The factor that affects enzyme activity is temperature. Enzymes, which are biological catalysts, have optimal temperature ranges at which they function most efficiently. Deviations from this range can lead to decreased enzyme activity or denaturation, where the enzyme's structure alters, impairing its functionality. Other factors influencing enzyme activity include pH, substrate concentration, and the presence of inhibitors or activators. Understanding how these factors interact is essential for controlling biochemical processes in various applications, including industrial biotechnology and medical treatments.