Answer:
In biological system, cell is known as the basic unit of all organisms. Unicellular organism consist of one cell only but that single cell helps them to perform all the functional activity.
Levels of organization in biological systems is defined as the hierarchy of several components from smallest to complex in biological system.
Cell is one of the important part of Levels of organization in biological systems, as in multicellular organisms group of cells form tissue that create an organ and many organs together form organ system within an organism. The cell is basic unit in all organisms and without a cell, an organism can not develop.
The group of these organism formed from a small cell then form complex component of Levels of organization such as population, community, ecosystem and Biosphere (in sequential order).