Which one is responsible for opening of stomata ?

Options

A. Decrease in `CO_(2)` concentration and increase in `H^(+)` ion concenration
B. Decrease in `CO_(2)` concentration and decrease in `H^(+)ion` concentration
C. Increase in `CO_(2)` concentration and increase in `H^(+)` ion concentration
D. More free `H^(+)` ions and less `Cl^(-)ions.`

Answer

### Step-by-Step Solution:

1. **Understanding Stomata Function**: Stomata are small openings on the surface of leaves that allow for gas exchange (CO2 in, O2 out) and transpiration (water vapor loss).

2. **Factors Influencing Stomatal Opening**: The opening and closing of stomata are influenced by several factors including light intensity, carbon dioxide concentration, pH, and the concentration of hydrogen ions (H+).

3. **Role of Carbon Dioxide (CO2)**: A decrease in CO2 concentration inside the leaf is a significant factor that triggers the opening of stomata. When CO2 levels drop, the plant needs to take in more CO2 for photosynthesis.

4. **Role of Hydrogen Ions (H+)**: The concentration of hydrogen ions (H+) affects the pH level within the guard cells surrounding the stomata. A decrease in H+ concentration leads to an increase in pH (less acidic), which is conducive to stomatal opening.

5. **Conclusion**: Therefore, the combined effect of decreased CO2 concentration and decreased H+ concentration (leading to increased pH) results in the opening of stomata.

6. **Correct Answer**: The correct option that identifies the factors responsible for the opening of stomata is: **Decrease in CO2 concentration and decrease in H+ concentration**.