NCERT BOOK CLASS 12TH BIOLOGY MCQ
Chapter 8 : Microbes in Human Welfare
Important MCQs with Answers
1. Which of the following microorganisms is useful in making curd?
a) Lactobacillus
b) Saccharomyces
c) Penicillium
d) Rhizobium
Answer: a) Lactobacillus
2. The bacterium Streptococcus is used in the production of?
a) Antibiotic
b) Cheese
c) Ethanol
d) Biogas
Answer: b) Cheese
3. Which microorganism fixes nitrogen in soil?
a) Rhizobium
b) Lactobacillus
c) Penicillium
d) Aspergillus
Answer: a) Rhizobium
4. Which microbes play the main role in biogas production?
a) Methanogens
b) Yeast
c) Cyanobacteria
d) Virus
Answer: a) Methanogens
5. Who discovered penicillin?
a) Robert Koch
b) Alexander Fleming
c) Louis Pasteur
d) Edward Jenner
Answer: b) Alexander Fleming
6. Which microorganism is used in citric acid production?
a) Aspergillus niger
b) Saccharomyces cerevisiae
c) Lactobacillus
d) Clostridium
Answer: a) Aspergillus niger
7. Which antibiotic is obtained from fungi?
a) Tetracycline
b) Streptomycin
c) Penicillin
d) Erythromycin
Answer: c) Penicillin
8. The breakdown of organic matter by microbes is called?
a) Nitrogen fixation
b) Decomposition
c) Photosynthesis
d) Fermentation
Answer: b) Decomposition
9. Which microorganism is used in bread making?
a) Saccharomyces cerevisiae
b) Lactobacillus
c) Rhizobium
d) Aspergillus
Answer: a) Saccharomyces cerevisiae
10. Which microorganism causes malaria?
a) Plasmodium
b) Trypanosoma
c) Leishmania
d) Entamoeba
Answer: a) Plasmodium
11. What is the use of microbes in bioreactors?
a) Food preservation
b) Industrial products
c) Biofertilizers
d) Biocontrol
Answer: b) Industrial products
12. Which microorganism improves soil fertility?
a) Cyanobacteria
b) Virus
c) Protozoa
d) Yeast
Answer: a) Cyanobacteria
13. Which microorganism is used in ethanol production?
a) Saccharomyces cerevisiae
b) Lactobacillus
c) Penicillium
d) Aspergillus
Answer: a) Saccharomyces cerevisiae
14. Which microorganism is used in biocontrol?
a) Bacillus thuringiensis
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Bacillus thuringiensis
15. Which microorganism produces antibiotics?
a) Streptomyces
b) Yeast
c) Virus
d) Protozoa
Answer: a) Streptomyces
16. Which microorganism is used in wine production?
a) Saccharomyces cerevisiae
b) Lactobacillus
c) Penicillium
d) Aspergillus
Answer: a) Saccharomyces cerevisiae
17. Which microorganism acts as a biofertilizer?
a) Rhizobium
b) Lactobacillus
c) Penicillium
d) Aspergillus
Answer: a) Rhizobium
18. Which microorganism is used in sewage treatment?
a) Methanogens
b) Yeast
c) Cyanobacteria
d) Virus
Answer: a) Methanogens
19. Which microorganism causes plant diseases?
a) Bacteria
b) Fungi
c) Virus
d) All of the above
Answer: d) All of the above
20. Which microorganism works as a probiotic?
a) Lactobacillus
b) Saccharomyces
c) Penicillium
d) Rhizobium
Answer: a) Lactobacillus
21. Which microorganism is found in the human gut and aids digestion?
a) E. coli
b) Lactobacillus
c) Streptococcus
d) All of the above
Answer: d) All of the above
22. Which microorganism helps in plastic degradation?
a) Penicillium
b) Pseudomonas
c) Aspergillus
d) Cyanobacteria
Answer: b) Pseudomonas
23. Which microorganism helps solubilize phosphate in soil?
a) Bacillus
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Bacillus
24. Which microorganism acts as a bio-pesticide?
a) Bacillus thuringiensis
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Bacillus thuringiensis
25. Which microorganism converts milk into curd?
a) Lactobacillus
b) Saccharomyces
c) Penicillium
d) Rhizobium
Answer: a) Lactobacillus
26. Which microorganism is used in bioplastic production?
