What is the basic unit of structure and function in living organisms?

The basic unit of structure and function in living organisms is the cell. Cells are the smallest units of life, capable of carrying out all the processes necessary for an organism's existence. They can perform vital functions such as metabolism, energy production, and reproduction. Each cell can carry out these functions independently, which is essential for the survival of multicellular organisms as well.

For example, in multicellular organisms, cells can work together to form tissues, which then combine to create organs, but it is the cell that serves as the fundamental building block of all life forms. Without cells, there would be no tissues, organs, or systems, as they are all composed of cells. This concept underscores the importance of cells in biology and their role as the foundational elements of living organisms.