1. Cells: The basic unit of life. They carry out all the functions necessary for life.
2. Tissues: Groups of similar cells that work together to perform a specific function. Examples include muscle tissue, nervous tissue, and connective tissue.
3. Organs: Structures made up of different tissues that work together to perform a more complex function. Examples include the heart, lungs, and stomach.
4. Organ Systems: Groups of organs that work together to carry out major bodily functions. Examples include the digestive system, circulatory system, and respiratory system.
5. Organism: A complete living being made up of all the organ systems working together.
Let me know if you'd like more detail on any of these levels!
