DNA replicates-

Options

A. Only once in each cell cycle
B. Twice in each cell cycle
C. Once in mitotic cell cycle, once in meiotic I (Reductional division) and Once in meiotic II (equational division)
D. None of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Cell Cycle**: The cell cycle consists of several phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis or Meiosis). During these phases, the cell prepares for division and replicates its DNA.

2. **Identifying the S Phase**: The S phase is specifically where DNA replication occurs. This is the phase where the genetic material is duplicated, resulting in two identical sets of chromosomes.

3. **Recognizing the Importance of Interphase**: Interphase includes G1, S, and G2 phases. It is during this time that the cell grows and prepares for division. DNA replication only occurs in the S phase, which is part of interphase.

4. **M Phase Overview**: The M phase is where the actual cell division occurs, either through mitosis or meiosis. Importantly, DNA replication does not occur during this phase.

5. **Conclusion on DNA Replication**: DNA replicates only once during each complete cell cycle. This means that regardless of whether the cell undergoes mitosis or meiosis, the DNA will only replicate once in the S phase of interphase.

6. **Final Answer**: Therefore, the answer to the question "DNA replicates" is that it occurs once in each cell cycle, specifically during the S phase of interphase.