Microorganisms: Friend and Foe Part 4: MCQs (Q76–Q100)
🦠 Microorganisms: Friend and Foe – MCQs for Class 8 Science
Part 4: Q76 – Q100
Q76. The first antibiotic discovered was:
A) Streptomycin
B) Penicillin
C) Tetracycline
D) Erythromycin
✅ Correct Answer: B) Penicillin
Explanation:
- A) Streptomycin – Discovered later.
- B) Penicillin – ✔ First antibiotic by Alexander Fleming (1928).
- C) Tetracycline – Later antibiotic.
- D) Erythromycin – Later antibiotic.
Q77. Which microorganism is responsible for food poisoning?
A) Penicillium
B) Salmonella
C) Yeast
D) Rhizobium
✅ Correct Answer: B) Salmonella
Explanation:
- A) Penicillium – Antibiotic producer.
- B) Salmonella – ✔ Causes food poisoning.
- C) Yeast – Fermentation, not poisoning.
- D) Rhizobium – Nitrogen fixer.
Q78. Which disease is caused by Bacillus anthracis?
A) Anthrax
B) Cholera
C) Typhoid
D) Polio
✅ Correct Answer: A) Anthrax
Explanation:
- A) Anthrax – ✔ Bacterial disease in humans and cattle.
- B) Cholera – Vibrio cholerae.
- C) Typhoid – Salmonella typhi.
- D) Polio – Virus.
Q79. The disease caused by HIV virus is:
A) Dengue
B) AIDS
C) Malaria
D) Tuberculosis
✅ Correct Answer: B) AIDS
Explanation:
- A) Dengue – Dengue virus.
- B) AIDS – ✔ HIV virus infection.
- C) Malaria – Protozoa.
- D) Tuberculosis – Bacteria.
Q80. Which of the following is an example of protozoa?
A) Lactobacillus
B) Amoeba
C) Penicillium
D) Aspergillus
✅ Correct Answer: B) Amoeba
Explanation:
- A) Lactobacillus – Bacterium.
- B) Amoeba – ✔ Protozoan.
- C) Penicillium – Fungus.
- D) Aspergillus – Fungus.
Q81. Which microorganism is used in preparation of antibiotics?
A) Algae
B) Bacteria and fungi
C) Protozoa
D) Amoeba
✅ Correct Answer: B) Bacteria and fungi
Explanation:
- A) Algae – Oxygen producers.
- B) Bacteria and fungi – ✔ Main sources of antibiotics.
- C) Protozoa – Disease-causing, not antibiotic producers.
- D) Amoeba – Protozoa.
Q82. Which microorganism causes leprosy?
A) Mycobacterium leprae
B) Salmonella typhi
C) Plasmodium
D) HIV
✅ Correct Answer: A) Mycobacterium leprae
Explanation:
- A) Mycobacterium leprae – ✔ Causes leprosy.
- B) Salmonella typhi – Typhoid.
- C) Plasmodium – Malaria.
- D) HIV – AIDS.
Q83. Which microorganism is used in production of wine?
A) Penicillium
B) Lactobacillus
C) Yeast
D) Aspergillus
✅ Correct Answer: C) Yeast
Explanation:
- A) Penicillium – Antibiotics.
- B) Lactobacillus – Curd formation.
- C) Yeast – ✔ Converts sugar into alcohol.
- D) Aspergillus – Citric acid production.
Q84. Which microorganism is responsible for kala-azar?
A) Leishmania
B) Plasmodium
C) Amoeba
D) Salmonella
✅ Correct Answer: A) Leishmania
Explanation:
- A) Leishmania – ✔ Protozoan causing kala-azar.
- B) Plasmodium – Malaria.
- C) Amoeba – Dysentery.
- D) Salmonella – Typhoid.
Q85. Which method of preservation is used in packaging chips?
A) Salting
B) Adding oil
C) Packing in nitrogen gas
D) Refrigeration
✅ Correct Answer: C) Packing in nitrogen gas
Explanation:
- A) Salting – For fish/meat.
- B) Oil – For pickles.
- C) Nitrogen gas – ✔ Prevents oxidation and spoilage in chips.
- D) Refrigeration – For perishable foods.
Q86. The microorganism used in producing insulin is:
A) Yeast
B) E. coli (engineered bacteria)
C) Rhizobium
D) Penicillium
✅ Correct Answer: B) E. coli (engineered bacteria)
Explanation:
- A) Yeast – Alcohol, not insulin.
- B) E. coli – ✔ Genetically modified to produce insulin.
- C) Rhizobium – Nitrogen fixation.
- D) Penicillium – Antibiotics.
Q87. Which microorganism is used in sewage treatment plants?
A) Protozoa
B) Bacteria
C) Fungi
D) Algae
✅ Correct Answer: B) Bacteria
Explanation:
- A) Protozoa – Not main agents.
- B) Bacteria – ✔ Decompose organic matter.
- C) Fungi – Decomposers but not main.
- D) Algae – Not sewage treatment agents.
Q88. Which microorganism was first observed by Anton van Leeuwenhoek?
