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

What happens to enzyme activity as temperature increases?

1. Enzyme activity decreases significantly

2. Enzyme activity increases at first

3. There is no change in enzyme activity

4. Enzymes become inactive immediately

The correct answer is: Enzyme activity increases at first

As temperature increases, enzyme activity typically increases at first due to the increase in kinetic energy. This rise in temperature causes molecules to move faster, which leads to more frequent collisions between enzymes and substrates. This enhances the likelihood of complex formation and speeds up the rate of reaction, effectively increasing enzyme activity. However, this trend only continues up to a certain optimal temperature, which varies for different enzymes. Beyond this optimal point, enzyme activity can decline due to denaturation, where the enzyme's structure begins to break down, rendering it less effective or inactive. The correct understanding of this process highlights the importance of temperature as a factor in enzyme kinetics and emphasizes that while an initial increase in temperature boosts activity, it is important to remain within the optimal range to maintain functionality.