The National Curriculum report on Science sets out Attainment Targets which bring new topics such as earth sciences, materials science, genetics, environmental science and history of science into the secondary syllabus. This book contains new material written to meet these targets. Whilst retaining entries on traditional biological topics such as cytoplasm, metabolism and species, entries on agriculture, environmental issues, mutagenic agents, protein synthesis and selection and breeding provide information relevant to the new demands of the National Curriculum. Also included are nine appendices which include information on topics which range from the classification of plants and animals to the units of measurement and symbols, and the geological time scale.