Unit 10: Evaluation of Biological Disease Management - Practice Quiz

1 What is the main purpose of evaluating a biological control agent under laboratory conditions?

2 Which laboratory technique commonly tests the interaction between a fungal biocontrol agent and a fungal pathogen on the same plate?

3 Which medium is commonly used to grow many fungi during laboratory evaluation?

4 What does a clear inhibition zone around a bacterial biocontrol colony usually indicate?

5 Why is an untreated pathogen culture included in a laboratory experiment?

6 Which measurement is commonly used to evaluate the growth of a fungal pathogen on an agar plate?

7 What is the purpose of maintaining aseptic conditions during laboratory evaluation?

8 What does reduced pathogen growth in a treated plate suggest?

9 Why are replicate plates used in a laboratory bioassay?

10 In a dual-culture assay, where are the pathogen and fungal biocontrol agent usually placed?

11 What is a major advantage of greenhouse evaluation over field evaluation?

12 Which group provides a basic comparison when testing a biocontrol treatment on diseased plants?

13 What does disease incidence measure in a greenhouse experiment?

14 What does disease severity describe?

15 Why should greenhouse treatments be assigned randomly to pots?

16 Which observation most directly indicates successful biological disease management in a greenhouse?

17 Why are plants deliberately inoculated with a pathogen in many greenhouse trials?

18 Which method can be used to apply a biological control agent to plant roots?

19 Why should the same plant variety be used across greenhouse treatments?

20 What should be recorded if a biological treatment causes yellowing or stunting in otherwise healthy plants?

21 A bacterial biocontrol isolate produces a clear inhibition zone against a fungal pathogen on agar. What is the most appropriate interpretation?

22 In a dual-culture assay, a fungal pathogen grows 80 mm in the control plate and 50 mm when exposed to a biocontrol fungus. What is the percentage inhibition of radial growth?

23 Why should a laboratory assay include a pathogen-only control when testing a microbial antagonist?

24 A biocontrol bacterium inhibits a pathogen only when both organisms are separated by a membrane that permits chemical diffusion. Which mechanism is most strongly indicated?

25 Which experimental design best tests whether a biofertilizer indirectly reduces pathogen growth by improving plant nutritional status in vitro?

26 A volatile-compound assay shows pathogen inhibition, but no inhibition occurs in a contact assay. What should be tested next?

27 A treatment produces highly variable inhibition zones among replicate plates. Which action would most improve the reliability of the assay?

28 A fungal antagonist overgrows the pathogen colony in an assay. Which additional observation would provide stronger evidence of mycoparasitism?

29 When screening several biocontrol isolates, why is pathogen growth rate important to consider before comparing inhibition percentages?

30 A candidate biocontrol agent suppresses a pathogen in vitro but also inhibits germination of the crop seed. What is the best conclusion?

31 A greenhouse experiment compares a biofertilizer treatment with an untreated control, but the treatment pots receive more irrigation. Why is this a major problem?

32 Which treatment arrangement most directly determines whether a microbial inoculant protects plants after pathogen challenge?

33 Disease severity is recorded on a to scale for treated and control plants. What is the main advantage of using several plants per treatment?

34 A treatment lowers disease severity but also reduces plant height and biomass. Which additional result is most important before recommending the treatment?

35 A biocontrol treatment works well at high humidity but not at low humidity. What does this result suggest about the treatment?

36 Why should pots in a greenhouse experiment be randomized and periodically repositioned?

37 A greenhouse treatment reduces disease incidence from to . What is the relative reduction in disease incidence?

38 A microbial inoculant reduces symptoms in greenhouse plants, but pathogen populations in roots remain unchanged. Which explanation is most plausible?

39 A greenhouse trial includes a chemical fungicide standard, a biological treatment, an untreated control, and plants without pathogen inoculation. What is the purpose of the non-inoculated plants?

40 A biological treatment performs inconsistently across two greenhouse trials. Which interpretation is most scientifically appropriate?

41 A bacterial antagonist produces a clear inhibition zone against a fungal pathogen on agar. Which additional experiment most directly determines whether inhibition is caused by a diffusible metabolite rather than nutrient competition?

42 A biocontrol treatment reduces pathogen colony diameter by 40% in dual culture, but the pathogen grows equally well when exposed to a nonliving antagonist biomass control. What is the strongest interpretation?

43 When comparing three microbial antagonists in a plate assay, pathogen growth differs among experimental runs because inoculum age varies. Which design best addresses this source of variation?

44 A volatile-compound assay shows pathogen inhibition only when antagonist and pathogen share the same sealed vessel but do not contact each other. Which control is essential for interpreting the result?

45 A treatment lowers pathogen spore germination from 80% to 40%, but the untreated control has only 50% germination in a repeated experiment. Which conclusion is most defensible?

46 A filtrate inhibits pathogen growth at pH 5.5 but not after neutralization to pH 7.0. Which comparison best tests whether acidity, rather than a specific antimicrobial, explains inhibition?

47 Two antagonists produce identical inhibition zones, but one grows much faster than the pathogen and the other grows slowly. Which additional measurement is most useful for distinguishing their suppression mechanisms?

48 A fungal biocontrol isolate suppresses one pathogen strain strongly but has no effect on a second strain. Which interpretation is most scientifically appropriate?

49 In a laboratory assay, disease suppression is calculated as , where and are pathogen growth measurements. If and , what is suppression?

50 A bacterium reduces pathogen growth in vitro, but its effect disappears when the medium is supplemented with excess iron. Which mechanism is most consistent with this observation?

51 A greenhouse trial compares a microbial biocontrol treatment with a fungicide, but plants in different benches receive different light and temperature levels. Which design most effectively limits bench effects?

52 A treatment reduces disease severity but also reduces plant biomass because of temporary phytotoxicity. Which endpoint best supports a recommendation for practical disease management?

53 In a greenhouse experiment, plants treated with an antagonist before pathogen inoculation show lower disease, whereas simultaneous application does not. Which conclusion is most justified?

54 A greenhouse treatment reduces disease in sterilized soil but not in nonsterilized soil. Which follow-up is most informative for identifying the cause?

55 Disease severity scores are recorded on an ordinal 0-to-5 scale at six dates. Which analysis best represents disease development over time?

56 A biocontrol treatment appears effective in a greenhouse trial, but pathogen inoculum is applied unevenly among pots. Which result would most strongly weaken the efficacy claim?

57 A microbial treatment reduces disease only under high humidity, while the product is intended for field use across variable weather. Which next step provides the strongest evaluation?

58 A greenhouse study places five plants in each pot and analyzes all plants as independent replicates. What is the main statistical problem?

59 A treatment lowers disease severity, but pathogen quantitative PCR values remain unchanged while viable pathogen counts decrease. Which interpretation is most plausible?

60 A combined treatment of a biofertilizer and a biocontrol agent performs better than either treatment alone. Which comparison is required to determine whether the interaction is synergistic rather than merely additive?