Phytochrome was isolated by

Options

A. Butler et al
B. W. Went
C. R. Hill
D. Borthwick et al.

Answer

**Step-by-Step Solution:**

1. **Understanding Phytochrome**: Phytochromes are proteins found in plants, fungi, and some bacteria. They play a crucial role in detecting light, particularly sunlight.

2. **Forms of Phytochrome**: Phytochromes exist in two forms:
- **PR (inactive form)**: This form absorbs red light.
- **PFR (active form)**: This form absorbs far-red light and is responsible for triggering various physiological responses in plants.

3. **Isolation of Phytochrome**: The first successful isolation of phytochrome was conducted by a scientist named **H.A. Bortwig**. He is credited with discovering the phytochrome and its functions.

4. **Evaluating Other Options**:
- **R. Hill**: Known for the Hill reaction related to photosynthesis, not phytochrome.
- **W. Vent**: Recognized for proving the existence of auxins in plants, unrelated to phytochrome.
- **Butler**: Associated with forensic discoveries, not phytochrome.

5. **Conclusion**: Based on the information, the correct answer to the question "Phytochrome was isolated by" is **H.A. Bortwig**.

**Final Answer**: H.A. Bortwig

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