Which plant hormone mainly promotes cell elongation?
Answer and explanation
Correct answer: D. Auxin
- Step 1: Plant hormones (phytohormones) direct growth, morphological differentiation, and developmental responses.
- Step 2: Auxins, primarily indole-3-acetic acid (IAA), stimulate proton efflux into cell walls, activating expansins that loosen microfibrils and drive polar cell elongation in growing stems.
- Step 3: Cytokinins primarily stimulate cell division, whereas abscisic acid acts as a growth inhibitor.
Answer
Auxin.
Why not the others: Ethylene is a gaseous phytohormone primarily promoting fruit ripening, leaf epinasty, and senescence; Abscisic acid is a stress hormone that promotes stomatal closure, seed dormancy, and growth inhibition; Cytokinin primarily promotes cell division (cytokinesis) and delays leaf senescence.
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