Class 10 Science Notes - Our Environment PDF

CLASS 10 NOTES SCIENCE Our Environment PRASHANT KIRAD  PRASHANT KIRAD ENVIRONMENT- It refers to the complete range of physical and biological conditions in which org. like and interact with bi...

CLASS 10 NOTES SCIENCE Our Environment PRASHANT KIRAD  PRASHANT KIRAD ENVIRONMENT- It refers to the complete range of physical and biological conditions in which org. like and interact with biotic and abiotic factors. ECOSYSTEM: All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem. E.g. forest, pond etc. The ecosystem which exist Man-made ecosystem are in nature on its own. e.g., called artificial ecosystem. forest, lake, ocean. e.g., crop field, aquarium, garden. note- Agro-ecosystem is the largest man-made ecosystem. other examples are aquariums, botanical gardens, parks, field crops, etc. Components of, an Ecosystem I Abiotic components Biotic components (air, water, land) (Plant, animals) I producer Consumer Decomposers I I I I E. M.A Herbivore Carnivore Omnivore Parasites 1. Biotic component: It includes three types of organisms : (a) Producers: All green plants, blue green algae can produce their food (Sugar and starch) from inorganic substance using light energy (Photosynthesis). Therefore, all green plants are called producers. They are also called autotrophs. done by priyanshu.  PRASHANT KIRAD (b) Consumers: They are organisms which consume other organisms or their products as their food. All animals belong to this category. The consumers depend upon producers for their food directly or indirectly. They get their food by eating other organisms or their products. For example, man, goat, deer, fish, lion, cow, buffalo, etc., are common consumers. The consumers can be classified into the following types : Herbivores, carnivores, omnivores and parasites are the various type of consumers. 1. Herbivores: These are organisms (animals) which get their food by eating the producers (or plant) directly. Herbivores are also called first order consumers. Some common examples of herbivores are : deer, rabbit, rat, squirrel, goat, cattle, etc. 2. Carnivores: These are organisms (animals) which consume other animals. Therefore, carnivores feed on the flesh of herbivores. These are also called primary carnivores or second order consumers. Some common examples are snake, wild cat, jackal, frog, some birds, fishes, etc. 3. Omnivores: The organisms which feed on both plants and animals are called omnivores. Human beings are common example of omnivores because they eat both plants (For example; pulses, grams, oilseeds, fruit, etc.) and animal products (milk, meat, egg, etc.). 4.parasites - Those who live on body of host and take food from it without killing them. Egdice, cascuta etc (c) Decomposers: They are those micro-organisms that obtain energy from the chemical breakdown of dead organisms or animals or plant wastes. These micro organisms are decomposers as they breakdown the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants. 2. Abiotic Components: All the nonliving components such as air, water, land , CO2 , Oz , light etc. form abiotic.These component are physical factors such as light , temp. , water etc. Climatic factors: These are sunlight temperature, pressure humidity, moisture, rainfall, etc. these factors affect the distribution of the organisms. Light energy (sunlight) is the primary source of energy in nearly all ecosystems. It is used by green plants (which contain chlorophyll). During photosynthesis plants manufacture organic substances by combining inorganic substances. Temperature The distribution of plants and animals is greatly influenced by extremes in temperature. The pattern of rain also affects the growth of the plant. This plant growth determines the overall variety of animals living in that place. Atmospheric Gases Oxygen is required for respiration and carbon dioxide for photosynthesis. Nitrogen is made available to plants by certain bacteria and through the action of lightening. Wind It helps in pollination and seed dispersal of some plants. It can remove and redistribute top soil, especially where vegetation has been reduced. done by priyanshu.  PRASHANT KIRAD Water It is essential for life. Plant and animal habitats vary from entirely aquatic environments to very dry deserts. E.M.A Trophic levels: Trophic levels are the various steps or levels in the food tertiary 1st chain where transfer of food or energy takes place. secondary Producers are the first trophic level, herbivores are second 2nd consumer trophic level, carnivores or secondary consumers are third primary trophic level and large carnivores or tertiary consumers are 3rd consumer the fourth trophic level. producers 4th E.M.A trophic levels in Food chain: an eco-system Food chain is sequence of organisms through which energy is transferred in the form of food by the process of one organism consuming the other. e.g: Grass > Grasshopper > Frog > Snake > Eagle (Producer) (Herbivore) (Carnivore) (Carnivore) (Top Carnivore) On the basis of choice of habitat. food chains are of two types: (1).Terrestrial food chain It is the food chain present on land. e.g. Grass > Insects > Snake + Hawk. (2).Aquatic food chain It is the food chain in different water bodies. e.g. Phytoplankton — Zooplankton — Fish — shark. Significance of Food Chain: 1.Exploring food chains helps us see how different creatures in an ecosystem share food and interact. Think of food chains as nature's delivery system, moving energy and resources between the different living parts of an ecosystem. 