ABSTRACT
Energy is introduced and dealt with systematically elsewhere (28). Here we focus on the energy metabolism of living organisms. Energy, which is informally defined as the ability to do work, is a key topic when considering life processes because all living organisms are working entities. We consider the different modes of energy acquisition and energy use by organisms, the various energy transformations involved and the chemical reactions that are associated with these transformations. This information will contribute to a better understanding of topics as diverse as the origin of life, the function of ecological systems, the productivity of the biosphere, the circulation of carbon and oxygen in the environment, and global warming.
