Welcome dear students! Today we are going to learn about Nature's Treasures from Class 6 Science. School vacations are always fun for Bhoomi and Surya. This vacation, they visit their Ajji, which means grandmother. Ajji lives in a village on the edge of a forest in the Western Ghats. The air in the village is fresh and cooler than in the city. They can see beautiful hills, streams, and many interesting plants, animals and birds around them. One afternoon, Bhoomi and Surya ask Ajji to tell them more about the place. Ajji says, Children, do you know that this place has several treasures of nature that enrich our lives? The pure air is refreshing and the soil is so fertile that it supports a variety of living beings. Moreover, this place gets plenty of sunlight which is useful in many ways. Different varieties of trees provide food and shelter to animals including various birds and insects. Can you think of more such treasures of nature? Bhoomi replies, Ajji, we use water for drinking and growing vegetables. Ajji says, Yes. We need these treasures for our survival and for making our lives more comfortable. Without these treasures of nature, any form of life on Earth is not possible. We all are a part of nature.
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Section eleven point one is about Air. One morning, Bhoomi and Surya see Ajji performing some breathing exercises. Ajji asks them to join her. She says, I am taking deep breaths in, and letting them out. This helps in getting more fresh air in the lungs to stay healthy. Let us also perform Activity eleven point one, titled Let us experience. Take a deep breath in, and then breathe out slowly. Take a deeper breath in again. Hold your breath for as long as you can and then breathe out slowly. Ask yourself, how long can you hold your breath? How do you feel when you hold your breath? Caution: Do not hold your breath for so long that you start feeling uncomfortable. From this activity, we find that it is difficult to hold our breath for a long time. The air which we breathe in has oxygen. Our body needs oxygen to perform its functions. When we hold our breath for a long time, the body does not get enough oxygen to perform its functions. Thus, we need oxygen for our survival. Similarly, most of the living beings also need oxygen for their survival. We can survive without food or water for a few days, but we cannot survive without oxygen for even a few minutes.
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Do you know? The air which surrounds the Earth is a mixture of gases. Can you name some gases which are present in the air? Air contains nitrogen, oxygen, argon, carbon dioxide and other gases in small quantities. Figure eleven point one gives the composition of air in percentage. Notice that in Figure eleven point one there are one hundred squares. Out of one hundred squares, seventy eight are occupied by nitrogen, twenty one are occupied by oxygen, and one by argon, carbon dioxide and other gases. Percentage is the number of parts in one hundred. It is denoted by the symbol percent. You notice the presence of air when the leaves of a tree rustle, the clothes hanging on a clothes line sway, or the pages of an open book begin to flutter once a fan is switched on. Moving air is called wind. Sometimes it blows fast, for example, during a storm, and sometimes it blows gently as a breeze. You must have played with a firki, which is a paper pinwheel, many times. Let us make a firki by performing Activity eleven point two.
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Activity eleven point two is titled Let us make and decorate. Take a square paper of size fifteen centimeters by fifteen centimeters, a pair of scissors, an all pin and a soft stick. Follow the instructions shown in Figure eleven point two to make a firki. The figure shows five steps. Step one shows a square paper with diagonal cuts from each corner stopping before the center. Step two shows folding alternate cut corners towards the center. Step three shows securing the folded corners with an all pin. Step four shows attaching the all pin to a soft stick. Step five shows the completed firki ready to spin. Now, you can hold the firki in your hand and run. You can also blow air on it. What do you observe? Does the firki rotate? When you move it a little back and forth, the firki rotates. What makes a firki rotate? It is the wind that makes a firki rotate. The working of a windmill is similar to that of a firki. Wind rotates the wings of a windmill. Windmills can be used to run flour mills, to pull up water from a well, or to generate electricity. In India, there are many windmill farms. A windmill farm is an area that has a large number of windmills which use the energy of the wind to generate electricity. Figure eleven point three shows a windmill farm. It depicts a vast open landscape with multiple tall towers, each having three large blades rotating in the wind. Muppandal Wind Farm in Tamil Nadu, Jaisalmer Wind Park in Rajasthan and Brahmanvel Wind Farm in Maharashtra are some of the leading windmill farms in our country. More to know: Find out more other windmill farms in our country.
