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Practice Class 8 Science Chapter 2 Microorganisms: Friend and Foe MCQ Questions with Answers and Useful Details based on the NCERT syllabus. Revise bacteria, viruses, fungi, protozoa, algae, useful microorganisms, harmful microorganisms, and disease-causing microbes.
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Chapter Information
Subject: Science
Class: 8
Chapter: Microorganisms: Friend and Foe
Question Type: Multiple Choice Questions (MCQs)
Practice Set: 13
Difficulty Level: Difficult
Based On: NCERT Syllabus
Introduction
Microorganisms are tiny living organisms that are found almost everywhere. They live in soil, water, air, food, and even inside the bodies of plants and animals.
Microorganisms include groups such as bacteria, fungi, protozoa, algae, and viruses. Some are useful to humans, while others can cause diseases or spoil food.
A clear understanding of different types of microorganisms and their characteristics helps students identify their roles in everyday life, agriculture, medicine, and the environment.
This Practice Set 13 focuses on different groups of microorganisms and their examples and roles.
What You Will Learn
✔ Major groups of microorganisms
✔ Bacteria
✔ Fungi
✔ Protozoa
✔ Algae
✔ Viruses
✔ Useful microorganisms
✔ Harmful microorganisms
✔ Disease-causing microorganisms
✔ Examples of microorganisms
Why This Topic Is Important
Microorganisms have diverse roles in nature and human life. Some help in making food, medicines, and fertilisers, while others cause diseases in humans, animals, and plants.
Knowing the differences between bacteria, fungi, protozoa, algae, and viruses helps students understand how microorganisms affect living organisms and the environment.
These concepts are also frequently tested in school examinations through identification and example-based questions.
5 MCQs with Answers and Useful Details
Q1. Which group of microorganisms includes organisms such as Amoeba and Paramecium?
A) Protozoa
B) Bacteria
C) Fungi
D) Algae
Answer:
A) Protozoa
Useful Detail
Protozoa are microscopic organisms that are generally unicellular and animal-like in their characteristics.
Examples include Amoeba and Paramecium.
Some protozoa are harmless or useful, while others can cause diseases. For example, Plasmodium, a protozoan, causes malaria.
Correct Answer: A) Protozoa
Q2. Which microorganism is commonly used in the production of bread and alcoholic beverages?
A) Yeast
B) Rhizobium
C) Amoeba
D) Plasmodium
Answer:
A) Yeast
Useful Detail
Yeast is a microscopic fungus.
It carries out fermentation and is widely used in bread making and the production of alcoholic beverages.
During fermentation, yeast converts sugars into alcohol and carbon dioxide. The carbon dioxide produced during bread making causes the dough to rise.
Correct Answer: A) Yeast
Q3. Which of the following is a disease-causing protozoan?
A) Plasmodium
B) Lactobacillus
C) Rhizobium
D) Yeast
Answer:
A) Plasmodium
Useful Detail
Plasmodium is a protozoan that causes malaria in humans.
Malaria is transmitted through the bite of an infected female Anopheles mosquito, which acts as a vector.
This example shows that microorganisms can cause diseases and that some diseases require a carrier for transmission.
Correct Answer: A) Plasmodium
Q4. Which group includes microorganisms such as Lactobacillus and Rhizobium?
A) Bacteria
B) Fungi
C) Protozoa
D) Algae
Answer:
A) Bacteria
Useful Detail
Lactobacillus and Rhizobium are examples of bacteria.
Lactobacillus helps convert milk into curd, while Rhizobium is associated with the root nodules of leguminous plants and helps in nitrogen fixation.
Thus, bacteria can have both food-related and agricultural uses.
Correct Answer: A) Bacteria
Q5. Which statement about viruses is correct?
A) Viruses can reproduce independently in all environments.
B) Viruses generally reproduce only inside the living cells of a host.
C) Viruses are always useful to humans.
D) Viruses are multicellular organisms.
Answer:
B) Viruses generally reproduce only inside the living cells of a host.
Useful Detail
Viruses are extremely small infectious agents. They can reproduce only when they enter the living cells of a host organism.
Examples of viral diseases include polio, measles, and common cold.
Outside a host cell, viruses do not carry out reproduction in the same way as independently living organisms.
Correct Answer: B) Viruses generally reproduce only inside the living cells of a host.
Important Formulas & Concepts
Science Chapter 2 does not contain mathematical formulas. Important scientific concepts are given below.
1. Bacteria
Bacteria are microscopic organisms with many different forms and functions. Some are useful, while others cause diseases.
2. Fungi
Fungi include microorganisms such as yeast and are involved in processes such as fermentation.
3. Protozoa
Protozoa are generally unicellular microscopic organisms. Some, such as Plasmodium, cause diseases.
4. Algae
Some algae are microscopic and can prepare their own food through photosynthesis.
5. Viruses
Viruses are infectious agents that generally reproduce inside living host cells.
