Which of the following contributes most to transport of water from the ground to the leaves of a tall tree?

Options

A. Breakdown of ATP
B. Capillary rise of water is xylem
C. Cohesion of water and transpiration pull
D. Root pressure.

Answer

To determine which factor contributes most to the transport of water from the ground to the leaves of a tall tree, we can analyze the provided options step by step:

### Step-by-Step Solution:

1. **Understanding Water Transport in Plants**:
- Water is primarily transported in plants through specialized tissues called xylem. The movement of water from the roots to the leaves is crucial for the plant's survival.

2. **Evaluating the Options**:
- **Option A: Breakdown of ATP**:
- ATP (adenosine triphosphate) is the energy currency of the cell, but it does not directly contribute to the transport of water in the xylem.
- **Option B: Capillary Rise of Water in Xylem**:
- Capillary action does help in the movement of water, but it is not the main driving force for the transport of water in tall trees.
- **Option C: Cohesion of Water and Transpiration Pull**:
- Cohesion refers to the attraction between water molecules, which helps maintain a continuous column of water in the xylem. Transpiration pull occurs when water evaporates from the leaves, creating a negative pressure that pulls more water up from the roots. This is indeed the most significant factor in the transport of water in tall trees.
- **Option D: Root Pressure**:
- Root pressure can contribute to water movement, but it is generally more significant in smaller plants and does not have as much impact in tall trees.

3. **Conclusion**:
- After evaluating all options, the correct answer is **Option C: Cohesion of water and transpiration pull**, as this mechanism is the most effective in transporting water from the ground to the leaves of a tall tree.

### Final Answer:
**C: Cohesion of water and transpiration pull**

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