Science

CC PP MM RROOPP RROODDUUCCTTIIOONN AANNDD AANNAAGGEEMMEENNTT P aheli and Boojho went to their uncle's house during the summer vacation. Their uncle is a farmer. Food has to be One day they saw some tools like khurpi, produced on a large sickle, shovel, plough, etc. , in the field. scale. In order to provide food for a large population- regular production, proper I want to know management and distribution is where and how we necessary. use these tools. 1. 1Agricultural Practices You have learnt that all living organisms require food. Plants can make Till 10, 00 B. C. E. people were their food themselves. Can you recall nomadic. They were wandering in how green plants synthesise their own groups from place to place in search food? Animals including humans can of food and shelter. They ate raw not make their own food. So, where do fruits and vegetables and started animals get their food from? hunting animals for food. Later, they But, first of all why do we have to eat could cultivate land and produce rice, food? wheat and other food crops. Thus, You already know that energy from was born 'Agriculture'. the food is utilised by organisms for carrying out their various body When plants of the same kind are functions, such as digestion, respiration cultivated at one place on a large scale, and excretion. We get our food from it is called a crop. For example, crop of plants, or animals, or both. wheat means that all the plants grown in a field are that of wheat. You already know that crops are of different types like cereals, vegetables and fruits. These can be classified on the Since we all need food, basis of the season in which they grow. how can we provide India is a vast country. The climatic food to a large number conditions like temperature, humidity of people in our and rainfall vary from one region to country? another. Accordingly, there is a rich 2024-25 variety of crops grown in different parts to as agricultural practices which are of the country. Despite this diversity, listed below: two broad cropping patterns can be - Preparation of soil identified. These are: - Sowing - Kharif Crops: The crops which are - Adding manure and fertilisers sown in the rainy season are called - Irrigation kharif crops. The rainy season in India - Protecting from weeds is generally from June to September. - Harvesting Paddy, maize, soyabean, groundnut and - Storage cotton are kharif crops. - Rabi Crops: The crops grown in the


Science

1.3 Preparation of Soil winter season (October to March) are called rabi crops. Examples of rabi The preparation of

1. 3 Preparation of Soil winter season (October to March) are called rabi crops. Examples of rabi The preparation of soil is the first step crops are wheat, gram, pea, mustard before growing a crop. One of the most and linseed. important tasks in agriculture is to turn Besides these, pulses and vegetables the soil and loosen it. This allows the are grown during summer at many roots to penetrate deep into the soil. The places. loose soil allows the roots to breathe easily even when they go deep into the 1. 2 Basic Practices of Crop soil. Why does the loosening of soil allow Production the roots to breathe easily? The loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms are friends of the farmer since they further turn and loosen the soil and add humus to it. Why paddy can not be But why the soil needs to be turned and grown in the winter season? loosened? You have learnt in the previous classes that soil contains minerals, water, air and some living organisms. Paddy requires a lot of In addition, dead plants and animals water. Therefore, it is grown get decomposed by soil organisms. In only in the rainy season. this way, various nutrients in the dead organisms are released back into the soil. These nutrients are again absorbed Cultivation of crops involves several by plants. activities undertaken by farmers over a Since only a few centimetres of the period of time. You may find that these activities are similar to those carried out top layer of soil supports plant growth, by a gardener or even by you when you turning and loosening of soil brings the grow ornamental plants in your house. nutrient-rich soil to the top so that These activities or tasks are referred plants can use these nutrients. Thus, 2024-25 turning and loosening of soil is very Plough: This is being used since important for cultivation of crops. ancient times for tilling the soil, adding The process of loosening and turning fertilisers to the crop, removing the weeds of the soil is called tilling or ploughing. and turning the soil. This is made of This is done by using a plough. Ploughs wood and is drawn by a pair of bulls or are made of wood or iron. If the soil is other animals (horses and camels). It very dry, it may need watering before contains a strong triangular iron strip ploughing. The ploughed field may have called ploughshare. The main part of the big clumps of soil called crumbs. It is plough is a long log of wood which is necessary to break these crumbs. called a ploughshaft. There is a handle Levelling the field is beneficial for at one end of the shaft. The other end is sowing as well as for irrigation. Levelling attached to a beam which is placed on of soil is done with the help of a leveller. the bulls' necks. One pair of bulls and a Sometimes, manure is added to the man can easily operate the plough soil before tilling. This helps in proper. mixing of manure with soil. The soil is The indigenous wooden plough is moistened before sowing. increasingly being replaced by iron ploughs nowadays. Agricultural Implements Hoe: It is a simple tool which is used Before sowing the seeds, it is necessary to for removing weeds and for loosening break soil clumps to get better yield. This the soil. It has a long rod of wood or is done with the help of various tools. The main tools used for this purpose are iron. A strong, broad and bent plate of the plough, hoe and cultivator. iron is fixed to one of its ends and beam ploughshaft ploughshare Fig. 1. 1 (a): The plough 2024-25 works like a blade. It is pulled by ## Activity 1. 1 animals. Take a beaker and fill half of it grip beam with water. Put a handful of wheat handle seeds and stir well. Wait for some time. bent plate Are there seeds which float on rod water? Would those be lighter or Fig. 1. 1 (b): A hoe heavier than those which sink? Why Cultivator: Nowadays ploughing is would they be lighter? Damaged seeds done by tractor-driven cultivator. The become hollow and are thus lighter. use of cultivator saves labour and time. Therefore, they float on water. . This is a good method for separating good, healthy seeds from the damaged ones. Before sowing, one of the important tasks is to know about the tools used for sowing seeds. Traditional tool: The tool used traditionally for sowing seeds is shaped like a funnel. The Fig. 1. 1 (c): Cultivator driven by a tractor seeds are filled into the funnel, passed down through two or three 1. 4 Sowing pipes having sharp ends. These Sowing is an important part of crop ends pierce into the soil and place production. Before sowing, good quality, seeds there. clean and healthy seeds of a good variety-are selected. Farmers prefer to use seeds which give high yield. Selection of Seeds One day I saw my mother put some gram seeds in a vessel and pour some water on them. After a few minutes some seeds started to float on top. I wonder why some seeds float on water! Fig. 1. 2 (a): Traditional method of sowing 2024-25 sufficient sunlight, nutrients and water from the soil. At times a few plants may have to be removed to prevent overcrowding. 1. 5 Adding Manure and Fertilisers The substances which are added to the soil in the form of nutrients for the healthy growth of plants are called manure and fertilisers. Fig. 1. 2 (b): A seed drill Seed drill: Nowadays the seed drill is used for sowing with the help in a farm. In the neighbouring of tractors. This sows the seeds farm, the plants were weak. uniformly at equal distance and depth. Why do some plants grow It ensures that seeds get covered by the better than others? soil after sowing. This protects seeds from being eaten by birds. Sowing by Soil supplies mineral nutrients to the using a seed drill saves time and labour. crop plants. These nutrients are essential for the growth of plants. In certain areas, farmers grow crop after There is a nursery near my crop in the same field. The field is never school. I found that little left uncultivated or fallow. Imagine what plants were kept in small happens to the nutrients? bags. Why are they Continuous cultivation of crops kept like this? makes the soil poor in nutrients. Therefore, farmers have to add manure to the fields to replenish the soil with nutrients. This process is called Seeds of a few plants manuring. Improper or insufficient such as paddy are first manuring results in weak plants. grown in a nursery. When Manure is an organic substance they grow into seedlings, they are transplanted to obtained from the decomposition of the field manually. Some plant


Science

Activity 1.2 better growth of plants? In which glass

[Activity] ## Activity 1. 2 better growth of plants? In which glass was the growth fastest? Take moong or gram seeds and Fertilisers are chemicals which are germinate them. Select three equal rich in a particular nutrient. How are sized seedlings. Take three empty they different from manure? Fertilisers glasses or similar vessels. Mark them are produced in factories. Some A, B and C. To glass A add little examples of fertilisers are- urea, amount of soil mixed with a little cow ammonium sulphate, super dung manure. In glass B put the phosphate, potash, NPK (Nitrogen, same amount of soil mixed with a Phosphorus, Potassium). little urea. Take the same amount of soil in glass C without adding The use of fertilisers has helped anything. Now pour the farmers to get better yield of crops same amount of water in each glass such as wheat, paddy and maize. But and plant the seedlings in them. excessive use of fertilisers has made Keep them in a safe place and water the soil less fertile. Fertilisers have also them daily. After 7 to 10 days become a source of water pollution. observe their growth. Therefore, in order to maintain the fertility of the soil, we have to substitute fertilisers with organic manure or leave the field uncultivated (fallow) in between two crops. The use of manure improves soil texture as well as its water retaining capacity. It replenishes the soil with nutrients. Another method of replenishing Fig. 1. 3 (a): Preparation of the experiment the soil with nutrients is through crop rotation. This can be done by growing different crops alternately. Earlier, farmers in northern India used to grow legumes as fodder in one season and wheat in the next season. This helped in the replenishment of the soil with nitrogen. Farmers are being encouraged to adopt this practice. In the previous classes, you have Fig. 1. 3 (b): Growing seedlings with manure learnt about Rhizobium bacteria. and fertiliser These are present in the nodules of Did plants in all the glasses grow at roots of leguminous plants. They fix the same pace? Which glass showed atmospheric nitrogen. 2024-25 Differences between Fertiliser and Manure S. No. Fertiliser Manure 1. Fertiliser is a man-made Manure is a natural substance obtained inorganic salt. by the decomposition of cattle dung and plant residues. 2. Fertiliser is prepared in Manure can be prepared in the fields. factories. 3. Fertiliser does not provide Manure provides a lot of humus to the soil. any humus to the soil. 4. Fertilisers are very rich in Manure is relatively less rich in plant plant nutrients like nitrogen, nutrients. phosphorus and potassium. Table 1. 1 gives the differences protects the crop from both frost and between a fertiliser and manure. hot air currents. To maintain the moisture of the soil for healthy crop Advantages of Manure: The organic growth, fields have to be watered manure is considered better than regularly. fertilisers. This is because The supply of water to crops at - it enhances the water holding regular intervals is called irrigation. The capacity of the soil. time and frequency of irrigation varies - it makes the soil porous due to which from crop to crop, soil to soil and season exchange of gases becomes easy. to season. In summer, the frequency of - it increases the number of friendly watering is higher. Why is it so? Could microbes. it be due to the increased rate of - it improves the texture of the soil. evaporation of water from the soil and the leaves? 1. 6 Irrigation All living beings need water to live. Water is important for proper growth I am very careful this and development. Water is absorbed by year about watering the plant roots. Along with water, the plants. Last minerals and fertilisers are also summer my plants absorbed. Plants contain nearly 90% dried up and died. water. Water is essential because germination of seeds does not take place Sources of irrigation: The sources of under dry conditions. Nutrients water for irrigation are- wells, dissolved in water are transported to tubewells, ponds, lakes, rivers, dams each part of the plant. Water also and canals. 2024-25 Traditional Methods of Irrigation The water available in wells, lakes and canals is lifted up by different methods in different regions, for taking it to the fields. Cattle or human labour is used in these methods. So these methods are cheaper, but less efficient. The various traditional ways are: - moat (pulley-system) - chain pump Fig. 1. 4 (a): Moat Fig. 1. 4 (b): Chain pump Fig. 1. 4 (c): Dhekli - dhekli, and - rahat (Lever system). Pumps are commonly used for lifting water. Diesel, biogas, electricity and solar energy is used to run these pumps. Fig. 1. 4 (d): Rahat 2024-25 Modern Methods of Irrigation Modern methods of irrigation help us to use water economically. The main methods used are as follows: - Sprinkler System: This system is more useful on the uneven land where sufficient water is not available. The perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline Fig. 1. 5 (a): Sprinkler system at regular intervals. When water is allowed to flow - Drip system: In this system, the through the main pipe under pressure water falls drop by drop directly near with the help of a pump, it escapes from the roots. So it is called drip system. It the rotating nozzles. It gets sprinkled is the best technique for watering fruit on the crop as if it is raining. plants, gardens and trees. Sprinkler is very useful for lawns, coffee Water is not wasted at all. It is a boon in plantation and several other crops regions where availability of water is poor. . Fig. 1. 5 (b): Drip System 2024-25


