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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 communicable diseases, disease-causing microorganisms, modes of transmission, food preservation, and prevention of diseases.
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Chapter Information
Subject: Science
Class: 8
Chapter: Microorganisms: Friend and Foe
Question Type: Multiple Choice Questions (MCQs)
Practice Set: 3
Difficulty Level: Moderate
Based On: NCERT Syllabus
Introduction
Microorganisms are found almost everywhere around us. While many microorganisms are useful, some can cause diseases in humans, animals, and plants. Disease-causing microorganisms are known as pathogens.
Some diseases can spread from an infected person to a healthy person through air, water, food, direct contact, or insects. Such diseases are called communicable diseases.
Microorganisms can also spoil food. Proper food preservation methods help prevent the growth of harmful microorganisms and keep food safe for longer periods.
This Practice Set 3 focuses on disease-causing microorganisms, communicable diseases, modes of transmission, and basic methods of disease prevention and food preservation.
What You Will Learn
✔ Disease-causing microorganisms
✔ Pathogens
✔ Communicable diseases
✔ Modes of transmission
✔ Diseases caused by bacteria and viruses
✔ Role of insects in disease transmission
✔ Prevention of communicable diseases
✔ Food spoilage
✔ Basic food preservation methods
Why This Topic Is Important
Microorganism-related diseases can affect human health and may spread rapidly from one person to another.
Knowing how diseases are transmitted helps students understand the importance of clean drinking water, hygienic food, personal cleanliness, vaccination, and protection from disease-carrying insects.
Food preservation is also important because microorganisms can multiply in food and cause spoilage. Understanding these concepts connects science with everyday health and hygiene.
5 MCQs with Answers and Useful Details
Q1. Which of the following is a communicable disease?
A) Diabetes
B) Common cold
C) High blood pressure
D) Night blindness
Answer:
B) Common cold
Useful Detail
A communicable disease is a disease that can spread from an infected person to a healthy person, either directly or indirectly.
The common cold is caused by viruses and can spread through droplets released when an infected person coughs or sneezes.
Other examples of communicable diseases include tuberculosis, measles, chickenpox, and polio.
Diseases such as diabetes and high blood pressure are not spread from person to person like communicable diseases.
Correct Answer: B) Common cold
Q2. Which disease can be transmitted through the bite of an infected female Anopheles mosquito?
A) Malaria
B) Tuberculosis
C) Cholera
D) Typhoid
Answer:
A) Malaria
Useful Detail
Malaria is caused by a protozoan parasite called Plasmodium.
The disease is transmitted through the bite of an infected female Anopheles mosquito.
The mosquito acts as a carrier or vector that transfers the disease-causing organism from one person to another.
Preventing mosquito breeding and protecting oneself from mosquito bites are important measures for reducing the spread of malaria.
Correct Answer: A) Malaria
Q3. Which disease is commonly caused by bacteria and can spread through contaminated food and water?
A) Cholera
B) Influenza
C) Measles
D) Chickenpox
Answer:
A) Cholera
Useful Detail
Cholera is a bacterial disease that can spread through contaminated food and water.
Poor sanitation and unsafe drinking water can increase the risk of cholera transmission.
Using clean drinking water, maintaining proper sanitation, washing hands, and consuming hygienically prepared food are important preventive measures.
This shows why clean water and good hygiene are essential for preventing communicable diseases.
Correct Answer: A) Cholera
Q4. Which method can help prevent the growth of microorganisms in food by removing moisture?
A) Drying
B) Adding water
C) Keeping food uncovered
D) Increasing moisture
Answer:
A) Drying
Useful Detail
Drying is a traditional method of food preservation. It removes moisture from food, making it difficult for many microorganisms to grow and multiply.
Foods such as certain fruits, vegetables, fish, and grains can be preserved by drying.
Since microorganisms generally need suitable moisture and other favourable conditions for growth, reducing moisture can help slow down food spoilage.
Correct Answer: A) Drying
Q5. Which practice is most effective for reducing the spread of many communicable diseases?
A) Sharing personal items with infected people
B) Maintaining good hygiene and sanitation
C) Leaving food uncovered
D) Drinking untreated water
Answer:
B) Maintaining good hygiene and sanitation
Useful Detail
Good personal hygiene and sanitation can reduce the spread of many communicable diseases.
Important practices include washing hands regularly, drinking safe water, keeping surroundings clean, properly disposing of waste, and maintaining food hygiene.
Depending on the disease, additional preventive measures such as vaccination, mosquito control, and avoiding close contact with infected individuals may also be important.
Correct Answer: B) Maintaining good hygiene and sanitation
Important Formulas & Concepts
Science Chapter 2 does not contain mathematical formulas. Important scientific concepts are given below.
1. Pathogens
Microorganisms that cause diseases in humans, animals, or plants are called pathogens.
2. Communicable Diseases
Diseases that can spread from an infected person to another person, directly or indirectly, are called communicable diseases.
3. Common Cold
Common cold is a viral disease that can spread through infected droplets.
4. Malaria
Malaria is caused by the protozoan Plasmodium and is transmitted through the bite of an infected female Anopheles mosquito.
5. Cholera
Cholera is a bacterial disease commonly associated with contaminated food and water.
6. Disease Vectors
Some organisms, such as mosquitoes, can carry disease-causing microorganisms or parasites from one host to another. Such carriers are called vectors.