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We have learnt that air is very important for us. Water too is essential and precious for us. How do you feel when you cannot get water to drink, especially when you are thirsty? Let us find out more about water. Section eleven point two is about Water. Bhoomi and Surya help Ajji in filling the troughs of water for the cows. They also help her in watering plants such as vegetables and medicinal herbs in the garden. Ajji teaches them how to water the plants so that every drop is used and none of it goes waste. Can you think of some more uses of water in your daily life? Pause and write down your responses in the blank bubble provided in your textbook. We need water for many daily activities, such as drinking, cooking, bathing, washing and cleaning. It is also used for growing crops and for industrial purposes. Where do we get water from? Make a list of the different sources of water. Water covers about two thirds of the Earth surface. Most of the water is found in oceans and seas. However, this water is saline or salty. This saline water is not fit for domestic, agricultural and industrial use. For all these activities, we need freshwater, which is present in the form of ice sheets or snow, rivers or lakes on the surface of the Earth, and underground. Freshwater present in ice sheets and snow, or underground water is difficult to access. A very small fraction of the freshwater present in ponds, rivers, lakes and wells is easily accessible. Water is precious, that is why Ajji guides them to use it with care.
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Do you feel that water is being used efficiently in our daily activities? Have you observed water being wasted in your daily activities? Let us find out activities where water is wasted and how this wastage can be reduced. Activity eleven point three is titled Let us find out. You will see Table eleven point one, which has three columns: Activity, How is water wasted?, and Suggest ways to reduce wastage of water. The activities listed in the first column are hand washing, washing clothes, washing utensils, taking a shower, cooking, gardening, and brushing teeth. Please pause and fill in the second and third columns based on your own observations at home. Think carefully about how water might be wasted during each of these tasks, and write down practical ways to reduce that wastage. Once you have completed the table, ask yourself: What conclusion can you draw from the information you gathered in the table? What can you and your family do to reduce this wastage of water? There are many ways to reduce wastage of water. For example, turning off taps when not in use and fixing water leakages. Recycling water and water harvesting also help in saving water.
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Our country is blessed with numerous rivers, streams and lakes. Have you ever noticed plastic bags and wrappers floating on the surface of water? We pollute freshwater sources by throwing trash, which means waste materials, in them. Waste from homes and industries pollute our water sources when it is dumped into them. Identify other human activities that lead to water pollution. Discuss with your friends in the class what you can do to reduce water pollution. Polluted water is not fit for consumption by living beings. As freshwater sources are limited, there is a shortage of water in many parts of India. At some places, people have to walk long distances to fetch drinking water. Everyone does not have the same kind of access to water. It is important for us to conserve water and use it judiciously. We must also prevent it from being polluted so that water remains fit for consumption by all living beings. In what ways can you conserve water? Water harvesting is one of the methods for conserving water. In many buildings, rainwater is collected and stored in large quantities for later use. This is called rainwater harvesting. Figure eleven point four a shows a rooftop rainwater harvesting system where pipes from the roof channel rainwater into a large underground storage tank. Do you know that rainwater is also harvested in many homes, residential societies or schools? It is an age old practice in India. For example, stepwells, commonly known as Bawadi in Rajasthan and Vav in Gujarat are built for water harvesting as a response to the scarcity of water in these regions. Figure eleven point four b shows a Bawadi, which is Toorji ka Jhalra in Jodhpur, Rajasthan. These stepwells have a unique system of water harvesting. They store not only rainwater but also water seeping from nearby lakes, ponds and rivers. The walls of the trenches, which are long deep holes dug in the ground, are lined with blocks of stones that allow seepage of water. Find traditional water harvesting practices in your locality. Discuss with your teachers and parents to learn more about it.
