SSC Worksheet for Chapter - 3 Microorganisms: Friend and Foe Class 8

Worksheets For class 8

Find SSC Worksheet for chapter-3 Microorganisms: Friend and Foe class 8

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

1. Fill in the blanks:
   1. Cholera is caused by ___________.
   2. Blue green algae fix ___________ directly from air to enhance fertility of soil.
2. Viruses can reproduce in
   1. Water
   2. Air
   3. Milk
   4. Plants and animals
3. Tuberculosis is caused by
   1. Virus
   2. Protozoan
   3. Blue green algae
   4. Bacteria
4. Carrier for dengue fever is
   1. Housefly
   2. Anopheles mosquito
   3. Aedes mosquito
   4. Ticks
5. The most common carrier of communicable diseases is
   1. Ant
   2. Housefly
   3. Dragonfly
   4. Spider
6. Match the organisms in Column A with their action in Column B:
             A                            B
   1. Bacteria               (a) Fixing nitrogen
   2. Rhizobium          (b) Setting of curd
   3. Lactobacillus     (c) Baking of bread
   4. Yeast                (d) Causing malaria
   5. A protozoan      (e) Causing cholera
   6. A virus              (f) Causing AIDS
   7. Producing antibodies
7. How can we prevent mosquitoes from breeding?
8. Name the microorganisms which can fix atmospheric nitrogen in the soil.
9. What are preservatives? Name two common preservatives used to preserve jams and pickles.
10. Write a short paragraph on the harms caused by microorganisms.

Solutions: to worksheet-3 Topic- Microorganisms Friend and Foe

1. 1. Bacteria Vibrio cholerae
   2. Nitrogen
2. (d) Plants and animals
3. (d) Bacteria
4. (c) Aedes mosquito
5. (b) Housefly
6. 1. e
   2. a
   3. b
   4. v
   5. d
   6. f
7. Mosquitoes can be prevented from breeding by using the following ways:
   1. Do not allow water to stagnate in your surroundings
   2. Keep your surroundings neat and clean
   3. Use mosquito repellant
8. Rhizobium, Nitrobacter, Azotobacter are the microorganisms which fix atmospheric nitrogen into the soil.
9. Preservatives are the substances added to the food in order to maintain its taste and quality for a longer period of time. Sugar is commonly added to preserve jams, and oil and salt is added to preserve pickle.
10. Micro-organisms causing diseases in plants, animals and humans are termed as pathogens. The harms caused by these microbes are as follows:
    1. Bacteria like Vibrio cholerae and Salmonella typhi causes disease like cholera and typhoid respectively.
    2. Also diseases like pneumonia and tuberculosis is caused by bacteria Streptococcus pneumonae and Mycobacterium species.
    3. Female Anopheles mosquito is a carries for malarial parasite Plasmodium and female Aedes mosquito carries dengue virus causing dengue fever.
    4. Bacillus anthracis causes anthrax which a dangerous disease for humans as well as cattles.
    5. Canker is caused in citrus fruits due to bacteria.
    6. Yellow vein mosaic disease is caused in okra (bhindi) by virus transmitted through insect.
    7. Serious diseases caused by viruses are chicken pox, jaundice, AIDS. SARS, Herpes, swine flu, mumps, polio etc.