IAA and serotonin are derived (formed) from which of the following

Options

A. Tyrosine
B. Tryptophan
C. Phenylalanine
D. Glycine.

Answer

To determine the source of IAA (Indole Acetic Acid) and serotonin, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compounds**:
- IAA (Indole Acetic Acid) is a plant hormone that promotes growth.
- Serotonin is a neurotransmitter found in animals, including humans, that helps transmit neural signals.

2. **Understand the Derivation**:
- Both IAA and serotonin are derived from amino acids. Amino acids are the building blocks of proteins and can also serve as precursors for various biological molecules.

3. **List the Options**:
- Option 1: Tyrosine
- Option 2: Tryptophan
- Option 3: Phenylalanine
- Option 4: Glycine

4. **Analyze Each Option**:
- **Tyrosine**: This amino acid is a precursor for dopamine and other catecholamines but not for IAA or serotonin.
- **Tryptophan**: This is an essential amino acid that is the precursor for serotonin. It is also involved in the synthesis of IAA in plants.
- **Phenylalanine**: This amino acid is a precursor for tyrosine and other compounds but not directly for IAA or serotonin.
- **Glycine**: This is a simple amino acid that does not serve as a precursor for either IAA or serotonin.

5. **Conclusion**:
- Since both IAA and serotonin are derived from tryptophan, the correct answer is **Option 2: Tryptophan**.

### Final Answer:
**Option 2: Tryptophan**