A Level Biology Practice Exam

What is the primary function of enzymes in biological systems?

1. To act as energy sources

2. To lower the activation energy of chemical reactions

3. To provide structural integrity to cells

4. To transport molecules across membranes

The correct answer is: To lower the activation energy of chemical reactions

The primary function of enzymes in biological systems is to lower the activation energy of chemical reactions. Enzymes are biological catalysts that speed up chemical reactions by providing an alternative pathway with a lower activation energy. This means that reactions can occur more quickly and efficiently at the temperatures typically found in living organisms. By lowering the activation energy, enzymes enable metabolic processes to proceed at rates sufficient for life, allowing cells to carry out essential functions such as digestion, energy production, and biosynthesis of molecules. Moreover, enzymes are highly specific, meaning that each enzyme catalyzes only a particular reaction or type of reaction, further optimizing the biochemical processes in living organisms. The other options do not accurately represent the primary function of enzymes. While energy sources, structural integrity, and transport mechanisms are vital functions in biological systems, they are not the role enzymes play in facilitating chemical reactions.