A) Viruses
B) Bacteria
C) Fungi
D) Algae
✅ Correct Answer: B) Bacteria
Explanation:
- A) Viruses – Too small for early microscopes.
- B) Bacteria – ✔ First microbes seen by Leeuwenhoek.
- C) Fungi – Visible to naked eye (moulds).
- D) Algae – Some are visible.
Q89. Which microorganism is responsible for polio?
A) Bacteria
B) Virus
C) Fungi
D) Protozoa
✅ Correct Answer: B) Virus
Explanation:
- A) Bacteria – Not correct.
- B) Virus – ✔ Poliovirus causes polio.
- C) Fungi – Not correct.
- D) Protozoa – Not correct.
Q90. Which is the carrier of plague?
A) Housefly
B) Rat flea
C) Mosquito
D) Tick
✅ Correct Answer: B) Rat flea
Explanation:
- A) Housefly – Spreads cholera, diarrhea.
- B) Rat flea – ✔ Carrier of plague.
- C) Mosquito – Spreads malaria, dengue.
- D) Tick – Spreads Lyme disease.
Q91. Which microorganism is used in antibiotics production like erythromycin?
A) Streptomyces
B) Amoeba
C) Yeast
D) Blue-green algae
✅ Correct Answer: A) Streptomyces
Explanation:
- A) Streptomyces – ✔ Produces many antibiotics.
- B) Amoeba – Protozoa.
- C) Yeast – Alcohol fermentation.
- D) BGA – Nitrogen fixation.
Q92. Which microorganism is used to produce lactic acid?
A) Rhizobium
B) Lactobacillus
C) Penicillium
D) Amoeba
✅ Correct Answer: B) Lactobacillus
Explanation:
- A) Rhizobium – Nitrogen fixation.
- B) Lactobacillus – ✔ Converts lactose → lactic acid.
- C) Penicillium – Antibiotic.
- D) Amoeba – Protozoa.
Q93. Which microorganism spoils orange and bread with green patches?
A) Penicillium (mould)
B) Amoeba
C) Lactobacillus
D) Rhizobium
✅ Correct Answer: A) Penicillium (mould)
Explanation:
- A) Penicillium – ✔ Fungus that grows on bread/oranges.
- B) Amoeba – Protozoa.
- C) Lactobacillus – Converts milk into curd.
- D) Rhizobium – Nitrogen fixation.
Q94. Which microorganism causes measles?
A) Bacteria
B) Virus
C) Fungi
D) Protozoa
✅ Correct Answer: B) Virus
Explanation:
- A) Bacteria – Not measles.
- B) Virus – ✔ Measles virus.
- C) Fungi – Not measles.
- D) Protozoa – Not measles.
Q95. Which microorganism is used in making antibiotics like chloramphenicol?
A) Bacteria
B) Virus
C) Amoeba
D) Fungi
✅ Correct Answer: A) Bacteria
Explanation:
- A) Bacteria – ✔ Chloramphenicol is produced by Streptomyces.
- B) Virus – Not used.
- C) Amoeba – Not used.
- D) Fungi – Some produce antibiotics but not chloramphenicol.
Q96. The disease kala-azar is spread by:
A) Aedes mosquito
B) Sandfly
C) Housefly
D) Rat flea
✅ Correct Answer: B) Sandfly
Explanation:
- A) Aedes – Dengue.
- B) Sandfly – ✔ Spreads kala-azar.
- C) Housefly – Spreads diarrhea, cholera.
- D) Rat flea – Spreads plague.
Q97. Which microorganism is used in producing vitamin B12?
A) Algae
B) Bacteria
C) Amoeba
D) Fungi
✅ Correct Answer: B) Bacteria
Explanation:
- A) Algae – Not producers of B12.
- B) Bacteria – ✔ Certain bacteria synthesize vitamin B12.
- C) Amoeba – Not correct.
- D) Fungi – Not correct.
Q98. Which microorganism is used in single-cell protein (SCP) production?
A) Amoeba
B) Spirulina
C) Penicillium
D) Yeast
✅ Correct Answer: B) Spirulina
Explanation:
- A) Amoeba – Protozoa, not edible.
- B) Spirulina – ✔ Algae used as SCP (rich protein).
- C) Penicillium – Antibiotic.
- D) Yeast – Used in alcohol, not SCP directly.
Q99. Which disease is caused by Salmonella typhi?
A) Typhoid
B) TB
C) Cholera
D) Malaria
✅ Correct Answer: A) Typhoid
Explanation:
- A) Typhoid – ✔ Caused by Salmonella typhi.
- B) TB – Mycobacterium tuberculosis.
- C) Cholera – Vibrio cholerae.
- D) Malaria – Protozoa.
Q100. Which method kills microorganisms in milk without affecting its taste?
A) Boiling for hours
B) Pasteurization
C) Freezing
D) Salting
✅ Correct Answer: B) Pasteurization
Explanation:
- A) Boiling for hours – Changes taste.
- B) Pasteurization – ✔ Gentle heating + quick cooling kills microbes, keeps taste.
- C) Freezing – Slows microbes, doesn’t kill all.
- D) Salting – Not for milk.
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