What is the smallest unit of life?

The smallest unit of life is the cell. Cells are the basic building blocks of all living organisms, serving as the fundamental structural and functional units. Each cell can carry out essential life processes independently, such as metabolism, growth, and reproduction.

Cells can exist as single-celled organisms, like bacteria and some protozoa, or they can form complex multicellular organisms, like plants and animals, where they specialize into various types of tissues and organs that perform specific functions. Understanding that the cell is the smallest unit highlights its significance in biological organization, where higher levels, such as tissues, organs, and organisms, are built from aggregations and interactions of numerous cells.