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WHY STUDY PLANTS?, Plants are the only source of oxygen on the earth., They are a major source of the food which we eat., They maintain soil fertility., They prevent soil erosion., They cause rain., They regulate the temperature of the earth., Give shelter to many animals, insects and birds, ……the list goes on…….., AUDITI DEY/6/SCI/ONLINE/2020, 2
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CLASSIFICATION OF PLANTS, On the basis of the , thickness of their stems and the , place of origin of their branches,, plants can broadly be classified into three categories: , Herbs, Shrubs and Trees, AUDITI DEY/6/SCI/ONLINE/2020, 3
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HERBS, These are plants that have green and frail stems. , Usually, these are small plants with fewer branches., AUDITI DEY/6/SCI/ONLINE/2020, 4, FENUGREEK (METHI), MINT (PUDINA), CORIANDER (DHANIA)
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SHRUBS, These are plants with hard, but not exactly thick stems. , Their branches generally originate from the base of their stems. , These are much taller than herbs, but are usually shorter than trees., AUDITI DEY/6/SCI/ONLINE/2020, 6, JASMINE, ROSE, TULSI, HIBISCUS (CHINA ROSE)
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TREES, These are plants which are very tall and have a thick and hard stem., The branches originate from the upper part of the tree and are very high above the ground., AUDITI DEY/6/SCI/ONLINE/2020, 7, COCONUT TREE, BANYAN TREE, MANGO TREE
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There are two other kinds of plants. They are: Creepers & Climbers, AUDITI DEY/6/SCI/ONLINE/2020, 8
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CREEPERS, These are plants which have soft, weak and green stems; hence they cannot stand straight and instead spread themselves on the ground., AUDITI DEY/6/SCI/ONLINE/2020, 9, BOTTLE GOURD, PUMPKIN
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CLIMBERS, These are also plants with soft and weak stems. Instead of spreading themselves on the ground, they take the support of a nearby object to climb up., AUDITI DEY/6/SCI/ONLINE/2020, 10, BITTER GOURD, GRAPEVINE
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PARTS OF A PLANT, AUDITI DEY/6/SCI/ONLINE/2020, 11
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STEM, The stem is that part of a plant which bears branches, flowers, leaves, fruits and buds. It grows above the ground., FUNCTIONS:, It is responsible for supplying water and minerals from roots to all parts of the plant. , It also helps in transporting food prepared by leaves to different parts of the plant, including roots., AUDITI DEY/6/SCI/ONLINE/2020, 12
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ACTIVITY: To show how the stem helps in the conduction of water., First, let us take a glass and fill one-third of it with water. Then add a few drops of coloured ink to the water. , Cut the base of a stem and put it in the glass having coloured water. , Observation: We observe that after a while the stem and leaves of the plant change colour and take after the colour of the ink. This is proof that the stem carries water to different parts of the plant., Stems have narrow tubes inside them, through which the water travels upwards., AUDITI DEY/6/SCI/ONLINE/2020, 13
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LEAF : PARTS OF A LEAF, Petiole: This is the stalk via which the leaf is joined to the plant. , Lamina: This is the expanded part or the green portion of a leaf which is responsible for photosynthesis., Midrib: This is the central, prominent thick structure/line right in the middle of a leaf which helps support the leaf and prevents it from breaking., Veins: The many lines that run through the surface of a leaf are called veins. They transport water and minerals., AUDITI DEY/6/SCI/ONLINE/2020, 14
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BRAIN TEASERS, DO ALL LEAVES HAVE A PETIOLE?, , Find out some plants which have leaves with a petiole and some which have leaves without any petiole., Do you know their names? If not, try to find out., AUDITI DEY/6/SCI/ONLINE/2020, 15
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LEAF VENATION, Leaf venation is the design made by veins on the leaf surface. , There are two major types of leaf venation., RETICULATE VENATION: It is a type of venation in which the veins form a net-like shape on either side of the midrib., AUDITI DEY/6/SCI/ONLINE/2020, 16, PEEPAL, HIBISCUS, ROSE, NEEM
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LEAF VENATION continued, Parallel venation is said to exist when the veins run parallel to one another., AUDITI DEY/6/SCI/ONLINE/2020, 17, TULIP, TURMERIC, BAMBOO, BANANA
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FUNCTIONS OF A LEAF, TRANSPIRATION: Transpiration is the process by which plants release the excess amount of water (in the form of vapour) into the air. , It helps in cooling the plants down. , ACTIVITY: We can observe transpiration by enclosing the leafy part of a plant in a closed polythene bag and leaving it in the sun. , After a while, we see tiny droplets of water on the insides of the polythene bag. This proves that the leaves have performed transpiration., AUDITI DEY/6/SCI/ONLINE/2020, 18
