What is the basic unit of life?

The cell is the basic unit of life because it is the smallest structure that can carry out all the functions essential for life. Cells are the building blocks for all living organisms and are capable of independent reproduction, metabolism, and response to environmental stimuli. In multicellular organisms, cells come together to form tissues and organs, but it is the cell that fundamentally fulfills the requirements necessary for life, such as energy production, waste elimination, and the ability to grow and replicate. In contrast, tissue represents a group of similar cells working together, organs are made up of different tissues working in concert, and systems consist of multiple organs that work together for a common function. Hence, the cell serves as the foundational unit upon which all biological organization is built.