Levels of Organization
1. Cells: The basic units of life. Each cell has a different size for the jobs they do.
red blood cells
2. Tissues: group of similar cells that work together to do a specific job in the body.
3. Organs: made up of two or more tissues to do a specific job.
Examples: heart, lungs, and liver
4. Organ Systems: Human organ systems
Examples: circulatory, reproductive,digestive
5. Organisms: Sum of all cells, tissues, organs, and organ systems makes and organism.