This PowerPoint presentation offers an in-depth look at enzymes, the biological catalysts essential for all metabolic reactions. It explains how enzymes function using the lock and key model, detailing the interaction between substrates and active sites. The slides also explore key factors influencing enzyme activity, including optimum temperature and pH, and demonstrate how these factors can lead to enzyme denaturation. A controlled experiment using amylase to break down starch illustrates these concepts in a practical, engaging way. Designed for IGCSE biology students and educators, this resource enhances understanding of enzyme kinetics and biochemical processes.