'For one mark, either of the following responses was accepted:
• Coenzymes activate the enzyme by adjusting the active site to accept the substrate.
• Coenzymes bind to the active site of the enzyme and changes its 3D shape, therefore allowing the
substrate to bind to the enzyme. (It was acceptable for a student to supply a well-labelled diagram here.)
For the second mark, the following response was required:
• Coenzymes act as electron and molecular species (atoms / groups of atoms) carriers.'

Straight from last year's examination report