02. Microorganisms: Friend and Foe
Q. What are micro organisms? What are main types of microorganisms?
Ans. Such organisms that are not visible to our naked eyes and we need a microscope to see then are called microorganisms.
Microorganisms are divided into five parts that are given below:
01. Bacteria
02. Virus
03. Protozoa
04. Algae
05. Fungi
Q. What are vaccine? How it works?
Ans. The vaccine are weakened or died microbes which are introduced in the healthy body. The body fight and kills them by produceing suitable antibodies. These antibodies remain in body and we are procted from the disease causing the microbes.
Edward Jenner discovered the vaccine for smallpox in 1798.
Q. What are antibiotics? How they work? What is name of the discoverer of first antibiotics? What was its name?
Ans. The chemical substance which destroys the bacteria’s is known as antibiotics. The first antibiotic is discovered by Alexander Fleming. The name of this antibiotic was Penciline. Streptomycin, tetracycline and erythromycin are some of the commonly known antibiotics
Antibiotics destroy the bacteria’s at the time to cell wall formation in its life cycle.
Mind it the antibiotics destroys only bacteria’s or it is affected in Bacterial infection it have no effect on viral infection.
Q. What precautions must be taken while taking antibiotics? What will be in our body if we well take antibiotics unnecessarily?
Ans. Antibiotics should be taken only on the advice of a qualified doctor. Also you must finish the course prescribed by the doctor.
If you take antibiotics when not needed or in wrong doses, it may make the drug less effective when you might need it in future. Antibiotics may kill the beneficial bacteria in the body.
Q. Doctors does not prescribe Antibiotics against cold and flu ?
Ans. Antibiotics, however, are not effective against cold and flu as these are caused by viruses.
Q. What is Pasteurizations?
Ans. The method invented by Louis Pasteur to preserving the milk is known as pasteurization.
To pasteurization the milk is heated to about 700C for 15 to 30 seconds and then suddenly chilled and stored. This whole process is known as pasteurization.
Q. How bacteria are beneficial in increasing fertility of soil?
OR
How the bacteria increase the fertility of soil?
OR
How the leguminous plants increase the fertility of soil?
OR
How the leguminous plants fixed the nitrogen gas?
OR
Why are leguminous plants the main source of protein?
Ans. The roots of leguminous plant like Pea, Methi, and pulses plants have root nodules. The Rhizobium bacteria are present in these root nodules. These bacteria fixed the nitrogen of atmosphere into the nitrate.
Nitrate is used in soil like a fertilizer to increase the fertility of soil. That is why leguminous plants increase the fertility of soil by adding the nitrate.
The leguminous plants used this nitrate to synthesize the protein that is why the leguminous plants are main source of protein.
Exercises
01. Fill in the blanks:
(a) Microorganisms can be seen with the help of a ____________.
(b) Blue green algae fix __________ directly from air to enhance fertility of soil.
(c) Alcohol is produced with the help of __________.
(d) Cholera is caused by __________.
Ans. (a) microscope. (b) nitrogen (c) yeast. (d) bacteria.
2. Tick the correct answer:
(a) Yeast is used in the production of
(i) sugar (ii) alcohol (iii) hydrochloric acid (iv) oxygen
(b) The following is an antibiotic
(i) Sodium bicarbonate (ii) Streptomycin (iii) Alcohol (iv) Yeast
(c) Carrier of malaria-causing protozoan is
(i) female Anopheles mosquito (ii) cockroach (iii) housefly (iv) butterfly
(d) The most common carrier of communicable diseases is
(i) ant (ii) housefly (iii) dragonfly (iv) spider
(e) The bread or idli dough rises because of
(i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading
(f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection
Ans. (a) (ii) alcohol (b) (ii) Streptomycin (c) (i) female Anopheles mosquito (d) (ii) housefly (e) (iii) growth of yeast cells (f) (iii) fermentation
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03. Match the organisms in Column I with their action in Column II.
Column I
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Column II
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(i) Bacteria
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(a) Fixing Nitrogen
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(ii) Rhizobium
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(b) Setting of curd
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(iii) Lactobacillus
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(c) Baking of bread
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(iv) Yeast
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(d) Causing Malaria
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(v) A protozoan
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(e) Causing Cholera
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(vi) A Virus
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(f) Causing AIDS
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(g) Producing antibodies
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Ans.
