In biological terms, which of the following is the smallest unit of structure and function?

The smallest unit of structure and function in biological terms is a cell. Cells are considered the basic building blocks of all living organisms. They are capable of performing all fundamental life processes, which include metabolism, energy conversion, and reproduction, thereby functioning as the smallest unit that can sustain life.

While tissues, organs, and organisms are essential biological structures, they are composed of multiple cells or groups of cells working together. Tissues comprise similar cells that perform a specific function, organs consist of different tissues working together, and organisms are entire living entities made up of multiple organ systems. Thus, the cell is the most fundamental unit in biology, as it represents the simplest structural and functional unit capable of independent life.