2.Food chains act like energy highways, carrying vital energy and resources between the different living parts of an ecosystem or even across the whole biosphere. 3.Food chains are like the engines of an ecosystem or the biosphere, making everything alive and dynamic by showing how energy flows between different creatures. 4. When harmful substances like pesticides and weedkillers travel through food chains, they can become increasingly dangerous. This can lead to more serious effects on top-level creatures, including humans. It's a reminder of how important it is to understand and manage these harmful chemicals in ecosystems. done by priyanshu.  PRASHANT KIRAD SECRET QUESTIONS 1.a. What is an ecosystem? List its two main components. b. We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Explain. a. A self-sustaining functional unit consisting of living (biotic) and nonliving (abiotic) components, is called an ecosystem. 1. Biotic components: Plants and animals. 2. Abiotic components: Light, soil, temperature, humidity, wind, air, etc. b. An aquarium is an artificial and incomplete ecosystem in contrast to a pond or lake which is natural, self- sustaining and complete ecosystem. In natural ecosystem, decomposers help in recycling waste. So, an aquarium needs to be cleaned regularly. 2.Mention the differences between food habits of organisms belonging to the first and third trophic level. Give one example of each of them First Trophic Leve Third Trophic Level The organisms of this trophic The organisms of this trophic level are plants and are also level are animals and are also called producers. called secondary. They transform solar energy They obtain chemical energy by into chemical energy by eating other animals. e.g., all photosynthesis. e.g., grass (all carnivores (like lion). green plants) 3. State one important function of ozone layer in the atmosphere. How is it formed there? Which compounds are responsible for the depletion of ozone layer? How do these compounds enter into the atmosphere? Ozone present in the upper regions of the atmosphere protects us from dangerous UV radiations. Formation of ozone layer : Ozone at the higher levels of the atmosphere is a product of UV radiations acting on oxygen (O2) molecule. The higher energy UV radiations split apart some molecular oxygen (O2 ) into free oxygen (O) atoms. These atoms then combine with the molecular oxygen to form ozone as shown:  PRASHANT KIRAD E.M.A FOOD WEB: Food web is the network of various food chains which are interconnected at various tropic levels. Since an organism can occupy position in more than one food chain, in a food web it occupies more than one trophic level. E.M.A FOOD CHAIN CONSISTS OF MANY INTERLINKED FOOD CHAINS ENERGY FLOW Energy is accumulated by the primary producers and its transferred through food chain to different trophic This phenomenon is called energy flow. It is unidirectional and there is no recycling or going back to previous level, whenever energy is transferred from one to another, some energy is always lost. The flow of energy in an ecosystem: The energy in a food chain only moves in one direction. It goes from the plants (the autotrophs) to the plant-eating animals (the herbivores) and doesn't go back to the sun. The flow of energy in different trophic levels: Energy in a food chain only goes in one direction. Green plants capture a small part of sunlight (about 1%) and turn it into food energy. According to the 10 percent law, only about 10% of this energy is passed on to the next level of creatures. The rest, the remaining 90%, is used up by the current level of organisms for their life processes like digestion, growth, and reproduction. Because energy decreases at each step, most food chains consist of 3 to 4 levels of different creatures. Biological magnification is when harmful chemicals become more concentrated as you move up the food chain. This can be a problem because the highest concentration of these chemicals often ends up in human bodies since humans are typically at the top of many food chains. Ozone (O3) is a special form of oxygen made up of three oxygen atoms. Ozone plays a crucial role in protecting the Earth's surface from the sun's harmful ultraviolet radiation. O, + O—> 0, Depletion of ozone layer: Ozone layer gets depleted – due to the use of chemicals called aerosol, spray propellants like chlorofluorocarbons. Depletion of ‘ ozone layer would cause skin cancer in men and animals and severe damage to the plants. Biological magnification happens when harmful, non-biodegradable chemicals like pesticides accumulate in organisms as you move up the food chain, increasing their concentration. done by priyanshu.  PRASHANT KIRAD Top 7 questions 1. Distinguish between biodegradable , and nonbiodegradable substances. ‘ List two effects of each of them on our environment. Biodegradable Non-biodegradable Substances that are broken down by Substances that are not broken down biological processes are said to be by biological processes are said to be biodegradable. nonbiodegradable. These substances get recycled and, These substances require a lot of therefore, do not require any space for dumping which causes dumping sites. wastage of land. 2. a. What is the height of ozone from the equator? b. Name the rays against which ozone layer provides protection. c. Name one effect of depletion of ozone. i. 10 to 16 km. ii. UV rays. iii. Global wanning. 