Column I
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Column II
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(i)
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Bacteria
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(e)
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Causing cholera
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(ii)
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Rhizobium
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(a)
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Fixing nitrogen
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(iii)
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Lactobacillus
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(b)
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Setting of curd
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(iv)
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Yeast
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(c)
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Baking of bread
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(v)
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A protozoan
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(d)
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Causing malaria
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(vi)
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A virus
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(f)
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Causing AIDS
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04. Can microorganisms be seen with the naked eye? If not, how can they be
seen?
Ans. Microorganisms are too small so they cannot be seen with naked eye. They can be seen with the help of a magnifying glass or microscope.
05. What are the major groups of microorganisms?
Ans There are five major groups of micro-organisms:
Bacteria - They are single celled disease-causing micro-organisms. They can be spiral or rod- shaped.
Fungi - They are mostly multicellular disease-causing microbes. Bread moulds are common examples of fungi.
Protozoa - They mainly include organisms such as Amoeba, Plasmodium,etc. They can be unicellular or multicellular.
Virus -Viruses are disease-causing microbes that reproduce only inside the host organism.
Algae - They include multicellular, photosynthetic organisms such as Spirogyra, Chlamydomonas, etc.
06. Name the microorganisms which can fix atmospheric nitrogen in the soil.
Ans. Bacteria such as Rhizobium and certain blue-green algae can fix atmospheric nitrogen in the soil.
07. Write 10 lines on the usefulness of microorganisms in our lives.
Ans. Micro-organisms are too small to be seen through naked eyes. However, they are vital to plants and the environment.Lactobacillus is used to form curd from milk. Rhizobium present in the roots of pulse plants fix nitrogen from air and supply nitrogen compounds to the pulse plants. Micro-organisms are also used in winemaking, baking, pickling, and other food making processes.
Alcoholic fermentation by yeast is widely used in the preparation of wine and bread. Microbes are used to reduce pollution. For example, decomposers such as bacteria and fungi break down dead bodies and excreta to form inorganic compounds, which can be absorbed by plants. Microbes also play an important role in the preparation of medicines. Antibiotics are chemicals produced by micro-organisms to kill bacteria. Penicilin is an antibotic made from Penicilium. Bacteria present in our intestine helps in proper digestion and release Vitmain B which is absorbed by intestine.
Many vaccines are prepared from micro-organisms. These vaccines are given to children to protect them from disease. Certain microbes are also used in the biological treatment of sewage and industrial effluents. Yeast is used in making idlis, bhaturas, bread, pastries and cakes.
08. Write a short paragraph on the harms caused by microorganisms.
Ans. Micro-organisms cause diseases in animals. For example, in humans, bacteria cause diseases such as tuberculosis, cholera, typhoid, etc. In cattle, the foot and mouth disease is caused by a virus. Also, several microbes cause diseases in plants. For example, the productivity of wheat, orange, apple, etc. is reduced due to microbial diseases in plants. Certain microbes, on entering into our body, produce toxic substances. This leads to food poisoning. Some micro-organisms such as fungus spoil our food. For example, bread when left unused under moist conditions gets spoilt by fungus, producing a white cotton-like growth on the bread.
09. What are antibiotics? What precautions must be taken while taking antibiotics?
Ans. Antibiotics are medicines produced by certain micro-organisms to kill other disease-causing micro-organisms.
Precautions to be taken while using antibiotics: Antibiotics should be taken under the supervision of a well qualified doctor. Course (intake) of antibiotics should be completed as per the prescription given by the doctor. Antibiotics should be taken in the right amount and at the right time. A wrong dose of antibiotics makes the drug ineffective. Also, excessive consumption of drugs may kill. Certain microbes are also used in the biological treatment of sewage and industrial effluents. Some microbes decompose the dead bodies and checks from the bed foul.
Some Important Questions asked in Papers
01. Who discovered the vaccine for small pox?
02. How does a vaccine works?
03. How do micro organisms help in cleaning the environment?
Ans. Certain microbes are also used in the biological treatment of sewage and industrial effluents.
Some microbes decompose the dead bodies and checks from the bed foul.
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