Name the microorganisms which can fix atmospheric nitrogen in the soil.
Can microorganisms be seen with the naked eye? If not, how can they be
seen?
Match the organisms in Column A with their action in
Column B.
A 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
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
Fill in the blanks.
(a) Microorganisms can be seen with the help of a ____________.
(b) Blue green algae fix __________ directly from air and enhance fertility
of soil.
(c) Alcohol is produced with the help of __________.
(d) Cholera is caused by __________.
Explain how soil gets affected by the continuous plantation of crops in
a field.
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