At higher light intensities the rate of photosynthesis decreases because of -

Options

A. other factors becoming limiting
B. destruction/photoxidation of chlorophyll
C. Both (1) and (2)
D. carotenoids are killed

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**: Photosynthesis is the process by which plants, using chlorophyll, convert light energy into chemical energy. This process requires light, carbon dioxide, and water.

2. **Role of Light Intensity**: Initially, as light intensity increases, the rate of photosynthesis also increases. This is because more light energy is available for chlorophyll to absorb, which enhances the photosynthetic process.

3. **Limitations of High Light Intensity**: However, if light intensity continues to increase beyond a certain threshold, it can lead to negative effects. This is due to the fact that excessive light can damage the chlorophyll molecules.

4. **Chlorophyll Damage**: The damage to chlorophyll occurs through a process known as photo-oxidation. In this process, the high energy from the light can cause the chlorophyll to break down or become less effective, leading to a decrease in the rate of photosynthesis.

5. **Conclusion**: Therefore, at higher light intensities, the rate of photosynthesis decreases primarily due to the destruction of chlorophyll through photo-oxidation.

**Final Answer**: At higher light intensities, the rate of photosynthesis decreases because of the destruction (photo-oxidation) of chlorophyll.

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