An AQA AS Biology Revision resource for Section 3 Exchange. The worksheet covers 5 sides of A4 and is closely matched to the specification. The students fill in the gaps to complete the sheet. A full set of answers is given on the last pages. I ask students to have their specification alongside as they complete the sheet so that they familiarise themselves with its content. Once completed it forms a useful revision summary sheet for the day before the exam. It is appropriate for both AS and A2 students. I have produce similar resources for other sections of the specification.