- Fill in the blanks :
- Microorganisms can be seen with the help of a __________.
- Blue green algae fix __________ directly from air to enhance fertility of soil.
- Alcohol is produced with the help of __________.
- Cholera is caused by __________.
- i) microscope ii) nitrogen iii) yeast iv) bacteria
- Tick the correct answer :
- Yeast is used in the production of :
- i) sugar ii) alcohol (P)
iii) hydrochloric acid iv) oxygen
- The following is an antibiotic :
- i) Sodium bicarbonate ii) Streptomycin (P)
iii) Alcohol iv) Yeast
- Carrier of malaria-causing protozoan is :
- i) female Anopheles mosquito (P) ii) cockroach
iii) housefly iv) butterfly
- The most common carrier of communicable diseases is :
- i) ant ii) housefly (P)
iii) dragonfly iv) spider
- The bread or idli dough rises because of :
- i) heat ii) grinding
iii) growth of yeast cells (P) iv) kneading
- The process of conversion of sugar into alcohol is called :
- i) nitrogen fixation ii) moulding
iii) fermentation (P) iv) infection
- Match the organisms in Column A with their action in Column B.
Column A Column B
- i) Bacteria ( ) a) Fixing nitrogen
- ii) Rhizobium ( ) b) Setting of curd
iii) Lactobacillus ( ) c) Baking of bread
- iv) Yeast ( ) d) Causing malaria
- v) A protozoan ( ) e) Causing cholera
- vi) A virus ( ) f) Causing AIDS
- g) Producing antibodies
- i) e ii) a iii) b iv) c v) d vi) f
- Can microorganisms be seen with the naked eye ? If not, how can they be seen ?
- i) Microorganisms cannot be seen with the naked eye.
- ii) They can be seen with the help of a magnifying glass or microscope.
- What are the major groups of microorganisms ?
- Microorganisms are classified into four major groups. They are –
- i) Bacteria ii) Fungi iii) Protozoa v) Algae
- Name the microorganisms which can fix atmospheric nitrogen in the soil.
- Rhizobium, Anabaena, Nostoc, Azotobacter etc.
- Write 10 lines on the usefulness of microorganisms in our lives.
- i) Microorganisms play an important role in our lives.
- ii) Microorganisms are used for various purposes such as bread making, preparation of curd, alcoholic beverages, vinegar etc.
iii) Some of the bacteria are used in the preparation of medicines.
- iv) They play an important role in the decomposition of organic wastes and keeping the environment clean.
- v) Some microorganisms increase the fertility of the soil by fixing nitrogen.
- vi) Microorganisms are used for the production of vaccines.
vii) Certain microorganisms are used in the biological treatment of sewage.
viii) They are also used for the production of antibiotics.
- Write a short paragraph on the harms caused by microorganisms.
- i) Microorganisms cause diseases in animals. Eg : In cattle, the foot and mouth disease is caused by a virus.
- ii) Several microbes cause diseases in plants. Eg : The productivity of wheat, orange, apple etc. is reduced due to microbial diseases in plants.
iii) Certain microbes, on entering into our body, produce toxic substances. This leads to diseases.
- iv) Some microorganisms such as fungus spoil our food. For example, bread when left unused under moist conditions gets spoilt by fungus.
- v) Some of the protozoans cause serious diseases like dysentery and malaria.
- What are antibiotics? What precautions must be taken while taking antibiotics?
- The medicines produced by certain microorganisms used to kill other disease-causing micro-organisms are called antibiotics. (or) The chemical substances that kill or stop the growth of microorganisms are called antibodies.
Eg : Streptomycin, tetracycline, penicillin etc.
Precautions to be taken while using antibiotics :
- i) Antibiotics should be taken under the supervision of a well qualified doctor.
- ii) Course (intake) of antibiotics should be completed as per the prescription given by the doctor.
iii) Antibiotics should be taken in the right amount and at the right time.