cells
Organisms are highly organized, coordinated structures that consist of one or more cells. Even very simple, single-celled organisms are remarkably complex: inside each cell, atoms make up molecules; these in turn make up cell organelles and other cellular inclusions. In multicellular organisms Figure 1.10 , similar cells form tissues. Tissues, in turn, collaborate to create organs body structures with a distinct function . Organs work together to form organ systems. Sensitivity or Response to Stimuli.