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1.7 Protection from Weeds Boojho and Paheli went to a nearby wheat field and saw that there were some other plants in

1. 7 Protection from Weeds Boojho and Paheli went to a nearby wheat field and saw that there were some other plants in the field, growing along with wheat plants. Have these other plants been planted purposely? In a field many other undesirable plants may grow naturally along with Spraying weedicide the crop. These undesirable plants are called weeds. The removal of weeds is called Do weedicides have any weeding. Weeding is necessary since effect on the person handling weeds compete with the crop plants for the weedicide sprayer? water, nutrients, space and light. Thus, they affect the growth of the crop. Some As already mentioned, the weedicides weeds interfere even in harvesting and are sprayed during the vegetative growth may be poisonous for animals and of weeds before flowering and seed human beings. formation. Spraying of weedicides may Farmers adopt many ways to remove affect the health of farmers. So they weeds and control their growth. Tilling should use these chemicals very carefully. before sowing of crops helps in They should cover their nose and mouth uprooting and killing of weeds, which with a piece of cloth during spraying of may then dry up and get mixed with these chemicals. the soil. The best time for the removal of weeds is before they produce flowers 1. 8 Harvesting and seeds. The manual removal includes physical removal of weeds by uprooting Harvesting of a crop is an important or cutting them close to the ground, task. The cutting of crop after it is from time to time. This is done with the mature is called harvesting. In help of a khurpi. A seed drill harvesting, crops are pulled out or cut is also used to uproot weeds. close to the ground. It usually takes 3 Weeds are also controlled by using to 4 months for a cereal crop to mature. certain chemicals, called weedicides, Harvesting in our like 2, 4-D. These are sprayed in the country is either done fields to kill the weeds. They do not manually by sickle damage the crops. The weedicides are (Fig. 1. 7) or by a machine diluted with water to the extent required called harvester. In the and sprayed in the fields with a sprayer. harvested crop, the grain (Fig. 1. 6). seeds need to be separated Sickle 2024-25 from the chaff. This process is called Harvest Festivals threshing. This is carried out with the After three or four months of hard help of a machine called 'combine' which work there comes the day of the is in fact a harvester as well as a thresher harvest. The sight of golden fields (Fig. 1. 8). of standing crop, laden with grain, fills the hearts of farmers with joy and a sense of well-being. The efforts of the past season have borne fruit and it is time to relax and enjoy a little. The period of harvest is, thus, of great joy and happiness in all parts of India. Men and women celebrate it with great enthusiasm. Special festivals associated with the harvest season are Pongal, Baisakhi, Holi, Diwali, Nabanya and Bihu. Combine 1. 9Storage After harvesting, sometimes Storage of produce is an important task. stubs are left in the field, which If the harvested grains are to be kept are burnt by farmers. Paheli is for longer time, they should be safe worried. She knows that it causes pollution. It may also from moisture, insects, rats and catch fire and damage the crops microorganisms. Harvested grains have lying in the fields. more moisture. If freshly harvested grains (seeds) are stored without drying, Farmers with small holdings of land they may get spoilt or attacked by do the separation of grain and chaff by organisms, making them unfit for use winnowing (Fig. 1. 9). You have already or for germination. Hence, before studied this in Class VI. storing them, the grains are properly dried in the sun to reduce the moisture in them. This prevents the attack by insect pests, bacteria and fungi. I saw my mother putting some dried neem leaves in an iron drum containing wheat. I wonder why? Winnowing machine 2024-25 Fig. 1. 10 (a): Silos for storage of grains 1. 10Food from Animals


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[Activity] ## Activity 1. 3 Make the following Table in your note book and complete it. S. No. Food Sources 1. Milk Cow, Buffalo, She- goat, She-camel. . . 2. 3. 4. After completing this Table, you must have seen that, like plants, animals also provide us with different kinds of food. Many people living in the coastal areas consume fish as a major part of their diet. In the previous classes Fig. 1. 10 (b): Storage of grains in you have learnt about the food that we gunny bags in granaries obtain from plants. We have just seen Farmers store grains in jute bags or that the process of crop production metallic bins. However, large scale involves a number of steps like selection storage of grains is done in silos and of seeds, sowing, etc. Similarly, animals granaries to protect them from pests reared at home or in farms, have to be like rats and insects. care. When this is done on a large scale, Dried neem leaves are used for it is called animal husbandry. storing food grains at home. For storing large quantities of grains in big godowns, specific chemical treatments Fish is good for health. are required to protect them from pests We get cod liver oil from fish which is rich in vitamin D. and microorganisms. 2024-25 KKEEYYWWOORRDDSS WWHHAATT YYOOUU HHAAVVEE LLEEAARRNNTT AGRICULTURAL Ü In order to provide food to our growing PRACTICES population, we need to adopt certain agricultural practices. ANIMAL HUSBANDRY Ü Same kind of plants cultivated at a place CROP constitute a crop. Ü In India, crops can be broadly categorised into FERTILISER two types based on seasons - rabi and kharif crops. GRANARIES Ü It is necessary to prepare soil by tilling and HARVESTING levelling. Ploughs and levellers are used for this purpose. IRRIGATION Ü Sowing of seeds at appropriate depths and distances gives good yield. Good variety of KHARIF seeds are sown after selection of healthy seeds. MANURE Sowing is done by seed drills. Ü Soil needs replenishment and enrichment PLOUGH through the use of organic manure and fertilisers. Use of chemical fertilisers has RABI increased tremendously with the introduction SEEDS of new crop varieties. Ü Supply of water to crops at appropriate SILO intervals is called irrigation. Ü Weeding involves removal of unwanted and SOWING uncultivated plants called weeds. STORAGE Ü Harvesting is the cutting of the mature crop manually or by machines. THRESHING Ü Separation of the grains from the chaff is called threshing. WEEDS Ü Proper storage of grains is necessary to protect WEEDICIDE them from pests and microorganisms. Ü Food is also obtained from animals for which WINNOWING animals are reared. This is called animal husbandry.


Science

[Exercise] ## Exercises 1. Select the correct word from the following list and fill in the blanks. float, water, crop, nutrients, preparation (a) The same kind of plants grown and cultivated on a large scale at a place is called __. (b) The first step before growing crops is __ of the soil. 2024-25 - Damaged seeds would __ on top of water. - For growing a crop, sufficient sunlight and __ and __ from the soil are essential. 2. Match items in column A with those in column B. A B - Kharif crops (a) Food for cattle - Rabi crops (b) Urea and super phosphate - Chemical fertilisers (c) Animal excreta, cow dung urine and plant waste - Organic manure (d) Wheat, gram, pea (e) Paddy and maize 3. Give two examples of each. (a) Kharif crop (b) Rabi crop 4. Write a paragraph in your own words on each of the following. (a) Preparation of soil (b) Sowing - Weeding (d) Threshing 5. Explain how fertilisers are different from manure. 6. What is irrigation? Describe two methods of irrigation which conserve water. 7. If wheat is sown in the kharif season, what would happen? Discuss. 8. Explain how soil gets affected by the continuous plantation of crops in a field. 9. What are weeds? How can we control them? 10. Arrange the following boxes in proper order to make a flow chart of sugarcane crop production. S E S I C R E X E Sending crop to Irrigation Harvesting Sowing sugar factory 1 2 3 4 Preparation of Ploughing the Manuring soil field 5 6 7 2024-25 11. Complete the following word puzzle with the help of clues given below. Down 1. Providing water to the crops. 2. Keeping crop grains for a long time under proper conditions. 5. Certain plants of the same kind grown on a large scale. Across 3. A machine used for cutting the matured crop. 4. A rabi crop that is also one of the pulses. 6. A process of separating the grain from chaff. S E S I C R E X E Extended Learning - ## Activities and Projects 1. Sow some seeds in the soil and arrange to water them by drip irrigation. Observe daily. - Do you think it can save water? - Note the changes in the seed. 2. Collect different types of seeds and put them in small bags. Label them. 3. Collect pictures of some other agricultural machines and paste them in a file. Write their names and uses. 4. ## Project Work Visit a farm, nursery or a garden nearby. Gather information about - importance of seed selection. - method of irrigation. 2024-25 - effect of extreme cold and extreme hot weather on the plants. - effect of continuous rain on the plants. - fertilisers/manure used. An Example for Field Trip Work Himanshu and his friends were very anxious and curious to go to Thikri village. They went to Shri Jiwan Patel's farmhouse. They had taken bags to collect some seeds and other things. Himanshu: Sir namaskar, I am Himanshu. Here are my friends Mohan, David and Sabiha. We want some information about crops. Please guide us. Shri Patel: Namaskar and welcome all of you. What are your queries? Sabiha: When did you start this work and what are the main crops that you grow? Shri Patel: About 75 years ago, my grandfather started this work. The main crops that we grow are wheat, gram, soyabean and moong. David: Sir, can you tell us the difference between traditional and modern agricultural practices? Shri Patel: Earlier we used traditional tools like sickle, bullock plough, trowel, etc. , and depended on rain water for irrigation. But now we use modern methods of irrigation. We use implements like tractors, cultivators, seed drill and harvester. We get good quality seeds. We carry out soil testing and use manure and fertilisers. New information about agriculture is obtained through radio, T. V. and other sources. As a result we are able to get good crops on a large scale. This year we got 9 to 11 quintals of gram crop/acre and 20 to 25 quintals of wheat/acre. In my opinion awareness of new technology is important for better crop yield. Mohan: Sabiha, come here and see some earthworms. Are they helpful to the farmers? Sabiha: Oh Mohan! we learnt about it in Class VI. Shri Patel: Earthworms turn the soil and loosen it for proper aeration, so they help the farmer. David: Can we have some seeds of the crops you grow here? [They put some seeds, fertilisers and soil sample in the bags. ] Himanshu: Sir, we are thankful to you for making this visit pleasant and for providing useful information. 2024-25


