BIOMOLECULES AND ENZYMES

Detailed explanation-1: -A type of plant hormone that promotes cell division in plant roots and shoots is called cytokinins. It is synthesized in the apices of roots and developing shoot buds where rapid division occurs. It also promotes root apical dominance and regulates root gravitropism along with auxin.

Detailed explanation-2: -Cytokinin positively regulates cell division and also serves a key role in establishing organization within shoot stem cell centers. Both auxin-dependent and auxin-independent mechanisms have been uncovered by which cytokinin stimulates the endocycle in roots.

Detailed explanation-3: -The hormone cytokinin promotes cell differentiation in plant roots by repressing both auxin transport and responses to auxin at the boundary between the meristem and the root elongation zone.

Detailed explanation-4: -Root-specific reduction of cytokinin causes enhanced root growth, drought tolerance, and leaf mineral enrichment in Arabidopsis and tobacco. Plant Cell.

Detailed explanation-5: -Cytokinins promote cell division and increase cell expansion during the proliferation and expansion stages of leaf cell development, respectively. During leaf senescence, cytokinins reduce sugar accumulation, increase chlorophyll synthesis, and prolong the leaf photosynthetic period.