Question

From the phytohormones given below, identify the pairs which have mutually opposite influence on seed germination, stem elongation and stomatal movement respectively.
(I) IAA (II) ${GA}_3$ (III) Zeatin (IV) ABA (V) $C_2{H}_4$

• A. (II)-(IV); (II)-(III); (IV)-(V)
• B. (III)-(V); (II)-(IV); (I)-(V)
• C. (II)-(IV); (I)-(V); (III)-(IV)
• D. (III)-(V); (II)-(V); (I)-(III)

Answer 1

Answer: (C)

(II)-(IV); (I)-(V); (III)-(IV)

Phytohormones or plant hormones are chemicals that regulate plant growth. These include auxin (indole-3-acetic acid or IAA), cytokinins, ethylene, gibberellins (gibberilic acid, GA${}_3$) and abscisic acid (ABA). A few new one are brassinosteroids (BRs), jasmonates, salicylates, and strigolactones. All of these have an impact on the seed germination, stem elongation and stomatal movement. However, gibberrillic acid and ABA show opposite influence. On the same lines, auxin or IAA an ethylene as well as zeatin and ABA show opposite infuence.