Practice and Revision - Chemical Coordination in Plants (Plant Hormones)

Core concept

Auxins promote cell elongation and are responsible for phototropism (growth towards light) and apical dominance (suppressing side branch growth).

How it works

Gibberellins promote stem elongation, seed germination, and flowering, often used commercially to increase fruit size.

Why it matters

Cytokinins promote cell division and delay ageing (senescence) in plant parts, often working together with auxins to regulate growth.

Key detail

Abscisic acid (ABA) is often called the 'stress hormone,' promoting seed dormancy and closing stomata during water stress conditions.