#9.3i
Understand that chemical control in plants is brought about by plant growth substances such as auxins, cytokinins and gibberellins.
#9.3ii
Know that auxin has several effects, including cell elongation, suppression of lateral buds (apical dominance) and promoting root growth.
#9.3iii
Understand that plant growth substances often interact with each other as shown by the antagonistic actions of cytokinin and auxin on apical dominance.
#9.3iv
Understand how phytochrome controls flowering and photomorphogenesis.