Class 10 Science: Our Environment PDF

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

CLASS 10 NOTES SCIENCE Our Enviroment PRASHANT KIRAD  PRASHANT KIRAD Enviroment 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. Natural Ecosystem Ecosystem Artificial Ecosystem D Natural Ecosystem: The ecosystem which Artificial Ecosystem: Man-made ecosystems RA exists in nature on its own. e.g. Forest, lake, are called artificial ecosystem. e.g., crop ocean. field, aquarium, garden. KI Components of an Ecosystem T AN Abiotic components Biotic components Producer Consumer Decomposers H AS EMA PR Herbivore Carnivore Omnivore Parasites Biotic component: 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. 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: 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.  PRASHANT KIRAD 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. 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.). Parasites: Those who live on body of host and take food from it without killing them. e.g.- Lice, Cascuta etc. Decomposers: They are those micro-organisms that obtain energy from the chemical breakdown of dead organisms or animals or plant wastes. These microorganisms 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. Abiotic component: D All the nonliving components such as air, water, land, RA CO2, O2, light etc. form abiotic. These components are physical factors such as light, temp., water etc. KI Climatic factors: These are sunlight temperature, pressure humidity, moisture, rainfall, etc. these factors affect the distribution of the organisms. T AN 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. H 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. AS This plant growth determines the overall variety of animals living in that place. Atmospheric Gases Oxygen is required for respiration and carbon dioxide for PR 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 topsoil, especially where vegetation has been reduced. Water It is essential for life. Plant and animal habitats vary from entirely aquatic environments to very dry deserts. Trophic levels: EMA Trophic levels are the various steps or levels in the food chain where transfer of food or energy takes place. Producers are the first trophic level, herbivores are second trophic level, carnivores or secondary consumers are third trophic level and large carnivores or tertiary consumers are the fourth trophic level. Food Chain : 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.  PRASHANT KIRAD Grass > Grasshopper > Frog > Snake > Eagle (Producer) (Herbivore) (Carnivore) (Carnivore) (Top Carnivore) Significance of Food Chain : rtion) VIP (very important po “Dhyaan se padhna Exam mei kaam aayega” - Prashant Bhaiya Significance Description/Defination D RA Connections in The food chain shows how different plants and animals are Nature connected and depend on each other for food. KI It explains how energy moves from plants to animals and then to Energy Transfer T other animals in a sequence. AN The food chain helps recycle nutrients in nature, making sure Nutrient Recycling plants and animals get what they need to grow. H AS A healthy food chain keeps nature in balance, and if one part is Ecosystem Balance disrupted, it can affect the whole system. PR Understanding food chains helps us see how human activities like Human Impact pollution can harm nature. Food Web : EMA 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. Energy Flow : EMA 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.  PRASHANT KIRAD 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 “Dhyaan se padhna this energy is passed on to the next level of creatures. The rest, the remaining 90%, is used up Exam mei kaam by the current level of organisms for their life aayega” processes like digestion, growth, and reproduction. - Prashant Bhaiya Because energy decreases at each step, most food chains consist of 3 to 4 levels of D different creatures. RA 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 KI typically at the top of many food chains. T Food web is the network of various food chains which are interconnected at various AN 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. H 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 AS radiation. O2 + O —> O3 PR 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.  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. Solution: A self-sustaining functional unit consisting of living (biotic) and nonliving (abiotic) components, is called an ecosystem. 1. Biotic components: Plants, animals, microbes and other livings. 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. D RA 2) Mention the differences between food habits of organisms belonging to the first and third trophic level. Give one example of each of them KI Solution: First Trophic Level Third Trophic Level T AN The organisms of this trophic level The organisms of this trophic level are are plants and are also called animals and are also called secondary H producers. consumers. AS They transform solar energy into They obtain chemical energy by eating PR chemical energy by green plants other animals. e.g., all carnivores (like lion). 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? Solution: 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 # TOP 7 IMPORTANT QUESTIONS 1) Distinguish between biodegradable and nonbiodegradable substances. List two effects of each of them on our environment. Solution: 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 space D therefore, do not require any dumping for dumping which causes wastage of RA sites. land. 2) a. What is the height of ozone from the equator? KI b. Name the rays against which ozone layer provides protection. c. Name one effect of depletion of ozone. T Solution: AN i. 10 to 16 km. ii. UV rays. H iii. Global warming. AS 3) State two advantages of conserving (i) forests (ii) wild life Solution: PR 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. Wildlife is important (a) To preserve biodiversity. (b) As each species has a position in the food chain so wildlife helps in balancing the nature. 4) Why are green plants called ‘producers’ ? Solution: ‘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.  PRASHANT KIRAD 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. Solution: 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 nonbiodegradable these chemicals get accumulated progressively in the food chain and enter our body. 6) Food web increases the stability of an ecosystem. Justify. Solution: Food web depicts feeding connection in an ecological community. It consists of many D 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. RA 7) What is wildlife? How is it important? How is it being protected by government of KI India? T Solution: AN Wildlife means our flora and fauna. It is important: to preserve biodiversity. H as each species has a position in the food chain, so wildlife helps in balancing the nature. AS Various species of plants and animals are preserved in botanical gardens, national parks, zoological parks and wildlife sanctuaries. PR “Class 10th Phodenge”