TRB PG Assistant - Microbiology - soil microbiology, soil microbes, N₂ fixation and biogeochemical cycles, food and water microbiology, microbial flora of fresh and spoiled foods, industrial microbiology - microbial applications in manufacture of alcohols, single cell protein, organic acids Online Test (MCQ Quiz)

1. Which of the following is a primary role of soil microorganisms in the ecosystem?

A) Increasing soil salinity B) Decomposition of organic matter C) Formation of heavy metal deposits D) Decreasing soil aeration

2. What is the main function of nitrogen-fixing bacteria in the soil?

A) Converting atmospheric nitrogen into ammonia B) Breaking down complex carbohydrates C) Producing plant growth hormones D) Increasing soil pH

3. Which type of microorganism is primarily responsible for nitrification in the soil?

A) Fungi B) Bacteria C) Viruses D) Archaea

4. The process by which nitrates are reduced to gaseous nitrogen compounds is called:

A) Nitrification B) Ammonification C) Denitrification D) Nitrogen fixation

5. Which element's cycle involves the conversion between organic and inorganic forms through microbial activity?

A) Oxygen B) Hydrogen C) Carbon D) Silicon

6. Rhizobium bacteria form symbiotic relationships with the roots of which type of plants?

A) Grasses B) Ferns C) Legumes D) Conifers

7. What is the primary role of decomposers in the carbon cycle?

A) Fixing atmospheric CO2 B) Releasing CO2 through respiration C) Producing methane in anaerobic conditions D) Converting organic carbon to inorganic carbon

8. Which of the following is a key process in the sulfur cycle driven by microorganisms?

A) Photosynthesis B) Respiration C) Sulfate reduction D) Nitrogen assimilation

9. The conversion of organic phosphorus into inorganic phosphate by microorganisms is known as:

A) Phosphorylation B) Mineralization C) Assimilation D) Fixation

10. Which microbial process is crucial for the removal of excess phosphate from aquatic ecosystems?

A) Nitrification B) Denitrification C) Phosphate solubilization D) Phosphate precipitation

11. What is the main concern regarding microbial contamination of drinking water?

A) Algal blooms B) Pathogenic bacteria and viruses C) Increased dissolved oxygen D) Nutrient enrichment

12. Which bacterium is commonly used as an indicator of fecal contamination in water?

A) Escherichia coli B) Staphylococcus aureus C) Lactobacillus acidophilus D) Bacillus subtilis

13. The process of microbial degradation of organic matter in water bodies, leading to oxygen depletion, is called:

A) Eutrophication B) Bioluminescence C) Bioremediation D) Biochemical Oxygen Demand (BOD)

14. Which of the following is a common spoilage organism in milk products?

A) Saccharomyces cerevisiae B) Penicillium roqueforti C) Lactobacillus species D) Pseudomonas fluorescens

15. What microbial activity causes the souring of milk?

A) Production of alcohol B) Fermentation of lactose to lactic acid C) Breakdown of proteins into amino acids D) Production of carbon dioxide

16. Which microorganism is primarily responsible for the fermentation of grapes into wine?

A) Acetobacter B) Saccharomyces cerevisiae C) Lactobacillus D) Penicillium

17. In bread making, yeast primarily produces which gas to cause leavening?

A) Oxygen B) Nitrogen C) Carbon dioxide D) Hydrogen

18. Which industrial application involves using microorganisms to produce edible biomass?

A) Alcohol production B) Enzyme production C) Single Cell Protein (SCP) D) Antibiotic production

19. What is the main type of microorganism used in the production of antibiotics like penicillin?

A) Bacteria B) Viruses C) Fungi D) Protozoa

20. Which organic acid is commonly produced industrially using the fermentation of Aspergillus niger?

A) Lactic acid B) Acetic acid C) Citric acid D) Formic acid

21. The process of converting sugars into ethanol by yeast is known as:

A) Respiration B) Fermentation C) Oxidation D) Reduction

22. Which microorganism is essential for the production of yogurt?

A) Saccharomyces cerevisiae B) Lactobacillus bulgaricus and Streptococcus thermophilus C) Penicillium camemberti D) Escherichia coli

23. What is the role of Acetobacter in vinegar production?

A) Fermenting sugars to alcohol B) Oxidizing alcohol to acetic acid C) Producing lactic acid D) Breaking down proteins

