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Class 8

Explore popular questions from Microorganisms: Friend and Foe for Class 8. This collection covers Microorganisms: Friend and Foe previous year Class 8 questions hand picked by experienced teachers.

Microorganisms: Friend and Foe

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Q 1. Pasteurization means -

A

Vaccination for a baby against smallpox.

B

Sterilization in steam cooker at 100° C.

Heating milk or other liquids to 60°C to 70°C for short duration.

D

A technique or curing people bitten by mad dogs.

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Q 2. Bacteria differ from other plants in that they do not have

A

DNA

B

RNA

C

Cell wall

A well defined nucleus

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Q 3. Who proposed the germ theory of disease?

A

Robert Koch

B

A.Fleming

C

E. Jenner

Louis Pasteur

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Q 4. Comma shaped bacteria are termed as -

A

Bacilli

B

Cocei

C

Spirilla

Vibrio

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Q 5. Food spoilage can be prevented by -

A

Healing of food

B

Using chemicals

C

Canning

All of these

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Q 6. Yeast is used in the production of

A

Sugar

Alcohol

C

Hydrochloric acid

D

Oxygen

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Q 7. The fixation of free nitrogen by bacteria in the soil is done by-

Azotobacter

B

Nitrosomonas

C

Nitrobacter

D

Thiobacillus

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Q 8. Nitrifying bacteria convert the-

A

Nitrates into nitrites

Ammonium salts into nitrates

C

Ammonium salts into amino acids.

D

All of the above

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Q 9. The bacterial genome is called :

A

Nucleus

B

Nucleolus

Nucleoid

D

None

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Q 10. Antibiotics are mostly obtained from-

Bacteria

B

Viruses

C

Angiosperms

D

Fungi

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Q 11. Nitrates are converted into nitrogen by-

Denitrifying bacteria

B

Nitrifying bacteria

C

Ammonifying bacteria

D

Nitrogen fixing bacteria

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Q 12. All bacteria have the following organelle.

Mesosomes

B

Golgibodies

C

Mitochondria

D

Chloroplast

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Q 13. Rounded bacteria are-

A

Bacilli

B

Vibrio

C

Spirilla

Cocci

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Q 14. The following is an antibiotic

A

Sodium bicarbonate

Streptomycin

C

Alcohol

D

Yeast

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Q 15. Virus possess-

A

DNA only

Nucleic acid, DNA or RNA

C

Protein only

D

Nucleic acid and protein

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Q 16. Capsid is-

A

Genetic material of virus

Protein cover of virus

C

Extra genetic material of bacterium

D

Genome of bacterium

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Q 17. Carrier of malaria-causing protozoan is

A

Female Anopheles mosquito

B

Cockroach

C

Housefly

Butterfly

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Q 18. Who discovered vaccination against small pox.

Jenner

B

Pasteur

C

Lister

D

Mayer

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Q 19. Bacteriophage is-

A

Virus attacking bacteria

B

Virus attacking virus

Bacterium attacking virus

D

Stage in bacterial life cycle

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Q 20. The most common carrier of communicable diseases is –

A

Ant

Housefly

C

Dragonfly

D

Spider

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Q 21. Thread like fungal structure are-

Hyphae

B

Mycelium

C

Rhizomorphs

D

Sclerotia

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Q 22. Fungal cell wall is composed of-

Chitin

B

Hemicellulose

C

Cellulose

D

None of these

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Q 23. Fleming discovered penicillin from-

Penicillium notatum

B

Penicillium roqueforti

C

Penicillium camemberti

D

Penicillium chrysogenum

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Q 24. Yeast are economically important because they-

A

Spread plant diseases

B

Spread animal diseases

C

Are used in tea and tobacco industry

Are used in wine and baking industry

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Q 25. The bread or idli dough rises because of –

A

Heat

B

Grinding

Growth of yeast cells

D

Kneading