Molecule
Organelles are of a level of organization smaller than a cell. Molecules are smaller than organelles.
The simplest level of organization as far as taxonomy goes would be the most inclusive one; a domain. If you are asking in terms of things such as organisms, it would be the smallest, the cell.
cell
The level of biological organization is composed of tissues is a organ. The smallest unit that has all of the characteristics of life is the cell.
cells
Organelles are of a level of organization smaller than a cell. Molecules are smaller than organelles.
The fourth level of cell organization is an organ system. The levels of organization are: Cell, Tissue, Organ, Organ system.
A cell.
cell
The cell which is the basic unit of life
Cell level
The lowest level is the cell.
The Biosphere!!
cell is the smallest level of organization in a unicellular organism
cell
cell
Think for a second there, if cells make tissues, than tissues make organs. Now the fourth level of organization will be that organs make the organ system.