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Unit 1: Introduction to laboratory techniques and media preparations - Practice Quiz

ENT203 — Biopesticides In Insect Pest Management 60 Questions
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1 What is a biopesticide?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. A chemical used only to clean glassware
B. A pest-control product derived from biological sources
C. A fertilizer produced entirely from minerals
D. A synthetic dye used to identify insects

2 Which organism is commonly used as an entomopathogenic fungus?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. Rhizobium leguminosarum
B. Azotobacter chroococcum
C. Lactobacillus acidophilus
D. Beauveria bassiana

3 What is the main aim of biorational pest management?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. To control pests with minimal non-target effects
B. To replace crops with resistant weeds
C. To increase pesticide residues on crops
D. To eliminate every organism from a field

4 Which item is appropriate personal protective equipment in a biopesticide laboratory?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. Culture label
B. Laboratory coat
C. Petri dish
D. Field notebook

5 What is the main purpose of aseptic technique?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. To increase the temperature of cultures
B. To identify insects by body color
C. To prevent unwanted microbial contamination
D. To measure the volume of liquids

6 Which device provides clean, filtered air during aseptic transfer of microbial cultures?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. Orbital shaker
B. Compound microscope
C. Hot-air oven
D. Laminar airflow cabinet

7 Which instrument sterilizes materials using steam under pressure?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. Colorimeter
B. Centrifuge
C. Autoclave
D. Incubator

8 Which tool is commonly used to transfer a bacterial culture onto solid medium?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. Mortar and pestle
B. Glass condenser
C. Inoculating loop
D. Measuring cylinder

9 Why should microbial culture plates be clearly labeled?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. To sterilize the culture surface
B. To identify the culture and date
C. To change the medium composition
D. To increase the growth temperature

10 Which substance is commonly used for routine disinfection of a laboratory work surface?

Introduction and acquaintance with biopesticide and biorational laboratory Easy
A. Glucose solution
B. Distilled water
C. 70% ethanol
D. Liquid paraffin

11 Which medium is commonly used to cultivate entomopathogenic fungi?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. Potato dextrose agar
B. MacConkey agar
C. Eosin methylene blue agar
D. Mannitol salt agar

12 Which medium is commonly used as a general-purpose medium for cultivating bacteria?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. Potato dextrose agar
B. Czapek-Dox agar
C. Rose Bengal agar
D. Nutrient agar

13 What is the main function of agar in a solid culture medium?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. To kill the microbes
B. To color the colonies
C. To sterilize the medium
D. To solidify the medium

14 What is the main role of dextrose in fungal culture media?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. To sterilize the medium
B. To remove microbial cells
C. To solidify the medium
D. To provide an energy source

15 What does peptone mainly provide in a culture medium?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. Agar and solid support
B. Oxygen and carbon dioxide
C. Nitrogen and amino acids
D. Light and thermal energy

16 What is a commonly used autoclaving temperature for culture media?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. 80°C
B. 100°C
C. 121°C
D. 150°C

17 Which instrument is used to measure the pH of a prepared culture medium?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. Incubator
B. Autoclave
C. pH meter
D. Centrifuge

18 Why are antibiotics sometimes added to media used for fungal isolation?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. To raise the incubation temperature
B. To dissolve fungal cell walls
C. To increase the agar concentration
D. To suppress unwanted bacterial growth

19 Why should molten agar medium be allowed to cool before pouring it into Petri dishes?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. To encourage contamination before inoculation
B. To permit safer handling and reduce condensation
C. To remove all nutrients from the medium
D. To convert agar into a liquid permanently

20 Why are inoculated Petri dishes commonly incubated in an inverted position?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Easy
A. To prevent condensation from dripping onto colonies
B. To sterilize the lid during incubation
C. To prevent agar from becoming solid
D. To increase the nutrient content of agar

21 A technician receives an insect cadaver suspected of carrying an entomopathogenic fungus. Which workflow best minimizes cross-contamination during examination?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Disinfect the workspace, process one sample aseptically, and sterilize tools between samples
B. Examine all samples together and separate contaminated cultures after incubation
C. Open the sample beside stock cultures and disinfect the bench afterward
D. Keep culture plates open during processing so airborne moisture can evaporate

22 Which practice is most appropriate when transferring a microbial suspension that may generate infectious aerosols?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Pipette rapidly on an uncovered laboratory bench
B. Work near an open window to improve ventilation
C. Use a chemical fume hood because it removes every biological aerosol and replaces the need for aseptic technique
D. Perform the transfer in a suitable biological safety cabinet

