ICSE Worksheet for Chapter - 2 Microorganisms: Friend and Foe Class 8

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Find ICSE Worksheet for chapter-2 Microorganisms: Friend and Foe class 8

CLASS-8

BOARD: ICSE

BIOLOGY Worksheet - 2

TOPIC: Microorganisms: Friend and Foe

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1. Which one of the following is not a microorganism?
   1. Protozoa
   2. Fungi
   3. Bacteria
   4. Algae
2. The term antibiotic was first used by
   1. Flemming
   2. Pasteur
   3. Waksman
   4. Jenner
3. Fermentation is the process used for making
   1. Curd
   2. Cheese
   3. Idlis
   4. Both (a) and (c)
4. What is Edward Jenner’s contribution in the field of medicine?
   1. Discovered compound microscope
   2. Discovered bacteria
   3. Created vaccination for small pox
   4. Created vaccination for polio
5. What are the major groups of microorganisms? Give two examples of each.
6. Define antibiotics.
7. Why Yeast is used in baking industry?
8. Which of the two is a spherical bacteria: Coccus or Bacillus.
9. What is Pastuerisation and who discovered this process?
10. Write a note on the usefulness of microorganisms in our lives.

Solutions: to worksheet-2 Topic- Microorganisms Friend and Foe

1. (d) Algae
2. (a) Flemming
3. (d) Both (a) and (c)
4. (c) Created vaccination for small pox
5. The major groups of micro-organisms are bacteria, fungi, protozoans, algae and viruses.
6. Antibiotics are drugs or medicines that are produced by certain microorganisms to eliminate or kill other disease causing microorganisms.
7. Yeast is a fungi which undergoes anaerobic respiration during which it releases CO₂. This CO₂ raises the dough and makes the bread soft and fluffy.
8. Coccus is the spherical bacteria while Bacillus is rod-shaped.
9. Micro-organisms are the integral part of our life. They are useful to us in various ways such as-
   1. Fungi and bacteria are decomposers and natural scavengers. They help in converting dead and decaying complex organic matter into simpler ones which one useful for the growth of plants.
   2. Bacteria like Rhizobium and Azotobacter present in the root nodules of leguminous plants help in fixing atmospheric nitrogen into soluble nitrates and nitrites which are useful fertilizer for plants.
   3. In food industry, Lactobacillus is used for fermentation of milk into curd. Also Acetobacter is used for production of acetic acid. Yeast is used in distilleries for the fermentation of fruit juices, molasses to make alcoholic drinks. In bakery, Yeast is used to raise the dough for making bread.
   4. Antibiotics like penicillin and streptomycin are manufactured with the help of microbes like Penicillium and Streptococcus.
   5. Bacteria like Pseudomonas and Nitrosomonas are useful for sewage treatment and breaking down hydrocarbon in oil spills present in marine water.