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Do you know? World Water Day is observed on twenty second March every year. Find out its importance. In the chapter A Journey through States of Water, we have learnt about the water cycle, where the Sun plays an important role in the evaporation of water. Have you ever observed your mother or grandmother cut raw mangoes and expose them to the hot sun for several days to dry? Let us explore more about energy from the Sun. Section eleven point three is about Energy from the Sun. On a sunny day, Bhoomi and Surya are helping Ajji dry chillies in the Sun. Ajji says, We use the heat from the Sun to dry it. We can use dried chillies when fresh ones are not available. I will give you some to take home. Do you know that the Sun is the main source of energy on Earth? All plants and animals are dependent on it. We use heat and light from the Sun for various purposes. What are some of the activities for which we need heat and light? Bhoomi draws some pictures to show the uses of heat and light from the Sun. Help her by adding more examples. Draw the pictures and write their descriptions in the space provided. Plants make food, drying of clothes, warming our homes, and generating solar electricity. One afternoon, Bhoomi and Surya pass by the field near Ajji house, where they see a cow grazing the grass. They talk about the Sun being the main source of energy. Look at this cow. It is grazing the grass and getting energy from it. No, I think this cow is getting energy from the Sun. The cow is standing in the Sun. But it does not mean that it is getting energy from the Sun. The cow is eating grass. Grass leaves need sunlight to grow. So, the main source of energy is the Sun. This way the cow gets energy from the Sun. According to you, whose statement is correct and why? The second statement is correct because the cow gets its energy indirectly from the Sun. Sunlight helps plants prepare food. The cow eats the grass, so the energy originally comes from the Sun.
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Sunlight helps plants prepare food. The Sun also provides all the living beings on Earth with heat and light. It is their main source of energy. In many households in India, water is offered to the Sun early in the morning as an expression of gratitude to the Sun. Do you know? Have you seen solar panels on rooftops, on top of street lights or on traffic signals? The solar panels capture the Sun energy and produce electricity. Energy from the Sun can also be directly used for cooking in a solar cooker or for heating water in a solar water heater. The diagram showing uses of solar energy depicts a solar water heater on a roof, solar panels on a building, and a solar cooker in a yard. What will happen if the Sun is not visible for a few days? We may have to depend on artificial lighting during day time also. Plants will not be able to perform photosynthesis and food production will stop. Temperatures will drop significantly, making it very cold. One cannot imagine life on Earth without the Sun. The Sun is the main source of energy on the Earth. Plants get energy from the Sun and produce food. Animals eat plants and grow. We get food from both plants and animals. This cycle on Earth is possible due to the Sun. So, we all are dependent on the Sun as the main source of energy. Where do we find a large variety of plants or animals? Let us explore.
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Section eleven point four is about Forests. One morning, Ajji takes Bhoomi and Surya for a walk in the forest. They find a variety of herbs, shrubs and trees in the forest. Ajji explains, Forests are large areas with dense growth of various types of plants. On the way, they collect some nellikai, which is the Kannada term for Indian gooseberries, that have fallen on the ground. Ajji tells them, We have a tradition in the village not to pluck fruits from the trees; they are left for animals and birds to eat. A forest is shown in the accompanying figure as a dense green area with tall trees, undergrowth, and a clear path winding through it. Discuss with your friends and make a list of at least five products that we get from forests. We get timber for furniture, fruits and nuts for food, medicinal herbs for medicines, gum and resin for industrial use, and bamboo for construction and crafts. Forests are a natural home for many wild animals, including birds and insects. Forests provide food and shelter to them. In nature, every animal depends on other life forms for survival. The diversity of life forms ensures food for every living being. However, over the years, the forest cover has been decreasing, mainly due to human activities like large scale cutting of trees. It takes many years to grow a new forest or restore lost forests. Therefore, we must preserve and use forests responsibly so that they get enough time to regenerate. Van Mahotsav is a week long event celebrated across the country during the month of July. It is a forest festival during which new plants and trees are planted, and awareness about respecting forests is raised. The aim of the event is to increase the green cover. You too can plan a Van Mahotsav in your community. What are the consequences of cutting a large forest area? Make a presentation or do a role play, or write a story or a poem that shows what could happen if we continue to cut down trees in our forests. Cutting large forest areas leads to soil erosion, loss of wildlife habitat, disruption of the water cycle, increased carbon dioxide in the atmosphere, and climate change.
