Advanced Placement (AP) Biology Practice Exam

What phase is referred to as the G0 phase?

1. A dividing state within the cell cycle

2. A nondividing state that has exited the cell cycle

3. The phase when chromosomes align in the middle

4. The phase where DNA is synthesized

The correct answer is: A nondividing state that has exited the cell cycle

The G0 phase is defined as a nondividing state that cells enter when they have exited the cell cycle. This phase can occur as a response to various signals that promote differentiation or when conditions are not favorable for cell division. Cells in the G0 phase are metabolically active but do not replicate their DNA or undergo division. This is important for maintaining cellular function and stability, particularly for specialized cells that do not need to divide frequently, such as neurons and muscle cells. In contrast to this, the other phases mentioned either involve active cell division or specific activities related to chromosome alignment and DNA synthesis, which are not characteristics of the G0 phase. Understanding the role of the G0 phase is essential, as it illustrates how cells can enter a quiescent state under certain conditions, allowing the body to regulate cellular proliferation effectively.