Science

MM: : FF FF IICCRROORRGGAANNIISSMMSS RRIIEENNDD AANNDD OOEE Y ou have seen several kinds of These observations show that water plants and animals. However, and soil are full of tiny organisms, though not all of them fall into the there are other living organisms category of microbes. These around us which we normally cannot microorganisms or microbes are so see. These are called microorganisms small in size that they cannot be seen or microbes. For example, you might with the unaided eye. Some of these, have observed that during the rainy such as the fungus that grows on bread, season moist bread gets spoilt and its can be seen with a magnifying glass. surface gets covered with greyish white Others cannot be seen without the help patches. Observe these patches through of a microscope. That is why these are a magnifying glass. You will see tiny, called microorganisms or microbes. black rounded structures. Do you know Microorganisms are classified into what these structures are and where do four major groups. These groups are these come from? bacteria, fungi, protozoa and some algae. Some of these common 2. 1 Microorganisms microorganisms are shown in Figs. 2. 1 - 2. 4.


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[Activity] ## Activity 2. 1 Viruses are also microscopic but are different from other microorganisms. Collect some moist soil from the They, however, reproduce only inside the field in a beaker and add water to cells of the host organism, which may be it. After the soil particles have a bacterium, plant or animal. Some of the settled down, observe a drop of viruses are shown in Fig. 2. 5. Common water from the beaker under a ailments like cold, influenza (flu) and microscope. What do you see? most coughs are caused by viruses. Serious diseases like polio and chicken


Science

Activity 2.2 pox are also caused by viruses.

[Activity] ## Activity 2. 2 pox are also caused by viruses. Diseases like dysentery and malaria Take a few drops of water from a are caused by protozoa(protozoans) pond. Spread on a glass slide and whereas typhoid and tuberculosis (TB) observe through a microscope. are bacterial diseases. You have learnt about some of Do you find tiny organisms moving these microorganisms in Classes VI around? and VII. 2024-25 Bacteria Amoeba Chlamydomonas Spirogyra Paramecium Algae Protozoa Bread mould Penicillium Aspergillus Fungi 2024-25 Friendly Microorganisms Microorganisms are used for various purposes. They are used in the preparation of curd, bread and cake. Microorganisms have been used for the production of alcohol since ages. They are also used in cleaning up of the environment. For example, the organic wastes (vegetable peels, remains of animals, faeces, etc. ) are broken down into harmless and usable substances by bacteria. Recall that bacteria are also used in the preparation of medicines. In agriculture they are used to increase soil fertility by fixing nitrogen. Viruses Making of Curd and Bread You have learnt in Class VII that milk is 2. 2Where do Microorganisms turned into curd by bacteria. Live? Microorganisms may be single-celled like bacteria, some algae and protozoa, I saw that my mother or multicellular, such as many algae and added a little curd to warm fungi. They live in all types of milk to set curd for the environment, ranging from ice cold next day. I wonder why? climate to hot springs; and deserts to marshy lands. They are also found Curd contains several micro- inside the bodies of animals including organisms. Of these, the bacterium, humans. Some microorganisms Lactobacillus promotes the formation grow on other organisms while others of curd. It multiplies in milk and exist freely. converts it into curd. Bacteria are also involved in the making of cheese, 2. 3 Microorganisms and Us pickles and many other food items. An Microorganisms play an important role important ingredient of rava (sooji) in our lives. Some of them are beneficial idlis and bhaturas is curd. Can you in many ways whereas some others are guess why? Bacteria and yeast are also harmful and cause diseases. Let us helpful for fermentation of rice idlis study about them in detail. and dosa batter. MICROORGANISMS: FRIEND AND FOE 19 2024-25


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[Activity] ## Activity 2. 3 spoon of yeast powder to the sugar solution. Keep it covered in a warm Take ½ kg flour (atta or maida), place for 4-5 hours. Now smell the add some sugar and mix with solution. Can you get a smell? warm water. Add a small amount of yeast powder and knead to This is the smell of alcohol as sugar make a soft dough. What do you has been converted into alcohol by yeast. observe after two hours? Did you This process of conversion of sugar into find the dough rising? alcohol is known as fermentation. Louis Pasteur discovered Maida with yeast powder fermentation in 1857. Medicinal Use of Microorganisms Raised maida Whenever you fall ill the doctor may Fig. 2. 6 give you some antibiotic tablets, capsules or injections such as of Yeast reproduces rapidly and penicillin. The source of these produces carbon dioxide during medicines is microorganisms. These respiration. Bubbles of the gas fill the dough and increase its volume (Fig. 2. 6). medicines kill or stop the growth of the This is the basis of the use of yeast in disease-causing microorganisms. Such the baking industry for making breads, medicines are called antibiotics. These pastries and cakes. days a number of antibiotics are being produced from bacteria and fungi. Commercial Use of Microorganisms Streptomycin, tetracycline and Microorganisms are used for the large scale erythromycin are some of the production of alcohol, wine and acetic acid (vinegar). Yeast is used for commercial In 1929, Alexander production of alcohol and wine. For this Fleming was working purpose yeast is grown on natural sugars on a culture of disease- present in grains like barley, wheat, rice, causing bacteria. crushed fruit juices, etc. Suddenly he found the spores of a little green mould in one of


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[Activity] ## Activity 2. 4 his culture plates. He observed that the presence of mould prevented the Take a 500 mL beaker filled upto growth of bacteria. In fact, it also killed ¾ with water. Dissolve 2-3 many of these bacteria. From this the teaspoons of sugar in it. Add half a mould penicillin was prepared. 2024-25 commonly known antibiotics which are from the disease-causing microbes for made from fungi and bacteria. The ever. This is how a vaccine works. antibiotics are manufactured by Several diseases, including cholera, growing specific microorganisms and tuberculosis, smallpox and hepatitis can are used to cure a variety of diseases. be prevented by vaccination. Antibiotics are even mixed with the feed of livestock and poultry to check microbial infection in animals. They are Edward Jenner discovered the also used to control many plant vaccine for small- diseases. pox in 1798. It is important to remember that antibiotics should be taken only on In your childhood, you must have the advice of a qualified doctor. Also you must complete the course been given injections to protect prescribed by the doctor. If you take yourself against several diseases. antibiotics when not needed or in Can you prepare a list of these wrong doses, it may make the drug diseases? You may take help from less effective when you might need your parents. it in future. Also antibiotics taken It is essential to protect all children unnecessarily may kill the beneficial against these diseases. Necessary bacteria in the body. Antibiotics, however, are not effective against vaccines are available in the nearby cold and flu as these are caused by hospitals. You might have seen the viruses. advertisement on TV and newspapers regarding protection of children against Vaccine polio under the Pulse Polio Programme. Polio drops given to children are actually a vaccine. A worldwide campaign against Why are children/infants smallpox has finally led to its eradication given vaccination? from most parts of the world. These days vaccines are made on a When a disease-carrying microbe enters large scale from microorganisms to our body, the body produces antibodies protect humans and other animals from to fight the invader. The body also several diseases. remembers how to fight the microbe if Increasing Soil Fertility it enters again. If dead or weakened microbes are introduced into a healthy Some bacteria (Fig. 2. 7) are able to fix body, the body fights and kills nitrogen from the atmosphere to enrich the invading bacteria by producing soil with nitrogen and increase its suitable antibodies. The antibodies fertility. These microbes are commonly remain in the body and we are protected called biological nitrogen fixers. MICROORGANISMS: FRIEND AND FOE 21 2024-25 The Nitrogen fixing cyanobacteria (blue green algae) Cleaning the Environment released in the process can be used by the plants again. Boojho and Paheli had observed the Did you notice that in pot B, the school gardener making manure. Along polythene bags, empty glasses, bottles with their friends, they collected wastes and broken toy parts did not undergo of plants, vegetables and fruits from any such change? The microbes could nearby houses and gardens. They put them in a pit meant for waste disposal. not 'act' on them and convert them into After some time, it decomposed and got manure. converted to manure. Boojho and You often see large amounts of Paheli wanted to know how this had dead organic matter in the form of happened. decaying plants and sometimes dead animals on the ground. You find


Science

Activity 2.5 that they disappear after some time.

