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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 antibiotics, medicinal uses of microorganisms, vaccine development, disease prevention, and important health-related concepts.
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Chapter Information
Subject: Science
Class: 8
Chapter: Microorganisms: Friend and Foe
Question Type: Multiple Choice Questions (MCQs)
Practice Set: 11
Difficulty Level: Difficult
Based On: NCERT Syllabus
Introduction
Microorganisms have played an important role in the development of modern medicine. Some microorganisms produce substances that can be used as medicines, while certain microbial preparations help protect people from infectious diseases.
The discovery of antibiotics was a major development in medicine. Antibiotics can be used to treat certain bacterial infections, while vaccines help the immune system develop protection against specific diseases.
However, medicines must be used responsibly. In particular, unnecessary use of antibiotics can contribute to antibiotic resistance.
This Practice Set 11 focuses on the medicinal importance of microorganisms, antibiotics, vaccines, and responsible disease prevention.
What You Will Learn
✔ Medicinal uses of microorganisms
✔ Antibiotics
✔ Penicillin
✔ Alexander Fleming
✔ Vaccines
✔ Immunity
✔ Antibiotic resistance
✔ Disease prevention
✔ Responsible use of medicines
Why This Topic Is Important
Microorganisms can be both harmful and extremely useful. Their role in medicine has helped scientists develop treatments and preventive measures against many infectious diseases.
Students should understand the difference between antibiotics and vaccines and should know why antibiotics should not be used unnecessarily.
These concepts are important not only for examinations but also for developing scientific awareness about health and responsible medicine use.
5 MCQs with Answers and Useful Details
Q1. Which antibiotic was discovered by Alexander Fleming?
A) Penicillin
B) Insulin
C) Aspirin
D) Paracetamol
Answer:
A) Penicillin
Useful Detail
Alexander Fleming discovered penicillin in 1928.
Penicillin was obtained from a fungus of the genus Penicillium. Its discovery opened an important new area in the treatment of bacterial infections.
Antibiotics derived from or inspired by microorganisms have saved millions of lives by providing effective treatments for many bacterial diseases.
Correct Answer: A) Penicillin
Q2. Which statement correctly distinguishes antibiotics from vaccines?
A) Both are exactly the same type of medicine.
B) Antibiotics are used to treat certain bacterial infections, while vaccines help prevent specific infectious diseases.
C) Vaccines are used only to preserve food.
D) Antibiotics are used only for plant diseases.
Answer:
B) Antibiotics are used to treat certain bacterial infections, while vaccines help prevent specific infectious diseases.
Useful Detail
Antibiotics are medicines used to treat certain bacterial infections.
Vaccines, on the other hand, stimulate the immune system to develop protection against particular infectious diseases.
Therefore, antibiotics and vaccines have different purposes and should not be treated as interchangeable.
Correct Answer: B) Antibiotics are used to treat certain bacterial infections, while vaccines help prevent specific infectious diseases.
Q3. Why should antibiotics not be taken without proper medical advice?
A) They always increase body temperature.
B) Unnecessary or inappropriate use can contribute to antibiotic resistance.
C) They destroy all microorganisms in the environment.
D) They are used only as food preservatives.
Answer:
B) Unnecessary or inappropriate use can contribute to antibiotic resistance.
Useful Detail
When antibiotics are used unnecessarily or incorrectly, bacteria may develop mechanisms that allow them to survive the medicine.
This is called antibiotic resistance.
Resistant bacteria can make infections more difficult to treat. Therefore, antibiotics should be taken only according to appropriate medical advice and should be used exactly as directed.
Correct Answer: B) Unnecessary or inappropriate use can contribute to antibiotic resistance.
Q4. Which of the following is an important role of vaccines?
A) They help the immune system recognise and respond to specific disease-causing organisms.
B) They directly digest food in the stomach.
C) They preserve all types of food.
D) They replace every type of antibiotic.
Answer:
A) They help the immune system recognise and respond to specific disease-causing organisms.
Useful Detail
Vaccines expose the immune system to a safe form or component related to a particular disease-causing organism.
This allows the body to develop an immune response and memory so that it can respond more effectively if exposed to the actual pathogen later.
Vaccination is therefore an important method of disease prevention.
Correct Answer: A) They help the immune system recognise and respond to specific disease-causing organisms.
Q5. Which statement about antibiotics is correct?
A) Antibiotics are effective against every viral infection.
B) Antibiotics are mainly used against certain bacterial infections.
C) Antibiotics are food preservatives.
D) Antibiotics are always produced by plants.
Answer:
B) Antibiotics are mainly used against certain bacterial infections.
Useful Detail
Antibiotics target bacteria or bacterial processes. They do not generally work against viruses because viruses are fundamentally different from bacteria.
For example, antibiotics are not normally used to treat common viral infections such as the common cold.
Using antibiotics only when medically appropriate helps reduce the development of antibiotic resistance.
Correct Answer: B) Antibiotics are mainly used against certain bacterial infections.
Important Formulas & Concepts
Science Chapter 2 does not contain mathematical formulas. Important scientific concepts are given below.
1. Antibiotics
Medicines used to treat certain bacterial infections.
