What is considered the basic unit of all living things?

The cell is regarded as the basic unit of all living things because it is the smallest structural and functional unit of an organism. Cells are the building blocks of life, capable of performing all biological processes necessary for the organism's survival. Each cell can carry out vital functions such as metabolism, energy conversion, and reproduction.

While tissues are groups of similar cells that work together to perform a specific function, they are composed of multiple cells and therefore not considered the most fundamental unit. Similarly, organs are structures made up of different types of tissues that serve a specific function within an organism, and organisms themselves are the complete living entities that may consist of numerous cells organized into tissues and organs. Thus, while tissue, organ, and organism levels represent successive complexities, the cell remains the fundamental unit in biology.