Unit 3: Botanical Pesticides and Bioassays - Practice Quiz

1 Which plant material is most suitable for preparing a botanical pesticide?

2 Why is plant material washed before preparing a botanical pesticide?

3 What is a major advantage of shade-drying plant material?

4 Why is dried plant material usually ground into powder?

5 What is the main role of an emulsifier in a botanical pesticide formulation?

6 A preparation contains 5 g of plant extract in a final volume of 100 mL. What is its concentration?

7 Where should a light-sensitive botanical pesticide generally be stored?

8 What does extraction mean in botanical pesticide preparation?

9 Which solvent is commonly used to extract highly polar plant compounds?

10 What is maceration?

11 What is the purpose of filtration after plant material has been soaked in a solvent?

12 Which apparatus repeatedly passes hot solvent through plant material?

13 Which instrument is commonly used to remove solvent from an extract under reduced pressure?

14 Which solvent is used to prepare an aqueous botanical extract?

15 Why is an untreated control included in a laboratory bioassay?

16 What is the main purpose of replication in a botanical pesticide bioassay?

17 In the poisoned food technique, how is a botanical extract tested against a fungus?

18 Which measurement is commonly used to assess fungal growth on an agar plate?

19 What is measured in a fungal spore germination bioassay?

20 What is the minimum inhibitory concentration (MIC)?

21 Why should plant material be collected from healthy, mature plants when preparing a botanical pesticide?

22 A farmer wants to prepare a neem leaf pesticide with maximum storage stability. Which preparation is most appropriate?

23 During preparation of a plant-based pesticide, why is grinding dried plant material into a uniform powder useful?

24 A botanical pesticide preparation gives different results in repeated trials. Which preparation factor should be standardized first?

25 Why should a botanical pesticide concentrate be diluted before application according to a tested protocol?

26 Which practice best reduces degradation of active compounds during preparation of a botanical pesticide?

27 Which solvent is generally preferred for extracting highly polar compounds from plant material?

28 A researcher wants to extract nonpolar compounds such as certain plant oils. Which solvent is most suitable?

29 What is the main purpose of maceration during botanical pesticide extraction?

30 Why can increasing extraction time beyond an optimum reduce the quality of a botanical extract?

31 A plant extract becomes cloudy after filtration. Which explanation is most likely?

32 What is the main advantage of using sequential extraction with solvents of different polarities?

33 Why should an extract be concentrated at a controlled low temperature when possible?

34 An extract prepared from 10 g of dried leaves has a final volume of 200 mL. What is the plant material concentration?

35 In a leaf-dip bioassay, why is an untreated control included?

36 If mortality in the untreated control is 15%, which correction is commonly used for treatment mortality?

37 A treatment causes 60% mortality, while the control causes 10% mortality. Using Abbott's formula, what is the corrected mortality?

38 Why are several concentrations of a botanical extract tested in a laboratory bioassay?

39 In a seed germination assay, a botanical pesticide reduces germination and produces short roots. What additional concern should be evaluated?

40 Which result best indicates that a botanical pesticide has selective toxicity toward a target insect?

41 A researcher wants to fractionate a powdered leaf sample into broadly nonpolar, intermediate-polarity, and polar fractions while minimizing carryover of lipids into later fractions. Which sequential extraction order is most appropriate?

42 An air-dried botanical sample weighs 300 g and contains 12% residual moisture. Extraction produces 26.4 g of solvent-free residue. What is the extraction yield on a dry-matter basis?

43 The principal pesticidal constituents of a plant are nonvolatile and degrade rapidly above . Which extraction method best limits thermal degradation while maintaining mass transfer?

44 After hydrodistillation of an aromatic plant, the distillate remains milky and no distinct oil layer forms because the oil yield is low and emulsification has occurred. What is the most appropriate recovery procedure?

45 A basic alkaloid is the target pesticidal constituent in a crude plant extract containing neutral lipids. Which acid-base partitioning sequence should selectively enrich the alkaloid?

46 A heat-sensitive crude extract must be concentrated accurately for comparative bioassays. Which procedure best minimizes decomposition and concentration error?

47 Two extraction batches have identical gravimetric yields but substantially different antifungal activity. Which action is most defensible for establishing batch-to-batch comparability?

48 A botanical emulsifiable concentrate contains 40% active extract on a mass-per-volume basis. What volume of concentrate is needed to prepare 2.5 L of spray containing 0.08% active extract on the same basis?

49 A neem formulation is being optimized to preserve azadirachtin during preparation and storage. Which combination of conditions is most appropriate?

50 Which pair of quality-control tests is most directly relevant to the field performance of a botanical wettable powder after dilution in water?

51 A diluted botanical emulsion develops a concentrated upper layer during standing, but gentle inversion restores a uniform dispersion. How should this observation be interpreted?

52 A tannin-rich botanical formulation forms a precipitate when mixed with a copper-based fungicide in hard water. What is the most appropriate recommendation?

53 During an accelerated stability test, a marker compound declines from 2.00% to 1.50% in 30 days. Assuming first-order degradation, what is the approximate , the time at which 90% of the initial marker remains?

54 In a poisoned-food assay, both control and treatment plates begin with a 5 mm fungal plug. Final colony diameters are 45 mm in the solvent control and 21 mm in the treatment. What is the inhibition of net radial growth?

55 In an insecticidal bioassay used to evaluate a botanical pesticide, observed mortality is 68% in the treatment and 20% in the solvent control. What mortality is obtained using Abbott's correction?

56 Botanical extract X produces a larger inhibition zone than extract Y in an agar-diffusion assay at the same loaded mass. Which conclusion is scientifically justified?

57 Several broth-microdilution wells are visibly clear after exposure to a botanical extract. Which procedure is required to determine the minimum fungicidal concentration rather than only the MIC?

58 Which detached-leaf experiment most clearly distinguishes preventive activity from curative activity of a botanical pesticide?

59 Two botanical formulations have the same in a Hill model, but formulation P has slope and formulation Q has slope . Using , which statement about is correct?

60 A dark botanical extract produces high absorbance at the same wavelength used to estimate microbial growth in a microplate assay. Which design best corrects this interference?