2. Penicillin
An important antibiotic discovered by Alexander Fleming in 1928.
3. Alexander Fleming
Scientist credited with the discovery of penicillin.
4. Vaccines
Preparations that stimulate the immune system to develop protection against specific infectious diseases.
5. Immunity
The body’s ability to defend itself against particular infections.
6. Antibiotic Resistance
A condition in which bacteria become less susceptible to antibiotics, making some infections harder to treat.
7. Pathogens
Disease-causing microorganisms are called pathogens.
8. Disease Prevention
Measures such as vaccination, hygiene, sanitation, safe water, and appropriate medical care help prevent infectious diseases.
9. Responsible Medicine Use
Medicines should be used according to appropriate professional medical advice.
10. Microorganisms in Medicine
Certain microorganisms and substances produced by them have important applications in modern medicine.
Related Practice Questions
Q1. Who discovered penicillin?
Q2. What are antibiotics?
Q3. What is the purpose of vaccination?
Q4. Why is antibiotic resistance dangerous?
Q5. Why are antibiotics not effective against viruses?
Mini Quiz Challenge
Try answering these questions within 60 seconds.
Q1. Penicillin was discovered by:
A) Alexander Fleming
B) Louis Pasteur
C) Robert Hooke
D) Edward Jenner
Q2. Antibiotics mainly act against:
A) Certain bacteria
B) All viruses
C) All fungi
D) All parasites
Q3. Vaccines are mainly used to:
A) Prevent specific infectious diseases
B) Preserve food
C) Make bread rise
D) Increase soil fertility
Q4. Unnecessary antibiotic use may lead to:
A) Antibiotic resistance
B) Better digestion
C) Faster plant growth
D) Food preservation
Q5. Which statement is correct?
A) Antibiotics and vaccines have the same function.
B) Antibiotics can generally cure viral infections.
C) Vaccination is an important method of disease prevention.
D) Antibiotics should be taken for every cold.
Exam Tips
✔ Remember the name Alexander Fleming.
✔ Learn that penicillin is an antibiotic.
✔ Understand the difference between antibiotics and vaccines.
✔ Remember that antibiotics mainly target certain bacterial infections.
✔ Do not write that antibiotics cure viral diseases.
✔ Learn the meaning of antibiotic resistance.
✔ Remember that vaccines help prevent specific infectious diseases.
✔ Understand why responsible medicine use is important.
✔ Revise the role of microorganisms in medicine.
✔ Use precise scientific language in health-related questions.
Quick Revision Notes
✔ Antibiotics: Medicines used against certain bacterial infections.
✔ Penicillin: Important antibiotic discovered by Alexander Fleming.
✔ Vaccines: Help the immune system develop protection against specific diseases.
✔ Immunity: Ability of the body to defend against particular infections.
✔ Antibiotic Resistance: Reduced effectiveness of antibiotics against resistant bacteria.
✔ Pathogens: Disease-causing microorganisms.
✔ Disease Prevention: Includes vaccination, hygiene, sanitation, and other protective measures.
✔ Responsible Medicine Use: Medicines should be used according to medical advice.
✔ Bacterial Infections: Some can be treated effectively with appropriate antibiotics.
✔ Viral Infections: Antibiotics generally do not work against viruses.
Common Mistakes Students Make
❌ Thinking antibiotics cure viral infections.
❌ Confusing vaccines with antibiotics.
❌ Thinking antibiotics should be taken whenever someone has a fever.
❌ Forgetting who discovered penicillin.
❌ Thinking antibiotic resistance means that a person’s body becomes resistant.
❌ Assuming vaccines treat every existing infection.
❌ Thinking all microorganisms are harmful.
❌ Forgetting that prevention is an important part of disease control.
Key Takeaways
✔ Microorganisms have important applications in medicine.
✔ Alexander Fleming discovered penicillin.
✔ Penicillin is an antibiotic.
✔ Antibiotics are used against certain bacterial infections.
✔ Vaccines help prevent specific infectious diseases.
✔ Antibiotics are not generally effective against viral infections.
✔ Improper antibiotic use can contribute to antibiotic resistance.
✔ Responsible use of medicines helps protect individual and public health.
FAQs
Q. Who discovered penicillin?
Answer:
Alexander Fleming discovered penicillin in 1928.
Q. What is an antibiotic?
Answer:
An antibiotic is a medicine used to treat certain bacterial infections.
Q. What is the main purpose of a vaccine?
Answer:
A vaccine helps the immune system develop protection against a specific infectious disease.
Q. Why are antibiotics not used for viral infections?
Answer:
Antibiotics act against bacteria and their processes. Viruses are different from bacteria, so antibiotics generally do not work against viral infections.
Q. What is antibiotic resistance?
Answer:
Antibiotic resistance occurs when bacteria become less susceptible to antibiotics, making some bacterial infections harder to treat.
Conclusion
Class 8 Science Chapter 2 – Microorganisms: Friend and Foe focuses on the important role of microorganisms in medicine.
Students revised antibiotics, penicillin, Alexander Fleming, vaccines, immunity, antibiotic resistance, and disease prevention.
Understanding these concepts helps students distinguish between treatment and prevention and recognise the importance of responsible medicine use.
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