AP BIOLOGY

Detailed explanation-1: -These cells that do not divide further exit G1 phase to enter an inactive stage called quiescent stage (G0) of the cell cycle. Cells in this stage remain metabolically active but no longer proliferate unless called on to do so depending on the requirement of the organism.

Detailed explanation-2: -If the cell reaches its ultimate stage of differentiation and will not divide anymore, the cell is said to be in phase G0 of the cycle. G0 applies also for the cells that have temporarily stopped dividing (Fig. 2-1).

Detailed explanation-3: -In the G0 phase, cells remain metabolically active but do not undergo any cell cycle. So, there is suspension for some time but not fully.

Detailed explanation-4: -Differentiated cells, those cells that have reached their mature and specialized forms, cannot exit the G0 phase. Their quiescence is said to be irreversible. These cells include heart muscle cells, blood cells, and neurons, as seen on the right in figure 3.

Detailed explanation-5: -Cells enter the G0 (inactive) phase after they exit the cell cycle when they are not actively preparing to divide; some cells remain in G0 phase permanently.