It is difficult for most plants to carryout photosynthesis in very hot, dry environments why ?

Options

A. Very intense light over powers pigment molecules
B. The closing of somata keeps away `CO_2` from entering and `O_2` from leaving plants
C. `CO_2` build up in the leaves , blocking carbon fixation
D. None of the above

Answer

### Step-by-Step Solution:

1. **Understanding Photosynthesis**:
- Photosynthesis is the process by which plants convert carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen (O2) using sunlight and chlorophyll. This process is essential for plant growth and energy production.

2. **Identifying the Conditions**:
- In very hot and dry environments, plants face extreme conditions that affect their physiological processes. High temperatures and low humidity can lead to water loss through transpiration.

3. **Role of Stomata**:
- Stomata are tiny openings on the leaves that allow for gas exchange. They enable the entry of carbon dioxide and the release of oxygen. However, in hot and dry conditions, plants often close their stomata to conserve water.

4. **Impact of Closing Stomata**:
- While closing stomata helps to retain water, it also limits the intake of carbon dioxide. Since carbon dioxide is a crucial ingredient for photosynthesis, its reduced availability hampers the process.

5. **Conclusion**:
- Therefore, in very hot and dry environments, the closing of stomata leads to a decrease in carbon dioxide concentration, making it difficult for most plants to carry out photosynthesis effectively. This is why the correct answer to the question is that the closing of stomata keeps away carbon dioxide from entering and oxygen from leaving the plants.