Final answer:
The cell is the smallest living unit in all organisms.
Step-by-step explanation:
A living thing, whether made of one cell (like bacteria) or many cells (like a human), is called an organism. Thus, cells are the basic building blocks of all organisms. Cells are responsible for carrying out all the functions necessary for an organism to survive, such as obtaining nutrients, eliminating waste, and reproducing.
Additionally, cells are specialized to perform specific functions in multicellular organisms, such as nerve cells transmitting electrical signals or muscle cells contracting to produce movement. In summary, cells are the fundamental units of life and are essential for the structure and function of all organisms.