54. Identify the CORRECT statements with regard to the function of plant hormones
P. ABA is synthesized from chorismate and promotes viviparous germination
Q. Auxin induces acidification of cell wall followed by turgour-induced cell expansion
R. Gibberellin-reponsive genes become activated by the repression of DELLA protein
S . Cytokinin regulates the G2 to M transition in the cell cycle
(A) P, Q
(B) Q, R
(C) Q, S
(D) P, R
Plant hormones regulate key growth and stress responses in plants. This article analyzes a multiple-choice question on their functions, identifying the correct answer (C) Q and S.
Option Analysis
-
P Incorrect: ABA derives from carotenoids via zeaxanthin, not chorismate (shikimate pathway for auxins/others). ABA inhibits vivipary and promotes dormancy; deficiency causes viviparous germination.
-
Q Correct: Auxin triggers proton pumps for cell wall acidification, activating expansins for loosening, enabling turgor-driven elongation (acid growth theory).
-
R Incorrect: DELLA proteins repress gibberellin responses; GA induces DELLA degradation, activating genes—repression of DELLA enables, but statement phrasing reverses mechanism.
-
S Correct: Cytokinins (e.g., zeatin) promote cyclin B/D expression, driving G2/M transition and mitosis in cell division.
Correct Answer
Option (C) Q, S matches verified functions: auxin in expansion, cytokinin in cell cycle. P misstates ABA pathway/role; R inverts DELLA action. Master these for exams like CSIR-NET/GATE Life Sciences.
