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Ls. 7 Getting to Know Plants - Part II.pdf

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Ls. 7 Getting to Know Plants - Part II.pdf

  1. 1. By : Suvarna Wadbudhe
  2. 2. Content of Lesson  Parts of Plant  Types of Roots  Reticulate and Parallel Venation  Photosynthesis
  3. 3. Parts of Plant and their Functions
  4. 4. Roots: It is the part of plant which is in the soil Functions of roots  Anchor the plants to the soil  Absorb water and minerals from the soil  Help in holding soil together
  5. 5. Types of Roots Tap root • Is a straight tapering root which grows vertically down and gives out branches on all the sides • Tap root is the main root and the smaller, side roots are called lateral roots Fibrous root • Some plants have bunch of similar roots called fibrous roots. • They consist of many thin, fibre- like roots. • They spread out in the soil and give firm support to the plant tap root lateral root fibrous roots
  6. 6. Mango Neem Gram Beet Grass Wheat Sugarcane Bamboo Examples Tap root Fibrous root
  7. 7. Stem: It is the part of plant which rises vertically up from the ground Functions of stem  Holds the plant upright  Carries water and minerals from the roots to the leaves and other parts of the plant  Carries prepared food from the leaves to the other parts of the plant  Holds the leaves in such a way that leaves are able to get plenty of sunlight for preparing food
  8. 8. Leaves: It is a thin, broad, flat and green part of a plant which is attached to the stem. Parts of Leaf Lamina: The broad green part of the leaf is called lamina. It is commonly called as leaf blade. Petiole: The thin stalk with which leaf attached to the stem is called petiole. It is commonly called as leaf stalk. Mid-rib: The mid-rib or mid-vein is in the centre of the lamina. Vein: Large number of veins spread out from the mid-rib. Stomata: These are small openings on the surface of the leaf
  9. 9. Functions of leaves  Make food for the plant  Get rid of excess water from the plant through transpiration  Carry out the process of respiration in plants
  10. 10. Photosynthesis • Factors required:  Carbon dioxide - taken by the leaves from air  Water - is carried into leaves from the soil through the stem  Sunlight- provides energy for making food.  Chlorophyll - present in green leaves, traps energy from the sunlight A process by which plants make their food in the presence of sunlight is called photosynthesis.
  11. 11. Carbon dioxide +Water Glucose Oxygen +
  12. 12. Activity to show that leaves make food by photosynthesis  Pluck a green leaf from a potted plant which has been kept in sunlight  Put the green leaf in a small beaker and cover it completely by adding alcohol or spirit.  Place the beaker containing leaf and alcohol in a bigger beaker containing water  Heat the water in bigger beaker over a burner The hot water will then heat alcohol in smaller beaker. The hot alcohol removes the green colour (chlorophyll) from the leaf. Keep heating till all the green colour of leaf is removed. The leaf becomes almost colourless.
  13. 13. 5. Remove the leaf from alcohol and wash it thoroughly with water to remove the chlorophyll. 6. Place the decolourised leaf in a petri-dish. Pour iodine solution over the leaf with the help of a dropper. The leaf turns blue-black showing the presence of starch.
  14. 14. ACTIVITY TO SHOW TRANSPIRATION IN PLANTS  The leaves of plants give out water constantly in the form of water vapour (which goes into air). This process is called transpiration.  Take a well-watered potted plant having big leaves.  Enclose a leafy stem (or branch) of the plant in a clean polythene bag and seal the mouth of polythene bag properly with cellotape.  Keep this potted plant in the sunshine for 2 to 3 hours  We will see a number of water droplets on the inner side of the polythene
  15. 15. This can be explained as follows: The leaves of plant give out water vapour. Since the leaves are enclosed in polythene bag, the water vapour cannot escape into air. The water vapour given out by the covered leaves keeps on collecting inside the polythene bag. Some of this water vapour condenses to form tiny drops of water. It is these droplets of water which we see sticking to the inner sides of the polythene bag. This activity shows that the leaves of a plant lose water through transpiration.
  16. 16. Venation :It is arrangement of veins in the lamina Reticulate venation : The veins in a leaf occur in an irregular way forming a net- like design. The veins spread out from the mid-vein haphazardly. Eg. Neem, mango, peas, orange, guava, rose etc Parallel venation : The veins in the leaf run parallel to one another on both the sides of the mid-rib. Eg . Wheat, rice, sugarcane, bamboo, lily, banana etc.
  17. 17. If you want the know what kind of roots a plant has, you need not pull out . You can easily find out by looking at its leaves. Plants having leaves with reticulate venation have tap roots Plants having leaves with parallel venation have fibrous roots

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