Which factor does not contribute to stomatal opening

Options

A. Light
B. Low pH
C. Reduced `CO_(2)`
D. Water

Answer

**Step-by-Step Solution:**

1. **Understanding Stomatal Function**: Stomata are small openings on the surface of leaves, primarily controlled by guard cells. Their opening and closing regulate gas exchange (CO2 and O2) and transpiration (water loss).

2. **Factors Influencing Stomatal Opening**:
- **Light**: Light is a crucial factor for stomatal opening. When light is present, particularly blue and red wavelengths, it stimulates the guard cells to absorb water, leading to turgidity and opening of the stomata. This is essential for photosynthesis, where CO2 is absorbed and O2 is released.

- **Reduced Carbon Dioxide**: When the concentration of CO2 is low, the plant needs to take in more CO2 for photosynthesis. This demand causes the stomata to open to allow more CO2 to enter, thus contributing significantly to stomatal opening.

- **Water**: The presence of water is vital for the turgidity of guard cells. When guard cells take up water, they swell and cause the stomata to open. Therefore, water is a significant factor in the process.

3. **Analyzing Low pH**: Low pH can influence stomatal behavior, but it does not have as significant an impact on stomatal opening compared to the other factors mentioned. While pH can affect the biochemical processes within the guard cells, it is not a primary factor that contributes to the opening of stomata.

4. **Conclusion**: Among the options provided (light, low pH, reduced carbon dioxide, and water), the factor that does not significantly contribute to stomatal opening is **low pH**. Therefore, the correct answer is option B.

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