Root pressure generates
(i)Positive pressure
(ii)Push to water column in herbs
(iii)Ascent of sap In all trees

Options

A. A and B
B. B and C
C. A and C
D. A only

Answer

### Step-by-Step Solution:

1. **Understanding Root Pressure**:
- Root pressure is generated when various ions from the soil are actively transported into the vascular tissue of the roots. This process creates a concentration gradient.

**Hint**: Think about how solutes in the soil influence water movement in plants.

2. **Water Movement**:
- Water follows the concentration gradient created by the ions. As solutes accumulate in the root cells, water moves into the roots to balance the concentration, leading to an increase in pressure within the xylem.

**Hint**: Recall the principle of osmosis and how it relates to solute concentration.

3. **Positive Pressure Generation**:
- The increase in pressure inside the xylem due to the influx of water is referred to as root pressure. This pressure is positive because it pushes water upward.

**Hint**: Consider how pressure differences can cause movement in fluids.

4. **Push to Water Column in Herbs**:
- Root pressure is effective in pushing water upward in herbaceous (non-woody) plants, helping them maintain turgor and support.

**Hint**: Think about the structure of herbaceous plants and how they differ from woody plants.

5. **Ascent of Sap in Trees**:
- While root pressure contributes to the upward movement of water, it is not the primary mechanism in tall trees. The main force for the ascent of sap in tall trees is transpiration pull, which is a negative pressure created by the evaporation of water from the leaves.

**Hint**: Reflect on the role of leaves in water loss and how that affects water movement in the plant.

6. **Conclusion**:
- Therefore, root pressure generates positive pressure and provides a push to the water column in herbs. However, it does not contribute significantly to the ascent of sap in all trees, as that is primarily due to transpiration pull.

**Final Answer**: (i) Positive pressure and (ii) Push to water column in herbs are correct. (iii) Ascent of sap in all trees is incorrect.

### Summary of Correct Options:
- (i) Positive pressure: **True**
- (ii) Push to water column in herbs: **True**
- (iii) Ascent of sap in all trees: **False** (mainly due to transpiration pull)