What is the smallest unit of life?

The smallest unit of life is the cell. Cells are the fundamental building blocks of all living organisms, from the simplest single-celled bacteria to complex multicellular organisms like humans. Each cell is capable of performing essential life processes, such as metabolism, growth, response to stimuli, and reproduction.

While tissues, organelles, and organs play crucial roles in the structure and function of living organisms, they are not independent units of life. Tissues are groups of similar cells that work together to perform a specific function, organelles are specialized structures within a cell that carry out particular tasks (like mitochondria for energy production), and organs are composed of multiple tissues that collaborate to perform complex functions. Therefore, the cell stands out as the smallest entity that can carry out all of life's essential processes by itself.