Final answer:
The Go phase is a period where cells are quiescent and do not prepare for division, performing regular functions until either condition improves or they permanently remain inactive in the case of certain cell types.
Step-by-step explanation:
The quiescent period, often referred to as the Go phase, is a stage within the cell cycle where cells are not actively preparing for cell division. This phase is characterized by a state of inactivity; cells are still performing their normal cell functions but have not initiated preparations for DNA replication or division. Cells might enter the Go phase temporarily due to external factors such as nutrient availability or lack of growth factors. During this time, these cells can re-enter the cycle, starting with the G₁ phase, when conditions are favorable or upon receiving a proper external signal. However, certain cells, such as nerve cells and mature cardiac muscle cells, can remain in the Go phase permanently as they rarely or never divide.