Since publication this outstanding textbook has been widely adopted throughout the words. This third edition has been written to reflect the latest developments in the subject and the new specifications for GCSE Science: Biology; the biology section of GCSE Science: Double Award; and equivalent examinations. Amendments have been made through the text and the illustrations to fulfill these aims. In particular: - there is additional information on topics such as clinical trials, B and T lymphocytes, infertility, performance-enhancing hormones, fluoridation of water supplies, impact of hunting and over fishing, global warning, biofuels and global travel and disease - a new chapter on Applied Genetics draws together and expands the information on selective breeding, genetic engineering, cloning, genetic fingerprinting and the human genome project - a new chapter on Conservation covers extinction, conservation of species, conservation of genes, conservation of habitats and conservation of resources - a revised chapter on Ecosystems includes information on adaptations and factors which affect communities - past examination questions have been updated - there is a new chapter on the development of biological ideas, and the principal contributions to these ideas from Galen, to Watson and Crick - a new final chapter on observation and experiment looks at the type of questions that can be investigated scientifically and the nature of evidence