A Level Biology Practice Exam

Which part of an enzyme allows it to bind specifically to a substrate?

1. Active transport

2. Active site

3. Allosteric site

4. Binding site

The correct answer is: Active site

The active site of an enzyme is a specific region where the substrate binds. This site is uniquely shaped to complement the substrate, allowing for a precise fit. The interaction between the enzyme and substrate at the active site is crucial for the enzyme's catalytic activity, as it facilitates the conversion of substrate to product by lowering the activation energy required for the reaction to occur. The unique structure of the active site, often determined by the enzyme's amino acid sequence, enables it to selectively interact with particular substrates, distinguishing enzymes from one another based on their specific functions. This specificity is vital for the proper functioning of metabolic pathways within living organisms, as enzymes catalyze countless biochemical reactions with high efficiency and precision.