Grade 3 | Science | Root-Shoot systems, Living, non living things and plants, Olympiad, CBSE, ICSE, SOF, ITO
Plants have 2 organ systems :
1) Root system: part of a plant which grows below the soil is called root system. This grows towards gravity.
2) Shoot system: Part of a plant which grows above the soil is called shoot system. This includes stem, leaves, fruits etc. Shoot system grows against gravity.
Roots of a plant absorb water and necessary minerals from the soil and pass it to stem. Roots also hold the plant firmly to the ground. Some roots also act as storage for extra food in plants e.g. carrots, sweet potato, radish, turnip etc.
Roots are classified in 2 categories :
1) Taproot - Large main root which comes of stem is called taproot. It has number of side roots or lateral roots. Carrot, radish and turnip are examples of taproots. Most trees have taproots.
2) Fibrous roots - Many roots come of stem. This roots are of the same size and break off into smaller roots. Examples of fibrous roots are grass, wheat, rice, marigold, maize, banana, bamboo and onion.
There is also one more type of root known as aerial roots. These are adventitious roots and grow from stem or leaves. e.g. banyan trees. These roots help plants in climbing over other plants. Sometimes these roots also help plants to breathe and thus are known as breathing roots e.g. mangrove roots.
Stem is a part of shoot system. Stem grows above the soil. Stem performs following functions :
1) It supports the plant.
2) It supplies water and minerals from roots to other parts of the plant.
3) It supplies food from leaves to other parts of the plant.
4) It also acts as storage for food.
Some stems are edible, e.g. sugarcane, potato, garlic and leeks etc.
Some stems are woody and some stems are soft.
Plants make their food with the help of sunlight, carbon-dioxide, water and minerals. This process is called photosynthesis. Process of photosynthesis occurs in leaves. Thus leaves are called food factory or kitchen of plant.
Imp Concept: Plant roots absorb water and transfer it to other parts of the plant through the stem. When a plant has excess water it releases some of the water through stomata. This process is called transpiration. Water is released from the underside of leaves and is converted into vapours. Transpiration is also called evaporation of water from plant leaves.