a) Bacillus
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Bacillus
27. Which microorganism is used in biofuel production?
a) Saccharomyces cerevisiae
b) Lactobacillus
c) Penicillium
d) Aspergillus
Answer: a) Saccharomyces cerevisiae
28. Which microorganism decomposes organic waste in soil?
a) Bacteria
b) Fungi
c) Protozoa
d) All of the above
Answer: d) All of the above
29. Which microorganism synthesizes vitamins in the human body?
a) E. coli
b) Lactobacillus
c) Streptococcus
d) All of the above
Answer: d) All of the above
30. Which microorganism plays a key role in the nitrogen cycle?
a) Rhizobium
b) Nitrosomonas
c) Nitrobacter
d) All of the above
Answer: d) All of the above
31. Which microorganism forms root nodules in plants?
a) Rhizobium
b) Azotobacter
c) Cyanobacteria
d) Bacillus
Answer: a) Rhizobium
32. Which microorganism converts nitrate to nitrogen gas?
a) Denitrifying bacteria
b) Nitrosomonas
c) Nitrobacter
d) Rhizobium
Answer: a) Denitrifying bacteria
33. Which microorganism produces streptomycin?
a) Streptomyces griseus
b) Penicillium notatum
c) Bacillus subtilis
d) Aspergillus flavus
Answer: a) Streptomyces griseus
34. Which microorganism produces ammonia in soil?
a) Ammonifying bacteria
b) Nitrosomonas
c) Nitrobacter
d) Rhizobium
Answer: a) Ammonifying bacteria
35. Which microorganism helps in vermicompost production?
a) Earthworms and microbes
b) Only fungi
c) Only bacteria
d) Only protozoa
Answer: a) Earthworms and microbes
36. Which microorganism is primarily responsible for gobar gas production?
a) Methanogenic archaea
b) Yeast
c) Lactobacillus
d) Cyanobacteria
Answer: a) Methanogenic archaea
37. Which microorganism synthesizes vitamin K in the human gut?
a) E. coli
b) Lactobacillus
c) Streptococcus
d) Pseudomonas
Answer: a) E. coli
38. Which microorganism acts as a biofertilizer?
a) Mycorrhiza
b) Penicillium
c) Aspergillus
d) Pseudomonas
Answer: a) Mycorrhiza
39. Which microorganism is used in biological control?
a) Trichoderma
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Trichoderma
40. Which microorganism produces tetracycline?
a) Streptomyces
b) Penicillium
c) Bacillus
d) Aspergillus
Answer: a) Streptomyces
41. Which microorganism plays a key role in the sulfur cycle?
a) Thiobacillus
b) Rhizobium
c) Nitrosomonas
d) Azotobacter
Answer: a) Thiobacillus
42. Which microorganism is used in biowaste management?
a) Methanogens
b) Yeast
c) Lactobacillus
d) Cyanobacteria
Answer: a) Methanogens
43. Which microorganism acts as a probiotic in the human gut?
a) Bifidobacterium
b) Pseudomonas
c) Streptococcus
d) Clostridium
Answer: a) Bifidobacterium
44. Which microorganism helps solubilize phosphate in soil?
a) Bacillus megaterium
b) Rhizobium
c) Nitrosomonas
d) Azotobacter
Answer: a) Bacillus megaterium
45. Which microorganism acts as a bio-pesticide?
a) Beauveria bassiana
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Beauveria bassiana
46. Which microorganism converts nitrite to nitrate?
a) Nitrobacter
b) Nitrosomonas
c) Rhizobium
d) Azotobacter
Answer: a) Nitrobacter
47. Which microorganism converts ammonia to nitrite?
a) Nitrosomonas
b) Nitrobacter
c) Rhizobium
d) Azotobacter
Answer: a) Nitrosomonas
48. Which microorganism helps in humus formation?
a) Decomposer bacteria and fungi
b) Yeast
c) Protozoa
d) Algae
Answer: a) Decomposer bacteria and fungi
49. Which microorganism produces digestive enzymes in the human gut?
a) Lactobacillus
b) E. coli
c) Bifidobacterium
d) All of the above
Answer: d) All of the above
50. Which microorganism is used in bioremediation?
a) Pseudomonas putida
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Pseudomonas putida
