Root pressure does not take an active part in the ascent of sap because

Options

A. it is not found in all the plants and water can rise in the absence of roots .
B. it is seen during most favourable periods like spring or rainy season.
C. it is never found to exist in the plants .
D. (1) and (2) are correct.

Answer

To answer the question "Root pressure does not take an active part in the ascent of sap because," we can analyze the options provided and the concept of root pressure in plants.

### Step-by-Step Solution:

1. **Understanding Root Pressure**:
- Root pressure is the pressure exerted in the xylem of plants, primarily due to the active uptake of water and minerals by the roots. This pressure can push water upward through the plant.

2. **Analyzing the Options**:
- **Option A**: "It is not found in all the plants and water can rise in the absence of roots."
- This statement is true. Root pressure is not present in all plants, especially in woody plants where other mechanisms (like transpiration pull) are more significant for the ascent of sap.
- **Option B**: "It is seen during most favorable periods like spring or rainy season."
- This statement is also true. Root pressure tends to be higher during periods of high soil moisture, such as spring or rainy seasons, but this does not mean it is the primary mechanism for sap ascent.
- **Option C**: "It is never found to exist in the plants."
- This statement is false. Root pressure does exist in certain plants, particularly herbaceous ones.
- **Option D**: "1 and 2 are correct."
- Since both statements 1 and 2 are correct, this option is valid.

3. **Conclusion**:
- The correct answer is **Option D**: "1 and 2 are correct." This indicates that root pressure does not play a significant role in the ascent of sap because it is not present in all plants and is more effective during specific favorable conditions.