What is considered the basic unit of life?

The cell is considered the basic unit of life because it is the fundamental structural and functional building block of all living organisms. Cells perform essential life processes, including metabolism, growth, and reproduction. They can live independently, as in unicellular organisms like bacteria, or function as part of larger multicellular organisms where they collaborate to form tissues and organs.

Cells are equipped with the necessary machinery to carry out the functions that sustain life, including the ability to respond to environmental changes, maintain homeostasis, and ultimately contribute to the health and function of an organism. This central role underscores the cell's significance in biology, making it the cornerstone of the study of life.

In contrast, atoms are the smallest units of matter and do not possess the properties of life on their own. Tissues represent a grouping of similar cells working together for specific functions, while organs are composed of various tissues collaborating to perform complex functions, making them higher levels of biological organization rather than the fundamental units.