What is G₀ (quiescent phase) of cell cycle?
Some cells in adult animals do not appear to exhibit division, such as heart cells, while others divide only occasionally to replace cells lost due to injury or death. These cells that do not divide further exit the G₁ phase to enter an inactive stage called the 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. This phase serves as a resting period where cells pause their cycle rather than preparing for division.
Explanation
The textbook defines the G₀ phase as an inactive stage entered by cells that exit the G₁ phase. It highlights that these cells (like heart cells) do not divide further but remain metabolically active. The answer is derived directly from the section discussing cells that do not exhibit division in adult animals.