Our Environment

CONCEPTS

1. All the organisms such as plants, animals, micro-organisms and human beings as well as the physical surroundings interact with each other and maintain a balance in nature.

2. All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem.

3. An ecosystem consists of biotic components comprising of living organisms and abiotic components comprising of physical factors like temperature, rainfall, wind, soil and minerals.

4. The term ‘environment’ refers to the complete range of physical and biological conditions in which organisms live.

5. An environment has four components — atmosphere, hydrosphere, lithosphere and biosphere.

6. Environmental biology, also called ecology, is the study of relationships between living things and the non-living components.

7. An ecosystem is a self-sustaining, structural and functional unit of biosphere.

8. An ecosystem is an open system in terms of energy and a closed system as far as flow of minerals is concerned.

9. The small plants floating on the surface of water are phytoplanktons.

10. A pond, lake, river, forest, desert, even a man-made aquarium and a crop field are examples of ecosystems.

11. Producers or autotrophs synthesise their food by photosynthesis.

12. Consumers or heterotrophs are dependent upon other organisms for food.

13. Consumers may be classified as herbivores, carnivores, omnivores and parasites.

14. Decomposers or saprophytes consume and thus decompose, the dead remains of other organisms (both autotrophs and heterotrophs).

15. The sequential process of eating and being eaten is called a food chain.

16. The flow of energy in a food chain is unidirectional.

17. A simple food chain operating in a grassland can be shown as follows : Grass → Deer → Lion.

18. The network of interconnected food chains is called a food web.

19. The various links or steps representing organisms in a food chain at which the transfer of food (and energy) takes place are called trophic levels.

20. There is a continuous transfer of energy from one trophic level to the next in a food chain.

21. Only 10 per cent of the total energy entering a particular trophic level is available for transferring to the next trophic level.

22. Biomagnification is the increase in harmful chemicals throughout the trophic levels.

23. The sum total of all the factors that make our surroundings is called the environment. Human activities have damaged the balance of this environment leading to problems like global warming, soil erosion, floods, etc.

24. The environmental problems are pollution, soil erosion, deforestation, thinning of ozone layer, global warming, depletion of natural resources, extinction of plant and animal species, formation of salt deserts, waste accumulation, etc.

25. Ozone is a molecule consisting of three atoms of oxygen.

26. Ultraviolet rays are known to cause skin cancer, eye damage and damage to the immune system.

27. There are several reasons for the depletion of ozone layer. The foremost is the use of chlorofluorocarbons (CFCs).

28. Municipal Solid Wastes (MSWs) are commonly called garbage.

29. Pollutants
Biodegradable -- These can be broken down by the activities of micro-organisms, e.g., agricultural residues.
Non-biodegradable -- These cannot be broken down into simple harmless products by the action of microbes, e.g., DDT, plastics, etc.

30. Main sources of non-biodegradable wastes are improved packaging methods and increased use of disposals. Biodegradable products work as pollutants only when in excess.

31. Ecofriendly ways of waste disposal —
 Most urban solid wastes can be burnt to make land fills.
 Wastes like plastics, metals, etc., may be recycled.
 Plastic wastes may be molten and mixed with asphalt to produce road making material.
 Many domestic wastes like vegetable refuse can be composted and effectively used as manure.
 Incineration, i.e., burning at a high temperature is recommended for many nonreutilisable waste.