimental error which causes the inaccuracies.

  1. The Effect of Catalase in the Breakdown of Hydrogen Peroxide

    Tub Spherical, deep. Holds water while experiment occurs. The higher the volume of water put into the tub, the less of a chance that the burette can move and ruin the experiment (bubbles escape up the burette and change the reading). Delivery Tube Attached to the stopper (on the conical flask)

  2. How Concentration affects the rate of reaction.

    These reactants are acids, which means that they are irritants, corrosive and harmful. The product produced may be harmful if you inhale it so people with asthma should be careful. We also have to be careful when we are pouring the acids into the measuring cylinder and not onto our hands.

  1. The effect of aspirin on the action of bovine liver catalase

    in rate of reaction is -0.10, the percentage difference is -6%, so a variability of � 4.6% in the results for 20gdm-3 means that these results cannot be used to prove that there is a difference in rate of reaction between aspirin concentrations of 15gdm-3 and 20gdm-3.

  2. What Affects the Enzyme Catalase?

    This is because temperatures usually above 45O Celsius will damage the enzymes protein. Another factor which affects an enzyme is the PH of the substance. All enzymes have an optimum PH as well as an optimum temperature at which it will work best.

  1. How varying the concentration of Hydrogen Peroxide changes the rate at which an alginate ...

    I chose the two extremes and the middle amount of concentration of both water and hydrogen peroxide. I found that many of my beads floated when I used the yeast-alginate solution with a ratio 1:1. To prevent the beads from floating, I made the beads thicker by adding some extra alginate.

  2. Enzymes - show how substrate concentration affects the rate of reaction for an enzyme ...

    This is because a greater number of substrate will mean that there are more chances for a substrate to collide successfully with an enzyme in order to form a product. As result of this there is a greater rate of reaction which means that more products formed in a given time.

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