Final answer:
An atom is the most basic unit of living and nonliving things.
Step-by-step explanation:
Living things are highly organized and structured, following a hierarchy that can be examined on a scale from small to large. The atom is the smallest and most fundamental unit of matter. It consists of a nucleus surrounded by electrons. Atoms form molecules, which are chemical structures consisting of at least two atoms held together by one or more chemical bonds.
Thus, an atom is the most basic unit of matter, fundamental to both living and nonliving entities. Comprising protons, neutrons, and electrons, atoms form molecules, the building blocks of all substances. Their interactions and arrangements determine the characteristics and properties of materials, influencing the complexity and behavior of entities in the universe.