Microorganisms: Friend and Foe Part 3: MCQs (Q51–Q75)
🦠 Microorganisms: Friend and Foe – MCQs for Class 8 Science
Part 3: Q51 – Q75
Q51. Which of the following diseases is caused by a protozoan?
A) Cholera
B) Typhoid
C) Malaria
D) Tuberculosis
✅ Correct Answer: C) Malaria
Explanation:
- A) Cholera – Bacteria (Vibrio cholerae).
- B) Typhoid – Bacteria (Salmonella typhi).
- C) Malaria – ✔ Protozoan parasite (Plasmodium).
- D) Tuberculosis – Bacteria.
Q52. The carrier of dengue virus is:
A) Female Anopheles mosquito
B) Male mosquito
C) Aedes aegypti mosquito
D) Housefly
✅ Correct Answer: C) Aedes aegypti mosquito
Explanation:
- A) Female Anopheles – Spreads malaria.
- B) Male mosquito – Do not spread disease.
- C) Aedes aegypti – ✔ Spreads dengue virus.
- D) Housefly – Spreads diarrheal diseases.
Q53. Which microorganism is used in nitrogen fixation?
A) Amoeba
B) Rhizobium
C) Yeast
D) Penicillium
✅ Correct Answer: B) Rhizobium
Explanation:
- A) Amoeba – Protozoa, no role in nitrogen fixation.
- B) Rhizobium – ✔ Nitrogen-fixing bacterium in legume roots.
- C) Yeast – Used in fermentation.
- D) Penicillium – Produces antibiotic.
Q54. Which disease is NOT caused by bacteria?
A) Typhoid
B) Tuberculosis
C) Cholera
D) Hepatitis
✅ Correct Answer: D) Hepatitis
Explanation:
- A) Typhoid – Bacteria.
- B) Tuberculosis – Bacteria.
- C) Cholera – Bacteria.
- D) Hepatitis – ✔ Viral infection.
Q55. Which of the following is a viral disease?
A) Polio
B) Anthrax
C) Dysentery
D) Ringworm
✅ Correct Answer: A) Polio
Explanation:
- A) Polio – ✔ Viral infection.
- B) Anthrax – Bacterial disease.
- C) Dysentery – Amoeba/bacteria.
- D) Ringworm – Fungal disease.
Q56. Which microorganism is used in bread making?
A) Rhizobium
B) Yeast
C) Amoeba
D) Penicillium
✅ Correct Answer: B) Yeast
Explanation:
- A) Rhizobium – Nitrogen fixation.
- B) Yeast – ✔ Produces CO₂ → makes bread fluffy.
- C) Amoeba – Protozoa.
- D) Penicillium – Produces antibiotic.
Q57. The microorganism that spoils pickles and jams is usually:
A) Fungi
B) Bacteria
C) Virus
D) Protozoa
✅ Correct Answer: B) Bacteria
Explanation:
- A) Fungi – Can grow but less common in pickles.
- B) Bacteria – ✔ Cause spoilage due to moisture.
- C) Virus – Do not spoil food.
- D) Protozoa – Not involved in spoilage.
Q58. The process of preserving food by heating and rapid cooling is called:
A) Salting
B) Pasteurization
C) Pickling
D) Refrigeration
✅ Correct Answer: B) Pasteurization
Explanation:
- A) Salting – Adding salt.
- B) Pasteurization – ✔ Heating at 70°C & cooling quickly.
- C) Pickling – Using oil/vinegar.
- D) Refrigeration – Cooling only.
Q59. Which disease is caused by protozoan Entamoeba histolytica?
A) Typhoid
B) Amoebic dysentery
C) Tuberculosis
D) Influenza
✅ Correct Answer: B) Amoebic dysentery
Explanation:
- A) Typhoid – Bacteria.
- B) Amoebic dysentery – ✔ Protozoan infection.
- C) Tuberculosis – Bacteria.
- D) Influenza – Virus.
Q60. Which microorganism is used to make curd?
A) Yeast
B) Lactobacillus
C) Amoeba
D) Rhizobium
✅ Correct Answer: B) Lactobacillus
Explanation:
- A) Yeast – Alcohol fermentation.
- B) Lactobacillus – ✔ Converts lactose → lactic acid.
- C) Amoeba – Protozoa.
- D) Rhizobium – Nitrogen fixation.
Q61. The carrier of malaria is:
A) Culex mosquito
B) Aedes mosquito
C) Female Anopheles mosquito
D) Sandfly
✅ Correct Answer: C) Female Anopheles mosquito
Explanation:
- A) Culex – Filariasis.
- B) Aedes – Dengue.
- C) Female Anopheles – ✔ Spreads malaria.
- D) Sandfly – Kala-azar.
Q62. Which microorganism produces oxygen in aquatic environments?
A) Amoeba
B) Blue-green algae
C) Fungi
D) Bacteria
✅ Correct Answer: B) Blue-green algae
Explanation:
- A) Amoeba – Protozoa, not photosynthetic.
- B) Blue-green algae – ✔ Photosynthetic and oxygen producers.
- C) Fungi – Decomposers.
- D) Bacteria – Some are decomposers.
Q63. Which disease is spread by contaminated water?
A) Cholera
B) Malaria
C) Dengue
D) TB
✅ Correct Answer: A) Cholera
Explanation:
- A) Cholera – ✔ Water-borne bacterial disease.
