Our Environment Class 10 Notes Science Chapter 15

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CBSE Class 10 Science Notes Chapter 15 Our Environment Pdf free download is part of Class 10 Science Notes for Quick Revision. Here we have given NCERT Class 10 Science Notes Chapter 15 Our Environment. According to new CBSE Exam Pattern, MCQ Questions for Class 10 Science pdf Carries 20 Marks.

CBSE Class 10 Science Notes Chapter 15 Our Environment

Biodegradable and Non-biodegradable Wastes, Ecosystem, Components of Ecosystem. The environment includes our physical surroundings like air (or atmosphere), water bodies, soil (land and all the organisms such as plants, animals, human beings and micro-organisms like bacteria and fungi (called decomposers). The waste materials produced by the various activities of man £nd animals are poisonous to some extent and can be divided into two main groups

1. Biodegradable Wastes: Substances that are broken down by the biological processes are said to be biodegradable. These substances are decomposed through the actions of fungi, bacteria, and other living organisms. Temperature and sunlight also play an important role in the decomposition of biodegradable substances.
For Examples: Food waste, trees leaves, urine and fecal matter, sewage agricultural residue, paper, wood, cloth, cow-dung etc.

2. Non-Biodegradable Wastes: Substances that are not broken down by biological
processes. These substances may be in solid, liquid or gaseous form. These substances are inert and simply persist in the environment for a long time or may harm the various members of the ecosystem.
For Examples: These includes DDT (Di-chloro-di phenyl trichloro ethane-in-pheneyle the cheoro ethane), insecticides, pesticides, mercury, lead, arsenic aluminum, plastics, polythene bags, glass, radioactive wastes. These non-biodegradable wastes are major pollutants of the environment.

Harmful effects of biodegradable and Non-Biodegradable Substance

1. The waste destroys the natural beauty and our surroundings become dirty.
2. Decomposition of these wastes results in the production of foul smell, which spreads to the surrounding areas.
3. These wastes may also block the drains creating pools of waste, which becomes the breeding sites of mosquitoes. The latter is carriers of diseases like malaria and dengue.

Difference between Biodegradable and Non-Biodegradable wastes

Biodegradable wastes	Non-Biodegradable wastes
1. The wastes that are broken down naturally by microbial action.	1. The wastes that are not broken down by the microbes.
2. Biodegradation forms harmless and non- poisonous products.	2. No such action is possible.
3. They release raw materials back to nature.	3. They do not release raw materials.
4. They pollute the environment only when they are produced in quantity beyond the capacity of the environment to degrade them.	4. Non-biodegradable wastes pollute the environment even in small quantity.
5. Bioconcentration does not occur.	5. Bioconcentration or biomagnifications occurs when wastes enter food chains.
6. Recycling is possible both naturally or through human efforts.	6. Recycling is possible only through human efforts.

Ecosystem: An ecosystem is a self-contained unit of living things (plants, animals and decomposers), and their non-living environment (soil, air and water). For example; a forest, a pond, a lake, a green land etc.
In an ecosystem, energy and matter are continuously exchanged between living and non¬living components.
An ecosystem can be both natural or man-made. Some examples of natural ecosystems are grass land, forest, sea, river, desert, mountain, pond, lake etc.

The desert, grass land and mountains represent the terrestrial ecosystem (land-based ecosystem).
The ponds, rivers, lakes and sea represent the aquatic ecosystem (water-based ecosystem). Man-made artificial ecosystems are garden, crop fields, park, aquarium, etc.

Components of Ecosystem: There are two components of an ecosystem : (i) biotic component and (ii) abiotic component.
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.
Planktons are very minute or microscopic organisms freely floating on the surface of water in a pond, lake, river or ocean. Planktons are of two types : Phytoplanktons and Zooplanktons.
The microscopic aquatic plants freely floating on the surface of water are called phytoplanktons.
The microscopic aquatic animals freely floating on water are called zooplanktons. The freely floating protozoa are an example of zooplankton.

(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.
• Parasite.
• Omnivores.

(i) 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.

(ii) 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.
There are animals which prey upon primary carnivores. They are called second order consumers or third order consumers. For example, owl, peacock, tiger, lion, etc., are some second order carnivores and may be eaten by third order carnivores. The carnivores which are not preyed upon further are called top carnivores. For example, lion is a top carnivore.

(iii) 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.).

(c) Decomposers: Fungi and bacteria which break down (decompose) the dead plants, animals complex compounds into the simpler one. The decomposers help in the replenishment of natural resources. These are also known as microorganism or saprotrophs. These are also called reducers.

Importance of Decomposers

• Decomposers help in disposing of the wastes and dead bodies of plants and animals. Therefore, they clean the environment and create space for a living of newer generations of organisms.
• The decomposers release minerals and other raw materials trapped in organic matter. These are picked up by plants. This also helps to maintain the fertility of soil.
• The decomposers produce some acids which are useful in solubilization of some minerals.
• Decomposers help in recycling the materials in the biosphere so that, the process of life may go on and on like an unending chain.

2. Abiotic Components: These are non-living components of an ecosystem. These include the physical environment.

• Edaphic factors like soil texture, topography, water, and air.
• Inorganic substances like carbon dioxide, nitrogen, oxygen, water, phosphorus, sodium, potassium, and calcium. These are involved in the cyclic of materials in the ecosystem.
• Organic compounds like proteins, carbohydrates, and lipids. These largely form the living body and link the abiotic and biotic components.

Climatic factors: These are sunlight temperature, pressure humidity, moisture, rainfall, etc. these factors affect the distribution of the organisms.

Functions of an Ecosystem

• Ecosystem indicates available solar energy and the efficiency of an ecosystem to trap the same.
• It gives information about the available essential minerals and their recycling periods.
• It provides knowledge about the web of interactions and inter-relationship among the various population as well as between the population and the abiotic environment.
• It helps human beings to know about conservation of resources, protection from pollution and inputs required for maximizing productivity.
• In the ecosystem, two processes of energy flow and biogeochemical cycles (nutrients movement) proceed side by side. The energy flow is unidirectional while the movement of nutrients is cyclic.

Food chain, Food web, Trophic levels. Flow of