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GATE 2023 BT – Question 29

Plant, Animal and Microbial Biotechnology · Plants: Totipotency, organogenesis, regeneration, growth regulators, tissue and cell suspension culture, secondary metabolites · 1 mark · Multiple choice

Which one of the following plant growth regulators facilitate adventitious root formation?

  1. Auxin
  2. Zeatin
  3. Dihydrozeatin
  4. Kinetin

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Correct answer: (A) Auxin

Explanation

**Auxins** (such as IAA, IBA and NAA) promote cell elongation and initiate **adventitious roots** on cuttings, which is why rooting powders contain IBA or NAA.

**Cytokinins** (zeatin, dihydrozeatin, kinetin) promote cell division and shoot formation. A high auxin-to-cytokinin ratio favours roots, and a low ratio favours shoots.

Answer **auxin** (A).