This book describes the structures of plants and microorganisms and examines their life processes, from feeding and growth to reproduction. Plants are crucial to life on Earth, providing oxygen and food and regulating the climate. Microorganisms are too small to see with the naked eye, but these tiny life-forms are vital to Earth's ecosystems. This book also looks at the wide variety of fungi that are classed in their own kingdom and are neither animals, plants, nor bacteria. This series covers the fundamental life-science concepts of biology, ecology, evolution, genetics, cell biology, and life-forms, including humans. From the building blocks of cells and the basics of genetic theory through the structure, anatomy, and behavior of living organisms, this series tells the story of life in all its forms.