Unit 8: Production Technology and Quality Control of Biofertilizers - Practice Quiz

1 What is the main purpose of preparing a pure microbial culture during biofertilizer production?

2 Which equipment is commonly used to sterilize culture media in a laboratory?

3 What is an inoculum in microbial biofertilizer production?

4 Which vessel is commonly used for large-scale multiplication of biofertilizer microorganisms?

5 Why is aseptic handling important during microbial biofertilizer production?

6 What is the main function of a carrier material in a carrier-based biofertilizer?

7 Which material is commonly used as a carrier for microbial biofertilizers?

8 Why is a suitable nutrient medium used during biofertilizer production?

9 What is done after sufficient microbial growth is obtained for a carrier-based biofertilizer?

10 What is the main purpose of sealing biofertilizer packages properly?

11 Which quality control parameter indicates the number of living microorganisms in a biofertilizer?

12 Which unit is commonly used to express the viable microbial count in a biofertilizer?

13 Which laboratory method is commonly used to estimate viable microorganisms in a biofertilizer sample?

14 What does a contamination test check in a microbial biofertilizer?

15 Which instrument is used to measure the pH of a biofertilizer sample accurately?

16 Why is the moisture content of a carrier-based biofertilizer monitored?

17 What does the shelf life of a microbial biofertilizer describe?

18 Why is the identity of a biofertilizer microorganism checked during quality control?

19 Which laboratory observation can help check the purity of a microbial culture?

20 What information should be checked on a microbial biofertilizer label as part of quality control?

21 Why is a pure mother culture used to initiate the production of a microbial biofertilizer?

22 A liquid culture medium becomes cloudy after sterilization but before inoculation. What is the most appropriate action?

23 Which factor is most important when selecting a carrier material for a solid biofertilizer formulation?

24 During preparation of a carrier-based inoculant, the carrier is sterilized before adding the microbial culture primarily to:

25 A bacterial culture has a high optical density but a low viable count. What does this result most likely indicate?

26 Why is serial dilution followed by plating commonly used during microbial biofertilizer production?

27 If 0.1 mL of a dilution produces 86 colonies, what is the estimated concentration of the original culture?

28 A production culture is harvested before entering the late stationary phase mainly because early harvesting can provide:

29 Why should the pH of a microbial production medium be monitored during fermentation?

30 What is the main purpose of using an inoculum of known age and concentration in a production run?

31 Which quality-control test best verifies that a biofertilizer contains the intended microbial strain rather than only viable microorganisms?

32 A biofertilizer sample meets its initial viable-count specification but fails after storage. Which quality parameter was most clearly inadequate?

33 Why are uninoculated media controls included in microbial quality testing?

34 A plate from a dilution series contains more than 300 colonies. Why is it generally unsuitable for accurate enumeration?

35 Which observation most strongly suggests contamination in a supposedly pure bacterial biofertilizer culture?

36 A product has an acceptable CFU count but contains a microorganism that inhibits the target strain. Which quality requirement has failed?

37 Why is moisture content measured in a carrier-based microbial biofertilizer?

38 A biofertilizer has a viable count of CFU/g, while the specification requires at least CFU/g. How should the batch be classified?

39 Which test is most appropriate for checking whether a microbial biofertilizer retains its functional ability after formulation?

40 Why should samples be collected from different portions of a large biofertilizer batch during quality control?

41 A bacterial biofertilizer is being scaled from a 100 mL seed culture to a 100 L fermenter. Which strategy best minimizes lag time and physiological instability during scale-up?

42 During aerobic fermentation, biomass accumulation stops even though carbon and nitrogen remain in excess. Dissolved oxygen is nearly zero, and increasing agitation damages the cells. Which intervention is most appropriate?

43 A carrier contains 600 g of oven-dry material. How much sterile water must be added to obtain a formulation containing 40% moisture on a wet-weight basis?

44 Repeated autoclaving makes a peat carrier darker and subsequently lowers survival of inoculated bacteria, although sterility tests are negative. What is the most likely production problem?

45 Which approach provides the strongest validation that a carrier sterilization cycle is reproducibly effective?

46 A freeze-dried bacterial inoculant loses most viability during drying but remains stable afterward. Which process modification most directly targets the major loss?

47 A phosphate-solubilizing bacterium produces the highest viable count at pH 7.0, but phosphate solubilization is induced near pH 6.0. Which production design best balances biomass yield and functional activity?

48 Why is conventional axenic broth fermentation generally unsuitable for mass multiplication of arbuscular mycorrhizal fungi?

49 A fermenter culture repeatedly becomes contaminated soon after inoculation, but uninoculated medium held under the same conditions remains sterile. Which source should be investigated first?

50 Two carrier formulations initially contain the same viable count. Formulation X has greater moisture but lower water activity than formulation Y. Which inference is scientifically justified?

51 A 10 g sample is homogenized in 90 mL diluent. After further dilution to relative to the original sample, 0.1 mL yields 64 colonies. What is the viable count?

52 Direct microscopy shows bacterial cells g, whereas plate counting shows CFU g. Which interpretation is most defensible?

53 A quantitative PCR assay reports a much larger population than plate counting after prolonged storage. Which modification best helps distinguish membrane-intact cells from cells with compromised membranes?

54 An inoculant contains CFU g initially and declines linearly by CFU g per month. If the minimum specification is CFU g, when is the predicted specification limit reached?

55 A product falls from to CFU g after four days in an accelerated storage test. Assuming log-linear inactivation, how long will it take to reach CFU g?

56 A phosphate-solubilizing isolate forms a large halo on agar but releases little soluble phosphate in liquid culture. What is the best quality-control conclusion?

57 All colonies recovered from a lot have the expected morphology, but a strain-specific PCR test is negative. Which conclusion is most appropriate?

58 A composite sample prepared from 20 packages passes a contamination test, but sporadic package-level contamination is suspected. Which revised sampling approach is most informative?

59 A Rhizobium inoculant has acceptable viable count and strain identity but consistently forms ineffective nodules on its intended legume host. Which quality attribute has failed?

60 A carrier-based product meets its viable-count specification immediately after manufacture but fails rapidly during storage. Which quality-control program would best detect this weakness before release?