Properties Of Living Organisms
A capacity for evolution
A capacity for self-replication
A capacity for growth and differentiation via a genetic program
A capacity for self-regulation, to keep the complex system in a steady state (homeostasis, feedback)
A capacity (through perception and sense organs) for response to stimuli from the environment
A capacity for change at the level of phenotype and of genotype
SOURCE: Ernst Mayr, This is Biology: The Science of the Living World (1997).