NCERT Class VIII Science Solutions: Chapter 2-Microorganisms: Friend and Foe Part 1 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 1:

Fill in the blanks:

  1. Microorganisms can be seen with the help of a ________.
  2. Blue green algae fix ________ directly from air to enhance fertility of soil.
  3. Alcohol is produced with the help of ________.
  4. Cholera is caused by ________.

Answer:

  1. Microorganisms can be seen with the help of a microscope.
  2. Blue green algae fix nitrogen directly from air to enhance fertility of soil.
  3. Alcohol is produced with the help of microorganisms.
  4. Cholera is caused by bacteria.

Question 2:

Tick the correct answer:

  1. Yeast is used in the production of
  2. Sugar
  3. Alcohol
  4. hydrochloric acid
  5. oxygen
  6. The following is an antibiotic
  7. Sodium bicarbonate
  8. Streptomycin
  9. Alcohol
  10. Yeast
  11. Carrier of malaria-causing protozoan is
  12. female Anopheles mosquito
  13. cockroach
  14. housefly
  15. butterfly
  16. The most common carrier of communicable diseases is
  17. Ant
  18. Housefly
  19. Dragonfly
  20. Spider
  21. The bread or idle dough rises because of
  22. Heat
  23. Grinding
  24. growth of yeast cells
  25. kneading
  26. The process of conversion of sugar into alcohol is called
  27. nitrogen fixation
  28. Eluding
  29. Fermentation
  30. infection

Answer:

  1. Alcohol
  2. Streptomycin
  3. Female Anopheles mosquito
  4. Housefly
  5. Growth of yeast cells
  6. Fermentation

Question 3:

Match the organisms in Column I with their action in Column II.

Match the Organisms in Column I with Their Action in Column II (Q)
Column IColumn II
BacteriaFixing Nitrogen
RhizobiumSetting of curd
LactobacillusBaking of bread
YeastCausing Malaria
A protozoanCausing Cholera
A VirusCausing AIDS
Producing antibodies

Answer:

Match the Organisms in Column I with Their Action in Column II (A)
Column IColumn II
BacteriaCausing Cholera
RhizobiumFixing Nitrogen
LactobacillusSetting of curd
YeastBaking of bread
A protozoanCausing Malaria
A VirusCausing AIDS

Question 4:

Can microorganisms be seen with the naked eye? If not, how can they be seen?

Answer:

No, microorganisms cannot be seen by naked eye as they are very small and are called microbes. They can be seen with the help of microscope.

As Showing in Image is a Result for Microscope

So, micro-organisms are very small organisms that cannot see with naked eye, but can be seen with the help of microscope.

Micro-organisms may be unicellular or multicellular; it may live alone or communities.

Question 5:

What are the major groups of microorganisms?

Answer:

Microorganisms are microscopic organisms that exist as unicellular, multicellular or cell clusters.

Microorganisms are widespread in nature and are beneficial to life, but some can cause serious harm. They can be divided into six major types: bacteria, archaic, fungi, protozoa, algae, and viruses.

This Diagram Shows Types of Microorganisms

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