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0:00 Hello everyone, today we are going to study the smallest, simplest and last chapter of class 10 science which is called our environment. This chapter is of 4 to 5 marks in the exam but children consider this chapter to be very easy and do not study it properly and make mistakes in the exam. So you guys should not make this mistake and secure your marks by studying this small chapter. So let's start [Music] So as the name of this chapter is our environment, we have to know what is environment. So environment is the total of everything around an organism including both living and non- living organisms. So
0:47 whatever is present around an organism, whether it is living or non-living, all that is called environment. For example, if there is an organism, then there are many living organisms around it like animals, bacteria, fungi and many other types. There are organisms and along with this, many non-living components are also present there, so all of them together are called environment. So now we understand the first topic of this chapter which is ecosystem. So if we talk about the definition of ecosystem, then it will be an ecosystem is a geographical area where living organisms interact with each other and the surrounding environment. That means an ecosystem is a geographical area where different living organisms such as plants, animals, micro organisms etc. interact with each other
1:34 and with the surroundings. So this is the definition of ecosystem. Here we have to study the ecosystem in a little deep detail. So today we are going to understand the components of the ecosystem, their types, their functioning and how energy flows in them. So first of all we understand the components of the ecosystem, that is, what things the ecosystem is made of. So the ecosystem is mainly made up of two types of components, which are abiotic. Components and biotic components, so now we understand them, so first we understand abiotic components, these are non-living part of an ecosystem that saves its environment, that is, abiotic components are those components which are non-living and play a role in shaping the ecosystem, so
2:21 under abiotic or non-living components, mainly physical and climatic factors are considered, so physical or climatic factors will be soil, water, air, light, temperature, rainfall, pH etc. So what you have just seen are the main abiotic components of the ecosystem, after this we have to understand about biotic components, so biotic components mean living components, that is, all the living components in the ecosystem are called biotic components, so the living organisms in the ecosystem have been divided into three categories which are producer, consumer and decomposer, so now we have to understand these three biotic components properly. So first of all we should understand producers. So producers are the organisms that can make their own food, for example green
3:07 plants and some bacteria. So producers are those organisms that make their own food, that is they do not depend on anyone for food. For example, plants make their food directly from sunlight through the process of photosynthesis. They do not depend on anyone. So mainly plants are producers. So the producers are also called autotrophs because they show autotrophic nutrition. Autotrophs means those organisms that make their own food. After this, there is the second type of component which is consumers. So these are those organisms that consume the food prepared by the producer, that is, the organisms that depend on the producers for their food are called consumers. So consumers get their food. On the
3:52 basis of habitats, it has been divided into three categories, in which the first is herbivores. These are the organisms that depend only on plant-based diet for their food, i.e. they eat only plants, for example, cow, buffalo, goat, etc. So about consumers, you have to remember that all consumers are not directly dependent on producers, i.e. they also indirectly depend on plants, like the second category of consumers includes carnivores. These are the organisms that depend on other organisms for food, i.e. they fill their stomach with organic meat, for example, la tiger, polar bear, etc. So you can see here that the carnivores are not directly dependent on producers for food, but
4:37 indirectly they are also dependent on producers because the herbivore animals eat plants, which directly They depend on plants. After this, the third type of consumers are omnivores. These are the organisms that can make their nutrition or food from both plants and animals. For example, human, dog etc. After this, the third category of living or biotic components are decomposers. These are basically saprotrophic organisms. Saprotrophic organisms are those organisms that feed on dead and decayed matter. For example, micro organisms such as bacteria and fungi. So you should understand that first the plants or the producers made food, then the consumers ate them. Then when the consumers died, the micro organisms or decomposers will eat them
