Biological organisation starts with
submicroscopic molecular level and passes through microscopic cellular level
and the microscopic or macroscopic organismic level. Finally it ends in
ecosystem and the biosphere. Thus, biological organisation shows the hierarchy
in organisation level from simple to more complex. The hierarchy in biological
organisation reveals that atoms are the lowest unit at the submicroscopic level
while the cells are the smallest unit at the microscopic level.
Atoms combine to form molecule which
undergo chemical reaction to form organelles of the cells. Several organelles
are contained in the cell. A group of cells which are similar and meant for a
specific function constitutes a tissue. Several tissues together contributing
to some specific function inside the body constitute an organ. Many organs
acting together to perform a specific life process constitute an organ system.
Several organ systems together constitute the organism. We see that several
systems are present in an organism and they are required to perform diverse
life process in a multicellular organism.
From lower organism to higher
organism life has passed through simple to complex structural hierarchical
level. The pictorial representation of biological organisation is shown in