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

The basic unit of structure and function in all living organisms is the cell. Cells are often referred to as the "building blocks of life" because they are the smallest unit that can carry out all the processes necessary for life. Every organism, whether unicellular or multicellular, is composed of cells that perform essential functions including metabolism, growth, and reproduction.

In multicellular organisms, cells often specialize and become organized into tissues, which are groups of similar cells working together to perform a specific function. These tissues then form organs, and organs are arranged into systems to carry out complex functions. However, the fundamental level at which life operates is at the cellular level. Hence, focusing on cells provides the foundational understanding of biological processes.