OCR GCSE Biology Practice Exam 2026 – Comprehensive All-in-One Guide to Exam Success

The term used to describe an enzyme's active site bonding to its substrate is best characterized by the Lock and Key Hypothesis. This concept illustrates that the enzyme and substrate have specific complementary geometric shapes that fit precisely together, much like a key fits into a lock. This model emphasizes the specificity of enzymes for their substrates, indicating that only the substrate with the correct shape can bind to the enzyme's active site, allowing the biochemical reaction to occur.

While other models, such as the Induced Fit Model, suggest that the active site of the enzyme can change shape to accommodate the substrate more snugly, the Lock and Key Hypothesis provides a straightforward illustration of the enzyme-substrate interaction based on pre-existing shapes. This foundational understanding of enzyme function is crucial in biochemistry, explaining how enzymes catalyze reactions efficiently and with specificity.