1. Cells: The basic, fundamental unit of life.
2. Tissues: Groups of similar cells working together to perform a specific function.
3. Organs: Structures made up of different tissues that work together for a common purpose.
4. Organ Systems: Groups of organs that cooperate to carry out major bodily functions.
5. Organism: A complete living being made up of multiple organ systems.
Example:
* Cell: A muscle cell
* Tissue: Muscle tissue (made of many muscle cells)
* Organ: Heart (made of muscle tissue, connective tissue, etc.)
* Organ System: Circulatory system (heart, blood vessels, etc.)
* Organism: A human (composed of all the organ systems)
