Final answer:
The smallest independently functioning unit of biological structure in the human body is a cell, which is the fundamental unit of life in all living organisms.
Step-by-step explanation:
The smallest level of organization within the human body is the cell. A cell is the smallest independently functioning unit of a living organism. Even single-celled organisms, like bacteria, are made up of one cell which contains all of the necessary components to be considered living. Within the human body, cells play a vital role as they make up all of the tissues and organs that allow the body to function.
Starting from the smallest levels, human body organization progresses through several stages: from chemical building blocks like subatomic particles and atoms to molecules and organelles, and then to cells. Cells then combine to form tissues, tissues come together to form organs, and organs are organized into organ systems, which work together to form a complete human organism.
The study of these structural levels contributes to understanding human anatomy and the complex processes that take place within us. Therefore, when asked about the basic unit of life in biology or human anatomy, the answer would be a cell.