Discovery of Emerson effect has already shown in existence of

Options

A. photorespiration
B. photophosphorylation
C. light and dark reactions
D. two distinct photochemical reactions

Answer

**Step-by-Step Solution:**

1. **Understanding the Emerson Effect**: The Emerson effect refers to the phenomenon observed in photosynthesis where the rate of photosynthesis increases when plants are exposed to light of two different wavelengths, particularly when red and far-red light are used together.

2. **Identifying the Key Components**: The Emerson effect indicates that there are two distinct reaction centers involved in the process of photosynthesis. These are known as Photosystem I (PSI) and Photosystem II (PSII).

3. **Explaining the Role of Reaction Centers**: Photosystem I is primarily responsible for the light-dependent reactions that produce NADPH, while Photosystem II is involved in the splitting of water molecules and the production of ATP. The interaction between these two systems enhances the overall efficiency of photosynthesis.

4. **Conclusion**: Based on the understanding of the Emerson effect and its implications, we can conclude that the discovery of the Emerson effect has shown the existence of two distinct photochemical reaction centers in photosynthesis.

5. **Final Answer**: Therefore, the correct answer to the question is option 4, which states that the discovery of the Emerson effect has shown the existence of two distinct photochemical reactions.

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