Class 12 Biology Microbes In Human Welfare Introduction


Microbes are the major components of biological systems on this earth.

Microbes are present everywhere that is in soil, water, air, inside the body of plants and animals, inside thermal vents, deep in the soil, under the layers of snow several meters thick and in highly acidic environments.

Microbes are diverse such that they are protozoa, bacteria, fungi and microscopic plants viruses, viroids and prions that are proteinacious infectious agents.

Microbes like bacteria and many fungi can be grown on nutritive media to form colonies which can be seen with naked eyes.

Microbes cause a large number of diseases in human beings, animals and plants but all microbes are not harmful; several microbes are useful to man in diverse ways.


Fig. bacteria

Fig: virus

Fig: fungi  

Fig. bacterial colony  

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