[Activity] ## Activity 2. 5 that they disappear after some time. This is because the microorganisms Take two pots and fill each pot half decompose dead organic waste of plants with soil. Mark them A and B. Put and animals converting them into plant waste in pot A and things like simple substances. These substances polythene bags, empty glass bottles are again used by other plants and and broken plastic toys in pot B. animals. Thus, microorganisms can Put the pots aside. Observe them be used to degrade the harmful and after 3-4 weeks. smelly substances and thereby clean up the environment. Do you find any difference in the contents of the two pots? If so, what is 2. 4 Harmful Microorganisms the difference? You will find that plant waste in pot A, has been decomposed. Microorganisms are harmful in many How did this happen? The plant waste ways. Some of the microorganisms has been converted into manure by the cause diseases in human beings, plants action of microbes. The nutrients and animals. Such disease-causing 2024-25 microorganisms are called pathogens. There are some insects and animals Some microorganisms spoil food, which act as carriers of disease- clothing and leather. Let us study more causing microbes. Housefly is one such about their harmful activities. carrier. The flies sit on the garbage and animal excreta. Pathogens stick to their Disease causing Microorganisms bodies. When these flies sit on uncovered in Humans food they may transfer the pathogens. Whoever eats the contaminated food is Pathogens enter our body through the likely to get sick. So, it is advisable to air we breathe, the water we drink or always keep food covered. Avoid the food we eat. They can also get consuming uncovered items of food. transmitted by direct contact with an Another example of a carrier is the infected person or carried by an animal. female Anopheles mosquito (Fig. 2. 8), Microbial diseases that can spread from which carries the parasite of malaria an infected person to a healthy person (Plasmodium). Female Aedes mosquito through air, water, food or physical acts as carrier of dengue virus. contact are called communicable How can we control the spread of malaria diseases. Examples of such diseases or dengue? include cholera, common cold, chicken pox and tuberculosis. When a person suffering from common cold sneezes, fine droplets of moisture carrying thousands of viruses are spread in the air. The virus may enter the body of a healthy person while breathing and cause infection. Female Anopheles mosquito Then how do you prevent the spread of Why does the teacher communicable keep telling us not diseases? to let water collect anywhere in the neighbourhood? All mosquitoes breed in water. Hence, one should not let water collect We should keep a anywhere, in coolers, tyres, flower pot, handkerchief on the etc. By keeping the surroundings clean nose and mouth while and dry we can prevent mosquitoes from sneezing. It is better to breeding. Try to make a list of measures keep a distance from which help to avoid the spread of infected persons. malaria. MICROORGANISMS: FRIEND AND FOE 23 2024-25 Some Common Human Diseases caused by Microorganisms Human Disease Causative Mode of Preventive Measures Microorganism Transmission (General) Tuberculosis Bacteria Air Keep the patient in complete isolation. Keep the personal Measles Virus Air belongings of the patient away from those of the others. Chicken Pox Virus Air/Contact Vaccination to be given at suitable age. Polio Virus Air/Water Maintain personal hygiene Cholera Bacteria Water/Food and good sanitary habits. Typhoid Bacteria Water Consume properly cooked food and boiled drinking water. Vaccination. Hepatitis AVirus Water Drink boiled drinking water. Vaccination. Use mosquito net and Malaria Protozoa Mosquito repellents. Spray insecticides and control breeding of mosquitoes by not allowing water to collect in the surroundings. Some of the common diseases in other animals. For example, anthrax affecting humans, their mode of is a dangerous human and cattle transmission and few general methods disease caused by a bacterium. Foot of prevention are shown in Table 2. 1. and mouth disease of cattle is caused by a virus. Disease causing Microorganisms in Animals Disease causing Microorganisms in Plants Several microorganisms not only cause diseases in humans and plants, but also Several microorganisms cause diseases in plants like wheat, rice, potato, Robert Köch (1876) sugarcane, orange, apple and others. discovered the bacterium The diseases reduce the yield of crops. (Bacillus anthracis) which See Table 2. 2 for some such plant causes anthrax disease. diseases. They can be controlled by the 2024-25 Some Common Plant Diseases caused by Microorganisms Plant Micro- Mode of Diseases organism Transmission Citrus Bacteria Air canker Rust of Fungi Air, wheat seeds Yellow vein Virus Insect mosaic of bhindi (Okra) use of certain chemicals which kill the make the food poisonous causing microbes. serious illness and even death. So, it is very important that we preserve Food Poisoning food to prevent it from being spoilt. Boojho was invited by his friend to a 2. 5 Food Preservation party and he ate a variety of foodstuff. On reaching home he started vomiting In Chapter 1, we have learnt about the and had to be taken to a hospital. The methods used to preserve and store food doctor said that this condition could be grains. How do we preserve cooked food due to food poisoning. at home? You know that bread left unused under moist conditions is attacked by fungus. Microorganisms spoil our food. Spoiled food emits bad smell and has a bad taste and changed Paheli wonders how food can become a colour. Is spoiling of food a chemical 'poison'. reaction? Paheli bought some mangoes but she Food poisoning could be due to the could not eat them for a few days. Later consumption of food spoilt by some she found that they were spoilt and microorganisms. Microorganisms rotten. But she knows that the mango that grow on our food sometimes pickle her grandmother makes does not produce toxic substances. These spoil for a long time. She is confused. MICROORGANISMS: FRIEND AND FOE 25 2024-25 Let us study the common methods Similarly, we keep our food in the of preserving food in our homes. We refrigerator. Low temperature inhibits have to save it from the attack of the growth of microbes. microorganisms. Chemical Method Salts and edible oils are the common Why does the milk that chemicals generally used to check the comes in packets not spoil? growth of microorganisms. Therefore My mother told me that the they are called preservatives. We add milk is 'pasteurised'. What salt or acid preservatives to pickles to is pasteurisation? prevent the attack of microbes. Sodium benzoate and sodium metabisulphite are Pasteurised milk can be consumed common preservatives. These are also without boiling as it is free from harmful used in jams and squashes to check microbes. The milk is heated to about their spoilage. 700C for 15 to 30 seconds and then suddenly chilled and stored. By doing Preservation by Common Salt so, it prevents the growth of microbes. Common salt has been used to preserve This process was discovered by Louis meat and fish for ages. Meat and fish Pasteur. It is called pasteurisation. are covered with


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that the they are called preservatives. We add milk is 'pasteurised'. What salt or acid preservatives to pickles to is pasteurisation? prevent the attack of microbes. Sodium benzoate and sodium metabisulphite are Pasteurised milk can be consumed common preservatives. These are also without boiling as it is free from harmful used in jams and squashes to check microbes. The milk is heated to about their spoilage. 700C for 15 to 30 seconds and then suddenly chilled and stored. By doing Preservation by Common Salt so, it prevents the growth of microbes. Common salt has been used to preserve This process was discovered by Louis meat and fish for ages. Meat and fish Pasteur. It is called pasteurisation. are covered with dry salt to check Storage and Packing the growth of bacteria. Salting is also used to preserve amla, raw mangoes, These days dry fruits and even tamarind, etc. vegetables are sold in sealed air tight packets to prevent the attack of Preservation by Sugar microbes. Jams, jellies and squashes are preserved 2. 6 Nitrogen Fixation by sugar. Sugar reduces the moisture content which inhibits the growth of You have learnt about the bacterium bacteria which spoil food. Rhizobium in Classes VI and VII. It is involved in the fixation of nitrogen in Preservation by Oil and Vinegar leguminous plants (pulses). Recall that Use of oil and vinegar prevents spoilage Rhizobium lives in the root nodules of of pickles because bacteria cannot live leguminous plants (Fig. 2. 9), such as in such an environment. Vegetables, beans and peas, with which it has a fruits, fish and meat are often preserved symbiotic relationship. Sometimes by this method. nitrogen gets fixed through the action of lightning. But you know that the Heat and Cold Treatments amount of nitrogen in the atmosphere You must have observed your mother remains constant. You may wonder boiling milk before it is stored or used. how? Let us understand this in the next Boiling kills many microorganisms. section. 2024-25 nitrogen cannot be taken directly by plants and animals. Certain bacteria and blue green algae present in the soil fix nitrogen from the atmosphere and convert it into compounds of nitrogen. Once nitrogen is converted into these usable compounds, it can be utilised by plants from the soil through their root system. Nitrogen is then used for the synthesis of plant proteins and other compounds. Animals feeding on plants get these proteins and other nitrogen compounds (Fig. 2. 10). When plants and animals die, Roots of a leguminous plant with root bacteria and fungi present in the soil nodules convert the nitrogenous wastes into nitrogenous compounds to be used by 2. 7 Nitrogen cycle plants again. Certain other bacteria Our atmosphere has 78% nitrogen gas. convert some part of them to nitrogen Nitrogen is one of the essential gas which goes back into the constituents of all living organisms as atmosphere. As a result, the percentage part of proteins, chlorophyll, nucleic of nitrogen in the atmosphere remains acids and vitamins. The atmospheric more or less constant. Nitrogen cycle MICROORGANISMS: FRIEND AND FOE 27 2024-25 KKEEYYWWOORRDDSS WWHHAATT YYOOUU HHAAVVEE LLEEAARRNNTT ALGAE Ü Microorganisms are too small and are not visible to the unaided eye. ANTIBIOTICS Ü They can live in all kinds of environment, ANTIBODIES ranging from ice cold climate to hot springs and deserts to marshy lands. BACTERIA Ü Microorganisms are found in air, water and CARRIER in the bodies of plants and animals. Ü They may be unicellular or multicellular. COMMUNICABLE Ü Microorganisms include bacteria, fungi, DISEASES protozoa and some algae. Viruses, though FERMENTATION different from the above mentioned living organisms, are considered microbes. FUNGI Ü Viruses are quite different from other LACTOBACILLUS microorganisms. They reproduce only inside the host organism: bacterium, plant or ani- MICROORGANISM mal cell. NITROGEN CYCLE Ü Some microorganisms are useful for commercial production of medicines and NITROGEN FIXATION alcohol. Ü Some microorganisms decompose the organic PASTEURISATION waste and dead plants and animals into simple PATHOGEN substances and clean up the environment. Ü Protozoans cause serious diseases like PRESERVATION dysentery and malaria. PROTOZOA Ü Some of the microorganisms grow on our food and cause food poisoning. RHIZOBIUM Ü Some microorganisms reside in the root VACCINE nodules of leguminous plants. They can fix nitrogen from air into soil and increase the VIRUS soil fertility. YEAST Ü Some bacteria present in the soil fix nitrogen from the atmosphere and convert into nitrogenous compounds. Ü Certain bacteria convert compounds of nitro- gen present in the soil into nitrogen gas which is released to the atmosphere. 2024-25