24. Which of the following is a major spoilage microorganism found on fresh fruits and vegetables?

A) Rhizobium B) Azotobacter C) Botrytis D) Nitrosomonas

25. The 'bloat' in cattle is often associated with excessive production of which gas by rumen microbes?

A) Ammonia B) Methane C) Hydrogen sulfide D) Carbon monoxide

26. Which process converts atmospheric nitrogen into ammonia, making it available for plants?

A) Nitrification B) Denitrification C) Nitrogen fixation D) Ammonification

27. What is the primary function of mycorrhizal fungi in soil?

A) Nitrogen fixation B) Decomposition of dead organic matter C) Enhancing nutrient uptake by plants (e.g., phosphorus) D) Producing toxins harmful to plants

28. Which microbial group is responsible for the decomposition of cellulose in soil?

A) Nitrobacter B) Cellulolytic bacteria and fungi C) Rhizobium D) Myxobacteria

29. The process of converting amino acids back into ammonia by microorganisms is called:

A) Nitrification B) Nitrogen fixation C) Denitrification D) Ammonification

30. Which type of microorganism is often involved in the spoilage of canned foods?

A) Aerobic bacteria B) Yeast C) Anaerobic spore-forming bacteria D) Lactic acid bacteria

31. The biological oxidation of methane by certain microorganisms is part of which biogeochemical cycle?

A) Nitrogen cycle B) Sulfur cycle C) Carbon cycle D) Phosphorus cycle

32. Which microorganism is a key producer of enzymes like amylase and protease used in industry?

A) Yeast B) Molds and Bacteria C) Viruses D) Algae

33. What is the primary role of microorganisms in the phosphorus cycle?

A) Fixing atmospheric phosphorus B) Converting organic phosphorus to inorganic phosphate C) Producing phosphine gas D) Reducing phosphate levels in oceans

34. Which of the following is a characteristic of spoiled meat, often due to microbial activity?

A) Sweet odor B) Slimy texture C) Bright red color D) Increased firmness

35. The production of enzymes from microbial sources for industrial use is known as:

A) Bioremediation B) Bioleaching C) Industrial enzymology D) Fermentation technology

36. Which bacterium is used in the production of cheese for its role in acid and flavor development?

A) Saccharomyces cerevisiae B) Propionibacterium C) Lactococcus lactis D) Clostridium botulinum

37. What is the purpose of pasteurization in food microbiology?

A) To increase microbial load B) To eliminate all microorganisms C) To reduce the number of pathogenic microorganisms D) To enhance fermentation

38. Which microbial process converts hydrogen sulfide back to sulfate in the sulfur cycle?

A) Sulfide oxidation B) Sulfate reduction C) Desulfurization D) Sulfonation

39. The study of microorganisms in relation to soil is called:

A) Environmental microbiology B) Industrial microbiology C) Soil microbiology D) Food microbiology

40. Which of the following is a potential health risk associated with contaminated food due to microbial toxins?

A) Allergic reactions B) Food poisoning C) Digestive upset D) Dehydration

41. What is the role of methanogens in the carbon cycle, particularly in anaerobic environments?

A) Producing CO2 B) Consuming methane C) Producing methane (CH4) D) Fixing atmospheric carbon

42. Which industrial product is made using the fermentation of molasses by yeast?

A) Vinegar B) Ethanol (alcohol) C) Lactic acid D) Citric acid

43. The presence of which microorganism in food is a strong indicator of poor hygiene during processing?

A) Saccharomyces cerevisiae B) Lactobacillus C) Staphylococcus aureus D) Penicillium

44. Which term describes the use of microorganisms to clean up environmental pollutants?

A) Biotechnology B) Bioremediation C) Bioaugmentation D) Biodegradation

45. What is the primary function of nitrifying bacteria like Nitrobacter?

A) Converting ammonia to nitrite B) Converting nitrite to nitrate C) Converting nitrate to nitrogen gas D) Fixing atmospheric nitrogen

46. Which type of microorganism is primarily responsible for the decomposition of dead plant and animal material in soil?

A) Nitrogen-fixing bacteria B) Nitrifying bacteria C) Fungi and aerobic bacteria D) Denitrifying bacteria

47. The conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) by living organisms is:

A) Nitrification B) Denitrification C) Ammonification D) Nitrogen fixation

48. Which industrial application uses microorganisms to produce enzymes like rennet for cheese making?

A) Alcohol production B) Single Cell Protein C) Enzyme production D) Organic acid production

49. What is the main characteristic of fresh food that is being spoiled by microbial action?

A) Improved texture and aroma B) Changes in color, odor, and texture C) Increased nutritional value D) Extended shelf life

50. Which microorganism is commonly used in the production of soy sauce and miso?

A) Lactobacillus B) Saccharomyces C) Aspergillus D) Penicillium

Microbiology - soil microbiology, soil microbes, N₂ fixation and biogeochemical cycles, food and water microbiology, microbial flora of fresh and spoiled foods, industrial microbiology - microbial applications in manufacture of alcohols, single cell protein, organic acids - Online Test

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