order the following statements so they represent the order of events that occurs as described by the flowing river model of stem-cell biology. tissue homeostasis (5 items) (drag and drop into the appropriate area) tissue-specific signals instruct cells to differentiate into specific cell types. stem cells become activated and undergo cell division. signals are received that indicate a need for additional cell types. new progenitor cells are generated to contribute to a growing cell population. the newly differentiated cells then contribute to the tissue, but they may be eliminated later as they age or become damaged.