Worried about your maternal effect or biological clock? Need to know a rhizoid from a rhizome? Think you're going to fail your zoology or botany exam? "The Penguin Dictionary of Biology" is your saviour, defining some 6000 terms relating to this rich, complex and constantly expanding subject - from amino acids, bacteria and the cell cycle to X-ray diffraction, Y chromosome, and zygotes. Long established as the definitive single-volume source, this dictionary is extensively updated for its eleventh edition.