Multicellular and unicellular organisms

Unicellular organisms are made of a single living cell. Multicellular organisms are made of more than one cell (sometimes millions), and different cells take on different jobs. In multicellular organisms, cells join together to form tissues with specific jobs. An organ is a group of tissues working together to do a specific job, and organs work together in an organ system. Unicellular organisms have different structures that have adaptations to help them function and stay alive.