This human-biology study guide is one of a series written by experienced examiners and teachers to follow the demands of all GCSE syllabuses and Scottish Standard Grade. The series aims to present the important information in a clear and direct way, with the emphasis on improving study skills and exam performance. Topic-by-topic coverage is presented with many examples and diagrams, together with quick tests to check progress, and there is a bank of recent GCSE exam questions (with answers) to fine-tune exam technique.