NCERT Grade 8-Microorganisms Friend and Foe-Questions

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Microorganisms Friend and Foe

Exercise 1

1.    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.

(c) Alcohol is produced with the help of ____________.

(d) Cholera is caused by ____________.

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 carbonate                           (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.

3.   Match the organisms in Column A with their action in Column B.

A                                                                              B

(i) Bacteria                                                        (a) Fixing nitrogen

(ii) Rhizobium                                                  (b) Setting curd

(iii) Lactobacillus                                             (c) Baking bread

(iv) Yeast                                                            (d) Causing malaria

(v) A protozoan                                                 (e) Causing cholera

(vi) A virus                                                         (f) Causing AIDS

      (g) Producing antibodies.

4.    Can microorganisms be seen with the naked eyes? If not, how can they be seen?

5.    What are the major groups of microorganisms?

6.    Name the microorganism which can fix atmospheric nitrogen in the soil.

7.    Write 10 lines on the usefulness of microorganisms in our lives.

8.    Write a short paragraph on the harms caused by microorganisms.

9.    What are antibiotics? What precautions must be taken while taking antibiotics?

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