Science

[Exercise] ## Exercises 1. Fill in the blanks. (a) Microorganisms can be seen with the help of a __. (b) Blue green algae fix __ directly from air and enhance fertility of soil. - Alcohol is produced with the help of __. - Cholera is caused by __. 2. Tick the correct answer. (a) Yeast is used in the production of - sugar (ii) alcohol (ii) hydrochloric acid (iv) oxygen (b) The following is an antibiotic - Sodium bicarbonate (ii) Streptomycin (ii) Alcohol (iv) Yeast - Carrier of malaria-causing protozoan is - female Anopheles mosquito (ii) cockroach - housefly (iv) butterfly - The most common carrier of communicable diseases is - ant (ii) housefly (ii) dragonfly (iv) spider (e) The bread or idli dough rises because of - heat (ii) grinding (ii) growth of yeast cells (iv) kneading (f) The process of conversion of sugar into alcohol is called - nitrogen fixation (ii) moulding (ii) fermentation (iv) infection 3. Match the organisms in Column A with their action in Column B. A B - Bacteria (a) Fixing nitrogen - Rhizobium (b) Setting of curd - Lactobacillus (c) Baking of bread - Yeast (d) Causing malaria - A protozoan (e) Causing cholera - A virus (f) Causing AIDS (g) Producing antibodies 4. Can microorganisms be seen with the naked eye? If not, how can they be seen? MICROORGANISMS: FRIEND AND FOE 29 2024-25 5. What are the major groups of microorganisms? 6. Name the microorganisms which can fix atmospheric nitrogen in the soil. 7. Write 10 lines on the usefulness of microorganisms in our lives. 8. Write a short paragraph on the harmful effects of microorganisms. 9. What are antibiotics? What precautions must be taken while taking antibiotics? S E S I C R E X E Extended Learning - ## Activities and Projects 1. Pull out a gram or bean plant from the field. Observe its roots. You will find round structures called root nodules on the roots. Draw a diagram of the root and show the root nodules. 2. Collect the labels from the bottles of jams and jellies. Write down the list of contents printed on the labels. 3. Visit a doctor. Find out why antibiotics should not be overused. Prepare a short report. 4. Project: Requirements - 2 test tubes, marker pen, sugar, yeast powder, 2 balloons and lime water. Take two test tubes and mark them A and B. Clamp these tubes in a stand and fill them with water leaving some space at the top. Put two spoonfuls of sugar in each of the test tubes. Add a spoonful of yeast in test tube B. Inflate the two balloons incompletely. Now tie the balloons on the mouths of each test tube. Keep them in a warm place, away from sunlight. Watch the setup every A B day for next 3-4 days. Record your observations and think of an explanation. Now take another test tube filled 1/4 with lime water. Remove the balloon from test tube B in such a manner that gas inside the balloon does not escape. Fit the balloon on the test tube and shake well. Observe and explain. 2024-25 Did You Know? Bacteria have lived on the earth for much longer than human beings. They are such hardy organisms that they can live under extreme conditions. They have been found living in boiling mudpots and extremly cold icy waters. They have been found in lakes of caustic soda and in pools of concentrated sulphuric acid. They can survive at depths of several kilometres. They probably can survive in space, too. A kind of bacterium was recovered from a camera which stood on the moon for two years. There is probably no environment in which bacteria cannot survive. MICROORGANISMS: FRIEND AND FOE 31 2024-25


Science

CC PP OOAALL AANNDD EETTRROOLLEEUUMM W e use various materials for our Can air, water and soil be exhausted basic needs. Some of them are by human activities? You have already found in nature and some studied about water in Class VII. Is water have been made by human efforts. a limitless resource? In the light of the availability of


Science

Activity 3.1 various resources in nature, natural

[Activity] ## Activity 3. 1 various resources in nature, natural resources can be broadly classified Make a list of various materials used into two kinds: by us in daily life and classify them as natural and man-made. - Inexhaustible Natural Resources: These resources are present in unlimited Natural Man-made quantity in nature and are not likely to be exhausted by human activities. Examples are: sunlight, air. - Exhaustible Natural Resources: The amount of these resources in nature is limited. They can be exhausted by human activities. Examples of these resources are forests, wildlife, minerals, coal, petroleum, natural gas etc.


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[Activity] ## Activity 3. 2 (It is a group activity) Does this list include air, water, soil Take some containers. Fill them and minerals? Since all these are with popcorn/peanuts/roasted obtained from nature, they are called gram/toffees. Divide students into natural resources. groups of seven each. Further divide each group into three subgroups containing 1, 2 and 4 students. Can we use all our Label them as first, second natural resources and third generation respectively. forever? 2024-25


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3.1 Coal These sub-groups represent the consumers. As population is You may have seen coal or heard about growing,

3. 1 Coal These sub-groups represent the consumers. As population is You may have seen coal or heard about growing, second and third it (Fig. 3. 1). It is as hard as stone and is generations have larger number of black in colour. consumers. Put one full container for each group on a table. Ask consumers of the first generation from each group to consume eatables from the container of their group. Now, ask the second generation consumers from each group to do the same. Ask students to observe carefully the Coal availability of eatables in each Coal is one of the fuels used to cook container. If some thing is left in the food. Earlier, it was used in railway containers, ask third generation engines to produce steam to run the from each group to consume it. Now, engine. It is also used in thermal power finally observe whether all the plants to produce electricity. Coal is also consumers of the third generation used as a fuel in various industries. got the eatables or not. Also observe if anything is still left in any of the Story of Coal containers. Where do we get Assume that the eatables in the coal from and how container represent the total is it formed? availability of an exhausible natural resource like coal, petroleum or About 300 million years ago the natural gas. Each group may have a earth had dense forests in low lying different consumption pattern. Are wetland areas. Due to natural processes, the earlier generations of any group like flooding, these forests got buried too greedy? It may be that the earlier under the soil. As more soil deposited generations in some groups were over them, they were compressed. The concerned about the coming temperature also rose as they sank generation(s) and left something for deeper and deeper. Under high pressure them. and high temperature, dead plants got In this chapter we will learn about slowly converted to coal. As coal some exhaustible natural resources contains mainly carbon, the slow like coal, petroleum and natural gas. process of conversion of dead vegetation These were formed from the dead into coal is called carbonisation. Since remains of living organisms (fossils). it was formed from the remains of So, these are all known as fossil vegetation, coal is also called a fossil fuel. fuels. A coal mine is shown in Fig. 3. 2. 2024-25 A coal mine When heated in air, coal burns and about 200 substances. Products produces mainly carbon dioxide gas. obtained from coal tar are used as Coal is processed in industry to get starting materials for manufacturing some useful products such as coke, coal various substances used in everyday tar and coal gas. life and in industry, like synthetic dyes, drugs, explosives, perfumes, Coke plastics, paints, photographic materials, It is a tough, porous and black roofing materials, etc. Interestingly, substance. It is an almost pure form of naphthalene balls used to repel moths carbon. Coke is used in the manufacture and other insects are also obtained from of steel and in the extraction of many coal tar. metals. These days, bitumen, a petroleum Coal Tar product, is used in place of coal-tar for metalling the roads. It is a black, thick liquid (Fig. 3. 3) with an unpleasant smell. It is a mixture of Coal Gas Coal gas is obtained during the processing of coal to get coke. It is used Coal gas was used for street lighting for the first time in London in 1810 and in New York around 1820. Now a days, it is used as a source of heat rather than light. Coal tar 2024-25 as a fuel in many industries situated transformed the dead organisms into near the coal processing plants. petroleum and natural gas. Look at Fig. 3. 4. It shows the deposits 3. 2 Petroleum of petroleum and natural gas. You see that the layer containing petroleum oil You know that petrol is used as a fuel in light automobiles such as motor cycles/ and gas is above that of water. Why is it scooters and cars. Heavy motor vehicles so? Recall that oil and gas are lighter like trucks and tractors run on diesel. than water and do not mix with it. Petrol and diesel are obtained from a natural resource called petroleum. The The world's first oil well was drilled word petroleum is derived from petra in Pennsylvania, USA, in 1859. Eight years later, in 1867, oil was struck (rock) and oleum (oil) as it is mined at Makum in Assam. In India, oil is from between the rocks under Earth as found in Assam, Gujarat, Mumbai shown in Fig. 3. 4. High and in the river basins of Do you know how petroleum is Godavari and Krishna. formed? Petroleum was formed from Refining of Petroleum organisms living in the sea. As these organisms died, their bodies settled at Petroleum is a dark oily liquid. It has the bottom of the sea and got covered an unpleasant odour. It is a mixture of with layers of sand and clay. Over various constituents such as petroleum millions of years, absence of air, high gas, petrol, diesel, lubricating oil, temperature and high pressure paraffin wax, etc. The process of Wells Impervious Gas rock Oil Reservoir rock Water Petroleum and natural gas deposits 2024-25 Various constituents of petroleum and their uses are given in Table 3. 1. Many useful substances are obtained from petroleum and natural gas. These are termed as 'Petrochemicals'. These are used in the manufacture of detergents, fibres (polyester, nylon, acrylic etc. ), polythene and other man-made plastics. Hydrogen gas obtained from natural gas, is used in the production of fertilisers (urea). Due to its great commercial importance, petroleum is also called 'black gold'. 3. 3 Natural Gas A petroleum refinery Natural gas is a very important fossil fuel because it is easy to transport separating the various constituents/ through pipes. Natural gas is stored fractions of petroleum is known as under high pressure as compressed refining. It is carried out in a petroleum natural gas (CNG). CNG is used for refinery (Fig. 3. 5). power generation. It is now being used Table 3. 1 Various Constituents of Petroleum and their Uses S. No. Constituents of Petroleum Uses 1. Petroleum Gas in Liquid form Fuel for home and industry (LPG) 2. Petrol Motor fuel, aviation fuel, solvent for dry cleaning 3. Kerosene Fuel for stoves, lamps and for jet aircrafts 4. Diesel Fuel for heavy motor vehicles, electric generators 5. Lubricating oil Lubrication 6. Paraffin wax Ointments, candles, vaseline etc. 7. Bitumen Paints, road surfacing 2024-25 as a fuel for transport vehicles because 3. 4Some Natural Resources it is less polluting. It is a cleaner fuel. are Limited The great advantage of CNG is that You have studied in the beginning of it can be used directly for burning in the chapter that some natural resources homes and factories where it can be are exhaustible like fossil fuels, forests, supplied through pipes. Such a network minerals etc. of pipelines exists in Vadodara (Gujarat), You know that coal and petroleum some parts of Delhi and other places. are fossil fuels. It required the dead