7. Food Spoilage
Microorganisms can grow on food and cause changes in its appearance, smell, taste, and quality.
8. Drying
Drying removes moisture from food and helps prevent or slow the growth of many microorganisms.
9. Hygiene
Good personal hygiene helps reduce exposure to disease-causing microorganisms.
10. Sanitation
Proper sanitation, including safe disposal of waste and clean water supplies, helps reduce the spread of many infectious diseases.
Related Practice Questions
Q1. What is a communicable disease?
Q2. How is malaria transmitted?
Q3. Why is clean drinking water important for preventing diseases?
Q4. What is the role of mosquitoes in the transmission of malaria?
Q5. How does drying help preserve food?
Mini Quiz Challenge
Try answering these questions within 60 seconds.
Q1. Which of the following is a communicable disease?
A) Common cold
B) Diabetes
C) Obesity
D) Hypertension
Q2. Malaria is caused by:
A) Bacterium
B) Protozoan
C) Fungus
D) Alga
Q3. Malaria is transmitted by:
A) Housefly
B) Female Anopheles mosquito
C) Butterfly
D) Honeybee
Q4. Which method removes moisture from food?
A) Drying
B) Washing
C) Boiling with extra water
D) Soaking
Q5. Which practice helps prevent many communicable diseases?
A) Poor sanitation
B) Drinking unsafe water
C) Good hygiene
D) Leaving food uncovered
Exam Tips
✔ Learn the meaning of pathogen.
✔ Understand the difference between communicable and non-communicable diseases.
✔ Remember that malaria is caused by Plasmodium.
✔ Remember the role of the female Anopheles mosquito in malaria transmission.
✔ Learn examples of diseases spread through contaminated food and water.
✔ Understand why safe drinking water is important.
✔ Revise common food preservation methods.
✔ Remember that drying reduces moisture available for microbial growth.
✔ Do not assume that every disease is communicable.
✔ Link disease prevention with hygiene and sanitation.
Quick Revision Notes
✔ Pathogen: Disease-causing microorganism.
✔ Communicable Disease: Disease that can spread from one person to another directly or indirectly.
✔ Common Cold: A viral communicable disease.
✔ Malaria: Caused by Plasmodium.
✔ Anopheles Mosquito: Female Anopheles mosquito transmits malaria.
✔ Cholera: A bacterial disease associated with contaminated food and water.
✔ Food Spoilage: Microbial growth can make food unsafe or unsuitable for consumption.
✔ Drying: Removes moisture and helps preserve food.
✔ Hygiene: Clean habits that help reduce disease transmission.
✔ Sanitation: Practices that help maintain clean and safe surroundings.
Common Mistakes Students Make
❌ Thinking all diseases are communicable.
❌ Confusing the organism causing malaria with the mosquito that transmits it.
❌ Thinking mosquitoes cause malaria directly rather than transmitting Plasmodium.
❌ Assuming contaminated food and water are always safe if they look clean.
❌ Forgetting that drying helps reduce moisture available to microorganisms.
❌ Thinking hygiene is important only for personal cleanliness.
❌ Confusing pathogens with vectors.
❌ Believing that every microorganism present in food is harmful.
Key Takeaways
✔ Some microorganisms cause diseases.
✔ Disease-causing microorganisms are called pathogens.
✔ Communicable diseases can spread from one person to another.
✔ Malaria is caused by Plasmodium.
✔ Female Anopheles mosquitoes transmit malaria.
✔ Contaminated food and water can transmit certain diseases.
✔ Food can spoil because of microbial growth.
✔ Drying helps preserve food by reducing moisture.
✔ Hygiene and sanitation are important for disease prevention.
FAQs
Q. What are pathogens?
Answer:
Pathogens are microorganisms that cause diseases in humans, animals, or plants.
Q. What is a communicable disease?
Answer:
A communicable disease is a disease that can spread from an infected person to another person, either directly or indirectly.
Q. How is malaria transmitted?
Answer:
Malaria is transmitted through the bite of an infected female Anopheles mosquito. The disease is caused by the protozoan parasite Plasmodium.
Q. How can contaminated water cause disease?
Answer:
Contaminated water may contain disease-causing microorganisms. Drinking such water can allow pathogens to enter the body and cause infections such as cholera.
Q. How does drying preserve food?
Answer:
Drying removes moisture from food. Reduced moisture makes it difficult for many microorganisms to grow and multiply, thereby helping to prevent spoilage.
Conclusion
Class 8 Science Chapter 2 – Microorganisms: Friend and Foe Practice Set 3 focuses on the harmful effects of microorganisms and the prevention of diseases.
Students revised important concepts such as pathogens, communicable diseases, malaria, Plasmodium, disease vectors, contaminated food and water, food spoilage, drying, hygiene, and sanitation.
These concepts are important for understanding how microorganisms affect human health and how proper hygiene and food preservation can reduce their harmful effects.
Related links
- Class 8 Social Science Chapter 1 How, When and Where part-14
- Class 8 Maths Chapter 4 Practical Geometry part-9
- Class 8 Science Chapter 2 Microorganisms Friend and Foe PART-2
- Class 8 Maths Chapter 4 Practical Geometry PART-8
- Class 8 English Chapter 1 Another Chance part-10
- Class 8 Social Science Chapter 1 How, When and Where part-13
- Class 8 Science Chapter 2 Microorganisms Friend and Foe part-1
- 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
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