Multicellular organisms have division of labour. Explain.
Unlike unicellular cells which have only one cells that perform all the functions, multicellular organisms have many cells. In multicellular organisms the cells perform specific functions. All the cell performing similar function are organized into group to form tissues. This is called division of labour as different functions are performed by different group of cells. For example the nervous tissue conducts signals to all parts of the body while epitheliat tissur forms the covering of the body and provides protection.
Receptor molecules are specific proteins in the cell's plasma membrane that receive chemical signals from outside the cell. When such chemical signals bind to a receptor, they cause some form of cellular response.