Welcome To My School Study
Practice Class 8 Science Chapter 2 Microorganisms: Friend and Foe MCQ Questions with Answers and Useful Details based on the NCERT syllabus. Revise microorganisms, bacteria, fungi, protozoa, algae, viruses, useful microbes, and their habitats.
Do You Know
Chapter Information
Subject: Science
Class: 8
Chapter: Microorganisms: Friend and Foe
Question Type: Multiple Choice Questions (MCQs)
Practice Set: 1
Difficulty Level: Moderate
Based On: NCERT Syllabus
Introduction
Microorganisms are extremely small organisms that generally cannot be seen with the naked eye. They are present in many different places, including air, water, soil, food, and the bodies of plants and animals.
Microorganisms include groups such as bacteria, fungi, protozoa, and some algae. Viruses are also microscopic and are studied along with microorganisms, although they differ from other microorganisms in important ways.
Some microorganisms are useful to humans. They are involved in making curd, bread and other products, producing medicines, increasing soil fertility, and decomposing organic matter. On the other hand, some microorganisms can cause diseases and spoil food.
This Practice Set 1 introduces the fundamental concepts of Microorganisms: Friend and Foe and helps students build a strong foundation for the chapter.
What You Will Learn
✔ Meaning of microorganisms
✔ Different groups of microorganisms
✔ Bacteria and fungi
✔ Protozoa and algae
✔ Basic information about viruses
✔ Habitats of microorganisms
✔ Useful microorganisms
✔ Harmful microorganisms
✔ Importance of microorganisms in daily life
Why This Topic Is Important
Microorganisms are an important part of our environment and daily life. Although most of them are too small to be seen without magnification, they perform many important functions.
Some microorganisms help in the preparation of food and medicines, while others can cause diseases in humans, animals, and plants.
Understanding the different types and roles of microorganisms helps students distinguish between their useful and harmful effects and understand why microorganisms are called both friends and foes.
5 MCQs with Answers and Useful Details
Q1. What are microorganisms?
A) Organisms that can always be seen with the naked eye
B) Organisms that are generally too small to be seen with the naked eye
C) Only organisms that live in water
D) Only disease-causing organisms
Answer:
B) Organisms that are generally too small to be seen with the naked eye
Useful Detail
Microorganisms, also called microbes, are extremely small organisms that generally cannot be seen without the help of a microscope.
They are found in many environments such as air, water, soil, food, and the bodies of living organisms.
Some microorganisms are useful, while others can be harmful. Therefore, microorganisms have both beneficial and harmful effects.
Correct Answer: B) Organisms that are generally too small to be seen with the naked eye
Q2. Which of the following is NOT one of the major groups of microorganisms described in the chapter?
A) Bacteria
B) Fungi
C) Protozoa
D) Mammals
Answer:
D) Mammals
Useful Detail
The major groups of microorganisms discussed in this chapter include bacteria, fungi, protozoa, and some algae.
Viruses are also microscopic and are discussed in the chapter, although they are different from other microorganisms in important respects.
Mammals, such as humans, cows, and dogs, are animals and are not classified as microorganisms.
Understanding these groups helps students identify microorganisms based on their characteristics.
Correct Answer: D) Mammals
Q3. Which microorganism is commonly used in the preparation of curd?
A) Lactobacillus
B) Plasmodium
C) Amoeba
D) Rhizobium
Answer:
A) Lactobacillus
Useful Detail
Lactobacillus is a bacterium that helps convert milk into curd.
It produces lactic acid, which causes milk proteins to change and results in the formation of curd.
This is an example of a microorganism that is useful to humans.
Microorganisms are also used in preparing other food products and in several industrial processes.
Correct Answer: A) Lactobacillus
Q4. Which microorganism is used in the production of bread?
A) Yeast
B) Plasmodium
C) Rhizobium
D) Amoeba
Answer:
A) Yeast
Useful Detail
Yeast is a type of fungus that is widely used in baking.
During fermentation, yeast uses sugar and produces carbon dioxide and alcohol. The carbon dioxide gas gets trapped in the dough and causes it to rise, making the bread soft and spongy.
Thus, yeast is an important useful microorganism in the food industry.
Correct Answer: A) Yeast
Q5. Where can microorganisms be found?
A) Only in soil
B) Only in water
C) Only inside animals
D) In many environments such as air, water, soil, and living organisms
Answer:
D) In many environments such as air, water, soil, and living organisms
Useful Detail
Microorganisms are widely distributed in nature. They can be found in air, water, soil, food, and the bodies of plants and animals.
They can survive in a variety of environmental conditions. Some microorganisms are found even in environments that may appear unsuitable for ordinary life.
Their widespread presence makes microorganisms an important part of ecosystems and natural processes.
Correct Answer: D) In many environments such as air, water, soil, and living organisms
Important Formulas & Concepts
Science Chapter 2 does not contain mathematical formulas. The following are the important scientific concepts for revision.
1. Microorganisms
Microorganisms are very small organisms that generally cannot be seen with the naked eye.
2. Microbes
The term microbes is commonly used for microorganisms.
3. Bacteria
Bacteria are microscopic organisms. Some bacteria are useful, while others can cause diseases.
4. Fungi
Fungi form an important group of microorganisms. Yeast is an example of a useful fungus.
5. Protozoa
Protozoa are microscopic organisms. Some protozoa are useful, while some cause diseases.
6. Algae
Some algae are microscopic and are included among the groups of microorganisms discussed in the chapter.
7. Viruses
Viruses are microscopic and are different from other microorganisms. They reproduce only inside the cells of a living host.
8. Lactobacillus
Lactobacillus is a useful bacterium involved in the formation of curd.
