GATE BT 2023 • Q29
MCQ • 1 Mark
Section 4: Bioprocess Engineering and Process Biotechnology
Mass transfer in bioprocesses (kLa)
Subtopic: Fundamentals of Mass transfer in bioprocesses (kLa)
Question Statement:
Which one of the following plant growth regulators facilitate adventitious root
formation?
Options:
-
(A) Auxin
-
(B) Zeatin
-
(C) Dihydrozeatin
-
(D) Kinetin
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2023 Q.29)**
**1. Governing Concept**:
- **Topic**: Plant Physiology & Phytohormones
- **Auxins** (indole-3-acetic acid, IBA, NAA) stimulate **adventitious root formation** and lateral root initiation by promoting cell division and redifferentiation in pericycle and stem tissues. Consequently, synthetic auxins (e.g., IBA) are commercially utilized as rooting powders in vegetative propagation and plant tissue culture.
- Cytokinins (zeatin, dihydrozeatin, kinetin) promote shoot bud formation and inhibit root initiation (high cytokinin/auxin ratio favours shoots; high auxin/cytokinin ratio favours roots).
**2. Option Analysis**:
- **Option (A) [Auxin] is CORRECT**: The primary phytohormone triggering adventitious root emergence.
- **Option (B) [Zeatin] is INCORRECT**: A natural cytokinin that promotes shoot differentiation and inhibits rooting.
- **Option (C) [Dihydrozeatin] is INCORRECT**: Cytokinin analog promoting shoot organogenesis.
- **Option (D) [Kinetin] is INCORRECT**: Synthetic cytokinin stimulating shoot development.
**3. Final Answer**:
- **Correct Choice**: **A**
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