A single-celled organism floats freely and lives independently. Its single cell is able to carry out all the processes of life without any help from other cells.
• A biofilm is a thin layer of bacteria that sticks to a surface. Cells in a biofilm are all alike, but they may play different roles, such as taking in nutrients or making the "glue" that sticks the biofilm to the surface. The sticky plaque that forms on teeth is a biofilm of bacterial cells.
• Some single-celled organisms, such as algae, live in colonies. A colony is an organized structure composed of many cells, like the Volvox sphere in Figure 3.21. Volvox are algae that live in colonies of hundreds of cells. All of the cells in the colony live and work cooperatively. For example, they can coordinate the movement of their flagella, allowing them to swim together through the water as though they were part of a single organism.
A multicellular organism consists of many cells and has different types of cells that are specialized for various functions. All the cells work together and depend on each other to carry out the life processes of the organism. Individual cells are unable to survive on their own.
i got this off of quizlet so i hope this helps you. Also this isnt plagarizim bc i gave you where i got it from.