Which sequence correctly lists the biological organization from smallest to largest?

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

Answer: (D)

From smallest to largest, the sequence goes: cells, tissues, organs, organ systems, organism. Cells are the basic units of life that perform the essential tasks of living things. When similar cells team up, they form tissues that specialize in particular functions. Different tissues come together to create organs, which are structures that carry out specific tasks necessary for the body. Organs that work together in a coordinated way make up organ systems, handling major life processes like digestion or circulation. All of the organ systems together comprise the organism, the complete living being. This order makes sense because each level builds on the one before it, with increasing complexity and specialization.