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FUNCTIONS OF A LEAF continued, PHOTOSYNTHESIS: Photosynthesis is defined as the process which helps leaves prepare food for the plant with the help of carbon-di-oxide and water in the presence of sunlight and a green pigment (in leaves) called chlorophyll. , The food prepared is stored in various parts of the plant in the form of starch. , ACTIVITY: In order to see if leaves really do perform photosynthesis, let us take a leaf and immerse it in a test tube filled with spirit. , Place this test tube in a beaker filled with water; then heat the beaker. , After the leaf loses its colour, wash it and pour iodine solution over it., We can see that it turns blue-black in colour; this shows the presence of starch., AUDITI DEY/6/SCI/ONLINE/2020, 19
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ROOTS, The root is a very important component of the plant system for the simple reason that in its absence, the plant ceases to exist. , Roots generally grow under the ground., AUDITI DEY/6/SCI/ONLINE/2020, 20
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TYPES OF ROOTS, There are two major types of roots which exist in plants., TAP ROOTS: In this type of root system, there is a prominent and long root and a bunch of smaller roots which grow from this main root called lateral roots., Plants showing reticulate venation in leaves have tap roots., AUDITI DEY/6/SCI/ONLINE/2020, 21, CORIANDER, RADISH
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TYPES OF ROOTS continued, FIBROUS ROOTS: In this type of root system, a group of similar-sized roots emerge from the base of the plant. They do not have a main root., Plants showing parallel venation in leaves have fibrous roots., AUDITI DEY/6/SCI/ONLINE/2020, 22, GRASS, RICE (PADDY), WHEAT
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FUNCTIONS OF ROOTS, Roots are responsible for absorbing minerals and water from the soil and transferring them to the stem. , Another important function of roots is to firmly anchor the plant in the ground. This is essential to support the upright position of the plants., AUDITI DEY/6/SCI/ONLINE/2020, 23
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FUNCTIONS OF ROOTS continued, Roots also perform the function of storing important nutrients and food for growth., There are some roots which are edible., AUDITI DEY/6/SCI/ONLINE/2020, 24, CARROTS, BEET ROOT, RADISH, TURNIP
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FLOWERS, Flowers are the colourful, seed- bearing parts of a plant which grow at the end of the stem. , They are the reproductive part of a plant., AUDITI DEY/6/SCI/ONLINE/2020, 25, HIBISCUS, ROSE, PETUNIA, LILY, DAHLIA, CHRYSANTHEMUM
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PARTS OF A FLOWER, A flower typically consists of the following parts:, RECEPTACLE: It is the base of a flower to which all the parts of a flower are attached., AUDITI DEY/6/SCI/ONLINE/2020, 26
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PARTS OF A FLOWER, AUDITI DEY/6/SCI/ONLINE/2020, 27
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PARTS OF A FLOWER continued, SEPALS: They are the green leaf-like parts in the outermost circle of a flower. All sepals taken together are called Calyx. , They protect the flower during its bud stage., Some flowers have jointed sepals, while some have separate sepals., AUDITI DEY/6/SCI/ONLINE/2020, 28, JOINTED SEPALS OF DATURA, SEPARATE SEPALS OF ROSE
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PARTS OF A FLOWER continued, PETALS: These are colourful, together known as corolla, and are present inside the sepals. , They attract insects for pollination and protect the reproductive organs of the flower., Some flowers have jointed petals and some others have separate petals., AUDITI DEY/6/SCI/ONLINE/2020, 29, JOINTED PETALS, SEPARATE PETALS
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PARTS OF A FLOWER continued, STAMEN: It is the male reproductive part. It consists of anther and filament., The anther is a sac-like structure that produces and stores pollen. , The filament supports the anther., AUDITI DEY/6/SCI/ONLINE/2020, 30
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PARTS OF A FLOWER continued, PISTIL/CARPEL: It is the female reproductive part. It is comprised of three parts- stigma, style and ovary., Stigma is the top-most part of a carpel. It is sticky and receives pollen during pollination., The style is the long tube which connects the stigma to the ovary., The ovary contains a lot of ovules., AUDITI DEY/6/SCI/ONLINE/2020, 31
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BRAIN TEASERS, Do all flowers have sepals, petals, stamens and pistils?, Are there flowers that do not have one or more of these?, Are there flowers which have parts other than these?, Do all flowers have the same number of sepals, petals, stamens and pistils? , Are the number of sepals and petals in a flower always the same?, AUDITI DEY/6/SCI/ONLINE/2020, 32
