There are 8 levels of organization in biology: 1. Cells are the basic unit of structure and function. 2. Tissues are groups of cells that perform specific functions. 3. Organs are made of different tissues working together to perform functions like the heart. 4. Organ systems are groups of organs that work together, like the circulatory system. 5. Organisms are made up of all cells, tissues, organs and organ systems. 6. Populations are groups of the same type of organisms living together. 7. Communities are groups of populations that interact in an area. 8. Ecosystems are populations living together in an area.