Introduction:Research Question:The purpose of this experiment is to investigate a factor affecting enzyme activity.
Hypothesis:A change in the pH of hydrogen peroxide will have an affect on enzyme activity.
Explanation of Hypothesis:Enzymes are catalytic globular proteins made by living things that regulate the movement of molecules through metabolic pathways, as well as speed up chemical reactions without being changed. They speed up metabolic reactions by lowering energy barriers. Catalyst is a chemical agent that changes the rate of a reaction without being consumed by the reaction (IB biology notes). Enzymes generally function best at a certain pH. The optimum pH changes depending on the enzyme in question. The enzyme experimented on in this experiment was the enzyme catalase, which works best at a pH of 7.0 (http://www.worthington-biochem.com/IntroBiochem/effectspH.html). If the pH of the substrate is changed even slightly the enzyme may become denaturation (IB biology notes). Denatuation is the changing of the structure of an enzyme so that it can no longer carry out its function, this is usually permanent (IB biology notes).
Variables:Dependent variable:Rate of catalase reaction when dropped into a clear vial containing 20ml of hydrogen peroxide at three different pH levels.
Independent variable:The pH of a 20ml clear vial of hydrogen peroxide.
Controlled variable:Temperature All tests were taken in the same room, at room temperature.
Time All tests were taken on the same day, in the same 90 minute lab session.
Light intensity All tests were taken under the same light intensity.
Concentration of solutions All three 20ml vials of hydrogen peroxide came from the same batch.
Source of biological material used All materials were taken from the same batch.
Total volume of reaction mixtureAll liquids were poured from the same 10ml graduated cylinder.
Materials:Notebook or scratch paperPen or pencil3 clear vials2 20ml hospital plastic cup100% Catalase...