5:23 and decompose them. Those decomposers will go into the soil in the form of minerals. Later, the same minerals will go into the plants through the soil and in this way, this process will continue. So, from here we come to know about the role of decomposers. So decomposers are also very important because they are the ones who decompose the dead consumers and deliver them to the soil in the form of minerals. So these were the components of the ecosystem, which were living and non-living. Both of them work together for the ecosystem. So after looking at the components of the ecosystem, now we have to see the types of ecosystems, that is, the types of ecosystems. So there are mainly two types of ecosystems, which are natural ecosystem and artificial ecosystem. So let us look at them now. So first we
6:09 understand natural ecosystems. So these are those ecosystems which are natural. They do not need anyone to run or move. There is no interference of humans in them. And these natural ecosystems are also divided into different two types, which are terrestrial ecosystem and aquatics. So terrestrial ecosystem means land based ecosystem, that is, an ecosystem that is based on land. So its examples will be forest mountain. Desert, glass, land etc., everything in all these is happening on land, that is, the main basis of the entire ecosystem is land here, that is why this type of ecosystem is also called land based ecosystem or terrestrial ecosystem. After this, the second type in natural ecosystem is
6:56 aquatic ecosystem, the ecosystem that is inside the water is called aquatics, its examples will be river, pond, lake, sea. After this, we have to see the second type of ecosystem which is artificial ecosystem, so this type of ecosystem is also called man made ecosystem. To create and maintain these ecosystems, humans are needed, for example, crop field, garden, aquarium, poultice farm etc. So you see, all these need humans to run them, they cannot run on their own like natural ecosystems such as crop field or poultice farming, they need humans to run them, such as to provide water, to provide food, so these ecosystems are created and maintained by humans only.
7:41 So after the components and types, now we have to understand the functioning of the ecosystem, that is, how the ecosystem works. So we just read that there are components of both biotech and abiotech types in the ecosystem, which are interdependent on each other, like the producers are dependent on the sun and the soil for food and minerals, that is, in the ecosystem, all are interdependent on each other. So we understand this thing more clearly through the food chain, so the sequence of living organisms in which one organism consumes another's energy to transfer food energy, that is, it is a sequence of living organisms in which one organism consumes another organism to transfer food energy. So
8:27 we know that in the ecosystem, everything is dependent on each other and this dependency starts with the abiotic component because after all, minerals for all living organisms come from these components. So abiotic. After the dependency of the components, if we talk about the biotic components, then these are also dependent on each other, so the food chain mainly considers the living organism, so there are different tropic levels in the food chain according to each organism, so the tropic level is basically the position of an organism in the food chain, that is, the position of the organism in the food chain, so now we look at the food chain, this is a terrestrial food chain in which at the bottom are the plants, which are also called producers, so these plants will be eaten by the grass hopper, so it is called primary consumer
9:13 and primary consumer because they are the first ones to take energy from the producer or eat them, so about primary consumers you have to remember that these are mostly herbivores, so this grass hopper is a mouse, if a mouse eats it, then it will become a secondary consumer and this mouse is a snake, if a snake eats it, then it will become a terrestrial consumer and this snake is eaten by an eagle If it eats it, it will become a quartan consumer. So this is how different trophic levels behave in an ecosystem. So this was the terrestrial ecosystem. So, if we look at the food chain in an aquatic ecosystem, then first of all, this is the hydroplatan which makes its food through photosynthesis. If a zooplatan eats it, then this zooplatan will be eaten by a small fish and this small fish will be
10:01 eaten by a big fish and this big fish will be eaten by a giant whale. So, this is how the ecosystem works. So, now you must be thinking that what happens to those who are at the top of the food chain. When they die, the decomposers break them down into simple substances by complexing them and then deliver them to the soil in the form of minerals and then this process continues. So, now you have seen how the food chain works in the ecosystem, but there is a problem here as well because we know that everything in the world does not work according to us, especially not at all in the ecosystem because No animal in the ecosystem has studied the ecosystem and when an animal is hungry, it will not wait for the organism of the lower tropic level, it will
