Energy source responsible for upward flow of water is:
(a) sun energy
(b) artificial light
(c) sucrose
(d) ATP

Options

A. sun energy
B. artificial light
C. sucrose
D. ATP

Answer

To determine the energy source responsible for the upward flow of water in plants, let's analyze the options provided:

1. **Understanding the Process**: The upward movement of water in plants primarily occurs through a process called transpiration. Transpiration is the loss of water vapor from the aerial parts of the plant, mainly through small openings called stomata.

2. **Role of Sun Energy**: The energy from the sun plays a crucial role in this process. When sunlight heats the leaves, it increases the temperature, which in turn raises the rate of transpiration. As water evaporates from the leaf surface, it creates a negative pressure within the plant's xylem vessels.

3. **Transpirational Pull**: This negative pressure, known as transpirational pull, is what helps to draw water upward from the roots through the xylem. The cohesion between water molecules and adhesion to the xylem walls also aid in this upward movement.

4. **Evaluating Other Options**:
- **Artificial Light**: While artificial light can influence plant processes, it is not the primary energy source for transpiration in natural conditions.
- **Sucrose**: Sucrose is a form of sugar and does not provide energy for the upward movement of water.
- **ATP**: ATP (adenosine triphosphate) is the energy currency of cells but is not directly responsible for the upward flow of water in plants.

5. **Conclusion**: Based on the analysis, the correct answer is (a) sun energy, as it is the primary energy source that drives the transpiration process, leading to the upward flow of water in plants.

**Final Answer**: (a) sun energy

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