1. cell
2. organ system
3. tissue
4. organ
What is cell?
"A cell is defined as the smallest, basic unit of life that is responsible for all of life's processes.” Cells are the structural, functional, and biological units of all living beings. A cell can replicate itself independently. Hence, they are known as the building blocks of life
What defines an organ system?
An organ system is defined as a group of organs that work together to perform bodily functions. For example, the organs in the gastrointestinal (GI) system each play a unique, important role in food digestion.
Learn more about organ system here
https://brainly.com/question/545314
#SPJ2
