CBSE Class 10 Answered

Auxins stimulate the elongation of cells whereas cytokinins promote cell division in mersistems.

Auxins are usually found in root and shoot tips whereas cytokinins are found in greater concentrations in areas of rapid cell division like fruits and seeds.

Auxin-regulated responses include induction of lateral and adventitious roots, stimulation of fruit growth, apical dominance, leaf and flower abscission and DNA synthesis.

Cytokinin responses include: cell division (cytokinesis), organ development (shoot formation), delayed senescence and promotion of chloroplast development, affect nutrient sink strength of organs, promotion of lateral bud growth, promotion of cotyledon expansion (only in certain species) and inhibition of auxin-induced elongation.

Auxins have found several uses in agriculture and horticulture. The auxin 2,4-D is a commonly used herbicide against broadleaf plants. NAA and IBA are often the active ingredient in products that stimulate root formation on plant cuttings. Auxins may be used to enhance fruit production or harvesting but these effects are species specific. Auxin, along with cytokinin, is used in for culturing plant tissues for mass propagation. Cytokinins have found few uses in agriculture. They are used in plant tissue culture and they have been used to delay senescence. Possible future applications will depend on clever bio-engineering.