Question

Examine the following chemical reaction, which is catalyzed by the enzyme catalase:



What molecule is catalase breaking down in this reaction?

A. O2
B. H2O2
C. H2O
D. There are no molecules in this reaction

Answer 1

First off, quick definition: molecules = a group of atoms/elements (not just a single element like "O" or "H", so all of these are molecules in this problem and we can instantly rule out answer choice D).

In this problem, your given chemical equation. The reactants (starting materials) are on the left side of the arrow (→). The products (finishing materials) are on the right side of the arrow. Sometimes special reactants (like enzymes i.e catalase) are written over top of the arrow instead of on the left side of the arrow.

Anyways, we can read this reaction like this:

- Start out with 2 molecules of $H_{2}O_{2}$

- Add Catalase

- End up with 2 molecules of $H_{2}O$ (water) and 1 molecule of $O_{2}$ (oxygen)

Therefore, catalase must helped break down the bigger $H_{2}O_{2}$ molecules into the small "building block" molecules of $H_{2}O$ and $O_{2}$.

***SEE PIC FOR VISUAL...if you want. This always helped me. You can see easier that the bigger molecules are being broken down into multiple smaller ones***

Correct Answer: B