Mark the incorrect statement.

Options

A. Guttation is observed when root pressure is high and transpiration is low
B. Root pressure is a negative hydrostatic pressure
C. Root pressure develops due to active solute accumulation in root xylem
D. Root pressure provides only a modest push in the overall process of water transport

Answer

To solve the question of identifying the incorrect statement, we will analyze each statement provided in the question one by one.

### Step-by-Step Solution:

1. **Understanding Guttation**:
- Guttation is the process where water is exuded from the leaves of plants in the form of liquid droplets. This typically occurs when root pressure is high and transpiration is low.
- **Hint**: Remember that guttation is associated with liquid water loss, while transpiration involves vapor loss.

2. **Analyzing Root Pressure**:
- Root pressure is a positive pressure that develops in the xylem of roots due to the accumulation of solutes. This pressure helps in the upward movement of water and nutrients.
- **Hint**: Think about how solute concentration affects water movement in plants.

3. **Transpiration and Its Relation to Root Pressure**:
- Transpiration is the process of water vapor loss from plant surfaces, primarily through stomata. When transpiration is low, root pressure can lead to guttation.
- **Hint**: Consider the relationship between transpiration rates and root pressure.

4. **Evaluating Each Statement**:
- **Statement 1**: "Guttation is observed when root pressure is high and transpiration is low." - This statement is correct.
- **Statement 2**: "Root pressure is negative hydrostatic pressure." - This statement is incorrect because root pressure is a positive pressure, not negative.
- **Statement 3**: "Root pressure develops due to solute accumulation in root xylem." - This statement is correct.
- **Statement 4**: "Root pressure is responsible for pushing water up to small heights in the stem." - This statement is also correct.

5. **Conclusion**:
- The incorrect statement is the second one: "Root pressure is negative hydrostatic pressure."

### Final Answer:
The incorrect statement is: **"Root pressure is negative hydrostatic pressure."**