With each step upward in the biological hierarchy, new properties emerge that were not present at the simpler organizational levels. Life is difficult to define because it is associated with numerous emergent properties that reflect a hierarchy of structural organization. Organisms are highly ordered, and other characteristics of life emerge from this complex organization. Growth and Development .
Heritable programs stored in DNA direct the species-specific pattern of growth and development.
Energy Utilization . Organisms take in and transform energy to do work, including the maintenance of their ordered state. Response to Environment . Organisms respond to stimuli from their environment. Organisms regulate their internal environment to maintain a steady-state, even in the face of a fluctuating external environment.