ORGANISMS Definition: Anything that can live on its own Types of organisms: 1. Unicellular organisms 2. Multicellular organisms Unicellular organisms: Definition: An organism that is made up of only one cell Single celled organisms have all the characteristics of living things Unicellular organisms have a variety of functions depending upon the type of organism, but they generally need to synthesize all of the nutrients necessary for the cell to survive. Features: These organisms are very small and need to be seen with a microscope. The organism must carry out all of the life processes for the cell to function and reproduce itself. (e.g.: Feeding, locomotion, expelling waste and reproduction) All single-celled organisms contain every structure they need to survive within their one cell. Many one-celled organisms are resistant to extreme temperatures. Organisms made of one cell do not grow as large as organisms made of many cells. Single-celled organisms reproduce by a process called binary fission.