Unit 9: Application Technologies for Plant Disease Management - Practice Quiz

1 What is the main purpose of sterilizing laboratory equipment?

2 Which instrument is commonly used to sterilize culture media with steam under pressure?

3 What is a culture medium?

4 Which practice helps prevent contamination during microbial culture work?

5 What is an inoculum?

6 Why are pure cultures important in biofertilizer production?

7 Which method is commonly used to separate individual microbial colonies?

8 What is the purpose of an incubator in microbial production?

9 Which factor is commonly controlled during microbial incubation?

10 What does aseptic technique mean?

11 Which device is used to view microorganisms under magnification?

12 Why is pH adjusted in a microbial growth medium?

13 What is fermentation in microbial production?

14 What is the main purpose of shaking an aerobic microbial culture?

15 Which material is commonly used as a carrier for some biofertilizer microorganisms?

16 What is a biofertilizer?

17 What is a biopesticide?

18 Why are microbial cultures examined before being used in a product?

19 What does colony-forming unit, or CFU, generally indicate?

20 Why are microbial products stored under recommended conditions?

21 A laboratory is preparing a Trichoderma biopesticide. After autoclaving the growth medium, what should be done before inoculation to minimize contamination?

22 A bacterial biofertilizer culture shows colonies with two different shapes after incubation. Which laboratory practice is most appropriate before mass multiplication?

23 During preparation of a broth inoculum, a technician wants to estimate viable bacterial cells rather than total cells. Which method is most suitable?

24 A plate inoculated with mL of a dilution produces 85 colonies. What is the estimated population in the original culture?

25 A phosphate-solubilizing bacterial strain is being screened on agar containing insoluble phosphate. Which observation most strongly indicates useful activity?

26 A production fermenter contains an aerobic Bacillus biopesticide culture, but dissolved oxygen falls sharply. Which adjustment is most appropriate?

27 Why is a seed culture usually transferred to progressively larger vessels before inoculating a production fermenter?

28 A carrier-based Rhizobium formulation loses viability soon after preparation. The carrier had been mixed with the culture while still warm. What is the most likely cause?

29 Which carrier property would best support the shelf life of a microbial biofertilizer?

30 A technician must sterilize a heat-sensitive vitamin solution before adding it to a microbial production medium. Which method should be selected?

31 During quality control, a biofertilizer sample gives the expected colony morphology on a selective medium but also produces colonies on a contamination-check medium. What should be concluded?

32 Two fungal biopesticide batches have equal spore counts, but Batch X has 92% germination and Batch Y has 54% germination. Which interpretation is most appropriate?

33 A fungal biocontrol agent produces abundant mycelium but few conidia in submerged culture. Which change is most likely to improve conidial production?

34 When maintaining a master culture of a biofertilizer organism, which practice best reduces the risk of genetic and functional deterioration?

35 A culture's optical density rises during fermentation, but viable plate counts decline. What is the best explanation?

36 A microbial antagonist is tested against a plant pathogen by placing both organisms on the same agar plate. A strong inhibition zone forms between them. What does this result directly demonstrate?

37 Why should pH be monitored during microbial fermentation for biofertilizer production?

38 A formulated biopesticide passes its viable-count test immediately after production. Which additional test is most useful for assigning a realistic expiry date?

39 Before filling a fermenter with sterile medium, a laboratory performs a pressure-hold test on the vessel. What is the main purpose of this test?

40 A liquid biofertilizer is being packaged for storage. Which combination best protects microbial viability and product quality?

41 A bacterial biofertilizer culture shows the expected colony morphology on selective medium, but its viable count declines sharply after transfer to carrier material. Which investigation best distinguishes physiological injury from contamination?

42 During scale-up of a fungal biopesticide, sporulation decreases even though biomass production increases. Which process adjustment is most likely to restore propagule quality?

43 A nitrogen-fixing inoculant gives positive growth on a nitrogen-free medium, but molecular testing reveals that the production batch contains several bacterial taxa. Which release decision is most defensible?

44 When estimating viable cells in a viscous carrier, serial dilutions produce highly variable plate counts despite careful pipetting. Which methodological change most directly addresses the problem?

45 A phosphate-solubilizing bacterial isolate forms clear halos on agar, but its activity is absent in liquid culture at the intended formulation pH. Which conclusion is most appropriate?

46 A biopesticide producer wants to compare two media for toxin-producing bacteria. Medium X gives higher biomass, while Medium Y gives lower biomass but greater toxin activity per unit biomass. Which metric is most useful for process selection?

47 A mixed microbial biofertilizer performs well in individual cultures but loses viability when combined in one carrier. Which preliminary test would best identify the cause?

48 A batch of fungal spores passes an initial germination test but fails after six weeks of storage. Which quality-control design would most effectively detect this problem before distribution?

49 An inoculant production line repeatedly shows low contamination levels in finished product, although all media sterility controls are negative. Which sampling strategy is most likely to locate the source?

50 A bacterial culture reaches stationary phase earlier after repeated laboratory subculturing, and its biocontrol activity declines. Which corrective action best protects production performance?

51 During aerobic fermentation, dissolved oxygen falls while agitation reaches its maximum setting. Biomass and product formation both decline. Which intervention is most technically justified?

52 A bacterial biofertilizer is formulated in a peat carrier whose pH varies substantially among production lots. Which control is most important for consistent viability?

53 A product contains a spore-forming biopesticide and a non-spore-forming bacterial inoculant. Heat treatment removes vegetative contaminants but also reduces the bacterial count. Which strategy best preserves both product components?

54 An antagonist suppresses a fungal pathogen on agar but fails in a plant assay. Which laboratory refinement would most improve the predictive value of screening?

55 A production batch has the required CFU count, but the cells are highly clumped and the product gives uneven field application. Which formulation test is most relevant before release?

56 A microbial formulation shows lower CFU counts on a selective medium than on a nonselective medium, but strain-specific PCR detects the production strain. Which interpretation is most plausible?

57 A bacterial biopesticide requires a specific plasmid for metabolite production, but the plasmid is unstable during high-density culture. Which production-control approach is most appropriate?

58 A carrier sterilization procedure is validated using a biological indicator, but the inoculated product later contains surviving contaminants. Which additional validation is necessary?

59 Two strains have complementary nitrogen-fixing and phosphate-solubilizing traits, but one strain strongly acidifies the medium and inhibits the other. Which development strategy is most defensible?

60 A freeze-dried microbial product retains high CFU counts immediately after drying but loses viability rapidly when exposed to humid air. Which formulation variable should be prioritized?