This demonstration requires adult help. Never handle hydrogen peroxide without adult permission and supervision.
In this demonstration, we're going to learn about enzymes. An enzyme is a special protein that living organisms use to break down other molecules. Our stomachs have many enzymes used to break down the foods that we eat, for example.
Catalase is an enzyme present in almost all land-dwelling organisms. Its purpose is to break down harmful oxygen-related compounds into its harmless components. These harmful compounds are extremely greedy for electrons, and can end up stealing them from the molecules found in cells. Hydrogen peroxide (H2O2) is one of these harmful compounds––in fact it's often used to kill germs because it can do so much damage to cells.
Because yeast is one such land-dwelling organism, its cells contain catalase to protect against these harmful compounds. By adding yeast to H2O2, we're going to examine the chemical reaction that takes place as the catalase breaks down the hydrogen peroxide into harmless water and oxygen. This reaction is what's called an exothermic reaction because it releases energy in the form of heat.
Hmm... it seems nobody's added a conclusion for this experiment yet. You can suggest one here.