The term 'auxin' is not applied to the following compound

Options

A. 2,4-D(2, 4dichlorophenoxyacetic acid)
B. NAA
C. IBA
D. ABA

Answer

To solve the question regarding which compound is not classified as an auxin, we can follow these steps:

### Step 1: Understand the Definition of Auxin
Auxins are a class of plant hormones that play a crucial role in regulating plant growth and development. They are primarily involved in processes such as cell elongation, apical dominance, and fruit development.

**Hint:** Remember that auxins are plant hormones that promote growth and have specific functions in plant development.

### Step 2: Identify the Compounds Listed
The question lists four compounds:
1. 2,4-D (2,4-Dichlorophenoxyacetic acid)
2. NAA (Naphthalene Acetic Acid)
3. IBA (Indole Butyric Acid)
4. ABA (Abscisic Acid)

**Hint:** Write down the full names of the compounds to better understand their classifications.

### Step 3: Classify Each Compound
- **2,4-D**: This is a synthetic auxin commonly used as a herbicide and is classified as an auxin.
- **NAA**: This is also a synthetic auxin used in plant tissue culture and rooting.
- **IBA**: This is a natural auxin that promotes root formation and is also classified as an auxin.
- **ABA**: Abscisic Acid is not an auxin; it is known as a stress hormone involved in processes like stomatal closure and seed dormancy.

**Hint:** Focus on the functions of each compound to determine if they fit the definition of auxins.

### Step 4: Identify the Incorrect Compound
From the classification, we see that ABA (Abscisic Acid) does not belong to the auxin category. Therefore, the correct answer to the question is ABA.

**Hint:** Look for the compound that does not promote growth or has a different role in plant physiology.

### Final Answer
The term 'auxin' is not applied to the following compound: **ABA (Abscisic Acid)**.