A Level Biology Practice Exam

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What is the primary function of catalase in biological systems?

To catalyse the formation of hydrogen peroxide
To catalyse the breakdown of glucose
To catalyse the breakdown of hydrogen peroxide
To facilitate cellular respiration

The correct answer is: To catalyse the breakdown of hydrogen peroxide

Catalase plays a crucial role in biological systems primarily by catalyzing the breakdown of hydrogen peroxide into water and oxygen. This enzyme is essential because hydrogen peroxide is a byproduct of various metabolic reactions and can be harmful to cells if not regulated. By facilitating its decomposition, catalase helps protect cells from oxidative damage, maintaining cellular health and integrity. The other options focus on functions that catalase does not perform. For example, catalase does not catalyze the formation of hydrogen peroxide; rather, it acts on it. The breakdown of glucose is generally the function of different enzymes like hexokinase and phosphofructokinase, not catalase. Similarly, while cellular respiration is crucial for energy production, it primarily involves other enzymes and processes, such as glycolysis and the citric acid cycle, rather than the specific action of catalase.