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

Worksheets For class 8

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

1. CLASS-8
2. BOARD: SSC
3. BIOLOGY Worksheet -2
4. TOPIC: Microorganisms Friend and Foe
5. For otherSCC Worksheet for class 8 Sciencecheck out main page of Physics Wallah.

1. Fill in the blanks:
   1. (a) Microorganisms can be seen with the help of a ­­­­­­­­­­­­­___________
   2. (b) Alcohol is produced with the help of ___________.
2. Yeast is used in the production of
   1. Sugar
   2. Alcohol
   3. Hydrochloric acid
   4. Oxygen
3. The following is an antibiotic
   1. Sodium bicarbonate
   2. Streptomycin
   3. Alcohol
   4. Yeast
4. The bread or idli dough rises because of
   1. Heat
   2. Grinding
   3. Growth of yeast cells
   4. Kneading
5. The process of conversion of sugar into alcohol is called
   1. Nitrogen fixation
   2. Molding
   3. Fermentation
   4. Infection
6. Can microorganisms be seen with the naked eye? If not, how can they be seen?
7. What are the major groups of microorganisms?
8. What is pasteurization?
9. What are antibiotics?
10. Write a note on the usefulness of microorganisms in our lives.

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

1. 1. Microscope
   2. Yeast
2. (b) Alcohol
3. (b) Streptomycin
4. (c) Growth of yeast cells
5. (c) Fermentation
6. No, microorganisms cannot be seen with a naked eye. They can only be observed using a simple or compound microscope depending upon the size of the microorganisms.
7. The major groups of micro-organisms are bacteria, fungi, protozoans, algae and viruses.
8. Pasteurization is a process in which milk is treated by alternate heating and cooling in order to make the milk free of pathogens.
9. Antibiotics are drugs or medicines that are produced by certain microorganisms to eliminate or kill other disease causing microorganisms.
10. Microorganisms 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 are useful for the growth of plants.
    2. Bacteria likeRhizobium andAzotobacter 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. AlsoAcetobacter 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 andStreptococcus.
    5. Bacteria likePseudomonas andNitrosomonas are useful for sewage treatment and breaking down hydrocarbon in oil spills present in marine water.