Class 8 Biology Microorganisms: Friend and Foe Classification of Microbes

Classification of Microbes

 Microbes are classified broadly into four groups:

  • Bacteria
    • Bacteria are one of the oldest life forms
    • They are unicellular i.e. they are made up of one cell
    • They appear in a variety of shapes & sizes (Spherical, elongated, spiral etc.)

 

  • They inhabit soil, water, radioactive waste & the deep portions of Earth's crust. In fact, they also live in plant /animal bodies
  • They live in colonies
  • Some of them are autotrophic (prepare their own food), while others are heterotrophic (depend on others for their food)

 

 

  • Fungi

You would have seen fungi as a white layer on bread when you leave it outside at room temperature for quite a few days. Fungi get favorable conditions & therefore they grow.

But, the same bread when kept inside a refrigerator remains fresh for a longer period of time.

 

                      

 

 

  • Fungi are multicellular e. they are made up of multiple cells
  • They are Heterotrophic (Depend on others for their food)
  • They live in colonies and prefer warm & moist places to grow
  • They are immobile
  • Some common examples of fungi are: Yeast, Mushroom, Molds

 

 

  • Protozoa
    • They are mostly Unicellular i.e. made of one cell
    • Some of them are autotrophic (prepare their own food), while others are heterotrophic (depend on others for their food)
    • They prefer moist & aquatic habitats
    • They can live singly, unlike bacteria & fungi
    • Some common examples of protozoa are: Amoeba, Paramecium, Trypanosoma

  • Algae
    • They are multicellular i.e. Made of multiple cells
    • They prefer mostly aquatic habitats
    • Some common examples of protozoa are: Spirogyra, Ulothrix, Chlamydomonas

 

Viruses: An exception

 

  • Viruses are also microscopic, but they are not considered as micro-organism. They behave like non-living when outside host cell, and reproduce only when inside the host cell

 

 

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