During the G\(_0\) phase of the cell cycle, what is the primary activity of the cell?

• A. The cell synthesizes spindle fibers for chromosome separation.
• B. The cell undergoes cytokinesis to produce two daughter cells.
• C. The cell exits the cycle and remains in a quiescent or non-dividing state.
• D. The cell actively replicates its DNA in preparation for mitosis.

Answer: (C)

Verified step by step guidance

1. Understand the context of the cell cycle: The cell cycle consists of several phases, including G\(_1\), S, G\(_2\), and M phases, which are involved in cell growth, DNA replication, and division. The G\(_0\) phase is a specialized state outside of this cycle.
2. Recognize the role of the G\(_0\) phase: The G\(_0\) phase is a quiescent or non-dividing state where the cell exits the active cycle. Cells in this phase are not preparing for division or actively replicating DNA.
3. Differentiate G\(_0\) from other phases: Unlike the S phase (where DNA replication occurs) or the M phase (where mitosis and cytokinesis occur), the G\(_0\) phase is characterized by cellular inactivity in terms of division. Cells may enter G\(_0\) due to differentiation or unfavorable conditions.
4. Clarify the incorrect options: The synthesis of spindle fibers for chromosome separation occurs during mitosis, not G\(_0\). Cytokinesis is part of the M phase, and DNA replication happens in the S phase. These activities are unrelated to the G\(_0\) phase.
5. Conclude the primary activity of the G\(_0\) phase: Cells in G\(_0\) remain metabolically active but do not divide. This phase is often associated with terminal differentiation or a temporary pause in the cycle, depending on the cell type.