The components of organisms can be divided into smaller units to examine life on different levels of organization.
Atom
the smallest unit of a pure substance.
Example: Carbon
Molecules
combinations of atoms forming a structure
Example: Water
Organelle
cellular structures that carry out specific functions
Example: Mitochondria
Cell
the smallest unit of life
Example: Bacteria
Tissue
cells that work together to perform a function
Example: Muscle Tissue
Organ
tissues that work together to perform a function
Example: Heart
Organ System
organs that work together to perform a function
Example: Circulatory
Organism
a living thing composed of a cell or cells and possibly tissues, organs, and organ systems.
Example: Kangaroo