10:47 eat whatever food it finds comfortable, so these different food chains are interlinked with each other and it is called food web, so its definition will be the network of interlinked food chain is called food web, that is, the network of interlinked food chains is called food web, so look at this diagram, this is a food web in which there are many food chains, so in this, we have been explained according to the diagram that how the biotic components work in the ecosystem, so the food web basically tells us that there are many food chains in the ecosystem, they are interlinked with each other like in this food chain, this red is eating this grass hopper, but this frog of the other chain can also eat this grass hopper or this rat is being eaten by a snake in this food chain, but
11:33 this rat is being eaten by a frog of the other chain. This is also eaten by a bat or an eagle can also eat it. So now you must have understood food wasp better. After this we have to understand about the flow of energy in the ecosystem, that is, how energy flows in the ecosystem. So this is the most important topic of this chapter. There are maximum chances that questions will come from here in your exam. So when we talk about food chain, in the food chain, when an organism eats another organism, then the energy of that organism is passed on further. So what happens when we talk about food chain, it starts with plants. So the plants make their food from sunlight. So here you have to remember that the amount of energy that is coming from the sun, the plants use that energy only for 1 to
12:19 make food. So the plants are producers. So suppose a grasshopper eats the plants, then the grasshopper will become the primary consumer here. So what happens here is that the energy from the plant is passed on to the other organism. The grass got transferred to the hopper because it ate it. Similarly, the energy from the grass hopper reached the snake and the snake is a secondary consumer here because it has eaten the primary consumer. Similarly, this snake will be eaten by the eagle, which will become the tertiary consumer of this food chain. So, if you look carefully here, you will find that the flow of energy in the food chain is in a pattern which runs from the producer mostly to the tertiary consumer or sometimes to the quartan consumer. So, we can find out how much energy is transferred in different tropic levels from the 10 per law. So, this law says that only 10 per of
13:06 energy entering a particular tropic level of an organism is available for transfer to the next higher tropic level, meaning that only 10 per of energy is transferred within the food chain to the organism of the next tropic level. So, understand it like this, these are the producers. So, when the primary consumers eat them, then their energy is transferred in them. Only 10% of the total energy will be transferred forward and when these primary consumers are eaten by secondary consumers, only 10% of their energy will be transferred forward. Similarly, when these secondary consumers are eaten by terrestrial consumers, only 10% of the energy present in the secondary consumers will be transferred. So, understand it like this, if there is a plant, then it has energy of 50000 Joules. So, when a grasshopper
13:51 eats the plant, it will get energy of 5000 Joules. So, when a snake eats this grasshopper, it will get energy of 10% of 5000, which will become 500 Joules. When an eagle eats this snake, it will get energy of 50 Joules. Now, you see here that the loss of energy is very high. Very little energy is left for the terrestrial consumers. That is why this food chain ends at a very low tropic level because there is very little energy left for organisms at higher tropic levels. Energy is saved. You have to remember this well because there are 90% chances that you may get questions from Law 10 in your exam. You have to practice some numericals based on Law 10 by yourself so that you do not get into any problem in the exam. After this, we have to understand a very important term which is
14:37 biomagnification. So, it is the increase in concentration of toxins and non- biodegradable substances in the body of tissues of an organism as it moves from one tropic level to the next. This means that when toxins or non-biodegradable substances enter the organism and they move to the next tropic level in the organic food chain, then their concentration increases. So, first you should understand what non-biodegradable substances are. These are those substances which are not broken down by natural organisms and these are the source of pollution. So, when toxins or these non-biodegradable substances enter the body of an organism, then their concentration increases. When substances enter a particular organism, they reach the entire food chain or ecosystem because organisms in an ecosystem are interlinked through food waves. For example, if there is a
15:22 pond that has become polluted and a lot of non-biodegradable substances have mixed in it, then these toxins will first go inside the plants. Suppose 2 ppm i.e. parts per million is inside them. Here, remember the concentration in plants, 2 ppm. When small fish eat them, this concentration will increase inside them because fish eat them repeatedly, so the concentration inside them will become 5 ppm. And when these small fish are eaten by larger fish, this concentration will increase even more. For example, this concentration in larger fish will become 200 ppm because those fish eat a lot of small fish. When humans eat these fish, the highest concentration in them reaches around 1600 ppm. PPM, here you have to
