Advanced Placement (AP) Biology Practice Exam

In which phase are cells likely to be in a nondividing state?

1. G1 phase

2. G2 phase

3. M phase

4. G0 phase

The correct answer is: G0 phase

Cells are likely to be in a nondividing state during the G0 phase. This phase is often referred to as the resting phase where cells exit the cell cycle and do not actively prepare to divide. Cells in G0 may have temporarily stopped dividing but can re-enter the cell cycle under certain conditions, such as in response to growth factors or environmental signals. In contrast, during the G1 phase, cells are actively growing and metabolically preparing for DNA synthesis, making it a part of the dividing cycle. The G2 phase is also part of the cell cycle where cells prepare for mitosis, ensuring that they have all the necessary components for successful cell division. The M phase, which includes mitosis and cytokinesis, is the actual phase of cell division. Therefore, G0 is distinct from these other phases as it signifies a halt in the cell cycle and a nondividing condition.