The **'Triple Response'** of seedlings (inhibition of stem elongation, swelling of stem, horizontal growth) is induced by:
AAuxin
BGibberellin
CEthylene (response to mechanical obstruction in soil)
DCytokinin
Answer & Solution
Correct answer: C. Ethylene (response to mechanical obstruction in soil)
Ethylene's classic 'triple response': (1) reduced longitudinal growth, (2) lateral swelling, (3) loss of normal vertical orientation. Adaptive response — helps seedling push around obstacles in soil. Used to identify ethylene signalling mutants in Arabidopsis.
Related questions
The four characteristic events of a typical **sigmoid growth curve** are:**Hydroponics** is:Yellowing of **young leaves** (chlorosis of young leaves) suggests deficiency of which eleWhich is **NOT** correctly paired (hormone–physiological role)?The **Richmond-Lang effect** describes the action of:In the **Avena curvature test**, the angle of curvature of the decapitated coleoptile is:Calcium deficiency in plants causes:Which element is a constituent of **nitrogenase enzyme** (catalyses biological N₂ fixation