Unit 3: Storage and Microbial Bioherbicide Production - Practice Quiz

1 What is the main purpose of storing plant-based herbicides properly?

2 Which condition is generally preferred for storing plant-based herbicides?

3 Why should plant-based herbicides be protected from direct sunlight?

4 What type of container is suitable for packaging a plant-based herbicide?

5 What information should be included on a herbicide package label?

6 Why should plant-based herbicides be kept away from food and animal feed?

7 Which practice is appropriate when handling a plant-based herbicide?

8 What is a seed culture in microbial herbicide production?

9 What is the main purpose of preparing a seed culture?

10 Which type of microorganism is commonly used to prepare a microbial herbicide seed culture?

11 Why is a suitable growth medium used for seed culture preparation?

12 What does sterilization of the culture medium help prevent?

13 A seed culture should generally be transferred to the production medium when it is:

14 What is an inoculum?

15 Which condition is important during seed culture preparation?

16 What is the main purpose of microbial herbicide production?

17 What is fermentation in microbial herbicide production?

18 Which factor is commonly monitored during microbial herbicide production?

19 Why is aseptic technique important during microbial herbicide preparation?

20 After microbial growth, what may be collected for preparing the herbicide?

21 A plant-based herbicide contains a light-sensitive botanical extract that oxidizes when exposed to air. Which packaging is most appropriate?

22 An emulsified plant-based herbicide separates after accidental freezing and does not become uniform after gentle mixing. What is the best action?

23 A botanical herbicide loses active ingredient when stored in a particular plastic container but remains stable in glass. Which investigation should be prioritized?

24 Two lots of a plant-based herbicide are in storage. Lot X was received first but expires in 12 months; Lot Y was received later but expires in 5 months. Which lot should be distributed first?

25 A refrigerated botanical herbicide must be sampled in a warm, humid laboratory. How should condensation inside the package be minimized?

26 A concentrated plant-based herbicide is spilled during transfer. Which response best follows safe handling practice?

27 An accelerated storage test shows rapid degradation of a botanical active ingredient at . How should this result be used?

28 Which practice best reduces genetic drift and contamination when initiating a seed culture for repeated production batches?

29 Two uncontaminated seed cultures have equal cell concentrations. Culture A is in exponential growth, while Culture B has remained in stationary phase for two days. Which is usually the better inoculum?

30 A production vessel must contain a final volume of with a seed inoculum level of . How much seed culture is required?

31 A bacterial seed flask expected to show uniform turbidity instead develops a surface film, an unusual odor, and cells of different shapes under the microscope. What is the most appropriate decision?

32 During scale-up of an aerobic seed culture, dissolved oxygen falls below its control limit while nutrient concentration remains adequate. Which adjustment should be evaluated first?

33 Seed flasks with equal liquid volumes produce inconsistent fermentation starts because their viable cell concentrations differ. Which control would most directly improve consistency?

34 A fungal bioherbicide requires abundant, stable conidia and grows well on moist cereal bran. Which production method is most suitable?

35 The herbicidal agent is a heat-sensitive extracellular metabolite, and living producer cells are not required in the final product. Which recovery sequence is most appropriate?

36 A live microbial herbicide loses most of its viability during drying, although fermentation produces a high viable count. Which process change is most appropriate to test?

37 A microbial concentrate and a carrier are individually stable, but viable count declines rapidly only after they are mixed. What is the most likely issue?

38 Two microbial herbicide batches have similar total dry mass, but Batch P gives much better weed control than Batch Q. Which quality measurement is most useful for explaining the difference?

39 Contamination is detected in a fermenter before the microbial herbicide is formulated. What should be done first?

40 Plating of a dilution of a microbial herbicide produces 80 colonies. What is the viable count of the original sample?

41 A botanical herbicide degrades by first-order kinetics with and activation energy . Assuming Arrhenius behavior, approximately what percentage of active ingredient remains after 90 days at ?

42 A hygroscopic powdered plant herbicide undergoes rapid hydrolysis above a critical water activity and also loses activity under light. Which packaging strategy most directly controls both dominant degradation pathways during humid storage?

43 A lipophilic phytotoxin is stable in glass but its measured concentration declines in high-density polyethylene bottles without detectable degradation products. Which investigation should receive highest priority?

44 After one freeze-thaw cycle, an oil-in-water botanical herbicide forms a cream layer that disappears with gentle inversion. After five cycles, inversion no longer restores uniformity and the median droplet size has tripled. What is the best interpretation?

45 Two lots of a plant-based herbicide have the same labeled expiry date. Lot X experienced 8 hours at during transport, whereas Lot Y remained at . What is the most scientifically defensible inventory decision?

46 An emulsifiable botanical herbicide is transferred from a bulk tank into small containers. The first containers pass assay, but later containers show lower active concentration even though the bulk average is within specification. Which handling control best addresses the likely cause?

47 A bacterial bioherbicide seed culture is scaled into a production fermenter requiring an oxygen uptake rate of at biomass. If oxygen saturation is and dissolved oxygen must remain at 30% saturation, what minimum is required, assuming negligible gas-phase limitations?

48 Replicate seed cultures reach the same optical density, but cultures transferred late in stationary phase produce longer production-fermenter lag times than cultures transferred during exponential growth. Which seed-release criterion is most appropriate?

49 A fungal seed suspension contains spores, hyphal fragments, and nonviable particles. Optical density is reproducible, but production performance varies substantially among batches. Which standardization method is most likely to improve inoculum consistency?

50 Increasing agitation in a filamentous fungal seed reactor restores dissolved oxygen but changes compact pellets into highly fragmented mycelia, causing excessive viscosity after transfer. What is the best corrective strategy?

51 A high-glucose seed medium gives rapid biomass formation, but transfer into production medium causes a prolonged lag and delayed phytotoxin synthesis because of catabolite repression. Which modification is most rational?

52 A bacterial seed vessel reaches its expected optical density, but oxygen uptake suddenly decreases, viable counts fall, and plaques appear when the culture filtrate is tested on the production strain. What is the appropriate action?

53 A production broth contains viable propagules per mL in a volume of 100 L. Downstream solids recovery is 80%, drying survival is 30%, and the final formulation mass is 20 kg. What is the expected final viable count per gram?

54 A dried microbial herbicide must contain at least after 12 months. Storage causes a linear decline of units per month. What minimum release potency is required, ignoring analytical uncertainty?

55 During solid-state production of fungal bioherbicide spores, the bed center has high moisture, low oxygen, and a temperature above the surface. The center yields mostly vegetative mycelium rather than spores. Which intervention best addresses the coupled limitation?

56 A microbial herbicide produces maximal biomass under carbon excess, but formation of the herbicidal secondary metabolite begins only after moderate carbon limitation. Which process strategy is most suitable?

57 A spray-dried microbial herbicide has high immediate viability but poor field efficacy because most cells are released before reaching the weed leaf and are damaged by ultraviolet radiation. Which formulation change is most appropriate?

58 A product must deliver viable spores per hectare at an application rate of . If only 60% of spores are expected to remain viable by use, what minimum release potency should be specified?

59 A wettable-powder bioherbicide retains acceptable viable counts, but efficacy falls after tank mixing with a copper-based pesticide. Microscopy shows damaged cell membranes within 20 minutes. Which recommendation is most defensible?

60 Two microbial herbicide batches have identical viable counts. Batch A controls 90% of the target weed, while Batch B controls only 35%. Genomic identity tests confirm the same production strain. Which additional quality-control test is most critical for disposition?