CBSE Class 10 Science 2019 · Paper 31/4/1 · Question 20(a)

(a) Vegetative propagation is a mode of asexual reproduction in which new plants are produced from the vegetative parts of a plant (root, stem or leaves) without seeds. Two methods: layering and grafting. (Cutting is another; in nature roots, stems and leaves, such as the leaf buds of Bryophyllum, also give new plants.) (b) It is practised because (i) some plants, such as banana, orange, rose and jasmine, have lost the capacity to produce seeds, so they can be grown only in this way; (ii) it takes less time: such plants bear flowers and fruits earlier than those grown from seeds. Also, the new plants are genetically similar to the parent and keep all its characteristics. (c) Hydra reproduces by budding, using its regenerative cells. At one specific site on the body the cells divide repeatedly and form an outgrowth, the bud. The bud grows, develops a mouth and tentacles and becomes a tiny Hydra; when fully mature it detaches from the parent and lives as an independent individual. Labelled diagrams: parent Hydra with tentacles and basal disc, bud, growing bud with tentacles, detached new Hydra (see the figure).