class 10 our environment notes
Answers
Answer:
Explanation:
Introduction
→ Everything that surrounds us is environment. It includes both living (biotic) and non-living (abiotic) components.
→ Interaction between these biotic and abiotic components form an ecosystem.
→ In an ecosystem living components depend on each other for their food which give rise to food chains and food webs in nature.
→ Human activities lead to environmental problems such as depletion of ozone layer and production of huge amount of garbage.
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.
Types of ecosystem
It is of two types
(i) Natural ecosystem: The ecosystem which exist in nature on its own.
Example: forest, lake, ocean.
(ii) Artifical ecosystem: Man-made ecosystems are called artificial ecosystem.
Example: crop field, aquarium, garden.
(i) Abiotic Components: All the non-living components such as air, water, land, light, temperature etc. form the abiotic components.
(ii) Biotic Components: All the living components such as plants, animals, bacteria, fungi etc. form the biotic components.
• On the basis of nutrition biotic components are further divided into:
→ Producers: All green plants and blue-green algae can produce their own food using abiotic components (photosynthesis), hence called producers.
→ Consumers: Include all animals which depend on producers directly or indirectly for their food.
Division of Consumers
(i) Herbivores: Plant eaters. Example: goat, deer.
(ii) Carnivores: Flash eaters. Example: tiger, crocodile.
(iii) Omnivores: Eats both plants and animals. Example: human.
(iv) Parasites: Live on the body of host and take food from it. Example: lice, cascuta.
Decomposers: Include organisms which decompose the dead plants and animals. Example: bacteria, fungi. These help in the replenishment of natural resources.
Food Chain
→ Food chain is a series of organisms in which one organism eats another organism as food. For example:
• Grass → Deer → Lion
→ In a food chain various steps where transfer of energy takes place is called a trophic level.
Flow of energy between trophic levels
→ Flow of energy in a food chain is unidirectional.
→ Green plants capture 1% of sunlight and convert it into food energy.
→ 10 percent law : Only 10% of energy is transferred to the next trophic level. The remaining 90% energy is used in life processes (digestion, growth, reproduction etc.) by present trophic level.
→ Due to this gradual decrease in energy, food chains contain 3-4 trophic levels.
Trophic levels
• Decrease in energy
1 kJ ↣ 10 kJ ↣ 100 kJ ↣ 1000 kJ
• Biological magnification: The concentration of harmful chemicals increases with every next trophic level in a food chain. This is called biological magnification.
→ Maximum concentration of such chemicals get accumulated in human bodies as human occupy the top level in any food chain.
Food web
→ In nature large numbers of food chains are interconnected forming a food web.
• Environmental problems: Changes in the environment affect us and our activities change the environment around us. Human activities leads to pollution, deforestation etc.
Ozone layer
→ Ozone layer is a protective blanket around the earth which absorbs most of the harmful UV (ultraviolet) radiations of the sunlight, thus protecting living beings from many health hazards such as skin cancer, cataract, destruction of plants etc.
→ Ozone (O3) layer is present at higher levels of atmosphere (i.e. stratosphere). It is a deadly poison at ground level.
Formation of ozone molecule
(i) The high energy UV radiations break down the O2 molecules into free oxygen (O) atoms.
O →(UV) O + O (atoms)
(ii) These oxygen atoms then combine with oxygen (O2) molecule to form the ozone molecule.
O2 + O → O3 (ozone)
Depletion of ozone layer
→ The decrease in the thickness of ozone layer over Antarctica was first observed in 1985 and was termed as ozone hole.
→ This decrease was linked to excessive use of synthetic chemicals like chlorofluorocarbons (CFCs) which are used in refrigerators, ACs, fire-extinguishers, aerosols sprays etc.
→ United Nations Environment Programme (UNEP) succeeded in forging an agreement to stop CFC production at 1986 levels (KYOTO PROTOCOL) by all countries.
Garbage disposal
→ Improvements in lifestyle have resulted in accumulation of large amounts of waste materials.