23 A bioassay tests mortality caused by a Beauveria bassiana formulation. Which treatment is the most appropriate negative control?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Insects treated with twice the recommended conidial concentration
B. Insects treated with the formulation carrier but without fungal conidia
C. Insects collected from another field and maintained under different temperature, humidity, diet, and handling conditions
D. Insects treated with a different entomopathogenic fungal species

24 Which information is most important to place directly on the base of an inoculated Petri plate?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Only the incubation temperature and the color of the medium
B. Only the expected organism and its recommended pesticide dose
C. Organism or sample code, medium, date, and operator initials
D. Incubator brand, room number, plate price, and supplier

25 During aseptic transfer, a sterile pipette tip accidentally touches the bench. What should the technician do next?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Use the tip only for transferring sterile water
B. Wipe the tip with disinfectant and continue
C. Discard the tip and attach a new sterile tip
D. Flame the plastic tip briefly and continue

26 Several uninoculated control plates show microbial growth after incubation. What is the most likely interpretation?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. The target microorganism grows without inoculation
B. The agar concentration was necessarily too high
C. The incubation period was too short for isolation
D. The medium or plate-handling process was contaminated

27 Why is a biorational pesticide not automatically equivalent to a microbial biopesticide?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Biorational products must always contain living bacteria
B. Biorational products may include selective nonmicrobial substances
C. Microbial products are never selective toward target insects
D. Biorational pesticides include every conventional pesticide that produces rapid mortality under laboratory conditions

28 What is the most appropriate treatment for disposable culture plates containing viable entomopathogenic microbes before disposal?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Rinse them in a sink and discard them as plastic
B. Place them directly in ordinary laboratory waste
C. Decontaminate them according to approved biosafety procedures
D. Leave them exposed to room air until the medium becomes dry

29 Replicate cultures inoculated from the same fungal stock show colonies with very different colors and textures. What should be checked first?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. Whether the agar contains enough distilled water
B. Whether all colonies have identical pathogenicity
C. Whether the microscope lamp was switched off
D. Whether contamination or culture mixing occurred

30 A researcher must prepare a series of microbial dilutions accurately. Which instrument is most suitable for transferring repeatedly?

Introduction and acquaintance with biopesticide and biorational laboratory Medium
A. A glass beaker marked at intervals
B. A measuring cylinder with a capacity of
C. An inoculating loop sterilized between each transfer
D. A calibrated micropipette covering the required volume

31 A dehydrated medium requires per liter. How much powder is needed to prepare ?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A.
B.
C.
D.

32 What is the main purpose of autoclaving a prepared culture medium?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. To remove all nutrients from the medium
B. To increase the medium's agar concentration
C. To destroy contaminating microorganisms and resistant spores
D. To make every heat-sensitive supplement more active

33 An antibiotic supplement is unstable at autoclaving temperatures. How should it normally be added to agar medium?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. Mix it into boiling agar and continue heating until the antibiotic becomes completely resistant to thermal degradation
B. Autoclave it separately at a higher pressure
C. Add it before heating the medium to dissolve the agar
D. Filter-sterilize it and add it to cooled sterile medium

34 A medium must have a specified pH before sterilization. What is the most appropriate procedure unless the protocol states otherwise?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. Adjust the pH after plates have solidified
B. Measure pH only after microbial colonies appear
C. Ignore pH because autoclaving makes it neutral
D. Adjust the pH before autoclaving the medium

35 Which medium is commonly selected for the primary cultivation of entomopathogenic fungi such as Beauveria and Metarhizium?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. Mannitol salt agar
B. Potato dextrose agar
C. MacConkey agar
D. Nutrient broth without agar

36 A soil sample is being examined for spore-forming entomopathogenic bacteria such as Bacillus thuringiensis. Why might a controlled heat treatment be applied before plating on nutrient agar?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. To convert all bacterial cells directly into fungal conidia
B. To ensure that only viruses survive in the sample
C. To select heat-resistant spores over many vegetative cells
D. To dissolve agar so bacterial colonies remain suspended

37 Why can an entomopathogenic virus generally not be propagated on ordinary nutrient agar?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. Viruses require agar concentrations above
B. Viruses use ordinary agar only after it has been enriched with sugars, proteins, lipids, minerals, and fungal extracts
C. Viruses grow only in media containing antibiotics
D. Viruses require living host cells for replication

38 A fungal isolation plate prepared from an insect cadaver is repeatedly overgrown by bacteria. Which modification is most appropriate?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. Remove the carbohydrate source from every fungal medium
B. Increase the incubation temperature to
C. Keep the plate uncovered throughout the incubation period
D. Add a suitable antibacterial agent after proper sterilization

39 How much agar is required to prepare of a weight-per-volume agar medium?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A.
B.
C.
D.