9. Yeast
Yeast is a fungus used in baking and fermentation.
10. Habitats of Microorganisms
Microorganisms can be found in air, water, soil, food, and inside living organisms.
Related Practice Questions
Q1. What are microorganisms?
Q2. Name four major groups of microorganisms.
Q3. Where are microorganisms found?
Q4. How is Lactobacillus useful to humans?
Q5. Why is yeast used in bread making?
Mini Quiz Challenge
Try answering these questions within 60 seconds.
Q1. Microorganisms are generally observed with the help of:
A) Telescope
B) Microscope
C) Periscope
D) Barometer
Q2. Which microorganism helps in making curd?
A) Lactobacillus
B) Plasmodium
C) Virus
D) Amoeba
Q3. Yeast belongs to which group?
A) Fungi
B) Protozoa
C) Algae
D) Mammals
Q4. Which of the following is a microscopic organism?
A) Bacterium
B) Cow
C) Elephant
D) Human
Q5. Microorganisms are found:
A) Only in air
B) Only in soil
C) In many different environments
D) Only in food
Exam Tips
✔ Learn the definition of microorganisms carefully.
✔ Remember the major groups: bacteria, fungi, protozoa, and some algae.
✔ Remember that viruses are different from other microorganisms.
✔ Learn examples of useful microorganisms.
✔ Remember that Lactobacillus helps in curd formation.
✔ Remember that yeast is used in bread making.
✔ Revise the different habitats of microorganisms.
✔ Understand that all microorganisms are not harmful.
✔ Pay attention to examples because they are frequently used in MCQs.
Quick Revision Notes
✔ Microorganisms: Very small organisms that generally cannot be seen with the naked eye.
✔ Microbes: Another common term for microorganisms.
✔ Bacteria: Microscopic organisms that may be useful or harmful.
✔ Fungi: A major group of microorganisms; yeast is an example.
✔ Protozoa: Microscopic organisms belonging to another major group.
✔ Algae: Some algae are microscopic and are included among microorganisms.
✔ Viruses: Microscopic entities that reproduce inside living host cells.
✔ Lactobacillus: Helps in the formation of curd.
✔ Yeast: Used in bread making and fermentation.
✔ Habitats: Microorganisms occur in air, water, soil, food, and living organisms.
Common Mistakes Students Make
❌ Thinking that all microorganisms cause diseases.
❌ Thinking that microorganisms are found only in dirty places.
❌ Confusing bacteria with fungi.
❌ Forgetting that yeast is a fungus.
❌ Thinking that Lactobacillus is harmful because it is a bacterium.
❌ Assuming that viruses are exactly the same as bacteria.
❌ Thinking that microorganisms live only in water.
❌ Forgetting that useful microorganisms are involved in food production.
Key Takeaways
✔ Microorganisms are extremely small organisms.
✔ They are found in many different environments.
✔ Bacteria, fungi, protozoa, and some algae are major groups discussed in the chapter.
✔ Viruses are microscopic and differ from other microorganisms.
✔ Some microorganisms are useful to humans.
✔ Lactobacillus helps in curd formation.
✔ Yeast is useful in bread making.
✔ Microorganisms can be both beneficial and harmful.
FAQs
Q. What are microorganisms?
Answer:
Microorganisms are very small organisms that generally cannot be seen with the naked eye and are usually observed with the help of a microscope.
Q. Where are microorganisms found?
Answer:
Microorganisms are found in many places, including air, water, soil, food, and the bodies of plants and animals.
Q. Name some major groups of microorganisms.
Answer:
The major groups discussed in the chapter are bacteria, fungi, protozoa, and some algae. Viruses are also discussed because they are microscopic and have important effects on living organisms.
Q. Which microorganism helps in making curd?
Answer:
The bacterium Lactobacillus helps in converting milk into curd.
Q. Which microorganism is used in bread making?
Answer:
Yeast is used in bread making. It produces carbon dioxide during fermentation, which helps the dough rise.
Conclusion
Class 8 Science Chapter 2 – Microorganisms: Friend and Foe introduces students to the basic world of microorganisms.
In this set, students revised the meaning of microorganisms, their major groups, their habitats, and some important useful microorganisms such as Lactobacillus and yeast.
A strong understanding of these basic concepts will make it easier to study the later topics of the chapter, including useful microorganisms, harmful microorganisms, food preservation, antibiotics, nitrogen fixation, and the nitrogen cycle.
Related links
- Class 8 Maths Chapter 4 Practical Geometry part-7
- Class 8 English Chapter 1 Another Chance part-9
- Class 8 Social Science Chapter 1 How, When and Where part-12
- Class 8 Maths Chapter 4 Practical Geometry part-6
- Class 8 Science Chapter 1 Crop Production and Management part-12
- Class 8 English Chapter 1 Another Chance part-8
- Class 8 Social Science Chapter 1 How, When and Where part-11
- Class 8 Maths Chapter 4 Practical Geometry part-5
- Class 8 Science Chapter 1 Crop Production and Management part-11
- Class 8 English Chapter 1 Another Chance part-7
- Class 8 Social Science Chapter 1 How, When and Where part-10
- Class 8 Maths Chapter 4 Practical Geometry part-4
Latest Posts
- Class 9 Maths Chapter 5 Introduction to Euclid’s Geometry
- Class 10 Maths Chapter 5 -Arithmetic Progressions
- Class 7 Maths Chapter 5 – Parallel and Intersecting Lines
- Class 8 Maths Chapter 5 – Number Play
- Class 9 English Chapter 2 The Pot Maker
Join Our Other Communities
Instagram , Youtube , Facebook
