Which plant hormone (phytohormone) promotes cell elongation and is responsible for phototropic bending of shoots toward unidirectional light?
Answer and explanation
Correct answer: A. auxin
- Step 1: Auxins are synthesized in shoot apical meristems. Step 2. When light shines from one side, auxins migrate to the shaded side of the shoot. Step 3. Higher auxin concentration on the shaded side stimulates greater cell elongation, causing the shoot to bend toward light. Answer: auxin (indole-3-acetic acid). Why not the others: Abscisic acid promotes dormancy and stomatal closure; ethylene promotes fruit ripening; cytokinins stimulate cell division.
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