NCERT 8th Science Chapter 2 MICROORGANISMS: FRIEND AND FOE ExerciseFill 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 _________.
Q2 : 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 Q3 : Match the organisms in Column I with their action in Column II. Answer : Column I Column IIi Bacteria e. Causing choleraii. Rhizobium a. Fixing Nitrogeniii. Lactobacillus b. Setting of curdiv. Yeast c. Baking of breadv. A protozoan d. Causing malariavi A Virus f. Causing AIDS Q4 : Can microorganisms be seen with the naked eye? If not, how can they be seen? Q5 : What are the major groups of microorganisms? Q6 : Name the microorganisms which can fix atmospheric nitrogen in the soil. Q7 : Write 10 lines on the usefulness of microorganisms in our lives. Q8 : Write a short paragraph on the harms caused by microorganisms. Q9 : What are antibiotics? What precautions must be taken while taking antibiotics?
Exercise Solution
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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 _________.
Q2 : 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
Q3 : Match the organisms in Column I with their action in Column II.
Answer :
Column I Column II
i Bacteria e. Causing cholera
ii. Rhizobium a. Fixing Nitrogen
iii. Lactobacillus b. Setting of curd
iv. Yeast c. Baking of bread
v. A protozoan d. Causing malaria
vi A Virus f. Causing AIDS
Q4 : Can microorganisms be seen with the naked eye? If not, how can they be seen?
Q5 : What are the major groups of microorganisms?
Q6 : Name the microorganisms which can fix atmospheric nitrogen in the soil.
Q7 : Write 10 lines on the usefulness of microorganisms in our lives.
Q8 : Write a short paragraph on the harms caused by microorganisms.
Q9 : What are antibiotics? What precautions must be taken while taking antibiotics?