40 Freshly poured agar plates develop heavy condensation on their lids. Which practice best reduces the chance that droplets will spread colonies during incubation?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Medium
A. Increase the medium volume until it touches the lid
B. Remove the lids after inoculation until the agar dries
C. Incubate the solidified plates in an inverted position
D. Incubate the plates upright with their lids loosened

41 A laboratory evaluates a microbial insecticide against an insect colony. Mortality is 92% in the treatment, 8% in the untreated control, and 47% in the control receiving only the formulation carrier. Which interpretation is most defensible?

Introduction and acquaintance with biopesticide and biorational laboratory Hard
A. The carrier effect prevents attribution of mortality to the microbe alone
B. The untreated control invalidates the assay because mortality was not zero
C. The treatment is effective because its mortality exceeded 50%
D. The microbial active ingredient caused all mortality above 8%

42 Which statement best distinguishes a biorational pesticide from a biopesticide in laboratory evaluation?

Introduction and acquaintance with biopesticide and biorational laboratory Hard
A. Biopesticide status depends exclusively on rapid environmental degradation
B. Biorational status depends on selectivity and use context, not only origin
C. A biorational pesticide must consist entirely of living microorganisms
D. A biopesticide must be harmless to every non-target organism

43 An unknown fungal isolate and a reference Metarhizium strain are handled in the same cabinet. Three days later, both cultures show identical colony morphology and genotype profiles. Which laboratory practice would most directly have reduced the risk of undetected cross-contamination?

Introduction and acquaintance with biopesticide and biorational laboratory Hard
A. Increasing incubation temperature to accelerate colony differentiation
B. Sealing both culture plates together inside one secondary container
C. Processing both isolates simultaneously with shared negative controls
D. Processing isolates separately with spatially assigned sterile consumables

44 A sterility control containing uninoculated broth becomes turbid, while all inoculated tubes show the expected phenotype. What is the appropriate disposition of the batch?

Introduction and acquaintance with biopesticide and biorational laboratory Hard
A. Subtract the sterility-control turbidity from each inoculated tube numerically
B. Accept the batch because the inoculated cultures have the expected phenotype
C. Reject the run because the sterility control demonstrates process contamination
D. Accept only cultures whose turbidity exceeds the control by twofold

45 Which procedure best addresses an aerosol-generating manipulation of an entomopathogenic fungal conidial suspension?

Introduction and acquaintance with biopesticide and biorational laboratory Hard
A. Perform it in a clean-air laminar-flow cabinet that blows air toward the operator
B. Perform it on an open bench beside a flame to create upward airflow
C. Perform it in a closed incubator immediately after surface disinfection
D. Perform it in a certified biological safety cabinet using aerosol-minimizing technique

46 After a spill containing a high concentration of fungal conidia, which response is most appropriate before routine cleaning resumes?

Introduction and acquaintance with biopesticide and biorational laboratory Hard
A. Wipe immediately with dry tissue to prevent disinfectant dilution
B. Expose the spill briefly to cabinet ultraviolet light and resume work
C. Add sterile water, spread the suspension thinly, and allow it to evaporate
D. Allow aerosols to settle, contain the spill, and apply a validated disinfectant

47 A candidate biopesticide produces high insect mortality, but the recovered microorganism differs genetically from the organism administered. Which conclusion is scientifically justified?

