Think about this!

Chemical reactions use catalysts too! Below is an example of a reaction that uses a potato as a catalyst. A potato is placed in a solution of hydrogen peroxide (H2O2). Potatoes contain an enzyme called catalase. Catalase breaks hydrogen peroxide down into water and oxygen. Oxygen bubbles can be seen forming on the potato.

It is similar to making a necklace with a needle and without a needle. The reaction goes quickly in the solution that is very near the potato, while the solution that is farther away from the potato goes slowly! The potato here was not used up during the reaction, so it can be used again for another reaction.