What is the basic unit of all living things?

• A. Cell
• B. Atom
• C. Molecule
• D. Tissue

Answer: (A)

Understanding cells as the basic unit of life helps explain why this answer is correct. The cell is the smallest unit that can carry out all the processes needed for life, such as metabolism, growth, response to the environment, and reproduction. This idea comes from cell theory: organisms can be unicellular or multicellular, but in all cases, life arises from cells and their activities. Some organisms are just a single cell, while others are made of many cells that specialize and organize into tissues and organs. Atoms and molecules are the building blocks of matter, not living systems on their own, and tissues are groups of similar cells functioning together, representing a higher level of organization rather than the basic unit of life. So the cell is the fundamental unit that defines living things.