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What factors will affect the rate of reaction of a controlled enzyme experiment?

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Jennifer Haselden 11G1 Mr. Griffin What factors will affect the rate of reaction of a controlled enzyme experiment? Variables which could affect my experiment are: * Amount of enzymes * Temperature * Amount of protein * Light * Sound * pH The variable I have chosen to change in my experiment is temperature. Prediction I predict that from 0�C to 40�C, the rate of reaction will increase as the temperature increases. As the temperature gets higher than 40�C, I predict the rate of reaction will decrease as the temperature increases. Scientific theory for my prediction Reactions between two substances occur successfully when the particles inside the substances collide with each other and break the bonds between them. This is the case with my experiment; the particles inside protein and pepsin need to collide and break the bonds in the protein, but to do this successfully the particles need energy. At higher temperatures, particles move faster and gain more energy, therefore collisions between the particles are more frequent and the reaction occurs quicker. This is the reason I predicted that as the temperature increases, the rate of reaction also increases. However, above a temperature of 40�C, this theory is not true. Enzymes are specific, which means they are adapted to a specific product, which they help to break down. ...read more.


I will ensure the experiment is a fair test by: * Keeping the amount of egg white used the same throughout the experiment. * Ensuring the same amount of pepsin and hydrochloric acid is used throughout the experiment. * Carrying out the experiment on the same day as the same equipment will need to be used. * Ensuring I record the time from when the black cross first becomes visible each time I do the experiment. I will use safety goggles as a safety precaution. Results Temperature of Time taken for water bath (�C) black cross to become visible (mins:secs) Secondary sources of information I used was Heinemann Co-ordinated Science by Richard Fosberry and Jean McLean. Jenny Haselden 11V1/11G1 - Biology AT1 Section B Results Experiment 1 Temperature Time taken for the solution to go clear (mins:secs) 5�C 11:36 12�C 1:28 34�C 00:28 50�C 4:21 69�C 6:56 80�C Hadn't turned clear after 15 mins Experiment 2 Temperature Time taken for the solution to go clear (mins:secs) 5�C 13:23 12�C 2:01 34�C 00:30 50�C 5:16 69�C 6:43 80�C Hadn't turned clear after 5 mins As it is difficult to obtain an average time, I calculated a total time for the two reactions: Temperature Total time for the two reactions (mins:secs) ...read more.


I do not think that my method was the most suitable as it was very difficult to obtain accurate results, ie it was difficult to assume when the reaction had taken place just by looking at how clear the solution was. Problems arose as many times the black cross being used could already be seen through the solution at the beginning of the reaction, even if the solution wasn't completely clear. If I was to repeat this experiment again, I could use the clear enzyme as a control to compare it with the reacted solution instead of the black cross method, to provide more accurate results. I would also use the egg white straight away and not let it stand around for as long, as this may affect the results. I would also keep the reactants in the water bath as the reaction is taking place, as allowing it to cool down may have affected the results. To extend my investigation I would try this experiment with different substrates, ie starch or carbohydrates and also with different enzymes to see if the same theory applies for them. I could also carry out the experiment at different temperatures to further extend my results and I could carry it out more times to ensure reliable results. 1 ...read more.

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