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

How do enzymes in washing powders function best?

1. At high temperatures

2. At low pH levels

3. At moderate temperatures

4. At very high concentrations

The correct answer is: At moderate temperatures

Enzymes in washing powders function best at moderate temperatures because this range allows them to maintain their structural integrity and catalytic activity. Enzymes are proteins that are sensitive to temperature changes; excessive heat can denature the enzyme, altering its shape and reducing its effectiveness. Moderate temperatures provide the optimal environment for the enzyme's active site to effectively interact with and facilitate the breakdown of stains and dirt. Furthermore, enzymes have pH levels at which they work best, which is often neutral or slightly alkaline for many laundry applications, rather than low pH levels, which can impair their function. Additionally, while higher concentrations can enhance reactions up to a point, there is a limit to the efficiency gained from concentration increases, and very high concentrations do not necessarily translate to better performance in washing powders.