Microorganisms: Friend and Foe Quiz - CBSE Class 8 Science

Free practice quiz: Microorganisms: Friend and Foe (CBSE Class 8 Science). 14 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which of the following is NOT a type of microorganism?

   1. Bacteria
   2. Virus
   3. Mushroom
   4. Protozoa
   Show answer

   Answer: C. Mushroom

   Mushrooms are fungi, not microorganisms. Bacteria, viruses, and protozoa are all types of microorganisms.

2. Which microorganism is responsible for nitrogen fixation in the soil?

   1. Rhizobium
   2. Vibrio cholerae
   3. Penicillium
   4. Aspergillus
   Show answer

   Answer: A. Rhizobium

   Rhizobium bacteria are nitrogen-fixing bacteria found in the root nodules of leguminous plants.

3. Explain the role of microorganisms in the recycling of nutrients in an ecosystem.

   1. They decompose organic matter, releasing nutrients back into the environment.
   2. They consume organic matter, storing nutrients.
   3. They produce organic matter, consuming nutrients.
   4. They have no role in nutrient recycling.
   Show answer

   Answer: A. They decompose organic matter, releasing nutrients back into the environment.

   Microorganisms like bacteria and fungi are decomposers, breaking down dead plants and animals and releasing essential nutrients back into the soil and air.

4. Discuss the challenges in developing effective antiviral drugs compared to antibacterial drugs.

   1. Viruses replicate within host cells, making it difficult to target them without harming the host. Bacteria are independent cells, easier to target.
   2. Viruses have simpler structures than bacteria.
   3. Viruses are less diverse than bacteria.
   4. There are no challenges.
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   Answer: A. Viruses replicate within host cells, making it difficult to target them without harming the host. Bacteria are independent cells, easier to target.

   The main challenge with antiviral drugs is that viruses use the host cell's machinery to replicate, making it hard to target the virus without damaging the host cell. Bacteria are independent organisms, making them easier to target with drugs.

5. Critically evaluate the advantages and disadvantages of using genetically modified microorganisms in various biotechnological applications.

   1. Advantages include enhanced efficiency and production of new products, disadvantages include potential risks of unintended environmental consequences and ethical concerns.
   2. Genetically modified microorganisms only have advantages.
   3. Genetically modified microorganisms have no disadvantages.
   4. Genetic modification of microorganisms is not possible.
   Show answer

   Answer: A. Advantages include enhanced efficiency and production of new products, disadvantages include potential risks of unintended environmental consequences and ethical concerns.

   Genetically modified microorganisms offer advantages like increased efficiency in producing valuable compounds, but potential risks related to unintended environmental impacts and ethical considerations must be carefully evaluated.

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