Action spectrum of photosynthesis was first studied by

Options

A. Blackman
B. Von Mayer
C. Engelmann
D. Boussingault.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks who first studied the action spectrum of photosynthesis. The action spectrum represents the effectiveness of different wavelengths of light in driving the process of photosynthesis.

2. **Identifying Key Figures**: The options provided are Blackman, von Meyer, Engelmann, and Bossingwald. We need to determine which of these scientists is associated with the study of the action spectrum.

3. **Engelmann's Experiment**: T. W. Engelmann conducted a significant experiment using the green alga Cladophora. He utilized a prism to split light into its spectral components, which allowed him to observe how different wavelengths affected photosynthesis.

4. **Setting Up the Experiment**: Engelmann placed Cladophora in a suspension of aerobic bacteria. The bacteria were used to detect where oxygen was being produced during photosynthesis, as they would accumulate in areas where oxygen was released.

5. **Observing Results**: Engelmann observed that the bacteria accumulated predominantly in the regions of blue and red light within the spectrum. This indicated that these wavelengths were most effective for photosynthesis.

6. **Conclusion**: From Engelmann's findings, it was concluded that the action spectrum of photosynthesis corresponds to the blue and red light regions. Therefore, Engelmann is credited with the first study of the action spectrum of photosynthesis.

7. **Final Answer**: The action spectrum of photosynthesis was first studied by Engelmann.

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