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Do you know? From ancient times, India had a tradition of respecting, protecting and preserving forests. You have already learnt about sacred groves in the chapter Diversity in the Living World. Many efforts have been made by common people to prevent the cutting of trees, and thus, saving forests. One such effort is the famous Chipko movement. It started in the early nineteen seventies in Uttarakhand, previously part of Uttar Pradesh. Local women actively participated in this movement. They encircled and hugged the trees to protect them from being felled. During their walk in the forests, Bhoomi and Surya notice that there are a lot of leaves on the ground and the soil feels damp. Ajji explains, The roots of plants hold on to the soil and prevent it from being washed away. The leaves that fall from the trees decay and enrich the soil with nutrients. This soil is used by new plants and trees to grow. This is an example of recycling in nature. Let us investigate the soil in more detail. Section eleven point five is about Soil, Rocks and Minerals. Figure eleven point five shows soil preparation for planting vegetables, where a person is using a hoe to loosen the soil in a garden bed. Bhoomi, Surya and Ajji come back home from the forest. Bhoomi and Surya help Ajji in preparing the soil in the garden for planting some vegetables. Ajji asks them to dig the soil gently and loosen the lumps. You have already learnt in the chapter Living Creatures: Exploring their Characteristics that for plants to grow, the space between the soil particles not only provides sufficient air but also space for the roots to grow easily. Bhoomi and Surya could see small pebbles, the roots of plants and a few earthworms too in the soil. Do you realise that earthworms are natural agents that help in turning and loosening the soil?
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While Bhoomi and Surya help Ajji, let us do our own experiment by performing Activity eleven point four, titled Let us investigate. Caution: Remember to wash your hands thoroughly after touching the soil collected from different places. Sometimes soil that has garbage carries germs that may be harmful to us. Collect samples of soils from different areas around your home and school. Guess what could be there in different soils. Observe carefully each soil sample and note its colour. Touch each soil sample and feel its texture. Observe the soil samples with your naked eye. If you have a magnifying lens, look at the soil through it. Record your observations in Table eleven point two. The table has four columns: location from which soil sample was collected, what I guessed about the soil, observation of soil with naked eye including its colour and texture, and observation of soil with magnifying lens. For the example row, soil from a farm after ploughing is listed. You would record your guess, then note its dark brown colour and crumbly texture with the naked eye, and finally use the magnifying lens to observe tiny root fragments, small insects, and organic matter. Is there any difference between your guess and what you can actually observe when you look closely? Do you see any differences in the soil samples taken from different places? Do you see differences in what you are able to observe with your naked eye and what you can observe with a magnifying lens? There are many things in the soil, such as sand, insects and worms. There may be many small organisms that we cannot see with our naked eyes. Plants and animals also become part of the soil as they decompose and decay. The soil samples collected from different places may be of different colours because they may contain different materials. Have you ever wondered how soil is formed? Soil is formed by the disintegration, which means breaking apart, of rocks by actions of the Sun, water and living organisms over a long time, thousands of years.
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There are different types of soils. Some are good for growing certain types of plants while some are good for making bricks for buildings. Forests have a variety of soils. Soil is a precious treasure that supports biodiversity. You may have seen rocks in your surroundings. Rocks are used in the construction of houses, buildings, temples, roads, dams and table tops. Some rocks, like slate, are used for roofing. Figure eleven point six shows a traditional house roof covered with flat, layered slate stones. Laterite can be used as a building material, like bricks. Figure eleven point seven shows reddish brown laterite blocks stacked neatly for construction. Some of the important rocks are granite, sandstone and marble. Human beings have been using rocks to make tools such as hand axes and arrowheads since thousands of years. Figure eleven point eight a shows ancient stone hand axes with sharp edges. Figure eleven point eight b shows pointed stone arrowheads used for hunting. What are rocks made up of? They are made up of minerals. Important metals, such as aluminium, gold, copper and iron are extracted from minerals. Minerals are used in the manufacturing of airplanes, cars, jewellery, cosmetics, and electrical and electronic equipment. For example, the basic mobile phones that we use contain about a dozen minerals like gold, silver, copper, cobalt, etc. The diagram showing mining of marble depicts heavy machinery extracting large blocks of white marble from a quarry. The diagram showing naturally occurring gold displays shiny yellow metallic nuggets embedded in white quartz rock. The diagram showing some minerals found in nature displays various colorful crystalline and metallic stones. Rocks play a vital role in our lives. It takes thousands to millions of years to form rocks. Therefore, it is important to conserve and use them responsibly. Do you know how rocks and minerals are transported from one location to another? Most vehicles that we use for transportation use fossil fuels. Let us explore more about fossil fuels.
