If `CO_(2)` concentration increases upto 0.05% the rate of photosynthesis -

Options

A. decreases
B. increases for short terms
C. first decreases and then increases
D. becomes zero

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**: Photosynthesis is the process by which plants convert carbon dioxide (CO₂) and water into glucose and oxygen using sunlight. The CO₂ is a crucial reactant in this process.

2. **Current CO₂ Levels**: The normal concentration of CO₂ in the atmosphere is approximately 0.03% to 0.04%. This is the baseline level that plants use for photosynthesis.

3. **Increasing CO₂ Concentration**: The question states that the CO₂ concentration is increased to 0.05%. This is slightly above the normal atmospheric level.

4. **Effect on Photosynthesis**:
- Initially, increasing CO₂ concentration can enhance the rate of photosynthesis. This is because higher CO₂ availability can lead to more carbon fixation in the Calvin cycle, which is part of the dark reactions of photosynthesis.
- Therefore, for a short term, the rate of photosynthesis will increase as plants utilize the additional CO₂.

5. **Long-term Effects**:
- However, if the CO₂ concentration remains elevated, it can lead to negative effects on the photosynthesis process. Prolonged exposure to high CO₂ levels can cause damage to the photosynthetic machinery in plants.
- Thus, while there is an initial increase in the rate of photosynthesis, this is not sustainable in the long term.

6. **Conclusion**: The correct interpretation is that the rate of photosynthesis will increase initially due to the higher CO₂ concentration but may lead to damage if maintained at that level for too long. Therefore, the answer to the question is that the rate of photosynthesis increases for a short term.

**Final Answer**: The rate of photosynthesis increases for a short term when CO₂ concentration increases to 0.05%.

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