The Earth is the only planet known to us where liquid water ─ the source of life ─ exists.
Every creature has its own metabolism, which is controlled via an information carrier – the genome. Living organisms are interlinked with their environment and can propagate.
The basic unit of all living organisms is the cell – an entity closed to the outside. Some living beings consist of an almost incredible variety of cells – humans, for example, of about 100 billions. Some organisms, however, consist of only one cell. All vital processes take place within this tiny cell.