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Section eleven point six is about Fossil Fuels. At a fuel station, Surya asks, why do different types of vehicles go to different filling stations? Ajji replies, The reason is that they use different types of fuels. For example, petrol and diesel. Let us explore more about it by performing Activity eleven point five, titled Let us conduct a survey. Conduct a survey of vehicles in your neighbourhood. Which types of vehicles are there? What types of fuels do they use? Record the information that you collect in Table eleven point three. The table lists type of vehicle in column one and type of fuel used in column two. For example, cars use petrol or diesel, motorcycles use petrol, buses use diesel, auto rickshaws use CNG or petrol, and trucks use diesel. What are the most common types of fuels used? Petrol and diesel are the two most widely used fuels for vehicles. Petrol, diesel and kerosene are obtained from petroleum. Petroleum along with natural gas and coal are commonly called fossil fuels. They are formed essentially from the remains of microorganisms and plants that got buried deep inside the earth, and were converted to petroleum, natural gas and coal. It takes millions of years for these fuels to form. Natural gas is used for cooking and generating electricity. Nowadays, it is also used in the form of Compressed Natural Gas, or CNG, as a fuel for vehicles. It is a cleaner fuel than petrol or diesel. Coal is mainly used for the production of electricity. It is found in several parts of India. Find out the major coal producing states and mark them in a map of India.
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Do you know? Earlier, coal, wood and dung cakes were used as fuels for cooking. Nowadays, less polluting natural gas and Liquefied Petroleum Gas, or LPG, have gradually replaced these domestic fuels. Fossil fuels are found in limited quantities. Hence, we will soon run out of fossil fuels if we continue to use them in the manner that we currently do. To avoid such a situation, we need to explore alternate sources of energy. When fossil fuels are burnt, smoke and carbon dioxide gas are produced which pollutes the air. Over dependence on fossil fuels for transportation and as domestic fuels has resulted in large scale air pollution. Let us do our bit to conserve the fossil fuels by walking or cycling to nearby places, and using public transport. Suggest some more ways. We can also switch to electric vehicles, use energy efficient appliances, and turn off lights and fans when not in use. Section eleven point seven is about Natural Resources: Renewable and Non renewable. Nature treasures fulfill our needs. They are essential resources to sustain all life forms on the Earth. For example, we get heat and light from the Sun, water from rivers, and food from plants and animals. These resources which we get from nature are called natural resources. We also use natural resources to make many useful things for our convenience. For example, electric bulbs, furniture, solar panels, bicycles, etc., make our lives comfortable. All such resources created by human beings are called human made resources. You have learnt about various natural resources, such as air, water, energy from the Sun, forests, soil, rocks, minerals and fossil fuels.
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Some of these natural resources get replenished through natural processes over a period of time. If you remember, Ajji told Bhoomi and Surya that they could collect only those nellikai that had fallen on the ground. This makes sure that there would be enough fruits for other animals and birds. The seeds from the droppings of animals and birds would enable new trees to grow, though it would take some years before we get fruits from these new trees. Thus, resources which get renewed, replenished or restored within a reasonable period of time are called renewable resources. Air, water and forest are some of the examples of renewable natural resources. Nature renews them. We should use our natural resources judiciously. On the other hand, fossil fuels take millions of years to form. They are found in limited quantities and once used, they get exhausted. They are not produced or replenished within a reasonable period of time. These resources are called non renewable resources. Examples of non renewable natural resources are minerals, soil, rocks, coal, petroleum and natural gas. Section eleven point eight is about Resources We Use. It is time for Bhoomi and Surya to go back home after a wonderful holiday at their Ajji home. Their Amma, which means mother, comes to pick them up. Bhoomi and Surya show her the vegetable plants that have started to grow in the garden and the dried chillies given by Ajji to take home. They notice changes in the colour of the skyline and the smell of the air once they reach the city. There are very few trees. The air does not smell as good as the air at Ajji place. They can smell smoke from the vehicles. The air is polluted. Amma says, Yes. When we use fossil fuels in our vehicles, smoke is generated. Now, there are vehicles which cause less pollution. For example, there are electric vehicles that do not release any smoke. So, people are making an effort to create alternatives. Can you list some alternatives for reducing air pollution? We can use bicycles, walk more, use public transport, plant more trees, and switch to electric or hybrid vehicles.
