B. Asexual reproduction in Multicellular organisms
1. Fragmentation:
- Occurs in multicellular organisms.
- Body of parent organism breaks up into many fragments.
- Each fragment starts to live as an independent new organism.
- Occurs in algae like Spirogyra, and sponges like Sycon.
- Whenever there is plenty of water and nutrients are available to Spirogyra, its filaments grow up very fast and break up into many small fragments.
- Each fragment starts to live independently as a new Spirogyra fiber.
- If the body of Sycon breaks up accidentally into many fragments, each fragment develops into new Sycon.
2. Regeneration :
- Wall lizard breaks up and discards some part of its tail in emergency.
- Discarded part is regenerated after a period. This is an example of limited regeneration.
- However, under certain situations, an animal-Planaria breaks up its body into two parts.
- Thereafter each part regenerates remaining part of the body.
- Thus two new Planaria are formed. This is called as regeneration.
3. Budding :
- In case of Hydra, under favourable conditions, at specific part of its body, an outgrowth is formed by repeated divisions of regenerative cells of body wall. This outgrowth is called as bud.
- Bud grows up progressively and finally forms a small hydra.
- Dermal layers and digestive cavity of the budding hydra are in continuity with those of parent hydra.
- Parent hydra supplies nutrition to the budding hydra.
- Budding hydra separates from parent hydra and starts to lead an independent life when it grows up and becomes able to lead an independent life.
4. Vegetative Propagation :
- Reproduction in plants with the help of vegetative parts like root, stem, leaf and bud is called as vegetative reproduction.
- Vegetative propagation in potatoes is performed with the help of ‘eyes’ present on tuber.
- In Bryophyllum it is performed with the help of buds present on leaf margin.
- In case of plants like sugarcane & grasses, vegetative propagation occurs with the help of buds present on nodes.
5. Spore Formation :
- Fungi like Mucor have filamentous body.
- They have sporangia.
- Once the spores are formed, sporangia burst and spores are released.
- Spores germinate in moist and warm place and new fungal colony is formed.