Stomatal movement is not affected by

Options

A. `CO_(2)` concentration
B. `O_(2)` concentration
C. Light
D. Temperature

Answer

**Step-by-Step Solution:**

1. **Understanding Stomatal Movement**: Stomata are small openings on the surfaces of leaves that allow for gas exchange (CO2 in, O2 out) and transpiration (water vapor loss). The movement of stomata (opening and closing) is crucial for photosynthesis and respiration.

2. **Factors Affecting Stomatal Movement**: Several factors influence the opening and closing of stomata:
- **CO2 Concentration**: High levels of CO2 outside the leaf promote stomatal opening to allow for gas exchange.
- **Light**: Light is essential for photosynthesis, and the presence of light typically causes stomata to open to facilitate CO2 intake.
- **Temperature**: Higher temperatures can increase the rate of transpiration, leading to stomatal opening as the plant tries to maintain water balance.

3. **Identifying the Unrelated Factor**: Among the options provided (CO2 concentration, O2 concentration, light, and temperature), we need to identify which factor does not affect stomatal movement.
- **O2 Concentration**: While O2 is a byproduct of photosynthesis, it does not directly influence the opening and closing of stomata in the same way that CO2, light, and temperature do.

4. **Conclusion**: Therefore, the factor that does not affect stomatal movement is **O2 concentration**.

**Final Answer**: Stomatal movement is not affected by **O2 concentration**.

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