Unit 4: Extractions of biorationals - Practice Quiz

1 Why is plant material commonly dried before preparing a botanical extract?

2 What is the main purpose of grinding dried plant material before extraction?

3 What is the primary role of a solvent in botanical extraction?

4 Which process separates solid plant residue from a liquid botanical extract?

5 Why is part of the solvent removed after botanical extraction?

6 Which information is most important on the label of a stored botanical extract?

7 What is the purpose of an untreated control in an insect bioassay?

8 Which observation most directly indicates the insecticidal efficacy of a botanical extract?

9 Why are several concentrations of a botanical extract tested against an insect pest?

10 Which result suggests that a botanical extract has repellent activity?

11 What is the active ingredient in a biorational biopesticide formulation?

12 What is the usual role of a carrier in a biopesticide formulation?

13 What is the main function of a surfactant in a spray formulation?

14 Which formulation is designed to form an emulsion when mixed with water?

15 Which formulation is a powder intended to be suspended in water before spraying?

16 Why are formulation ingredients mixed thoroughly during preparation?

17 What is a bioassay used for when evaluating a biopesticide formulation?

18 What does represent in an insecticidal activity test?

19 What does the shelf life of a biopesticide formulation describe?

20 Why should a biopesticide formulation be tested at the recommended application rate?

21 A researcher wants to extract both nonpolar terpenoids and polar phenolics from dried leaves by sequential extraction. Which solvent sequence is most appropriate?

22 How much dry botanical extract is required to prepare of a 5% test solution?

23 Leaves containing heat-sensitive insecticidal compounds must be dried before extraction. Which method is most suitable?

24 An extract causes 60% mortality, while mortality in the solvent control is 20%. Using Abbott's correction, what is the corrected mortality?

25 A plant extract is dissolved in acetone before being applied to insects. Which control is essential for determining whether acetone contributes to mortality?

26 Which bioassay is most appropriate for evaluating the activity of a botanical extract after larvae feed on treated foliage?

27 Extract X has an of , while extract Y has an of against the same insect stage. What is the best interpretation?

28 In a two-choice test for repellency, insects are released between treated and untreated leaf discs. Which result provides the strongest evidence of repellency?

29 Extraction of of dried leaf powder produces of dry crude extract. What is the extraction yield?

30 A light-sensitive botanical extract must be stored for later bioassays. Which storage condition is most appropriate?

31 A neem oil concentrate separates immediately when diluted with water. Which formulation change would most directly improve dispersion?

32 A wettable powder settles rapidly and forms a hard cake in the spray tank. Which adjustment is most likely to improve its performance?

33 What is the main advantage of microencapsulating a UV-sensitive botanical insecticide?

34 What volume of a 20% liquid concentrate is needed to prepare of a 2% spray mixture, assuming additive volumes?

35 A biorational formulation causes 90% pest mortality but also severe leaf scorching at the recommended dose. What is the most appropriate conclusion?

36 A botanical spray performs well under laboratory conditions but washes off leaves during light rain. Which additive would most directly improve rainfastness?

37 Two formulations contain the same botanical active ingredient. To compare formulation performance fairly, how should they be applied?

38 Pest density varies along a moisture gradient in a field. Which experimental design best controls this source of variation when evaluating four formulations?

39 Which evidence best demonstrates that a stored biorational formulation has retained acceptable shelf life?

40 A formulation produces rapid knockdown, but many insects recover within 24 hours. Which evaluation method would prevent overestimating its insecticidal activity?

41 Sequential extraction of the same plant powder gives a nonpolar extract with 2% yield and an ethanolic extract with 14% yield. At equal crude-extract concentrations, the nonpolar extract causes greater mortality. Which comparison best determines whether its apparent superiority reflects greater intrinsic potency of the active constituents?

42 A dry plant sample produces a crude extract containing 2.5% of an insecticidal marker. How much crude extract is required to prepare 2 L of spray containing 0.015% marker on a mass-per-volume basis?

43 Extract A has mg/L and probit slope , whereas extract B has mg/L and . Using , which conclusion is correct?

44 In a botanical-extract bioassay, observed mortality is 68% in the treatment and 20% in the solvent control. What is the Abbott-corrected mortality?

45 Increasing extract doses require different volumes of acetone, and acetone itself slightly affects larvae. Which design most effectively prevents solvent concentration from being confounded with extract dose?

46 The target botanical compound is both thermolabile and readily oxidized. Which extraction procedure is most appropriate when maximizing chemical integrity is more important than extraction speed?

47 Extracts X and Y individually cause 60% and 50% mortality. Under Bliss independent action, what combined mortality is expected, and how should a statistically significant observed mortality of 90% be interpreted?

48 A treated leaf-disc assay shows severe feeding reduction and 70% apparent mortality at 24 h. Most immobile insects recover after transfer to untreated leaves, paired-choice tests show strong avoidance, and topical application causes no mortality. What is the best interpretation?

49 To estimate the residual activity of a botanical deposit aged outdoors for 0, 1, 3, and 7 days, which protocol minimizes survivor-selection and insect-aging bias?

50 A plant contains insecticidal compounds that are weak organic bases. Which acid-base partitioning sequence most selectively transfers them from an aqueous plant extract into an organic solvent?

51 An emulsifiable concentrate requires a surfactant blend with HLB 10.0. Available surfactants have HLB values of 4.3 and 15.0. What percentage of the surfactant blend should be the high-HLB surfactant, assuming linear blending?

52 A microcapsule preparation contains 10 mg of active ingredient in total. After separation of intact capsules, 2 mg is measured in the external phase. Assuming complete recovery and no analytical loss, what is the encapsulation efficiency?

53 Two microcapsule formulations show nearly identical slow release in a dialysis-bag experiment, despite major differences in capsule-wall composition. Which follow-up test best determines whether the dialysis membrane, rather than the capsules, controls the measured release rate?

54 A nanoemulsion and an emulsifiable concentrate are applied at the same nominal tank concentration, but chemical analysis shows different active-ingredient deposition on leaves. Which comparison most validly tests whether formulation type changes biological efficacy?

55 Which treatment structure most directly tests whether a formulation additive protects a botanical active ingredient from ultraviolet degradation without independently killing insects?

56 In a randomized complete block field trial, each formulation is assigned to one plot per block, and 20 leaves are sampled from each plot. What is the correct experimental unit for testing formulation effects?

57 Formulation A has an estimated of 18 mg/L and formulation B has an estimated of 27 mg/L. Which analysis provides the strongest formal evidence that their potencies differ?

58 According to Stokes-type settling behavior, which formulation change should most effectively reduce sedimentation velocity in a suspension concentrate while preserving active-ingredient concentration?

59 An accelerated shelf-life study follows first-order active loss at 30, 40, and 50°C. At 50°C, however, the formulation undergoes irreversible phase separation that does not occur at lower temperatures. What is the most defensible use of the 50°C data in an Arrhenius shelf-life prediction?

60 A slow-acting biorational formulation and a fast-acting standard eventually produce similar mortality, but their times to death differ substantially and some insects remain alive at study termination. Which analysis uses the available information most appropriately?