- B) Malaria – Spread by mosquito.
- C) Dengue – Mosquito-borne virus.
- D) TB – Air-borne.
Q64. Which microorganism is used in making antibiotics?
A) Amoeba
B) Penicillium
C) Algae
D) Paramecium
✅ Correct Answer: B) Penicillium
Explanation:
- A) Amoeba – No role.
- B) Penicillium – ✔ Produces penicillin antibiotic.
- C) Algae – Photosynthetic.
- D) Paramecium – Protozoa.
Q65. The bacterium used to make vinegar is:
A) Acetobacter
B) Rhizobium
C) Lactobacillus
D) Yeast
✅ Correct Answer: A) Acetobacter
Explanation:
- A) Acetobacter – ✔ Alcohol → acetic acid.
- B) Rhizobium – Nitrogen fixation.
- C) Lactobacillus – Curd formation.
- D) Yeast – Alcohol fermentation.
Q66. Which is NOT a harmful effect of microorganisms?
A) Food spoilage
B) Causing diseases
C) Decomposition of dead bodies
D) Crop damage
✅ Correct Answer: C) Decomposition of dead bodies
Explanation:
- A) Food spoilage – Harmful.
- B) Diseases – Harmful.
- C) Decomposition – ✔ Helpful, recycles nutrients.
- D) Crop damage – Harmful.
Q67. Which microorganism is used in the production of vaccines?
A) Weakened microbes
B) Fungi
C) Protozoa
D) Amoeba
✅ Correct Answer: A) Weakened microbes
Explanation:
- A) Weakened microbes – ✔ Vaccines contain weakened or dead pathogens.
- B) Fungi – Not directly.
- C) Protozoa – Not used in vaccines.
- D) Amoeba – Not used.
Q68. The microorganism used to produce alcohol is:
A) Penicillium
B) Yeast
C) Rhizobium
D) Amoeba
✅ Correct Answer: B) Yeast
Explanation:
- A) Penicillium – Antibiotic.
- B) Yeast – ✔ Fermentation → alcohol.
- C) Rhizobium – Nitrogen fixation.
- D) Amoeba – Protozoa.
Q69. Which microorganism is unicellular fungus?
A) Yeast
B) Rhizobium
C) Mould
D) Algae
✅ Correct Answer: A) Yeast
Explanation:
- A) Yeast – ✔ Unicellular fungus.
- B) Rhizobium – Bacterium.
- C) Mould – Multicellular fungi.
- D) Algae – Photosynthetic, not fungus.
Q70. Which disease is caused by bacteria?
A) AIDS
B) Malaria
C) Typhoid
D) Polio
✅ Correct Answer: C) Typhoid
Explanation:
- A) AIDS – Virus (HIV).
- B) Malaria – Protozoa.
- C) Typhoid – ✔ Salmonella typhi.
- D) Polio – Virus.
Q71. The fungus used in production of citric acid is:
A) Yeast
B) Aspergillus
C) Penicillium
D) Mould
✅ Correct Answer: B) Aspergillus
Explanation:
- A) Yeast – Fermentation.
- B) Aspergillus – ✔ Produces citric acid.
- C) Penicillium – Antibiotic.
- D) Mould – Spoils bread.
Q72. Which microorganism is used in cheese production?
A) Penicillium
B) Rhizobium
C) Amoeba
D) Blue-green algae
✅ Correct Answer: A) Penicillium
Explanation:
- A) Penicillium – ✔ Used in ripening of cheese.
- B) Rhizobium – Nitrogen fixation.
- C) Amoeba – Protozoa.
- D) BGA – Nitrogen fixation.
Q73. Which microorganism is used in preparation of antibiotics?
A) Bacteria
B) Fungi
C) Both bacteria and fungi
D) Protozoa
✅ Correct Answer: C) Both bacteria and fungi
Explanation:
- A) Bacteria – Yes, but not only.
- B) Fungi – Yes, but not only.
- C) Both bacteria and fungi – ✔ Major sources of antibiotics.
- D) Protozoa – Not antibiotic producers.
Q74. Which of the following is NOT caused by microorganisms?
A) Diabetes
B) Cholera
C) Tuberculosis
D) Malaria
✅ Correct Answer: A) Diabetes
Explanation:
- A) Diabetes – ✔ Lifestyle/genetic disease, not microbial.
- B) Cholera – Bacteria.
- C) TB – Bacteria.
- D) Malaria – Protozoa.
Q75. Which microorganism causes influenza?
A) Bacteria
B) Virus
C) Fungi
D) Protozoa
✅ Correct Answer: B) Virus
Explanation:
- A) Bacteria – Cause TB, typhoid.
- B) Virus – ✔ Influenza virus causes flu.
- C) Fungi – Cause ringworm.
- D) Protozoa – Cause malaria.
Microorganisms Class 8 MCQs, CBSE Class 8 Science MCQs, NCERT Class 8 Microorganisms, Online Learning Science MCQs, Important MCQs Class 8, cbse class 8 science microorganisms mcqs with answers, ncert class 8 microorganisms friend and foe objective questions, important mcqs for class 8 microorganisms board exams, online learning mcqs for class 8 science microorganisms, chapter wise mcqs for class 8 science microorganisms friend and foe