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[Exercise] ## Exercises 1. What are the advantages of using CNG and LPG as fuels? 2. Name the petroleum product used for surfacing of roads. 3. Describe how coal is formed from dead vegetation. What is this process called? 4. Fill in the blanks. (a) Fossil fuels are, and. (b) Process of separation of different constituents from petroleum is called. - Least polluting fuel for vehicle is. 5. Tick True/False against the following statements. (a) Fossil fuels can be made in the laboratory. (T/F) (b) CNG is more polluting fuel than petrol. (T/F) - Coke is almost pure form of carbon. (T/F) - Coal tar is a mixture of various substances. (T/F) (e) Kerosene is not a fossil fuel. (T/F) 6. Explain why fossil fuels are exhaustible natural resources. 2024-25 7. Describe characteristics and uses of coke. 8. Explain the process of formation of petroleum. 9. The following Table shows the total power shortage in India from 1991-1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis. S. No. Year Shortage (%) 1 1991 7. 9 2 1992 7. 8 3 1993 8. 3 4 1994 7. 4 5 1995 7. 1 6 1996 9. 2 7 1997 11. 5 S E S I C R E X E Extended Learning - ## Activities and Projects 1. Get an outline map of India. Mark the places in the map where coal, petroleum and natural gas are found. Show the places where petroleum refineries are situated. 2. Choose any five families of your neighbourhood. Enquire whether their energy consumption (coal, gas, electricity, petrol, kerosene) has increased or decreased in the last five years. Enquire also about the measures they adopt to conserve energy. 3. Find out the location of major thermal power plants in India. What could be the reasons for their being located at those places? For more information, visit: - ww. energyarchive. ca. gov - web. ccsd. k12. wy. us - web. pcra. org 2024-25


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CC FF OOMMBBUUSSTTIIOONN AANNDD LLAAMMEE W e use different kinds of fuel for various purposes at home, in industry and for running automobiles. Can you name a few fuels used in our homes? Name a few fuels used in trade and industry. What fuels are used for running automobiles? Your list will contain fuels like cowdung, wood, coal, charcoal, petrol, diesel, compressed natural gas (CNG), etc. You are familiar with the burning of a candle. What is the difference between the burning of a candle and the burning of a fuel like coal? May be you were able to guess right: candle burns with a flame whereas coal does not. Similarly, you will find many other materials burning Burning of magnesium without a flame. Let us study the chemical process of burning and the types of flame A chemical process in which a produced during this process. substance reacts with oxygen to give off heat is called combustion. The 4. 1 What is Combustion? substance that undergoes combustion is said to be combustible. It is also called Recall the activity of burning of a fuel. The fuel may be solid, liquid or magnesium ribbon performed in gas. Sometimes, light is also given off Class VII. We learnt that magnesium burns to form magnesium oxide and during combustion, either as a flame or produces heat and light (Fig. 4. 1). as a glow. We can perform a similar activity with In the reactions mentioned a piece of charcoal. Hold the piece with above magnesium and charcoal are a pair of tongs and bring it near the combustible substances. flame of a candle or a Bunsen burner. What do you observe? We find that charcoal burns in air. We were told that We know that coal, too, burns in air food is a fuel for producing carbon dioxide, heat and our body. light. 2024-25


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[Activity] ## Activity 4. 2 (Caution: Be careful while handling Rightly so. In our body burning candle). food is broken down by Fix a lighted candle on a table. Put reaction with oxygen and a glass chimney over the candle and heat is produced. We rest it on a few wooden blocks in learnt that in Class VII. such a way that air can enter the


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[Activity] ## Activity 4. 1 Collect some materials like straw, matchsticks, kerosene oil, paper, iron nails, stone pieces, glass etc. Under the supervision of your teacher try to burn each of these materials one by one. If combustion takes place mark the material (a) (b) (c) combustible, otherwise mark it Experiment to show that air is non-combustible (Table 4. 1). essential for burning Combustible and Non- chimney. Observe what combustible Substances happens to the flame. Now remove the blocks and let the chimney rest Material Combustible Non- on the table. Again combustible observe the flame. Finally, put a Wood glass plate over the chimney. Watch the flame again. What happens in the three cases? Does Iron nails the flame flicker off? Does it flicker Kerosene oil and give smoke? Does it burn unaffected? Can you infer anything Stone piece at all about the role played by air in Straw the process of burning? Charcoal We find that for combustion, air is Matchsticks necessary. The candle burns freely in Glass case (a) when air can enter the chimney from below. In case (b), when Can you name some more air does not enter the chimney from substances which are combustible? You below, the flame flickers and produces can add those to Table 4. 1. smoke. In case (c), the flame finally Let us investigate conditions under goes off because the air is not which combustion takes place. available. 2024-25 is covered with a blanket to extinguish fire (Fig. 4. 3). Can you guess why? We have read that the sun produces its own heat and light. Is it also some kind of combustion? In the sun, heat and light are produced by nuclear reactions. You will learn about this process in higher classes. Blanket wrapped around a person whose clothes caught fire


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[Activity] ## Activity 4. 3 Now recall some of your experiences. Place a piece of burning wood or Does a matchstick burn by itself? charcoal on an iron plate or Tawa. How does it burn? Cover it with a glass jar or a You must have had an experience of tumbler, or a transparent plastic jar. burning a piece of paper. Does it burn Observe what happens. Does when a burning matchstick is brought charcoal stop burning after near it? sometime? Can you think of the Can you burn a piece of wood by reason why it stops burning? bringing a lighted matchstick near it? Why do you have to use paper or You might have heard that when the kerosene oil to start fire in wood or coal? clothes of a person catch fire, the person Have you heard of forest fires? During extreme heat of summer, at some places dry grass catches fire. From the grass, it spreads to trees, and very soon the whole forest is on fire (Fig. 4. 4). It is very difficult to control such fires. Forest fire 2024-25 Do these experiences tell you that We find that a combustible substance different substances catch fire at cannot catch fire or burn as long as its different temperatures? temperature is lower than its ignition The lowest temperature at which a temperature. Have you ever seen substance catches fire is called its cooking oil catching fire when a frying ignition temperature. pan is kept for long on a burning stove? Can you tell now why a matchstick Kerosene oil and wood do not catch fire does not catch fire on its own at room on their own at room temperature. But, temperature? Why does the matchstick if kerosene oil is heated a little, it will start burning on rubbing it on the side catch fire. But if wood is heated a little, of the matchbox? it would still not catch fire. Does it mean that ignition temperature of kerosene oil The history of the matchstick is very is lower than that of wood? Does it mean old. More than five thousand years that we need to take special care in ago small pieces of pinewood dipped storing kerosene oil? The following in sulphur were used as matches in activity shows that it is essential for a ancient Egypt. The modern safety substance to reach ignition temperature match was developed only about two to burn. hundred years ago. A mixture of antimony trisulphide,


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[Activity] ## Activity 4. 4 potassium chlorate and white phosphorus with some glue and starch was applied on the head of a (Caution: Be careful while handling match made of suitable wood. When burning candle). struck against a rough surface, white Make two paper cups by folding a phosphorus got ignited due to the heat sheet of paper. Pour about 50 mL of of friction. This started the water in one of the cups. Heat both combustion of the match. However, white phosphorus proved to be the cups separately with a candle dangerous both for the workers (Fig. 4. 5). What do you observe? involved in the manufacturing of matches and for the users. These days the head of the safety match contains only antimony water trisulphide and potassium chlorate. The rubbing surface has powdered paper glass and a little red phosphorus cups (which is much less dangerous). When the match is struck against the rubbing surface, some red phosphorus gets converted into white Heating water in a paper cup phosphorus. This immediately reacts with potassium chlorate in the What happens to the empty paper matchstick head to produce enough cup? What happens to the paper cup heat to ignite antimony trisulphide with water? Does water in this cup and start the combustion. become hot? 2024-25 If we continue heating the cup, we can even boil water in the paper cup. Can you think of an explanation for this phenomenon? The heat supplied to the paper cup is transferred to water by conduction. So, in the presence of water, the ignition temperature of paper is not reached. Hence, it does not burn. The substances which have very low ignition temperature and can easily catch fire with Firemen extinguish the fire by throwing water under pressure a flame are called inflammable substances. Examples of Does your city/town have a fire inflammable substances are petrol, brigade station? alcohol, Liquified Petroleum Gas (LPG) When a fire brigade arrives, what etc. Can you list some more inflammable does it do? It pours water on the fire substances? (Fig. 4. 6). Water cools the combustible material so that its temperature is 4. 2 How Do We Control Fire? brought below its ignition temperature. This prevents the fire You must have seen or heard of fire from spreading. Water vapours also breaking out in homes, shops and surround the combustible material, factories. If you have seen such an helping in cutting off the supply of air. accident, write a short description in So, the fire is extinguished. your note book. Also, share the You have learnt that there are three experience with your classmates. essential requirements for producing fire. Can you list these requirements? Find out the telephone number of the These are: fuel, air (to supply fire service in your area. If a fire oxygen) and heat (to raise the breaks out in your house or in your temperature of the fuel beyond the neighbourhood, the first thing to do ignition temperature). Fire can be is to call the fire service. controlled by removing one or more of these requirements. The job of a fire It is important that all of us extinguisher is to cut off the supply of know the telephone numbers air, or to bring down the temperature of the fire service. of the fuel, or both. Notice that the fuel 2024-25 The most common fire extinguisher is water. But water works only when things like wood and paper are on fire. If electrical equipment is on fire, water may conduct electricity and harm those trying to douse the fire. Water is also not suitable for fires involving oil and petrol. Do you recall that water is heavier than oil? So, it Fire extinguisher sinks below the oil, and oil keeps burning on the top. For fires involving electrical equipment and inflammable materials like petrol, carbon dioxide (CO ) is the best extinguisher. CO, being heavier than 2 2 oxygen, covers the fire like a blanket. Since the contact between the fuel and oxygen is cut off, the fire is controlled. The added advantage of CO is that in most cases it does not harm the electrical equipment. How do we get the supply of carbon dioxide? It can be stored at high pressure as a liquid in cylinders. In what form is the LPG stored in cylinders? When released from the cylinder, CO expands enormously in volume and cools down. So, it not only forms a blanket around the fire, it also brings down the temperature of the fuel. That is why it is an excellent fire extinguisher. Another way to get CO is to release a lot of dry powder of chemicals like sodium bicarbonate (baking soda) or potassium bicarbonate. Near the fire, these chemicals give off CO. in most cases cannot be eliminated. We find that the gas burns rapidly If, for instance, a building catches fire, and produces heat and light. Such the whole building is the fuel. combustion is known as rapid combustion. 4. 3 Types of Combustion There are substances like Bring a burning matchstick or a gas phosphorus which burn in air at room lighter near a gas stove in the kitchen. temperature. Turn on the knob of the gas stove. What The type of combustion in which do you observe? a material suddenly bursts into CAUTION: Do not handle the gas flames, without the application of any stove yourself. Ask your parents apparent cause is called spontaneous to help. combustion. 2024-25 Spontaneous combustion of coal dust has resulted in many disastrous fires in coal mines. Spontaneous forest fires are sometimes due to the heat of the sun or due to lightning strike. However, most forest fires are due to the carelessness of human beings. It is important to remember that the Colours of a candle flame and the campfires must be completely flame of a kitchen stove extinguished before leaving a forest after a picnic, or a visit. We generally have fireworks on festival days. When a cracker is ignited, a sudden reaction takes place with the evolution of heat, light and sound. A large amount of gas formed in the reaction is liberated. Such a reaction is called explosion. Explosion can also take place if pressure is applied on the cracker. 4. 4 Flame Observe an LPG flame. Can you tell the colour of the flame. What is the colour of a candle flame? Flames of kerosene lamp, candle and Recall your experience of burning a Bunsen burner magnesium ribbon in Class VII. If you do not have experience of burning the Record your observations and remaining items in Table 4. 2 you can mention whether on burning the do that now. material forms a flame or not. Table 4. 2 Materials forming Flame on Burning S. No. Material Forms flame Does not form flame 1. Candle 2. Magnesium 3. Camphor 4. Kerosene Stove 5. Charcoal 2024-25


