What is considered the basic unit of structure and function in living organisms?

The cell is recognized as the basic unit of structure and function in living organisms because it is the smallest unit that displays all the characteristics of life. Cells are the building blocks of all living things and perform essential functions necessary for the organism's survival, such as metabolism, energy production, and reproduction. Each type of cell has specialized functions, such as nerve cells transmitting signals or muscle cells facilitating movement.

Tissues, which are made up of groups of similar cells that work together to perform a specific function, are one level of organization above cells. Organs are composed of different types of tissues working together to carry out complex functions, while organisms encompass entire living entities made up of multiple organ systems. Therefore, the cell serves as the foundational unit from which all higher organizational levels in biology are built.