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We use many natural resources in our everyday life. Let us identify some resources that we use by performing Activity eleven point six, titled Let us make a list of natural resources used. Make a list of activities you do in your daily life and write down the natural resources used directly or indirectly for each activity. In Table eleven point four, some items are already filled in. Using them as a guide, fill the remaining blank rows. For washing clothes, the natural resource is water. For making clay toys, the natural resource is soil. For collecting firewood, the natural resource is forest. For making kites, the natural resource is bamboo and paper from trees. For having breakfast, the natural resource is food from plants and animals. How many natural resources did you list? Compare your list with that of your friend. You and your friends have listed many natural resources that we use everyday. These resources are air, water, soil, and food from plants and animals. We get these resources from nature and also make things using them for our consumption. Therefore, we must conserve our natural resources and use them responsibly without wasting them. This way, we can continue to fulfill our present needs while also saving for the future, without harming the environment. Earth provides enough to satisfy every man need but not for every man greed, said M. K. Gandhi. Now, let us review the keywords and summary for this chapter.
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Keywords for this chapter are: Air, Classify, Coal, Experience, Explore, Fossil fuels, Forests, Human made resources, Investigate, Natural gas, Natural resources, Non renewable resources, Observe, Petroleum, Rainwater harvesting, Renewable resources, Resources, Rocks, Soil, Sun, Survey, and Water. Summary Key Points: Resources required for our survival are provided by nature. Resources provided by nature are called natural resources. Some important natural resources are air, water, energy from the Sun, forests, soil, rocks, minerals and fossil fuels. Resources created by human beings to meet their needs are called human made resources. Natural resources can be classified as renewable resources and non renewable resources. Resources that get renewed, replenished or restored by natural processes within a reasonable period are called renewable resources. Resources that are in limited quantities and do not get replenished within a reasonable period are called non renewable resources. All living beings, including humans, depend on natural resources for their survival so we should use them judiciously. Now, let us enhance our learning with the exercises.
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Exercise one asks us to look at Figure eleven point nine which shows items related to natural resources. We must match them with their jumbled up names, make another table, write the names, and classify them as renewable or non renewable. The first item is a water tap. The jumbled name is atwre. Unscrambling gives water. The second item is a windmill. The jumbled name is ndiw. Unscrambling gives wind. The third item is a forest. The jumbled name is refost. Unscrambling gives forest. The fourth item is coal. The jumbled name is ocrk. Unscrambling gives rock. Matching them correctly: water tap matches water, windmill matches wind, forest matches forest, coal matches rock. Classification: Water is renewable. Wind is renewable. Forest is renewable. Rock is non renewable. Exercise two asks to state whether the statements are True or False, and correct them if false. Statement one: Nature has all the resources to meet human needs. This is True. Statement two: Machines are a resource found in nature. This is False. Correction: Machines are human made resources, not found in nature. Statement three: Natural gas is a non renewable resource. This is True. Statement four: Air is a renewable resource. This is True. Exercise three asks to fill in the blanks. A fuel that is commonly used in two wheelers like scooters or bikes is petrol. An example of a renewable resource is water.
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Exercise four asks to classify coal, natural gas, forests and minerals as renewable or non renewable. Coal is non renewable. Natural gas is non renewable. Forests are renewable. Minerals are non renewable. Exercise five asks why we say that petroleum is a non renewable resource. We say this because petroleum takes millions of years to form from buried organic matter, it is found in limited quantities, and once used, it cannot be replenished within a reasonable period of time. Exercise six asks to justify the statement that it is difficult to regrow forests. It is difficult to regrow forests because trees take many years, often decades or centuries, to reach maturity. The soil ecosystem, biodiversity, and complex interdependencies between plants, animals, and microorganisms take a very long time to reestablish after deforestation. Exercise seven asks to make a list of five daily activities in which you use natural resources and suggest ways to reduce their use. One, taking a bath uses water. We can reduce use by taking shorter showers or using a bucket. Two, cooking uses fossil fuels or natural gas. We can reduce use by using lids on pots and cooking in batches. Three, studying uses paper from trees. We can reduce use by writing on both sides and using digital notes. Four, traveling uses petrol or diesel. We can reduce use by carpooling or cycling. Five, using electricity uses coal or other fuels. We can reduce use by switching off lights and fans when leaving a room.