Types of materials in Garbage
(i) Biodegradable: Substances which can be decomposed by the action of micro-organisms are called biodegradable wastes.
Example: fruit and vegetable peels, cotton, jute, dung, paper, etc.
(ii) Non-biodegradable wastes: Substances which cannot be decomposed by the action of micro-organisms are called non-biodegradable wastes.
Example: plastic, polythenes, metals, synthetic fibres, radioactive wastes, pesticides etc
Explanation:
ENVIRONMENT : Our surrounding is called environment.
- Ecosystem and its components.
- Biotic and abiotic components.
- Food chain and Food web.
- Energy transfer through trophic levels.
- Ozone layer and its concerns.
ECOSYSTEM : This is a system of interdependencies among various living beings and non-living things in a given habitat.
COMPONENTS OF ECOSYSTEM : An ecosystem has two types of components, biotic component and abiotic component.
ABIOTIC COMPONENT : All non living things make the abiotic component of an ecosystem. Air, water, and soil are the abiotic components.
BIOTIC COMPONENT : All living beings make the biotic component of an ecosystem.
Green plants play the role of producers ; because they prepare the food by photosynthesis.
Animals and other living beings play the role of consumers; because they take food from plants.
Bacteria and fungi play the role of decomposers; as they decompose dead remains of plants and animals.
FOOD CHAIN : It is a simple representation of transfer of energy from the sun to different biotic components of an ecosystem. Sun is the ultimate source of energy. Green plants convert solar energy into chemical energy during photosynthesis.
PRODUCER -------> PRIMARY CONSUMER ---------> SECONDARY CONSUMER
FOOD WEB : A network of interconnected food chains.
TROPHIC LEVELS :
It is each step or level of the food chain.
I - TROPHIC LEVEL : Producers Eg green plants, blue green algae , Phytoplanktons. etc
II - TROPHIC LEVEL : Primary consumers or herbivores
III- TROPHIC LEVEL : Secondary consumers or small carnivore
IV - TROPHIC LEVEL : Tertiary consumers
FLOW OF ENERGY :
1 percent energy available from the sun to the terrestrial plants is converted into food.
10 percent energy in food is transferred to next level of consumer. 90 percent is lost.
No of steps of food chain is only 3 or 4 as very little energy is available to higher levels.
No of organisms decrease as we move up in a food chain.
Flow of energy in a food chain is unidirectional.
Biomagnification of pollutants : Progressive accumulation of harmful substances like pesticides take place.
TYPE OF WASTE :
I) Biodegradable : Can be broken down by the enzymes of bacteria or fungi Eg : Plant and animal waste , paper, wood etc.
II) Non Biodegradable : Can't be broken down by the enzymes of bacteria or fungi ( decomposers ) Eg : plastic etc.
BIOLOGICAL MAGNIFICATION :
The process of increase in concentration of a toxic chemical with increasing trophic level in a food chain.
OZONE LAYER DEPLETION :
Ozone layer is also known as stratosphere. When ultraviolet radiations act on oxygen, the oxygen gets converted into ozone.
UV radiation
O₂ --------------------------> O + O
O + O₂ ----> O₃
Ozone layer works like a protective shield for living beings.
EFFECT OF DEPLETION OF OZONE LAYER :
Due to depletion of ozone layer more UV rays reach to the earth and cause skin cancer , immune deficiency , reduces crop yield , reduce population of phytoplanktons and zooplanktons.
EFFECT OF CFCs : Use of CFCs ( chlorofluorocarbon ) has damaged the ozone layer. It is used in refrigerators and aerosol spray.
PROBLEM OF WASTE DISPOSAL :
Plastic waste is a serious concern because plastic is non biodegradable.
Proper segregation of wastes before disposal helps us to save our environment.
WASTE MANAGEMENT :
- Landfills
- Recycling
- Sewage treatment
- Incineration
- Use of Disposable
- Paper cups
hope it helps………:)