These comprehensive RBSE Class 10 Science Notes Chapter 15 Our Environment will give a brief overview of all the concepts.
RBSE Class 10 Science Chapter 15 Notes Our Environment
→ Environment – Environment is the collective form of all living and non-living materials, events and effects, in which organism lives. All organisms depend on the environment for their existance. For completing the basic needs of life there is a close interaction which takes place between organism and environment. An organism depends on many things of its environment-like energy, water, oxygen, food and shelter.
→ Biodegradable-Substances that are borken down by biological processes are called biodegradable. If the rate of degradation or decomposition is slow, they get accumulated and act as the pollutant.
Example-herb, fruit, animal excreta, dung, cloth, paper etc.
→ Non-biodegradable – Those substances which are not broken down by biological processes, are called non-biodegradable. These substances may be inert and simply persist in the environment for a long time.
Example – Plastic, D.D.T., aluminium cane, oxides of metals etc.
→ Ecosystem – Living organisms and their physical environment, both are reciprocally related to form a system or unit. Such an integrated system or unit is called ecosystem.
→ Ecosystem has two components –
(i) Biotic component – It includes all living organisms, like-Micro-organism, plants and animals.’
(ii) Abiotic component – Physical factors like soil, earth, water, light, temperature, rain, air, mineral etc. are the abiotic components. The various components of an ecosystem are independent.
→ Types of ecosystem – Mainly ecosystems are of two types-Natural and artificial.
(i) Natural ecosystem – Pond, lake and forests are the natural ecosystem. All green plants and blue green algae, having the capacity of photosynthesis, are the producers, herbivore fishes and insects etc. are the primary consumers which feed on the plants. Large size carnivorous fishes, frog, toad etc. are the secondary consumers.
(ii) Artificial ecosystem – Garden, agriculture field, aquarium are the man made ecosystem. Aquarium is one of the balanced type of ecosystem.
→ Organisms can be grouped as producers, consumers and decomposers according to the manner in which they obtain their substances from the environment.
→ Producers – They are the chlorophyll containing plants, in which algae, grasses and trees are included. They convert the solar energy into chemical energy by photosynthesis. They are the source of food for most of the animals. Green plants are also called autotrophs because they prepare own food.
→ Consumers – Those animals who can not prepare their food and depends on plants and animals are called consumers or heterotrophs. They are mostly animals. Those animals which directly depend on the plants, called herbivores. Example-Grass hopper, she-goat, sheep and rabbit.
→ Carnivores – Those animals who eat other animals as their food, called carnivores.
Example – Lion, cat, etc. They can also be parasite or predator.
→ Decomposers – Bacteria and fungi like micro-organism decompose the dead remains. So they are the decomposers because they break-down the complex organic substances into simple inorganic substances, which go into the soil and are used up once more by the plants.
→ The producers make the enrgy from sunlight available to the rest of the ecosystem.
→ Food chain and web – In the ecosystem a chain or a sequence of eating and being eaten is formed. This is called a food chain. The network formed by interconnecting food chains is called food web.
→ In food chain members of the successive higher level are generally smaller in number. The top level consists of lowest number. In this way a pyramid of numbers is formed.
→ Energy flow – Energy from producer to consumers reaches to the higher level and in food chain only about 10% of the energy of one trophic level is available to the next trophic level. This is called 10% rule. Flow of energy is unidirectional.
→ There is a loss of energy as we go from one trophic level to the next, this limits the number of trophic levels in a food chain.
→ Biological magnification – The process in which a non-biodegradable substance accumulates in larger and larger concentration as it is passed along a food chain is called biological magnification.
→ Ozone – One molecule of ‘On’ is formed by three atom of oxygen. Ozone is a deadly poison. It shields the surface of the earth from ultraviolet (UV) radiation comes from the sun. This radiation is highly damaging to organisms.
→ The use of chemicals like CFCs has endangered the ozone layer.
→ Changes in packaging have resulted in much of our waste becoming non biodegradable. The disposal of the waste we generate is causing serious environmental problems.