Life is difficult to define because it is associated with numerous emergent properties that reflect a hierarchy of structural organization. Other emergent properties emerge from this complex organization. Organisms reproduce . Organisms grow and develop . Heritable programs stored in DNA direct the species- specific pattern of growth and development.
Organisms take in and transform energy to do work, including the maintenance of their ordered state.
Organisms respond to stimuli from their environment. Life evolves in response to interactions between organisms and their environment. This leads to the concept of Holism The principle that a higher level of order cannot be meaningfully explained by examining component parts in isolation. An organism is a living whole greater than the sum of its parts. For example, a cell dismantled to its chemical ingredients is no longer a cell.