PREVIOUSLY ASKED IN:
WBPSC Miscellaneous Preliminary 2019
Answer
Indole Acetic Acid
Explanation
Indole Acetic Acid (IAA) is the most common naturally occurring plant hormone of the Auxin class. It is the primary chemical responsible for promoting plant growth. IAA is produced in the apical meristems (growing tips) of shoots and roots and controls key growth processes like cell elongation, apical dominance, and phototropism (bending towards light).
Key Points
- > Indole Acetic Acid (IAA) is the chemical name for the natural plant hormone Auxin.
- > Auxins are predominantly synthesized at the apical meristems of shoots and roots.
- > Chlorophyll is the green pigment responsible for capturing light energy for photosynthesis.
- > Citric acid is found in citrus fruits and plays a vital role in cellular respiration (Krebs cycle).
- > Examples of synthetic auxins include NAA and 2,4-D (often used as an herbicide).
Additional Information
Plant Hormones & Chemical Names
| Hormone | Chemical Name / Example | Primary Function |
|---|---|---|
| Auxin | Indole Acetic Acid (IAA) | Cell elongation, apical dominance |
| Gibberellin | Gibberellic Acid (GA3) | Stem elongation, breaking dormancy |
| Cytokinin | Zeatin / Kinetin | Promotes cell division |
| Ethylene | Ethylene (C2H4) | Gaseous hormone for fruit ripening |
Memory Tips
- Auxin = IAA: Remember that the most potent natural Auxin is IAA.
- Auxins are responsible for Phototropism (plants leaning towards the sun) because the hormone accumulates on the shaded side, making those cells grow longer.