Mike Boyle is Head of Biology at Cheadle and Marple Sixth Form College (one of the largest Sixth Form Colleges in the UK with over 2500 students). He is also a former examiner for AQA. Mike has 26 years' experience of teaching A-level and has written 12 successful A-level textbooks for HarperCollins and 4 GCSE textbooks. Kathryn Senior worked as a biomedical research scientist for five years before joining a scientific publishing company working on educational science textbooks. After four years in-house, she embarked on a freelance editing and writing career. In the last 15 years, she has written 10 popular science books for children. As an academic science writer, she also writes regular news articles and features for several journals, including The Lancet Infectious Diseases, The Lancet Oncology and Frontiers, the Journal of the Ecological Society of America and contributes research highlights articles to the various Nature Clinical Practice journals. Kathryn has also worked on writing projects for Macmillan Cancer Relief, the Physiological Society, the Guardian educational publishing division, the European Life Sciences Organisation, the European Commission and the BBC.