Ontario Grade 12 Kinesiology Practice Exam 2025 – Your All-in-One Resource to Excel in Kinesiology!

Enzymes play a fundamental role in energy metabolism by acting as catalysts in biochemical reactions. Their primary function is to speed up the reactions that break down nutrients, such as carbohydrates, fats, and proteins, into simpler molecules. This breakdown process is crucial because it ultimately leads to the production of adenosine triphosphate (ATP), the energy currency of the cell.

During energy metabolism, enzymes facilitate the various steps involved in metabolic pathways like glycolysis, the citric acid cycle, and oxidative phosphorylation. Each of these pathways relies on specific enzymes to convert substrates into energy, ensuring that the processes occur efficiently and at a suitable rate for the body's demands.

The other options suggest alternative roles that do not align with the fundamental function of enzymes. While energy production can occur in both aerobic and anaerobic conditions, enzymes are not limited to one set of conditions and are essential in both contexts for various reactions. Enzymes do not function to store energy; instead, they assist in breaking down substrates to release energy as needed. Lastly, rather than increasing fat storage, enzymes mainly facilitate the metabolism of fats, allowing the body to utilize stored fat for energy when necessary. Therefore, the correct choice correctly highlights the vital catalytic role of enzymes in the breakdown of