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

Worksheets For class 8

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

1. CLASS-8
2. BOARD: CBSE
3. BIOLOGY Worksheet - 3
4. TOPIC: Microorganisms : Friends And Foe.
5. For other
6. CBSE Worksheet for class 8 Science
7. check out main page ofPhysics Wallah.

1. Fill in the blanks:
(a) Common cold is a/an ___________borne disease. (b) The protection of the body from infectious disease by administration of vaccines is called _____.
2. Match the Columns:
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. Which one of the following sets includes the bacterial diseases?
   1. Cholera, typhoid, mumps
   2. Tetanus, Tuberculosis, Measles
   3. Malaria, typhoid, chicken pox
   4. Diptheria, typhoid, tuberculosis
6.  Amoebic dysentery is transmitted by
   1. Sneezing
   2. Using contaminated water
   3. Direct contact
   4. Mosquito
7.  How does our body fights when a disease carrying microbe enters our body?
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 Friends And Foe

1. 1. air
   2. immunization
2. 1. c
   2. d
   3. a
   4. b
3. (d) Bacteria
4. (c) Aedes mosquito
5. (d) Diptheria, typhoid, tuberculosis
6. (b) Using contaminated water
7. When a disease carrying microbe enters our body, the antibodies present in our cells detect it and gets activated. Once activated these acts as a defense mechanism and protects our body from its transmission. This is called natural immunity.
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 pickles.
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.