This concise A-level Biology nitrogen-cycle revision resource is designed to be used by students whose first language is not English. The most successful year 12 and 13 examination results are accomplished by a clear, accurate understanding and recall of scientific processes and by the correct interpretation of questions. Use this revision guide to successfully build new key science vocabulary. Academic English is introduced, explained and reinforced in questions, exercises and other activities. Use the examination strategies and tips given by this guide to help you answer multiple choice,comprehension and generic questions. You can then check your answers against the marking guidance provided for you. You will revise the role of nitrogen in:•Nitrogen-fixation. Access the details of nitrogen-fixing bacteria, the effect of lightning and the Haber process. •Nitrification. Unravel the differences between nitrification and nitrogen-fixation in the nitrogen-cycle. •Succession.•Denitrification.•Microbial saprobionts and decomposition. •Food chains. Read about how the nitrogen cycle changes nitrogen into compounds that living organisms can use. •Agriculture. Revise the advantages and disadvantages of organic and inorganic fertilisers.•Environmental issues. Understand the problems of sewage treatment, leaching, eutrophication and biochemical oxygen demand (BOD).