Moll's experiment explains that

Options

A. Carbon dioxide is essential for photosynthesis
B. Chlorophyll dioxide is essential for photosynthesis
C. Light and water are essential for photosynthesis
D. All the above are correct

Answer

### Step-by-Step Solution:

1. **Understanding Moll's Experiment**: Moll's experiment, also known as Moll's half-leaf experiment, was designed to investigate the role of carbon dioxide in photosynthesis.

2. **Setup of the Experiment**: In this experiment, Moll took a leaf from a plant and divided it into two halves. One half of the leaf was dipped in a solution of potassium hydroxide (KOH), which absorbs carbon dioxide from the air.

3. **Exposure to Light**: The plant with the leaf was then placed in sunlight for several hours. This exposure to light is crucial for photosynthesis to occur.

4. **Testing for Starch**: After the exposure, Moll tested both halves of the leaf for the presence of starch. Starch is an indicator of photosynthesis, as it is a product of the photosynthetic process.

5. **Observations**:
- The half of the leaf that was dipped in KOH tested negative for starch, indicating that photosynthesis did not occur in this part of the leaf.
- The half of the leaf that was not dipped in KOH tested positive for starch, indicating that photosynthesis occurred in this region.

6. **Conclusion**: Moll concluded that the absence of carbon dioxide (due to its absorption by KOH) in the dipped half of the leaf prevented photosynthesis from occurring. Therefore, he established that carbon dioxide is essential for photosynthesis.

### Final Answer:
Moll's experiment explains that **carbon dioxide is essential for photosynthesis**.

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