An RBC and a plant cell having same O.P. are placed in distilled water.

Options

A. None undergoes any change
B. Plant cell swells up and bursts but there is no change in RBC
C. RBC swells up and bursts but plant cell remains about the same size
D. Both decrease in size and collapse.

Answer

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- We have an RBC (Red Blood Cell) and a plant cell that both have the same osmotic potential (O.P.).
- Both cells are placed in distilled water, which is a hypotonic solution relative to the interior of the RBC.

2. **Analyzing the RBC**:
- Since the RBC is placed in distilled water, which is hypotonic, water will move into the RBC due to osmosis.
- The osmotic potential inside the RBC is higher than that of the distilled water, leading to water influx.
- As water enters, the RBC will swell. If too much water enters, the RBC will eventually burst (hemolysis).

3. **Analyzing the Plant Cell**:
- The plant cell also has the same osmotic potential as the RBC, but it is surrounded by a cell wall.
- When placed in distilled water, water will also move into the plant cell due to osmosis.
- However, the plant cell has a rigid cell wall that provides structural support. This means that while the plant cell will swell, it will not burst due to the pressure exerted by the cell wall (turgor pressure).

4. **Conclusion**:
- In summary, the RBC will swell and burst when placed in distilled water, while the plant cell will swell but remain intact due to its cell wall.
- Therefore, the correct answer is that the RBC swells up and bursts, while the plant cell remains about the same size.

### Final Answer:
- The correct option is: **RBC swells up and bursts, but the plant cell remains about the same size.**