Plant Growth Regulator Classes — NEET Biology
✅ Asked in NEET 2026Match List-I (Growth Regulator) with List-II (Function/Effect) — A. 2,4-D, B. GA3, C. Kinetin, D. ABA.
Match List-I (Growth Regulator) with List-II (Function/Effect) — A. 2,4-D, B. GA3, C. Kinetin, D. ABA.
Which of the following growth regulators is an adenine derivative? (NEET 2022 Phase 2)
Answer & NCERT explanation
Correct answer: A — A-III, B-I, C-IV, D-II
2,4-D is a synthetic auxin used as a herbicide; GA3 is used in the brewing industry; kinetin (cytokinin) helps in nutrient mobilisation; ABA promotes stomatal closure.
Read more NCERT concept on the PYQ
The plant growth regulators (PGRs) are small, simple molecules of diverse chemical composition. They could be indole compounds (indole-3-acetic acid, IAA); adenine derivatives (N6-furfurylamino purine, kinetin), derivatives of carotenoids (abscisic acid, ABA); terpenes (gibberellic acid, GA3) or gases (ethylene, C2H4). Plant growth regulators are variously described as plant growth substances, plant hormones or phytohormones in literature.
NTA focuses on the chemical classification of plant growth regulators, particularly that cytokinins are adenine derivatives with kinetin as the classic example. Students often confuse different PGR types and their chemical origins—they may mix up gibberellins (terpenes) with cytokinins or forget that ABA is a carotenoid derivative. The key is remembering: cytokinins = adenine derivatives (kinetin), gibberellins = terpenes, ABA = carotenoids, IAA = indole compounds, ethylene = gas. NEET repeatedly tests this classification because distinguishing PGR types by chemical structure is essential for understanding their distinct roles in plant development and growth regulation.
What does NCERT say about plant growth regulators PGRs?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.