A parenchymatous cell of medullary ray in dicot stem which is in `G_(0)` start is called on to divide. At what stage it enters cell cycle.

Options

A. `G_(1)` -stage
B. `G_(2)` -stage
C. S-stage
D. M-stage

Answer

To solve the question regarding the parenchymatous cell of the medullary ray in a dicot stem that is in the G0 state and is called on to divide, we need to analyze the cell cycle stages and determine where the cell will re-enter the cycle.

### Step-by-Step Solution:

1. **Understanding the G0 Phase**:
- The G0 phase is a resting state where the cell is not actively preparing to divide. Cells in this phase can remain metabolically active but do not undergo division.

2. **Re-entering the Cell Cycle**:
- When a cell in the G0 phase is stimulated to divide, it re-enters the cell cycle at the G1 phase. This phase is crucial for the cell to prepare for DNA synthesis.

3. **G1 Phase Characteristics**:
- In the G1 phase, the cell grows in size, synthesizes mRNA and proteins, and prepares the necessary components for DNA replication. This phase is essential for the cell to transition from a quiescent state (G0) to an active state of division.

4. **Exclusion of Other Phases**:
- **G2 Phase**: This phase occurs after DNA replication (S phase) and is focused on preparing for mitosis. A cell cannot enter G2 directly from G0.
- **S Phase**: This is the phase where DNA replication occurs. A cell cannot skip directly to S phase from G0.
- **M Phase**: This is the phase of mitosis where the cell divides. A cell cannot enter M phase without first completing G1 and S phases.

5. **Conclusion**:
- Therefore, the parenchymatous cell in the G0 state will enter the cell cycle at the G1 phase when it is stimulated to divide.

### Final Answer:
The parenchymatous cell in the G0 state will enter the cell cycle at the **G1 phase**.

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