Hi Im Doing An Experiment On The Affect Of Ph On Enzyme Activity And The Enzyme Being Used Is Catalase. Ive Done Some Research And Found That The Optimum Ph Of Catalase Is 7 But Wen I Carried Out The Experiment It Was Found That Ph10 Produced Themost Bubbles Rather Than Ph 7. I Need Some Help Figuring Out Why This Is The Case Because Everything Was Kept Constant...

Urgh one thing you've got to learn about scientific experiments is that 90% of the time they just don't work like they are supposed to!

What did you use to pH the solutions? PH meters are notoriously dodgy- you look at them wrong and they change the reading. Also what temperature was the reaction carried out at? Was it room temperature because that can change a lot without you realising, especially if there was a lot of people in the room. Another thought is do you know the organism the catalase was fro because sometimes different homologues behave in a different way.

You can say you kept everything constant but it only takes one slip up to pipette too much enzyme into the solution. Even the best researcher in the world slips up occasionally.

What did other people in the lab find?

ohh we used a pH buffer solution =] and our catalase was from potatoes. We used a borer to prepare the potato and to make sure each was a certain length. Hmm we didn't measure the room temp so that was probablyone of the errors!

Ah if you were using a potatoes borer there is no way you can guarantee that each segment contained the same amount of enzyme- or if the enzyme was still active. All it would have taken is for one part of the potatoes to have been put next to a radiator or left out in the sun and that would have denatured the enzyme.

Also you don't know how the buffered solutions were made up or stored- anything could have happened to them.

It is extremely difficult to set up an experiment where every condition is kept constant.

If this is a high school report make sure you don't mention anything that could have gone wrong that is your fault. This is because you'll get great marks for your results and discussion but it could lower your marks for practical skills. Say something like you couldn't control the room temperature/ the measuring equipment could have been more accurate, rather than we didn't stir enough.

It's ridiculous but you've got to know how to play the game to get good marks.