Which sequence correctly lists the organization of the human body from smallest to largest?

• A. Organ Systems, Organs, Tissues, Cells
• B. Cells, Tissues, Organs, Organ Systems
• C. Cells, Organs, Tissues, Organ Systems
• D. Tissues, Cells, Organs, Organ Systems

Answer: (B)

The concept here is how the body is built up from the smallest units to the largest. It goes from cells to tissues to organs to organ systems.

A cell is the basic unit of life. Similar cells group together to form tissues that share a common function. Tissues then come together to form organs, which have specific jobs in the body. Finally, organs work together as part of organ systems to carry out broad physiological tasks, like circulating blood or digesting food. That makes the sequence from smallest to largest: cells, tissues, organs, organ systems.

The other options misplace one or more levels. Starting with organ systems places the largest units first, which isn’t the smallest-to-largest order. Putting organs before tissues contradicts the idea that tissues are made of cells and thus come before organs. Beginning with tissues omits the fact that tissues themselves are built from cells, so it doesn’t start with the smallest unit.