Who discovered that green plant parts and light are essential for photosynthesis ?

Options

A. Engelmann
B. Ingenhousz
C. Sachs
D. Priestley.

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**:
- Photosynthesis is the process by which green plants convert carbon dioxide and water into glucose and oxygen using sunlight. This process is essential for plant growth and energy production.

2. **Identifying Key Components**:
- The key components necessary for photosynthesis are green plant parts (chlorophyll-containing parts) and light (sunlight).

3. **Historical Context**:
- Various scientists have contributed to our understanding of photosynthesis. The question asks specifically about who discovered the essential role of green plant parts and light in this process.

4. **Reviewing Options**:
- The options provided are Engelmann, Engenhaus, Saag, and Presley.

5. **Connecting Discoveries to Scientists**:
- Engelmann is known for his experiments with light and photosynthesis, but he did not specifically identify the necessity of green plant parts and light.
- Presley conducted experiments that demonstrated the role of light in photosynthesis but did not focus on the green parts of plants.
- Saag does not have a significant historical contribution related to the discovery of photosynthesis.
- Engenhaus (often referred to as Engelmann) conducted experiments that established the necessity of light for photosynthesis and showed that green parts of plants are crucial in this process.

6. **Conclusion**:
- Based on the historical contributions and experiments, the answer to the question is that Engenhaus discovered that green plant parts and light are essential for photosynthesis.

**Final Answer**: Engenhaus.

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