Enzymes are biological catalysts that significantly speed up chemical reactions by lowering the activation energy required for these reactions to occur. They achieve this by providing an alternative reaction pathway, thus increasing the rate at which substrates are converted into products. Enzymes are highly specific; each enzyme typically catalyzes a particular reaction. The efficiency of enzymes is influenced by factors such as temperature, pH, and concentration. Without enzymes, many vital physiological processes would occur too slowly to sustain life.