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4. 5 Structure of a Flame


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[Activity] ## Activity 4. 5 Light a candle (Caution: Be careful). Hold a 4-5 cm long thin glass tube with a pair of tongs and introduce its one end in the dark zone of a non-flickering candle flame (Fig. 4. 10). Bring a lighted Fig. 4. 11 matchstick near the other end of the glass tube. Do you see a flame When the candle flame is steady, caught at this end of the glass tube introduce a clean glass plate/slide into after a while? If so, what is it that the luminous zone of the flame produces a flame? Notice that the wax (Fig. 4. 11). Hold it there with a pair of near the heated wick melts quickly. tongs for about 10 seconds. Then remove it. What do you observe? Fig. 4. 12 A circular blackish ring is formed on Fig. 4. 10 the glass plate/slide. It indicates the The substances which vapourise deposition of unburnt carbon particles during burning, give flames. For present in the luminous zone of the example, kerosene oil and molten wax flame. rise through the wick and are vapourised Hold a thin long copper wire just during burning and form flames. inside the non-luminous zone of flame Charcoal, on the other hand, does not for about 30 seconds (Fig. 4. 12). vapourise and so does not produce a Notice that the portion of the copper flame. In ## Activity 4. 5, could the vapours wire just outside the flame gets red hot. of wax coming out of the glass tube be Does it indicate that the non-luminous the cause of the flame produced? zone of the flame has a high 2024-25 temperature? In fact, this part of the 4. 6 What is a Fuel? flame is the hottest part (Fig. 4. 13). Recall that the sources of heat energy for domestic and industrial purposes outer zone of hottest complete are mainly wood, charcoal, petrol, part combustion (blue) kerosene etc. These substances are called fuels. A good fuel is one which is moderately readily available. It is cheap. It burns hot middle zone of partial combustion easily in air at a moderate rate. It least (yellow) produces a large amount of heat. It does hot not leave behind any undersirable innermost zone of substances. wax candle unburnt wax There is probably no fuel that could vapours (black) be considered as an ideal fuel. We Different zones of candle flame should look for a fuel which fulfils most of the requirements for a particular use. Goldsmiths blow the outermost zone Fuels differ in their cost. Some fuels of a flame with a metallic blow-pipe for are cheaper than others. melting gold and silver (Fig. 4. 14). Why Make a list of fuels familiar to you. do they use the outermost zone of the Group them as solid, liquid and gaseous flame? fuels as in Table 4. 3. 4. 7 Fuel Efficiency Suppose you were asked to boil a given quantity of water using cow dung, coal and LPG as fuel. Which fuel would you prefer? Give your reason. You may take the help of your parents. Do these three fuels produce the same amount of heat? The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its calorific value. The calorific Goldsmith blowing through a metallic pipe value of a fuel is expressed in a unit Types of Fuels S. No. Solid Fuels Liquid Fuels Gaseous Fuels 1. Coal Kerosene oil Natural gas 2. 3. 2024-25 called kilojoule per kg (kJ/kg). particles. These fine particles are Calorific values of some fuels are given dangerous pollutants causing in Table 4. 4. respiratory diseases, such as asthma. 2. Incomplete combustion of these Calorific Values of different fuels gives carbon monoxide gas. It is a Fuels very poisonous gas. It is dangerous to burn coal in a closed room. The carbon Fuel Calorific Value monoxide gas produced can kill persons (kJ/kg) sleeping in that room. Cow dung cake 600-800 Wood 1700-2200 Oh! So, that is why we are Coal 2500-3300 advised never to sleep in a room with burning or Petrol 4500 smouldering coal fire in it. Kerosene 4500 Diesel 4500 3. Combustion of most fuels releases Methane 500 carbon dioxide in the environment. CNG 500 Increased concentration of carbon dioxide in the air is believed to cause global warming. Biogas 3500-400 Hydrogen 1500 Global warming is the rise in temperature of the atmosphere of the Burning of Fuels Leads to Harmful earth. This results, among other things, Products in the melting of polar glaciers, which leads to a rise in the sea level, causing The increasing fuel consumption has floods in the coastal areas. Low lying harmful effects on the environment. coastal areas may even be permanently 1. Carbon fuels like wood, coal, submerged under water. petroleum release unburnt carbon 4. Burning of coal and diesel releases For centuries, wood was used as sulphur dioxide gas. It is an extremely domestic and industrial fuel. But now suffocating and corrosive gas. Moreover, it has been replaced by coal and other petrol engines give off gaseous oxides fuels like LPG. In many rural parts of our country, people still use wood as a of nitrogen. Oxides of sulphur and fuel because of its easy availability and nitrogen dissolve in rain water and form low cost. However, burning of wood gives acids. Such rain is called acid rain. It is a lot of smoke which is very harmful for very harmful for crops, buildings human beings. It causes respiratory and soil. problem. Also, trees provide us with The use of diesel and petrol as fuels useful substances which are lost when wood is used as fuel. Moreover cutting in automobiles is being replaced by of trees leads to deforestation which is CNG (Compressed Natural Gas), because quite harmful to the environment, as CNG produces the harmful products in you learnt in Class VII. very small amounts. CNG is a cleaner fuel. 2024-25 KKEEYYWWOORRDDSS WWHHAATT YYOOUU HHAAVVEE LLEEAARRNNTT ACID RAIN (cid: 220) The substances which burn in air are called combustible. CALORIFIC VALUE (cid: 220) Oxygen (in air) is essential for combustion. COMBUSTION (cid: 220) During the process of combustion, heat and light are given out. DEFORESTATION (cid: 220) Ignition temperature is the lowest temperature at which a combustible substance catches EXPLOSION fire. (cid: 220) Inflammable substances have very low FLAME ignition temperature. FIRE EXTINGUISHER (cid: 220) Fire can be controlled by removing one or more requirements essential for producing fire. FUEL (cid: 220) Water is commonly used to control fires. (cid: 220) Water cannot be used to control fires involving FUEL EFFICIENCY electrical equipment or oils. GLOBAL WARMING (cid: 220) There are various types of combustions such as rapid combustion, spontaneous IDEAL FUEL combustion, explosion, etc. (cid: 220) There are three different zones of a flame - IGNITION dark zone, luminous zone and non-luminous TEMPERATURE zone. INFLAMMABLE (cid: 220) An ideal fuel is cheap, readily available, readily combustible and easy to transport. It has high SUBSTANCES calorific value. It does not produce gases or residues that pollute the environment. (cid: 220) Fuels differ in their efficiency and cost. (cid: 220) Fuel efficiency is expressed in terms of its calorific value which is expressed in units of kilojoule per kg. (cid: 220) Unburnt carbon particles


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[Exercise] ## Exercises 1. List conditions under which combustion can take place. 2. Fill in the blanks. (a) Burning of wood and coal causes of air. (b) A liquid fuel, used in homes is. - Fuel must be heated to its before it starts burning. - Fire produced by oil cannot be controlled by. 3. Explain how the use of CNG in automobiles has reduced pollution in our cities. 4. Compare LPG and wood as fuels. 5. Give reasons. (a) Water is not used to control fires involving electrical equipment. (b) LPG is a better domestic fuel than wood. - Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not. 6. Make a labelled diagram of a candle flame. 7. Name the unit in which the calorific value of a fuel is expressed. 8. Explain how CO is able to control fires. 9. It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain. 10. Which zone of a flame does a goldsmith use for melting gold and silver and why? 11. In an experiment 4. 5 kg of a fuel was completely burnt. The heat produced was measured to be 180, 00 kJ. Calculate the calorific value of the fuel. 12. Can the process of rusting be called combustion? Discuss. 13. Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time? 2024-25 Extended Learning - ## Activities and Projects 1. Survey the availability of various fuels in your locality. Find out their cost per kg and prepare a tabular chart showing how many kJ of various fuels you can get for every rupee. 2. Find out the number, type and location of fire extinguishers available in your school, nearby shops and factories. Write a brief report about the preparedness of these establishments to fight fire. 3. Survey 100 houses in your area. Find the percentage of households using LPG, kerosene, wood and cattle dung as fuel. 4. Talk to people who use LPG at home. Find out what precautions they take in using LPG. 5. Make a model of a fire extinguisher. Place a short candle and a slightly taller candle in a small dish filled with baking soda. Place the dish at the bottom of a large bowl. Light both the candles. Then pour vinegar into the dish of baking soda. Take care. Do not pour vinegar on the candles. Observe the foaming reaction. What happens to the candles? Why? In what order? baking soda + vinegar Fig. 4. 15 For more information, visit: - ww. newton. dep. anl. gov/askasci/chem03/chem03767. htm - http: //en. wikipedia. org/wiki/combustion 2024-25


