Useful and Harmful Bacteria

Bacteria are prokaryotic single-celled organisms which vary in their size and shape and possess glycogen as their reserve food.

Soil bacteria act as decomposers by breaking down the dead and decaying matter.

Nitrogen fixing bacteria convert atmospheric nitrogen into soluble nitrite & nitrates to make them available for use by the plants.

Symbiotic bacteria and free-living bacteria are two types of nitrogen-fixing bacteria.

Free-living bacteria fix and convert atmospheric nitrogen into ammonia, examples are Azotobacter and Clostridium.

Free living bacteria are further classified into Aerobic bacteria and Anaerobic bacteria.

Bacteria also useful in bio gas production and sewage treatment.

Oil spills are removed with the help of bacteria such as Pseudomonas.

Bacteria have various industrial uses in retting of jute fibre, curing of cheese, production of vinegar, curd formation and leather tanning.

Bacteria also have an important role in medicinal field such as synthesis of vitamin B12 along with the production of antibiotics, serum, vaccines and toxoids.

Bacteria causes various diseases in humans such as Typhoid, Tetanus, Tuberculosis, Pneumonia, Cholera and Diphtheria.

Bacteria are also used as bio-weapon and it has been assumed that some countries are preparing “germ bomb”.

Bacterial toxins cause food poisioning. Prevention of food spoilage by bacterial toxin can be done by extreme temperature, pasteurization, dehydration, chemicals, concentrated solution and irradiation.

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  • Q1

    What is serum?

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    Answer:

    Blood plasma from which fibrinogen has been removed is called serum. It contains all the proteins not used in blood clotting, electrolytes, antibodies, antigens and hormones etc.

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  • Q2

    How does concentrated salt solution in pickles prevent spoilage?

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    Answer:

    Concentrated salt solution in pickle destroys micro-organisms by draining out water from their cells through the process of osmosis and hence prevents spoilage.

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  • Q3

    Name nitrogen fixing bacteria present in the root nodule of leguminous plants.

    Marks:1
    Answer:

    Rhizobium is the nitrogen fixing bacteria present in the root nodule of leguminous plants.

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  • Q4

    Who discovered streptomycin antibiotic?

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    Answer:

    Selman Waksman discovered streptomycin antibiotic

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  • Q5

    What is bacteriology?

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    Answer:

    The branch of science dealing with the study of Bacteria is called bacteriology.

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