Ascent of water and minerals through xylem in plants

Options

A. Always active
B. Mostly active
C. Always passive
D. Mostly passive

Answer

**Step-by-Step Solution:**

1. **Understanding the Ascent of Water and Minerals**: The ascent of water and minerals in plants refers to the upward movement of water and dissolved minerals from the roots to the leaves through the xylem tissue.

2. **Identifying the Mechanisms**: There are two primary mechanisms responsible for the ascent of water and minerals:
- **Root Pressure**: This is the pressure generated in the roots when they absorb water and minerals from the soil. The absorption creates a positive pressure that pushes water upward through the xylem.
- **Transpirational Pull**: This occurs due to the evaporation of water from the leaves through small openings called stomata. As water evaporates, it creates a negative pressure within the plant, which pulls more water up from the roots through the xylem.

3. **Analyzing Energy Requirements**:
- **Root Pressure**: This mechanism does not require any active energy input from the plant. It relies solely on the pressure created by water absorption, making it a passive process.
- **Transpirational Pull**: Similarly, this process also does not require energy from the plant. It is driven by the natural process of evaporation, which creates negative pressure, thus it is also a passive process.

4. **Conclusion**: Since both root pressure and transpirational pull are passive processes, the overall ascent of water and minerals through the xylem in plants is classified as a passive process. Therefore, the correct answer to the question is that the ascent of water and minerals through xylem is **always passive**.

**Final Answer**: The ascent of water and minerals through xylem in plants is **always passive**.

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