3.State two advantages of conserving (i) forests (ii) wild life Advantages of conserving forest are termed as biodiversity hotspots. They have large number of species of plants and animals. (a) They purify air, help in recharging groundwater, bring rains and maintain the fertility of soil. (b) They are also a source of income for tribal people. Wild life is important (a) To preserve bio-diversity. (b) As each species has a position in the food chain so wildlife helps in balancing the nature. done by priyanshu.  PRASHANT KIRAD 4.Why are green plants called ‘producers’ ? ‘Producers’ are the organisms which prepare their own food in the presence of sunlight and chlorophyll. Therefore green plants are called producers as they prepare their own food. 5.Energy flow in a food chain is unidirectional. Justify this statement. Explain how the pesticides enter a food chain and subsequently get into our body. a. Energy moves progressively through the various trophic levels and is no longer available to the previous trophic level. The energy captured by autotrophs does not revert back to the solar input. Therefore flow of energy is unidirectional. b. Pesticides, used for crop rotation when washed down into the soil/water body, are absorbed by the plant/producer along with water and minerals. Being non-biodegradable these chemicals get accumulated progressively in the food chain and enter our body. 6. Food web increases the stability of an ecosystem. Justify. Food web depicts feeding connection in an ecological community. It consists of many food chains. Thus, if any of the organism becomes endangered or extinct, the one who is dependent on it has an alternative option available to him for its survival. In this way, food web increases stability in an ecosystem. 7. What is wild life? How is it important? How is it being protected by government of India? Wild life means our flora and fauna. It is important: a. to preserve bio-diversity. b. as each species has a position in the food chain so wildlife helps in balancing the nature. Various species of plants and animals are preserved in botanical gardens, national parks, zoological parks and wildlife sanctuaries. done by priyanshu.  PRASHANT KIRAD CASE BASED COUNTRY 1. 1. Alternatives are always Give one instance whereavailable in nature which people’s participation results helped in a to save sortthis of interlocking pattern natural resource? Why orshould food web. Forbe forests instance, if a conserved? particular species of producers get destroyed by a disease in an ecosystem, herbivores of that area can feed on other species. Chipko movement i.e., hug the trees movement is one of the Also inmovements a food web, any given species may operate simultaneously in India to conserve biodiversity and to the end the at more than one alienation trophic of people fromlevel. their forests which started in March 1973 by Sunder Lal Bahuguna in Hilly areas like Himachal Pradesh. Two benefits are: (i) Existing forest cover was protected reducing landslides, land erosion. It actually protected environment and maintained ecological balance. (ii) Forest wealth could be utilized for food, fodder, fuel, fertilizers and fibers keeping in mind its conservation. We should conserve forests as: (i) Forests purify the air and also prevent pollution of air and regulate the climate by maintaining the level of rainfall necessary for their own existence. (ii) Forests are a storehouse of biodiversity (hotspots of biodiversity). 2. Some wastes in nature persist for a long time while others get decomposed in a shorter period. Explain their difference. State in brief two ways each in which they affect the environment. All wastes generated are not of the same nature. Biodegradable wastes such as plant and animal can be acted upon by decomposers in nature and broken down easily in simpler substances as they possess enzymes to do so. Example: animal excreta, fruit peels, leftover food, crop refuge and so on. Some other wastes or materials especially the ones produced by man can not be broken down by decomposers as they do not possess enzymes to do so. They are non biodegradable wastes such as some pesticide- DDT, detergents, plastics, radioactive wastes, metals etc. These substance may be broken down by chemical and physical processes in nature such as rusting of iron but not by biological processes. done by priyanshu.  PRASHANT KIRAD 2. Ozone layer is present in the earth's atmosphere. It is in the form of a protective shield. It contains three oxygen atoms (O3) which are formed Two ways as a consequence each in which of photochemical biodegradable wastes reactions in affect the environment: the environment. Ozone absorbs harmful ultraviolet radiations of a. The beauty of a place and it stinks. the sun. b. ItIn this way, attracts flies,itcockroaches protects all andliving germs beings on the which spread earth. The diseases. thinning of ozone layer due to various human activities allows more Biodegradable pollutants are agricultural waste and sewage UV radiations to pass through it which leads to harmful effects on man, animals and plants. Non biodegradable wastes affect our environment by entering the food chain and accumulating in the body of organisms (biomagnification). (i) Ozoneand Nitrates layer is present phosphates in which entering layer the water of the bodies atmosphere? can result in (a) Troposphere eutrophication. Some(b)pesticide-DDT, Mesospheredetergents, (c) Stratosphere (d) plastics, radioactive wastes, metals etc. Thermosphere (ii) Enhanced UV-radiations would affect humans and other animals causing (a) skin cancer (b) blindness and increased chances of cataract in eyes (c) malfunctioning of the immune system (d) all of these. done by priyanshu.