Biology Regents 2025 – 400 Free Practice Questions to Pass the Exam

The basic unit of life is the cell. Cells are the smallest structural and functional units of an organism, capable of carrying out all life processes. They perform essential functions such as metabolism, energy conversion, and reproduction. Organisms can be unicellular, consisting of a single cell, like bacteria, or multicellular, made up of trillions of cells organized into tissues and organs.

While organ and tissue represent groups of cells working together for a specific function, and molecules are the chemical compounds that make up cells, they do not define the fundamental unit of life. The hierarchy of biological organization emphasizes that cells are the foundational building blocks from which all living organisms are constructed. This establishes why the cell is recognized as the basic unit of life.