Read the Five Plant Growth Regulators
Plant growth regulators overlap and interact, but their recurring functions and chemical families provide reliable recognition cues.
Living-system questions are solved by matching a structure or organism to its function, process and stated condition.
Compare major effects
Auxins support elongation and apical dominance; gibberellins promote stem elongation and germination; cytokinins promote division; ethylene promotes ripening; ABA supports dormancy, stomatal closure and stress tolerance. Hormones can interact, and different regulators may share some effects.
Recognise their chemistry
IAA contains an indole group; gibberellins are terpenoids; cytokinins are adenine derivatives; ABA is a carotenoid derivative. Auxin, GA and ABA are acidic compounds, while cytokinins are the odd one out in an acidity comparison. Natural IAA/zeatin contrast with synthetic NAA/ethephon.
OlympIQ exam lens
- ✓Auxin: elongation/apical dominance; GA: elongation/germination.
- ✓Cytokinin: division; ethylene: ripening; ABA: dormancy/stress.
- ✓Cytokinin: adenine-derived; GA: terpenoid; ABA: carotenoid-derived.
A hormone’s effect depends on tissue, concentration and interacting signals.
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