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

What is the primary consequence of an enzyme being denatured?

1. It can no longer bind substrates efficiently

2. It becomes a more effective catalyst

3. It can bind to multiple substrates

4. It resumes normal function immediately

The correct answer is: It can no longer bind substrates efficiently

An enzyme being denatured primarily means that its three-dimensional structure has been altered, which directly affects its functionality. Enzymes are proteins that rely on their specific shape to perform their catalytic functions. When an enzyme is denatured, often due to extreme temperatures or pH levels, the bonds that help maintain its structure break, leading to a loss of the precise shape required for substrate binding. As a result, the active site of the enzyme, which is the region responsible for binding to substrates, becomes distorted. This distortion prevents the enzyme from binding substrates efficiently, significantly impeding its ability to facilitate chemical reactions. Therefore, the primary consequence of denaturation is the enzyme's inability to interact with and act on substrates as it did before denaturation. This understanding highlights the critical nature of an enzyme's structure in maintaining its function, illustrating why option A accurately captures the primary consequence of an enzyme being denatured.