Microorganisms friend and foe | Chapter 2 | Class 8 NCERT by KTCC

1.Fill in the blanks

a) The microorganism can be seen with the help of.

Ans- Microscope

b) Blue-green algae fix directly from the air to enhance soil fertility.
Ans- Nitrogen
c) Alcohol is produced with the help of _

Ans- Microorganisms

d) Cholera is caused by.
Ans- Bacteria

  1. Tick The Correct Answer
    a) Yeast is used in the production of – Alcohol
    b) The following is an antibiotic – Streptomycin
    c) Carrier of Malaria -causing protozoan is – Female Anopheles Mosquito
    d) The most common carrier of communicable disease is – Housefly
    e) The bread or idli dough rises because – Growth of yeast cells
    f) The process of conversion of sugar into alcohol is called – Fermentation
  1. Match the organisms in Column A with their action in Column B

Column -A Column-B
(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

  1. Can microorganisms be seen with the naked eye? If not, how can they be seen?
    Answer
    – No, microorganisms can’t be seen by naked eyes because they are very small, they can be seen with the help of a microscope.
  2. What are the major groups of microorganisms?
    Answer
    – The major groups of microorganisms are as follows:-
    a) Bacteria
    b) Protozoans
    c) Algae
    d) Fungi
    e) Viruses
  3. Name the microorganisms which can fix atmospheric nitrogen in the soil.
    Answer
    – Rhizobium is the microorganism that can fix atmospheric nitrogen in the soil.
  4. Write 10 lines on the usefulness of microorganisms in our lives.
    Answer
    – a) They help in the formation of curd and cheese.
    b) They help in fermentation in bakery items.
    c) They help in making alcohol ( alcoholic beverages ).
    d) They help in the production of antibiotics.
    e) Bacteria present in our large intestine helps in bowel movement.
    f) They help in producing vaccines.
    g) They help to fix biological nitrogen that’s why they are called ”biological nitrogen fixers”.
    h) They help in fuel/energy production
    i) They also clean the environment as decomposers.
    j) Probiotics ( dietary supplements of live bacteria or yeasts) can prevent and treat disease through a number of mechanisms.
  5. Write a short paragraph on the harmful effects of microorganisms.
    Answer
    – Microorganisms that cause disease are known as pathogens. They release some harmful material in our bodies that are called Toxins. There are many infectious diseases which are caused by microorganisms e.g. Tuberculosis, cholera, malaria, etc., They also cause disease in animals like rabies, canine distemper,
    Anthrax, etc., also cause food poisoning that happens due to the presence of bacteria and other microbes. Bacteria like Clostridium, Staphylococci, and fungi like Aspergillus cause food poisoning. If microorganisms are our friends but on the other hand, they are our foes as well.

3 thoughts on “Microorganisms friend and foe | Chapter 2 | Class 8 NCERT by KTCC”

  1. Ram naresh roy

    Very helpful thanks for uploading these types of question answers it’s very innovative (•‿•)(•‿•)(•‿•)(•‿•)(•‿•)

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