16:08 remember an important point that the highest concentration of toxins is reached in the highest tropic level, if we talk about energy, then the least energy reaches them, as we have read in the 10th law, so in biomagnification, you have to remember only this much, but what I have explained to you now, I myself was not satisfied with it, and when this fish eats the same toxin platen every day, then obviously the
16:58 concentration of toxins in its aqueous body will increase even more and when humans eat these fish repeatedly, then this concentration increases the most in them, so now you must have understood why the percentage of toxins in biomagnification increases with each tropic level, after this we have to understand the last topic of this chapter, which is environmental problems and its management. First of all, there is ozone layer and its depletion. So, in our environment, there is a layer present in the stratosphere, which is the ozone layer, which is made up of ozone molecules. Ozone is a molecule which is made up of three atoms of oxygen. So, generally we call O2 as oxygen, which is very important for aerobic life. But this ozone
17:48 acts as a poison for us on Earth. But in the stratosphere, it acts as a protection for us. So, first we have to see how the molecular form of ozone is formed. So, this form is through the harmful ultraviolet rays emanating from the sun. A lot of harmful ultraviolet rays are emitted from the sun, which are harmful for us. So, those ultraviolet rays break down oxygen into o and o. So, here, the o combines with oxygen to form ozone, that is, it forms O3. Many such o All single oxygen atoms combine with O2 to form ozone and they form a layer in the Earth's stratosphere which protects us from UV rays. So this ozone layer
18:34 protects us from UV rays. So what happened is that the ozone molecule is formed through UV rays and this ozone molecule or ozone layer protects us from UV rays but this ozone layer is getting depleted due to some activities of humans. So now we see the cause of ozone layer depletion, that is, the main reasons for the depletion of ozone layer are some chemicals such as chlorofluorocarbon, hydro chloro fluorocarbon, methyl bromide and methyl chloroform extra. So mainly due to these chemicals the ozone layer gets depleted. So we have seen that due to which things the ozone layer gets depleted. So now We have to see how this ozone layer gets depleted.
19:20 First of all, this chlorofluorocarbon is released and when it is released, it reaches the ozone layer in the stratosphere and when this CFC reaches the ozone layer, it breaks down due to UV rays and in that breakdown, the atoms of chlorine are released in the ozone layer. After that, these chlorine molecules break the ozone molecules and deplete the ozone layer. When this ozone layer gets depleted, more ultraviolet rays reach the earth, which has a very serious effect on the environment and on us. Now we see those effects. Due to the depletion of the ozone layer, there can be CS impacts like skin cancer, cataracts, DNA damage, sunburns. If we have to
20:05 prevent the depletion of the ozone layer, then we will have to reduce the release of these chemicals significantly. So after this The second environmental problem is waste management. This is the last term which we have to understand here. So what is waste? Any thing which is of no use to us or which we do not need is waste. This waste is mainly of two types, which are biodegradable waste and non-biodegradable waste. If we understand them now, biodegradable waste is that waste which is made from biodegradable waste. These wastes get decomposed with the help of decomposers like bull, paper, fruits, jaggery etc. which means that these wastes get degraded in the environment through decomposers. Whereas the non- biodegradable wastes do not get decomposed in the environment
20:52 through decomposers. For example, aluminium, fossils, iron, nails, DDT, radioactive wastes etc. which means that these wastes do not get degraded in the environment. After this, we have to look at some techniques for the management of these wastes. The first one is preparation of compost. This technique is used only for the management of biodegradable waste. If you have ever been to a village, you must have seen that the waste there is collected at one place and with time, this waste gets converted into managed or composed. So, in this way, biodegradable waste is converted into managed or composed. After this, the second technique of waste management is landfills. With this technique, both types of wastes are managed or composed. The wastes are managed.
21:38 In this, a big pit is dug and filled with the waste. Here, the biodegradable waste gets converted into compost. On the other hand, the non- biodegradable waste does not convert into anything but it is at least dumped in one place on the ground. So, it does less harm to the environment. Its third technique is incineration. In this technique, the best thing is burnt and converted into ash or ash. Then that ash is used in the form of manure or for some other purpose. And another best technique of waste management is recycling. In this technique, the waste is recycled and it is prepared for reuse. So, with this, our chapter ends here. I hope you understood.
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