Page 1 :
&, =, S, , PART-A, , PLANTS-THE SOURCE, , OF FOOD, , * How are plants useful to us? * How do plants prepare their food?, , Materials required for photosynthesis, , Structure of a leaf, , How do roots contribute towards food production?, , How does the stem help in transporting food and water?, , Food stored in roots, leaves and stems of plants, * Presence of starch in stems and leaves, , , , Plants give us many useful things, , , , © <Plants are very important for us. Apart from, , giving us many useful products like wood,, medicines, etc. plants are also the primary, source of food for us. Most of the food items, that we eat come directly or indirectly from, plants. But, have you ever thought about what, plants eat? Plants make their own food. They, make food in their leaves, in the presence of, sunlight through the process of photosynthesis., , Apart from food plants give us another thing, that we cannot live without. Do you know what, it is?, , This precious resource is oxygen., , When plants make their food by the process of, photosynthesis, they give out oxygen., , Let us learn more about this process., , ee

Page 2 :
PART-A, , Lo eq<PHOTOSYNTHESIS, The green-coloured substance present in, , the leaves is called chlorophyll. Photosynthesis is a Greek word in which, Photosynthesis Is the process of making ‘photo’ means light and ‘synthesis’ means, Ce sree EN ICCD putting together. Plants use this process to, , ek wabecanis earbom closice nine: make their food. Photosynthesis takes place, , , , presence of sunlight., in the presence of carbon dioxide, water, and sunlight., ed-coloured leaves. This is Materials Required for Photosynthesis, , Have you seen your mother prepare food?, She gets all the vegetables, flour and spices, from the market before preparing food in the, kitchen. Similarly, plants get raw materials, from the environment before making their, food. The raw materials needed for this, process are water, minerals, carbon dioxide, and sunlight. Different parts of a plant collect, different raw materials, and leaves make food, using all of these. Therefore, leaves are also, known as the ‘kitchen’ of the plant. Let us, understand how all these raw materials are, collected., , @@<Leaves have tiny pores on the surface which, can be seen only under a microscope. These, pores are called stomata. Air enters the, leaves through the stomata. When the leaves, make food, they take in carbon dioxide and, give out oxygen through the stomata. Water, is absorbed from the soil by the roots., Chlorophyll present in the leaves traps the, sunlight. Once all the ingredients are, collected, leaves produce food in the form, of sugar., , , , Oxygen is released as a by-product of the, photosynthesis. It is used by all living things, for breathing. In addition to leaves,, photosynthesis also takes place in other green, parts of the plant., , Oxygen, Leaves take up carbon dioxide through stomata A

Page 3 :
PART-A, , may vel’ @@<LEAF - THE FOOD FACTORY, Leaves are mostly broad and flat green structures, of plants but there is a great variety in their shapes, and sizes. The flat broad part of the leaf is called, the leaf blade. In the middle of the leaf blade is the, , side Main vein and several side veins or tubes are, , veins connected with it. These veins carry water and, minerals to all the parts of a leaf. Leaves also have, special structures called stomata, which play an, , Leaf blade important role in photosynthesis., , , , , e@@<Have you ever wondered why a plant has so many, , Structure of a leaf leaves? Why are leaves mostly green in colour?, , iis, Tin Kepeivoge on the carta ot niet, , The green colour of the leaves is because of the, presence of a green coloured pigment, called, chlorophy|! which helps in trapping sunlight for, photosynthesis., , , , Larger the plant, more food it needs to live., Therefore, bigger plants have more number of, leaves. We should water plants properly to keep, the leaves healthy and green., , 1, Take two potted plants of the same, kind., , 2. Water one of the plants every day., Do not water the other., , 3. Observe the changes after two, , days, Which plant looks weak with, dried up leaves? Why?, , , , SE iviy-1, , e@@<ROLE OF ROOTS, How do plants get water?, The root is that part of the plant which remains, under the soil. Roots not only fix the plant firmly to, the ground but also soak water and minerals for, the plants. They have small tube-like structures, which absorb the minerals and water from soil and, carry them to the stem., , ee

Page 4 :
PART-A, , @@<ROLE OF STEM, , How are food, water and minerals transported, from one place to another?, , The stem grows above the ground. It bears, branches on which leaves and flowers grow. The, stem also has many tube-like structures inside it, a Stem and leaves Which are extended also from roots. Can you, : become red guess the functions of these tubes? Let us perform, &e the following activity to know the answer., &, , , , oe \ Fa 1. Take a balsam plant with oft stem and clan its, E 2. Te ro waa ink ory, — colour to it., Se PES Put the plant in the jar in such a way that only, Balsam plant i the roots are dipped in the coloured water. i, & 4. Observe the plant after few hours. Do you see, , any roms in colour of the stem or leaves?, eset See, , A stem carries water from roots, to all parts of the plant, , , , The stem and the leaves turn red. This happens, because the roots absorb the red-coloured water, and pass it into the long tubes of the stem from, where this colour reaches the leaves., , Now, we know that the stem carries water from, the roots to all parts of the plant., , Sunlight and carbon dioxide required for, photosynthesis are taken up by the leaves, themselves., , @@<STORAGE OF FOOD, , The food prepared by photosynthesis is in the, form of glucose. It is a kind of sugar and is, converted into starch by plants., , Do you know what happens to the food made by, the plants?, , The food prepared in leaves is sent to all parts of, the plant by long tube-like structures., , ee, , , , , , , ( Pie, ‘Starch is a bigger sugar which is formed by, ing many glucose units.

Page 5 :
PART-A, , o@<Some part of the food is used by the plants to, produce energy for their survival and for their, growth. The rest of the food is converted into, starch and is stored in different parts of the plant, like fruits, stems and roots., , For example, food is stored in roots in the plants of, radish and carrot., , Similarly, the leaves of cabbage and mint store the, , , , food in them., Some of the food-storing stems are potato and, sugarcane., Leaf - cabbage, Stem - potato Humans and other animals use this stored plant, Parts of plant store food food for eating and obtaining energy., , Is starch present in a stem (potato)?, , Let us check the presence of stored food (starch), in potato by performing Activity-3., , , , oo EN, , , , f, i, i, i, i, j, , , , Here, we see that the slice of potato, , changes its colour from golden yellow, to blue-black. This shows the presence, of starch in potato which is a stem., , <Is starch present in a green leaf?, , Bleaching Bleachi oe a in cold water oa uae, in water in —" Let us perform the iodine test to know, , this. Take a green leaf from a healthy, , a _-® < plant. To see any change in colour first, - _ D> bleach the leaf. Bleaching is the, ie = process of removing green colour of, ral ha Sone the leaf by boiling it first in water and, , Testing presence of starch in leaves then in alcohol., , fe