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Exercise eight asks to list four activities that are possible due to the presence of air. Breathing and survival of living beings, flying of birds and airplanes, drying of clothes, and generation of wind energy using windmills. Exercise nine asks how you can contribute towards enhancing the green cover of your locality and to make a list of actions to be taken. I can contribute by planting native trees in my neighborhood, organizing community tree planting drives, protecting existing trees from being cut, watering young plants regularly, and educating others about the importance of forests. Exercise ten refers to an illustration where food is being cooked. Question one asks what type of energy is being used for cooking. The energy being used is thermal energy from burning fossil fuels like LPG or natural gas. Question two asks to name one benefit and one drawback of using this type of energy for cooking. One benefit is that it provides quick and controllable heat for cooking. One drawback is that it releases carbon dioxide and other pollutants into the air, contributing to air pollution. Exercise eleven asks why cutting down trees on a large scale impacts the quality of the soil. Cutting down trees removes the root systems that hold the soil together, leading to soil erosion. It also stops the supply of decaying leaves that enrich the soil with nutrients, making the soil less fertile and more prone to drying out.
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Exercise twelve asks to explain two ways in which human activities pollute the air and propose one action to reduce air pollution. Two ways are burning fossil fuels in vehicles and factories, and burning crop residue or garbage in open areas. One action to reduce air pollution is to promote and use public transportation, electric vehicles, or bicycles instead of personal petrol or diesel cars. Exercise thirteen presents a scenario where a family uses solar panels to generate electricity, a gas stove to cook food, and a windmill for pumping water. It asks what would happen if there were no sunlight for a week. Without sunlight for a week, the solar panels would not generate electricity, causing a power shortage for the house. The windmill might still pump water if there is wind, but solar water heating would stop. The gas stove would still work for cooking since it uses stored gas, but overall daily routines relying on solar power would be disrupted. Exercise fourteen asks to fill up the blanks using the terms fossil fuels, forest, air, petroleum, coal, water and non renewable resource in a classification structure. The structure has Natural Resources at the top, branching into Renewable Resources and Non Renewable Resources. Under Renewable Resources, the blanks are filled with air, water, and forest. Under Non Renewable Resources, the blank is filled with non renewable resource as a category label, with branches for fossil fuels, which then branch into natural gas, petroleum, and coal.
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Exercise fifteen asks if it is justified to fell trees due to increasing demand for industries and housing, and to discuss and prepare a brief report. It is not justified to fell trees on a large scale because forests are essential for maintaining ecological balance, preventing soil erosion, regulating climate, and providing habitat for wildlife. While development is necessary, it should be sustainable. We can use alternative building materials, recycle wood, build vertically instead of clearing forests, and implement strict afforestation policies to compensate for any tree loss. A brief report would highlight the long term environmental damage versus short term economic gains, and recommend sustainable urban planning and green building practices. Exercise sixteen asks to propose a plan to use less water in your school, what steps to take, and how it would help the environment. The plan includes installing low flow taps and dual flush toilets, fixing leaking pipes immediately, collecting rainwater for gardening, and running awareness campaigns for students to turn off taps while washing hands. Steps to take are forming a water conservation club, auditing current water usage, getting administration approval for installations, and monitoring monthly water bills. This plan would help the environment by reducing freshwater extraction, lowering energy used for water treatment and pumping, and preserving local water tables for future generations.
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Now let us look at the Learning Further section. First, investigate the effect of air pollution on human health by interacting with elders or community members and identify main sources of air pollution in your local area. Based on findings, suggest two practical steps your school or community could take to reduce air pollution. You might find that pollution causes coughing, asthma, and eye irritation. Main sources could be vehicle exhaust, industrial smoke, and dust from construction. Two practical steps are organizing carpooling days for staff and students, and planting a green belt of trees around the school boundary to filter dust and pollutants. Second, prepare a list of the names and uses of important minerals and rocks used in your village, town, or city. For example, limestone is used for making cement, granite is used for kitchen countertops and flooring, iron ore is used for making steel in construction, and clay is used for making pottery and bricks. Third, as an eco club monitor, organize a tree plantation drive in your school. Steps required are getting permission from the principal, selecting native tree species, arranging saplings and gardening tools, assigning student groups to plant and water them, and creating a maintenance schedule. Prepare a one page report listing the names of trees planted, such as Neem for shade and medicinal value, Peepal for oxygen production, and Banyan for soil conservation, along with their ecological importance.
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We have now covered every concept, activity, experiment, and exercise from this chapter. Remember, nature provides us with incredible treasures like air, water, soil, forests, and minerals. It is our responsibility to use them wisely, conserve them, and protect them for future generations. Always observe the world around you, ask questions, and take small steps every day to reduce waste and pollution. Thank you for listening! Keep revising and practicing. Goodbye! [CHAPTER_COMPLETE]