BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Mitogens trigger cell division in animals. In plants, cytokinins, a group of phytohormones derived from adenine, stimulate cell proliferation. Cytokinin signaling is initiated by membrane-associated histidine kinase receptors and transduced through a phosphorelay system.

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: -Auxin promotes cell division and meristem maintenance and also plays an important role in the establishment of cellular patterning. Plant development thus integrates the regulation of cell proliferation and growth with further cell expansion and differentiation.

Detailed explanation-4: -Cytokinins are plant hormones which promotes cytokinesis or cell division. It also helps in opening of stomata, delaying ageing in leaves, etc.

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.