What is the number of light quanta required for the evolution of one `O_2` ?

Options

A. 8
B. 16
C. 24
D. 30

Answer

To determine the number of light quanta (photons) required for the evolution of one molecule of oxygen (O₂) during photosynthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photosynthesis**: Photosynthesis occurs in two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle). The light-dependent reactions are crucial for the production of oxygen.

2. **Role of Photosystems**: In the light-dependent reactions, there are two photosystems involved: Photosystem I (PSI) and Photosystem II (PSII). Each of these photosystems absorbs light energy to drive the process of photosynthesis.

3. **Photon Requirement**: For the evolution of one molecule of oxygen (O₂), we need to consider how many photons are absorbed by each photosystem:
- Photosystem II (PSII) requires 4 photons.
- Photosystem I (PSI) also requires 4 photons.

4. **Total Photon Calculation**: Since both photosystems are required for the complete process of oxygen evolution, we add the photons absorbed by both:
- Total photons = Photons from PSII + Photons from PSI
- Total photons = 4 (from PSII) + 4 (from PSI) = 8 photons.

5. **Conclusion**: Therefore, the number of light quanta required for the evolution of one molecule of oxygen is **8**.

### Final Answer:
The number of light quanta required for the evolution of one O₂ molecule is **8**.

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