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CC PP AA OONNSSEERRVVAATTIIOONN OOFF LLAANNTTSS AANNDD NNIIMMAALLSS W e saw in Class VII that Some natural causes of deforestation Paheli and Boojho had visited are forest fires and severe droughts. the forest along with Professor Ahmad and Tibu. They were eager to ## Activity 5. 1 share their experiences with their Add more causes of deforestation to classmates. Other children in the class your list and classify them into were also eager to share their experiences natural and man-made. as some of them had visited Bharatpur Sanctuary. Some others had heard 5. 2Consequences of about Kaziranga National Park, Deforestation Lockchao Wildlife Sanctuary, Great Nicobar Biosphere Reserve and Tiger Paheli and Boojho recalled the Reserve, etc. consequences of deforestation. They remembered that deforestation increases the temperature and pollution level on the earth. It increases the level of carbon What is the purpose of dioxide in the atmosphere. Ground water making national parks, level also gets lowered. They know that wildlife sanctuaries and biosphere reserves? deforestation disturbs the balance in nature. They were told by Professor 5. 1 Deforestation and Its Ahmad that if cutting of trees continues, Causes rainfall and the fertility of the soil will A great variety of plants and animals exist on earth. They are essential for the well-being and survival of mankind. How does deforestation reduce Today, a major threat to survival of these rainfall on the one hand and organisms is deforestation. We know lead to floods on the other? that deforestation means clearing of forests and using that land for other decrease. Moreover, there will be purposes. Trees in the forest are cut for increased chances of natural calamities some of the purposes mentioned below: such as floods and droughts. - Procuring land for cultivation. Recall that plants need carbon - Building houses and factories. dioxide for photosynthesis. Fewer trees - Making furniture or using wood as would mean that less carbon dioxide will fuel. be used up resulting in its increased 2024-25 amount in the atmosphere. This will lead Biosphere is that part of the earth in to global warming as carbon dioxide which living organisms exist or which traps the heat rays reflected by the earth. supports life. Biological diversity or The increase in temperature on the earth biodiversity, refers to the variety of disturbs the water cycle and may reduce organisms existing on the earth, their rainfall. This could cause droughts. interrelationships and their Deforestation is a major cause which relationship with the environment. leads to the change in soil properties. Physical properties of the soil get affected Professor Ahmad organises a visit to by plantation and vegetation. Fewer a biosphere reserve for Paheli, Boojho and trees result in more soil erosion. their classmates. He selects a place Removal of the top layer of the soil named Pachmarhi Biosphere Reserve. He knows that the plants and animals found exposes the lower, hard and rocky here are similar to those of the upper layers. This soil has less humus and is Himalayan peaks and to those belonging less fertile. Gradually the fertile land to the lower western ghats. Professor gets converted into deserts. It is called Ahmad believes that the biodiversity desertification. found here is unique. He requests Deforestation also leads to a decrease Madhavji, a forest employee, to guide the in the water holding capacity of the soil. children inside the biosphere reserve. He The movement of water from the soil explains that preserving areas of such surface into the ground (infiltration rate) biological importance make them a part is reduced. So, there are floods. The of our national heritage. other properties of the soil like nutrient Madhavji explains to the children content, texture etc. , also change that apart from our personal efforts and because of deforestation. efforts of the society, government We have studied in Class VII that we get many products from forests. List these To protect our flora and fauna and their products. Will we face shortage of these habitats, protected areas called products if we continue cutting trees? wildlife sanctuaries, national parks and biosphere reserves have been


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Activity 5.2 earmarked. Plantation, cultivation,

[Activity] ## Activity 5. 2 earmarked. Plantation, cultivation, grazing, felling trees, hunting and Animal life is also affected by poaching are prohibited there. deforestation. How? List the points Wildlife Sanctuary: Areas where and discuss them in your class. animals are protected from any disturbance to them and their habitat. National Park: Areas reserved for 5. 3 Conservation of Forest wild life where they can freely use the and Wildlife habitats and natural resources. Biosphere Reserve: Large areas of Having become aware of the effects of protected land for conservation of wild deforestation, Paheli and Boojho are life, plant and animal resources and worried. They go to Professor Ahmad traditional life of the tribals living in and ask him how forests and wildlife the area. can be saved. 2024-25 agencies also take care of the forests and 5. 4Biosphere Reserve animals. The government lays down Children along with Professor Ahmad rules, methods and policies to protect and Madhavji enter the biosphere and conserve them. Wildlife sanctuaries, reserve area. Madhavji explains that national parks, biosphere reserves etc. , biosphere reserves are the areas meant are protected areas for conservation for conservation of biodiversity. As you of plants and animals present in are aware that biodiversity is the variety that area. of plants, animals and microorganisms generally found in an area. The


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[Activity] ## Activity 5. 3 biosphere reserves help to maintain the Find out the number of national biodiversity and culture of that area. A parks, wildlife sanctuaries and biosphere reserve may also contain other protected areas in it. The biosphere reserves in your district, Pachmarhi Biosphere Reserve consists state and country. Record in Table of one national park named Satpura and 5. 1. Show these areas in an outline two wildlife sanctuaries named Bori and map of your state and India. Pachmarhi (Fig. 5. 1). Protected Areas for Conservation Protected Areas - National Park Wildlife Sanctuary Biosphere Reserve In my district In my state In my country ↑ N PACHMARHI SANCTUARY TAWA TO PIPARIYA RESERVIOR NEEMGHAN PANARPANI GATE SATPURA NATIONAL PARK CHURNA PACHMARHI DHAIN BORI BORI SANCTUARY Pachmarhi Biosphere Reserve 2024-25


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Activity 5.4 green wealth of the forest. They are

[Activity] ## Activity 5. 4 green wealth of the forest. They are very happy to see tall teak trees and List the factors disturbing the animals inside the forest. Suddenly, biodiversity of your area. Some of Paheli finds a rabbit and wants to these factors and human activities catch it. She starts running after it. may disturb the biodiversity Professor Ahmad stops her. He unknowingly. List these human explains that animals are comfortable activities. How can these be checked? and happy in their own habitat. We Discuss in your class and write a should not disturb them. Madhavji brief report in your notebook. explains that some animals and plants typically belong to a particular area. 5. 5 Flora and Fauna The plants and animals found in a As the children walk around the particular area are termed flora and biosphere reserve they appreciate the fauna respectively of that area. Sal, teak, mango, jamun, silver ferns, arjun, etc. , are the flora and chinkara, blue- bull, barking deer, cheetal, leopard, wild dog, wolf, etc. are examples of the fauna of the Pachmarhi Biosphere Reserve (Fig. 5. 2). (a) (b) (c) - (e) (f) (a) Wild dog (b) Cheetal (c) Wolf (d) Leopard (e) Fern (f) Jamun tree 2024-25


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[Activity] ## Activity 5. 5 Try to identify the flora and fauna of your area and list them. I have heard that some of the endemic species may vanish. 5. 6 Endemic Species Is it true? Soon the group quietly enters the deep endemic flora of the Pachmarhi forest. Children are surprised to see a Biosphere Reserve. Bison, Indian giant very big squirrel. This squirrel has a big squirrel and flying squirrel fluffy tail. They are very curious to know about it. Madhavji tells them that this are endemic fauna of this area. Professor is known as the giant squirrel and is Ahmad explains that the destruction of endemic to this area. their habitat, increasing population and Endemic species are those species introduction of new species may affect of plants and animals which are found the natural habitat of endemic species exclusively in a particular area. They are and endanger their existence. not naturally found anywhere else. A particular type of animal or plant may be endemic to a zone, a state or a country. Madhavji shows sal and wild mango (Fig. 5. 3 (a)] as two examples of the Fig. 5. 3 (b): Giant squirrel Species is a group of population which are capable of interbreeding. This means that the members of a species can reproduce fertile offspring only with the members of their own species and not with members of other species. Members of a species have common characteristics.


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[Activity] ## Activity 5. 6 Find out the endemic plants and animals of the region where you live. Fig. 5. 3 (a): Wild Mango 2024-25


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5.7 Wildlife Sanctuary instead of their natural habitat? In Soon Paheli sees a board with ‘Pachmarhi your opinion, will

5. 7 Wildlife Sanctuary instead of their natural habitat? In Soon Paheli sees a board with 'Pachmarhi your opinion, will the animals be Wildlife Sanctuary' written on it. comfortable in a zoo or in their Professor Ahmad explains that killing natural habitat? (poaching) or capturing animals in general is strictly prohibited and punishable 5. 8 National Park by law in all such places. Wildlife On the roadside there was another Sanctuaries like reserve forests provide board on which was written 'Satpura protection and suitable living conditions National Park'. to wild animals. He also tells them that Children are now eager to go there. people living in wildlife sanctuaries are Madhavji tells them that these reserves allowed to do certain activities such as are large and diverse enough to protect grazing by their livestock, collecting whole sets of ecosystems. They preserve medicinal plants, firewood, etc. flora, fauna, landscape and historic objects of an area. Satpura National Some of the threatened wild animals Park is the first Reserve Forest of India. like black buck, white eyed buck, The finest Indian teak is found in this elephant, golden cat, pink headed forest. There are more than one hundred duck, gharial, marsh crocodile, National Parks in India. python, rhinoceros, etc. , are protected and preserved in our wild life sanctuaries. Indian sanctuaries Rock shelters are also found inside have unique landscapes-broad level the Satpura National Park. These are forests, mountain forests and bush evidences of prehistoric human life lands in deltas of big rivers. in these jungles. These give us an idea of the life of primitive people. It is a pity that even protected forests Rock paintings are found in these are not safe because people living in the shelters. A total of 55 rock shelters neighbourhood encroach upon them have been identified in Pachmarhi and destroy them. Biosphere Reserve. Figures of animals and men Children are reminded of their visit fighting, hunting, dancing and to the zoo. They recall that zoos are also playing musical instruments are places where animals receive protection. depicted in these paintings. Many tribals still live in the area. What is the difference between As children move ahead, they see a a zoo and a wildlife sanctuary? board with 'Satpura Tiger Reserve' written on it. Madhavji explains that