Which of the following is incorrect about the experiment performed by T. W. Engelmann ?

Options

A. The experimental organism used was Cladophora (green algae).
B. For the experimental purpose, the suspension of aerobic bacteria was utilized .
C. The bacteria accumulated mainly in the region of the orange and green parts of the light spectrum.
D. For splitting of light into its spectral component prism was used .

Answer

### Step-by-Step Solution:

1. **Identify T.W. Engelmann**: T.W. Engelmann, or Theodore Wilhelm Engelmann, was a German botanist known for his work on the action spectrum of photosynthesis.

**Hint**: Remember that Engelmann's experiment is significant in understanding how different wavelengths of light affect photosynthesis.

2. **Understand the Action Spectrum**: The action spectrum refers to the rate of photosynthesis at different wavelengths of light. Engelmann aimed to determine which wavelengths were most effective for photosynthesis.

**Hint**: Think about how different colors of light (wavelengths) can influence plant processes.

3. **Engelmann's Experiment Setup**: Engelmann used a prism to split sunlight into its spectral components (the colors of the rainbow) and illuminated green algae, specifically Cladophora, with this light.

**Hint**: Visualize how a prism works to separate light into different colors.

4. **Use of Aerobic Bacteria**: Engelmann introduced aerobic bacteria to the experiment. These bacteria would accumulate in areas where oxygen was being produced, indicating the rate of photosynthesis.

**Hint**: Consider why oxygen production is a key indicator of photosynthesis.

5. **Results of the Experiment**: Engelmann found that the aerobic bacteria accumulated mainly in the red and blue regions of the spectrum, indicating that these wavelengths were most effective for photosynthesis.

**Hint**: Recall that red and blue light are often associated with higher rates of photosynthesis in plants.

6. **Identifying the Incorrect Statement**: The question asks for the incorrect statement regarding Engelmann's experiment. The correct aspects of the experiment include the use of Cladophora and the use of aerobic bacteria. The incorrect statement would be regarding the accumulation of bacteria in the orange and green parts of the spectrum, as they actually accumulated in the red and blue regions.

**Hint**: Pay attention to the specific colors mentioned in the options provided in the question.

### Conclusion:
The incorrect statement about Engelmann's experiment is that the bacteria accumulated in the orange and green regions of the spectrum when they actually accumulated in the red and blue regions.