A Level Biology Practice Exam

What role does catalase play when breaking down hydrogen peroxide?

1. It produces energy for cells

2. It converts it into water and oxygen

3. It enhances cell signaling

4. It synthesizes proteins

The correct answer is: It converts it into water and oxygen

Catalase is an enzyme that specifically facilitates the breakdown of hydrogen peroxide, a potentially harmful byproduct of cellular metabolism. In its action, catalase effectively converts hydrogen peroxide into harmless products: water and oxygen. This reaction is crucial because hydrogen peroxide is toxic and can cause cellular damage if it accumulates. By catalyzing this decomposition, catalase helps protect cells from oxidative stress and ensures their proper functioning. The other options do not accurately describe the primary role of catalase. For instance, while some metabolic processes involve energy production, catalase does not directly contribute to generating energy for cells. Enhancing cell signaling typically involves different mechanisms and molecules, while protein synthesis is a function associated with ribosomes and not catalase. Thus, the correct understanding of catalase's function lies in its ability to break down hydrogen peroxide into safe substances, reflecting choice B.