What is the basic unit of life?

The basic unit of life is the cell. Cells are the smallest structural and functional units of living organisms. All life forms, from the simplest bacteria to complex multicellular organisms like humans, are composed of cells. They perform essential functions such as metabolism, energy transformation, and reproduction. Cells can exist as independent organisms, such as unicellular organisms, or combine to form more complex structures in multicellular organisms.

Understanding that cells are the foundational units of life helps clarify the distinction between the other options. Atoms are the building blocks of matter but do not exhibit the characteristics of life on their own. Organs are composed of multiple types of tissues working together to perform a specific function, and tissues are groups of similar cells that work together for a particular task. Therefore, while atoms, tissues, and organs are important in biology, they do not represent the most basic unit of life, which is the cell.