Advanced Placement (AP) Biology Practice Exam

In which phase of the cell cycle do cells typically spend most of their time?

1. M phase

2. G1 phase

3. Interphase

4. S phase

The correct answer is: Interphase

Cells typically spend most of their time in interphase, which is the phase of the cell cycle that encompasses three distinct stages: G1 (gap 1), S (synthesis), and G2 (gap 2). During interphase, the cell is actively preparing for division, engaging in various vital processes such as growth, DNA replication, and synthesis of proteins necessary for cell division. Within interphase, the G1 phase is primarily focused on cell growth and metabolic activity, while the S phase specifically involves the replication of DNA. The G2 phase continues to support growth and prepares the cell for mitosis. The M phase, or mitotic phase, is significantly shorter than interphase and involves the actual process of cell division. Given that interphase is the longest phase of the cell cycle, it is the best answer for determining where most of the cell's time is spent. Therefore, the correct answer highlights the extensive duration cells remain in interphase compared to the other stages.