Name the process which causes water to be pulled upwards through xylem vessels from the roots to the leaves. How do the movement of water in a plant differ from the movement of food in it?

Answer

**Step-by-Step Solution:**

1. **Identify the Process:**
The process that causes water to be pulled upwards through xylem vessels from the roots to the leaves is called **transpirational pull**.

2. **Explain Transpirational Pull:**
Transpirational pull occurs when water evaporates from the leaves through small openings called stomata. This loss of water creates a negative pressure in the xylem vessels, which pulls more water up from the roots to replace the lost water.

3. **Movement of Water vs. Movement of Food:**
- The movement of water in a plant is **unidirectional**, meaning it flows in one direction—from the roots to the leaves.
- In contrast, the movement of food (which is transported through phloem) is **multi-directional**, meaning it can flow both upwards and downwards, distributing nutrients from the leaves to various parts of the plant.

4. **Summary of Differences:**
- **Water Movement:** Unidirectional (roots to leaves) via xylem.
- **Food Movement:** Multi-directional (from leaves to all parts) via phloem.

---