6. Lactobacillus
Lactobacillus is a bacterium that helps convert milk into curd.
7. Rhizobium
Rhizobium is a nitrogen-fixing bacterium associated with leguminous plants.
8. Yeast
Yeast is a fungus used in fermentation and bread making.
9. Plasmodium
Plasmodium is a protozoan that causes malaria.
10. Pathogens
Microorganisms that cause diseases are called pathogens.
Related Practice Questions
Q1. Name five major groups of microorganisms.
Q2. What is the role of Lactobacillus?
Q3. Which microorganism causes malaria?
Q4. Why are viruses dependent on host cells for reproduction?
Q5. Give two examples of useful microorganisms.
Mini Quiz Challenge
Try answering these questions within 60 seconds.
Q1. Amoeba belongs to the group:
A) Protozoa
B) Bacteria
C) Fungi
D) Algae
Q2. Yeast belongs to:
A) Fungi
B) Protozoa
C) Bacteria
D) Viruses
Q3. Rhizobium is a:
A) Bacterium
B) Fungus
C) Virus
D) Protozoan
Q4. Malaria is caused by:
A) Plasmodium
B) Lactobacillus
C) Rhizobium
D) Yeast
Q5. Viruses generally reproduce:
A) Inside living host cells
B) Only in soil
C) In clean water independently
D) On dry surfaces independently
Exam Tips
✔ Learn the major groups of microorganisms.
✔ Remember yeast → fungus.
✔ Remember Lactobacillus → bacterium → curd.
✔ Remember Rhizobium → bacterium → nitrogen fixation.
✔ Remember Plasmodium → protozoan → malaria.
✔ Remember that viruses require living host cells for reproduction.
✔ Learn examples of useful and harmful microorganisms.
✔ Do not confuse protozoa with bacteria.
✔ Revise examples rather than memorising only group names.
✔ Pay attention to questions asking for the correct microorganism-disease pair.
Quick Revision Notes
✔ Bacteria: Microscopic organisms with useful and harmful members.
✔ Fungi: Include yeast and many other microscopic forms.
✔ Protozoa: Include Amoeba, Paramecium, and Plasmodium.
✔ Algae: Some microscopic algae perform photosynthesis.
✔ Viruses: Reproduce inside living host cells.
✔ Lactobacillus: Helps convert milk into curd.
✔ Yeast: Used in fermentation and bread making.
✔ Rhizobium: Helps in nitrogen fixation.
✔ Plasmodium: Causes malaria.
✔ Pathogens: Disease-causing microorganisms.
Common Mistakes Students Make
❌ Thinking yeast is a bacterium.
❌ Confusing Plasmodium with a bacterium.
❌ Thinking Rhizobium causes malaria.
❌ Forgetting that Lactobacillus is a bacterium.
❌ Thinking viruses reproduce independently like bacteria.
❌ Confusing fungi with protozoa.
❌ Assuming all microorganisms are harmful.
❌ Forgetting examples of useful microorganisms.
Key Takeaways
✔ Microorganisms include bacteria, fungi, protozoa, algae, and viruses.
✔ Different microorganisms have different characteristics and roles.
✔ Yeast is a fungus used in fermentation.
✔ Lactobacillus is useful in curd formation.
✔ Rhizobium helps in nitrogen fixation.
✔ Plasmodium is a protozoan that causes malaria.
✔ Viruses generally reproduce inside living host cells.
✔ Microorganisms may be useful, harmful, or disease-causing.
FAQs
Q. What are the major groups of microorganisms?
Answer:
The major groups discussed in Class 8 Science include bacteria, fungi, protozoa, algae, and viruses.
Q. Is yeast a bacterium?
Answer:
No. Yeast is a fungus.
Q. Which microorganism causes malaria?
Answer:
Malaria is caused by the protozoan Plasmodium.
Q. What is the role of Lactobacillus?
Answer:
Lactobacillus helps convert milk into curd by converting milk sugar into lactic acid.
Q. Where do viruses reproduce?
Answer:
Viruses generally reproduce only inside the living cells of a host organism.
Conclusion
Class 8 Science Chapter 2 – Microorganisms: Friend and Foe focuses on the major groups of microorganisms and their important examples.
Students revised bacteria, fungi, protozoa, algae, viruses, Lactobacillus, yeast, Rhizobium, Plasmodium, and pathogens.
Understanding these examples makes it easier to identify the useful and harmful roles of microorganisms in food production, agriculture, medicine, and disease transmission.
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- Class 8 English Chapter 2 A Concrete Example part-9
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- Class 8 Science Chapter 2 Microorganisms Friend and Foe part-11
- Class 8 History Chapter 2 From Trade to Territory part-8
- Class 8 Maths Chapter 5 – Number Play part-1
- Class 8 English Chapter 2 A Concrete Example part-8
- Class 8 Science Chapter 2 Microorganisms Friend and Foe part-10
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