What is correct

Options

A. DNA content becomes double during `G_(1)`-phase
B. Duration of interphase is short as compared to M-phase
C. `G_(2)`-phase follows mitotic phase
D. DNA-replication occurs in S-phase

Answer

To determine which statements about the cell cycle are correct, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding the Cell Cycle Phases**:
- The cell cycle consists of several phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).
- G1 phase is where the cell grows and prepares for DNA replication.
- S phase is where DNA replication occurs, resulting in doubled DNA content.
- G2 phase is where the cell prepares for mitosis.
- M phase is where actual cell division occurs.

2. **Analyzing Each Statement**:
- **Statement A**: "DNA contents become double during G1 phase."
- **Analysis**: This statement is incorrect. DNA content does not double during G1; it remains the same until the S phase when DNA replication occurs.

- **Statement B**: "Duration of interphase is short as compared to M phase."
- **Analysis**: This statement is also incorrect. Interphase (G1 + S + G2) typically lasts much longer than the M phase. Interphase can take about 20-21 hours, while M phase lasts about 1-2 hours.

- **Statement C**: "G2 phase follows mitotic phase."
- **Analysis**: This statement is incorrect. The G2 phase follows the S phase, not the M phase. The correct order is G1 → S → G2 → M.

- **Statement D**: "DNA replication occurs in S phase."
- **Analysis**: This statement is correct. The S phase is specifically designated for DNA replication, where the DNA content doubles.

3. **Conclusion**:
- The only correct statement among the options is **Statement D**: "DNA replication occurs in S phase."

### Final Answer:
The correct statement is: **DNA replication occurs in S phase.**

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