1. Which of the following is a mutualistic interaction between microorganisms and plants?
A. Parasitism
B. Commensalism
C. Mycorrhizae
D. Amensalism
Answer: C. Mycorrhizae
2. What term describes the relationship where one organism benefits, and the other is neither harmed nor benefited?
A. Symbiosis
B. Commensalism
C. Competition
D. Parasitism
Answer: B. Commensalism
3. In which process do bacteria convert atmospheric nitrogen into a form usable by plants?
A. Nitrification
B. Denitrification
C. Nitrogen fixation
D. Ammonification
Answer: C. Nitrogen fixation
4. Which group of microorganisms primarily drives the process of decomposition in soil?
A. Viruses
B. Fungi and bacteria
C. Protozoa
D. Cyanobacteria
Answer: B. Fungi and bacteria
5. Which microorganism is commonly used as a biofertilizer?
A. Escherichia coli
B. Rhizobium
C. Plasmodium
D. Candida albicans
Answer: B. Rhizobium
6. What is the primary role of denitrifying bacteria in the nitrogen cycle?
A. Convert ammonia to nitrite
B. Convert nitrate to nitrogen gas
C. Fix atmospheric nitrogen
D. Decompose organic matter
Answer: B. Convert nitrate to nitrogen gas
7. The process by which microorganisms degrade organic pollutants is called:
A. Bioremediation
B. Biomagnification
C. Bioaugmentation
D. Bioaccumulation
Answer: A. Bioremediation
8. Which of the following bacteria is involved in nitrification?
A. Azotobacter
B. Nitrosomonas
C. Clostridium
D. Methanobacterium
Answer: B. Nitrosomonas
9. What is the relationship between a pathogen and its host?
A. Commensalism
B. Parasitism
C. Mutualism
D. Amensalism
Answer: B. Parasitism
10. Lichens represent a symbiotic relationship between:
A. Algae and fungi
B. Bacteria and fungi
C. Fungi and plants
D. Algae and protozoa
Answer: A. Algae and fungi
11. Which of the following microorganisms participates in methane production?
A. Cyanobacteria
B. Methanogens
C. Rhizobacteria
D. Halophiles
Answer: B. Methanogens
12. The term for microbes competing for the same resource is:
A. Symbiosis
B. Parasitism
C. Competition
D. Mutualism
Answer: C. Competition
13. What is an example of microbial commensalism?
A. Algae and fungi in lichens
B. Rhizobium in leguminous plants
C. Escherichia coli in the human gut
D. Streptococcus on human skin
Answer: D. Streptococcus on human skin
14. Which gas is a major product of anaerobic respiration in wetlands?
A. Oxygen
B. Carbon dioxide
C. Methane
D. Nitrous oxide
Answer: C. Methane
15. What is the primary role of mycorrhizal fungi in plant-microbe interactions?
A. Nitrogen fixation
B. Phosphorus uptake
C. Decomposition of cellulose
D. Pathogenesis
Answer: B. Phosphorus uptake
16. In the sulfur cycle, which bacteria convert sulfates into hydrogen sulfide?
A. Sulfate-reducing bacteria
B. Nitrifying bacteria
C. Methanogens
D. Denitrifying bacteria
Answer: A. Sulfate-reducing bacteria
17. Which microorganism helps in the production of bioethanol?
A. Saccharomyces cerevisiae
B. Clostridium difficile
C. Pseudomonas aeruginosa
D. Bacillus subtilis
Answer: A. Saccharomyces cerevisiae
18. The symbiotic relationship between Rhizobium and leguminous plants occurs in:
A. Leaves
B. Roots
C. Stem
D. Flowers
Answer: B. Roots
19. Microorganisms that derive energy from inorganic compounds are called:
A. Phototrophs
B. Chemotrophs
C. Autotrophs
D. Heterotrophs
Answer: B. Chemotrophs
20. Which of the following microbes produces antibiotics?
A. Penicillium
B. Vibrio
C. Salmonella
D. Clostridium
Answer: A. Penicillium
21. An example of amensalism is:
A. Antibiotic production by fungi
B. Nitrogen fixation by Rhizobium
C. Decomposition by bacteria
D. Symbiosis in lichens
Answer: A. Antibiotic production by fungi
22. Which of the following microorganisms is used in sewage treatment?
A. Bacillus anthracis
B. Zoogloea ramigera
C. Plasmodium vivax
D. Mycobacterium tuberculosis
Answer: B. Zoogloea ramigera
23. What role do cyanobacteria play in aquatic ecosystems?
A. Nitrogen fixation
B. Pathogenesis
C. Methane production
D. Sulfur reduction
Answer: A. Nitrogen fixation
24. Microorganisms that require oxygen for survival are called:
A. Obligate anaerobes
B. Facultative anaerobes
C. Obligate aerobes
D. Microaerophiles
Answer: C. Obligate aerobes
25. Which bacterium is involved in the fermentation of dairy products?
A. Lactobacillus
B. Staphylococcus
C. Escherichia coli
D. Clostridium tetani
Answer: A. Lactobacillus
26. What is the main function of soil microbes in the carbon cycle?
A. Carbon sequestration
B. Methane production
C. Photosynthesis
D. Decomposition
Answer: D. Decomposition
27. Endosymbiosis is best illustrated by the relationship between:
A. Coral and algae
B. Amoeba and bacteria
C. Plants and nitrogen-fixing bacteria
D. Mitochondria and eukaryotic cells
Answer: D. Mitochondria and eukaryotic cells
28. Which microorganism is used in the production of vinegar?
A. Acetobacter
B. Rhizobium
C. Methanogens
D. Clostridium
Answer: A. Acetobacter
29. What role do fungi play in nutrient cycling?
A. Methane production
B. Photosynthesis
C. Decomposition
D. Nitrogen fixation
Answer: C. Decomposition
30. The term for microorganisms that grow in extreme environments is:
A. Mesophiles
B. Extremophiles
C. Psychrophiles
D. Thermophiles
Answer: B. Extremophiles
