A plant hormone that is used to kill dicotyledonous weed and is also known as 'Agent Orange' is derived from

Options

A. Tryptophan
B. Phenylalanine
C. Acetyl CoA
D. Modified purines

Answer

To solve the question regarding the plant hormone known as 'Agent Orange' that is used to kill dicotyledonous weeds, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the source of a plant hormone that is used as a herbicide known as 'Agent Orange'.

2. **Identify Agent Orange**: Research indicates that Agent Orange is a potent herbicide used primarily during the Vietnam War. It is known for its ability to kill broadleaf (dicotyledonous) weeds.

3. **Components of Agent Orange**: Agent Orange is a mixture of two herbicides:
- 2,4,5-T (2,4,5-trichlorophenoxyacetic acid)
- 2,4-D (2,4-dichlorophenoxyacetic acid)

4. **Determine the Origin of These Herbicides**: Both 2,4,5-T and 2,4-D are synthetic auxins, which are plant hormones that mimic the natural growth hormone auxin.

5. **Identify the Precursor**: The precursor for the synthesis of these synthetic auxins is the amino acid **tryptophan**. Tryptophan is an aromatic amino acid that plays a crucial role in the biosynthesis of auxins.

6. **Evaluate the Options**: The options given are:
- A) Tryptophan
- B) Phenylalanine
- C) Acetyl CoA
- D) Modified purine

Based on our understanding, the correct answer is **A) Tryptophan**, as it is the precursor from which the synthetic auxins (and thus Agent Orange) are derived.

7. **Conclusion**: Therefore, the plant hormone used to kill dicotyledonous weeds, known as Agent Orange, is derived from **tryptophan**.

### Final Answer:
**A) Tryptophan**

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