Answer:
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1 Mark each
[Mention any three]
1. In some plants, the underground stem is modified to store food in the form of starch. Three types of underground stem modifications are tubers (e.g. Potato), rhizome (e.g.Ginger) and bulb (e.g.Onion).
2. In some desert plants, leaves are absent or reduced to spines. Here, the stem is green and performs photosynthesis to synthesise food.
3. In some plants like rose, stems are modified into thorns to protect the plant from being eaten by animals.
4. In climbing plants, stems are modified sometimes into structures which twine around the support.
5. In some plants like cactus and jade, stems become fleshy and succulent to store water.