OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

At what temperature do human enzymes typically function best?

1. 37 degrees Celsius

2. 25 degrees Celsius

3. 50 degrees Celsius

4. 0 degrees Celsius

The correct answer is: 37 degrees Celsius

Human enzymes typically function best at around 37 degrees Celsius, which is the normal body temperature. At this temperature, enzymes can achieve optimal kinetic energy, allowing substrate molecules to effectively collide with the active sites of the enzymes. This enhances the rate of biochemical reactions, which is crucial for maintaining metabolic processes within the body. Enzymes are proteins that act as catalysts, and their activity is highly dependent on temperature. When the temperature is too low, the kinetic energy of the enzyme and substrate molecules decreases, leading to fewer successful collisions and a slower reaction rate. Conversely, at temperatures significantly above 37 degrees Celsius, enzymes can denature, losing their shape and functionality, which results in a decline in activity. Thus, 37 degrees Celsius strikes the right balance for optimal enzymatic activity in humans.