DNA replication is found in :-

Options

A. Mitosis and meiosis-I
B. Mitosis and meiosis-I and meiosis-II
C. Meiosis only
D. Mitosis only

Answer

To determine where DNA replication occurs, we need to analyze the different phases of the cell cycle and the processes of mitosis and meiosis. Here’s a step-by-step solution:

### Step-by-Step Solution

1. **Understanding DNA Replication**: DNA replication is the process by which a cell makes an identical copy of its DNA. This occurs during the S phase of the cell cycle.

2. **Identifying the S Phase**: The S phase, or synthetic phase, is part of interphase, which precedes both mitosis and meiosis. During this phase, the DNA is replicated to ensure that each daughter cell will have a complete set of chromosomes.

3. **Mitosis and Meiosis Overview**:
- **Mitosis**: This process involves one round of cell division and occurs after the S phase. Therefore, DNA replication must have occurred before mitosis.
- **Meiosis**: This process consists of two rounds of cell division (meiosis I and meiosis II). DNA replication occurs before meiosis I during the S phase.

4. **Analyzing the Options**:
- **Option 1**: Mitosis and Meiosis I - This is correct because DNA replication occurs in the S phase before both processes.
- **Option 2**: Mitosis, Meiosis I, and Meiosis II - This is incorrect because there is no DNA replication before meiosis II.
- **Option 3**: Meiosis only - This is incorrect as DNA replication also occurs in mitosis.
- **Option 4**: Mitosis only - This is incorrect as DNA replication also occurs in meiosis I.

5. **Conclusion**: The correct answer is **Option 1: Mitosis and Meiosis I**.