51. Which microorganism completes the nitrogen cycle?
a) Nitrosomonas
b) Nitrobacter
c) Rhizobium
d) All of the above
Answer: d) All of the above
52. Which microorganism produces ethanol in fermentation?
a) Saccharomyces cerevisiae
b) Lactobacillus
c) Penicillium
d) Aspergillus
Answer: a) Saccharomyces cerevisiae
53. Bacillus thuringiensis is used as?
a) Bio-pesticide
b) Biofertilizer
c) Antibiotic
d) Probiotic
Answer: a) Bio-pesticide
54. Which microorganism synthesizes vitamin B12 in the human gut?
a) E. coli
b) Lactobacillus
c) Streptococcus
d) Pseudomonas
Answer: a) E. coli
55. The main gas in gobar gas is?
a) Methane
b) Carbon dioxide
c) Hydrogen
d) Nitrogen
Answer: a) Methane
56. Which microorganism solubilizes phosphorus in soil?
a) Bacillus megaterium
b) Rhizobium
c) Nitrosomonas
d) Azotobacter
Answer: a) Bacillus megaterium
57. Which microorganism acts as a biofertilizer?
a) Azospirillum
b) Penicillium
c) Aspergillus
d) Pseudomonas
Answer: a) Azospirillum
58. Which microorganism helps in plastic degradation?
a) Pseudomonas putida
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Pseudomonas putida
59. Which microorganism oxidizes sulfur in soil?
a) Thiobacillus
b) Rhizobium
c) Nitrosomonas
d) Azotobacter
Answer: a) Thiobacillus
60. Which microorganism is used in biocontrol?
a) Trichoderma
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Trichoderma
61. Which microorganism aids digestion in the human gut?
a) Lactobacillus
b) Pseudomonas
c) Streptococcus
d) Clostridium
Answer: a) Lactobacillus
62. Which microorganism converts nitrite to nitrate?
a) Nitrobacter
b) Nitrosomonas
c) Rhizobium
d) Azotobacter
Answer: a) Nitrobacter
63. Which microorganism converts ammonia to nitrite?
a) Nitrosomonas
b) Nitrobacter
c) Rhizobium
d) Azotobacter
Answer: a) Nitrosomonas
64. Which microorganism helps in vermicompost production?
a) Earthworms and microbes
b) Only fungi
c) Only bacteria
d) Only protozoa
Answer: a) Earthworms and microbes
65. Which microorganism is used in bioremediation?
a) Pseudomonas putida
b) Rhizobium
c) Lactobacillus
d) Cyanobacteria
Answer: a) Pseudomonas putida
66. Which microorganism helps in humus formation?
a) Decomposer bacteria and fungi
b) Yeast
c) Protozoa
d) Algae
Answer: a) Decomposer bacteria and fungi
67. Which microorganism produces digestive enzymes in the human gut?
a) Lactobacillus
b) E. coli
c) Bifidobacterium
d) All of the above
Answer: d) All of the above
68. Which microorganism is used in biofuel production?
a) Saccharomyces cerevisiae
b) Lactobacillus
c) Penicillium
d) Aspergillus
Answer: a) Saccharomyces cerevisiae
69. Which microorganism decomposes organic waste in soil?
a) Bacteria
b) Fungi
c) Protozoa
d) All of the above
Answer: d) All of the above
70. Which microorganism synthesizes vitamins in the human body?
a) E. coli
b) Lactobacillus
c) Streptococcus
d) All of the above
Answer: d) All of the above
71. Which microorganism plays a key role in the nitrogen cycle?
a) Rhizobium
b) Nitrosomonas
c) Nitrobacter
d) All of the above
Answer: d) All of the above
72. Which microorganism forms root nodules in plants?
a) Rhizobium
b) Azotobacter
c) Cyanobacteria
d) Bacillus
Answer: a) Rhizobium
73. Which microorganism converts nitrate to nitrogen gas?
a) Denitrifying bacteria
b) Nitrosomonas
c) Nitrobacter
d) Rhizobium
Answer: a) Denitrifying bacteria
74. Which microorganism produces streptomycin?
a) Streptomyces griseus
b) Penicillium notatum
c) Bacillus subtilis
d) Aspergillus flavus
Answer: a) Streptomyces griseus
75. Which microorganism produces ammonia in soil?
a) Ammonifying bacteria
b) Nitrosomonas
c) Nitrobacter
d) Rhizobium
Answer: a) Ammonifying bacteria