Introduction and acquaintance with biopesticide and biorational laboratory Hard
A. The recovered organism is irrelevant if untreated-control mortality was low
B. Causality remains unconfirmed because identity was not maintained through recovery
C. The administered isolate is causal because both organisms are microbial
D. Pathogenicity is confirmed because mortality occurred after treatment

48 Which approach is required to propagate an entomopathogenic baculovirus for routine laboratory production?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Incubation in nutrient broth supplemented with insect hemolymph salts
B. Cultivation in a suitable insect host or permissive insect cell line
C. Growth on blood agar under reduced-oxygen conditions
D. Inoculation onto potato dextrose agar under acidic conditions

49 A soil dilution is being plated to isolate Beauveria and Metarhizium. Which medium design is most likely to improve recovery while suppressing common contaminants?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. A nonselective glucose broth incubated until all visible organisms reach stationary phase
B. A fungal nutrient base with validated antibacterial and selective antifungal additives
C. A rich bacterial broth containing broad-spectrum fungicides and no solidifying agent
D. A minimal agar containing cycloheximide at a concentration lethal to target fungi

50 An antibiotic supplement is heat labile. Which preparation sequence best preserves its activity and medium sterility?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Autoclave the antibiotic repeatedly before mixing it with unsterilized medium
B. Filter-sterilize the stock and add it aseptically to cooled sterile medium
C. Add the unsterilized stock after the medium has completely solidified
D. Mix the stock with boiling medium and immediately pour the plates

51 A medium requires an antibiotic concentration of in a final volume of . What volume of a stock is required?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A.
B.
C.
D.

52 After plating of a dilution, 86 colonies are counted. Assuming one colony-forming unit produced each colony, what was the original concentration?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A.
B.
C.
D.

53 A technician autoclaves a tightly packed set of large medium bottles for 15 minutes, timing the cycle from the moment the machine is switched on. Contamination later occurs throughout the bottles. What is the most likely process failure?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. The holding time was measured before the load reached sterilizing temperature
B. The medium contained too much agar for microbial growth to occur
C. The bottles cooled too slowly after complete sterilization
D. The autoclave pressure prevented steam from contacting the bottle exteriors

54 A phosphate-rich medium containing calcium salts forms a precipitate after autoclaving, reducing nutrient availability. Which modification is most appropriate?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Lower the agar concentration while autoclaving all ingredients together
B. Increase both salt concentrations until the precipitate redissolves
C. Extend the autoclave cycle until the precipitate becomes biologically available
D. Sterilize incompatible components separately and combine them aseptically

55 An insect cadaver is heavily overgrown by fast-growing saprophytic fungi, but an entomopathogenic fungus is suspected internally. Which isolation strategy best improves the chance of recovering the causal fungus?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Surface-disinfect the cadaver, aseptically sample internal tissue, and use selective agar
B. Plate the untreated cadaver directly onto a nutrient-rich nonselective medium
C. Homogenize the entire cadaver with its external growth in enrichment broth
D. Incubate the cadaver at high humidity until every fungal species sporulates

56 A fungal isolate grows normally on nonselective agar but fails to grow on a newly formulated selective medium. Positive-control bacteria are suppressed as intended. What is the strongest inference?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Suppression of bacteria proves that the fungal inoculum was contaminated
B. The medium is differential rather than selective for the target fungus
C. The isolate was nonviable before inoculation onto either medium
D. At least one selective component also inhibits the target fungus

57 A Bacillus thuringiensis culture reaches high vegetative cell density but produces few spores and parasporal crystals. Which medium adjustment is most rational?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Remove mineral ions and buffer the medium at an extreme pH
B. Maintain continuous excess glucose to prevent nutrient limitation
C. Add a broad-spectrum antibacterial agent during exponential growth
D. Use a balanced sporulation medium that permits controlled nutrient depletion

58 Which quality-control design provides the strongest evidence that a newly prepared selective medium is fit for use?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Comparing colony color without using reference or challenge organisms
B. Measuring only the pre-autoclave pH of one plate from the batch
C. Testing target recovery, non-target inhibition, sterility, and physical properties
D. Confirming that uninoculated plates remain clear during incubation

59 A fungal medium was accidentally prepared with twice the specified concentration of every soluble ingredient but the correct agar concentration. Colonies are unusually small despite adequate incubation. Which mechanism is most likely?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Reduced water activity and increased osmotic stress restrict radial growth
B. Reduced agar concentration allows colonies to disperse through the medium
C. Increased oxygen solubility causes irreversible oxidative sterilization
D. Complete absence of carbon forces the fungus to use agar as its substrate

60 One litre of final medium must contain 1% of a heat-labile supplement. Which preparation preserves the stated final concentration?

Preparation of different culture media for the isolation and cultivation of entomopathogenic microbes Hard
A. Prepare 990 mL of base and add 10 mL of supplement
B. Prepare 1000 mL of base and add 10 mL of supplement
C. Prepare 1000 mL of base and add 1 mL of supplement
D. Prepare 900 mL of base and add 1 mL of supplement
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