To find out how enzymes are affected by a variation in Temperature, the enzyme for the study is Catalase commonly found in potatoes. I will also find the optimum temperature of when the enzyme reacts quickest.

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Andrew Wright                5th Form Biology Coursework (Catalase)

Aim: To find out how enzymes are affected by a variation in Temperature, the enzyme for the study is Catalase commonly found in potatoes. I will also find the optimum temperature of when the enzyme reacts quickest.

Hypothesis: The hypothesis for this investigation is that when the temperature is increased, the amount of bubbles will increase in one minute so therefore the rate of reaction will increase. I believe this hypothesis to be true because of the collision theory that particles with more energy will move faster increasing the chance that a reaction will take place. Also the particles will have more energy so there will be more chance of the activation energy being reached. I also predicted that there will be an optimum temperature of around 40oC I predict this because body temperature is at about 37 oC. There will be an optimum temperature because enzymes denature at certain temperatures; denaturing is when the active site changes shape and the substrate cannot fit so it can be broken down. This is known as the lock and key theory. This causes that there is no reaction and no or very little bubbles will be counted. I predict the graph below will be obtained from the averages:

The reaction, which happens in the experiment, is

Hydrogen Peroxide + Catalase  Water + Oxygen

H202(brokedown by Catalase) H20 + 02

Research and Preliminary Work:

Definition of an Enzyme: an Enzyme is a Biological Catalyst, this means it is the same as a chemical catalyst which affects the rate of a reaction but is not affects consumed or changed but it is found in Biology.

Preliminary Work: I used my preliminary work to investigate the following aspects

  • Temperature range I would be using in the experiment.
  • The apparatus I would be using.
  • The amount of Hydrogen Peroxide I would need
  • How many segments of potato I would need.

I started by using a gas syringe but the gas produced (oxygen) did not have a high enough pressure so the syringe did not move so the volume of the oxygen could not be measured.

I then chose to bubble the gas produced, through water and count the bubbles I used a range of 20oC to 60oC, I found that the following results:

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  This showed me that this range is too low because there is no optimum rate of reaction so I chose to change the range to 20oC to 60oC at 10oC intervals so, as I would get an Optimum rate. I chose this rate based on that the human body is approximately 37oC.  

The preliminary work solved these issues:

Research: Catalase is an enzyme found in all living cells. It makes Hydrogen Peroxide decompose into water and oxygen.

The reaction in the experiment is affected by the following Variables:

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