1.6.4: Multiple Choice / Multiple Select

1. The Centers for Disease Control and Prevention (CDC) classifies microorganisms into how many biosafety levels (BSL)?

• a) Two
• b) Three
• c) Four
• d) Five
• e) Six

2. The four biosafety levels classify microorganisms according to:

• a) The level of measures needed to safely work with the organism
• b) The temperature at which the organism grows best
• c) The type of growth media the organism requires
• d) The size of the colonies the organism produces

3. A microorganism that is capable of causing disease is best described as a:

• a) Fastidious organism
• b) Pathogen
• c) Inoculum
• d) Anaerobe
• e) Solidifying agent

4. If a chemical or other agent splashes into your eyes, you should flush your eyes at the eyewash station for a minimum of:

• a) 5 minutes
• b) 10 minutes
• c) 15 minutes
• d) 20 minutes
• e) 30 minutes

5. If your body or clothing is exposed to chemicals or infectious agents, you should remain under the emergency safety shower for a minimum of:

• a) 5 minutes
• b) 10 minutes
• c) 15 minutes
• d) 20 minutes

6. While wearing examination gloves, a student must NOT do which of the following? Select all that apply.

• a) Leave the laboratory room
• b) Touch a microscope or other equipment
• c) Touch personal items such as a cell phone
• d) Touch doorknobs
• e) Handle the assigned culture at their own bench

7. How should UNCONTAMINATED broken glassware be handled?

• a) Picked up with bare hands and placed in the trash can
• b) Moved with a broom and dustpan into the container marked Broken Glass
• c) Picked up with bare hands and placed in the container marked Broken Glass
• d) Moved with autoclavable tongs into the biohazard container

8. How should CONTAMINATED broken glassware be handled?

• a) Placed directly into the container marked Broken Glass
• b) Transported with autoclavable tongs to the appropriate autoclave/biohazard container
• c) Rinsed with disinfectant and placed in the trash can
• d) Swept up with a broom and placed in the trash can

9. Which materials are considered biohazardous and must be placed in a biohazard container?

• a) Any glassware, whether or not it has contacted microorganisms
• b) Materials that have been exposed to bodily fluids or microorganisms
• c) Only materials that are visibly soiled
• d) Any item used during a laboratory session

10. How are the contents of a biohazard container treated before they are disposed of?

• a) They are soaked in disinfectant for 20 minutes
• b) They are autoclaved to sterilize the contents
• c) They are rinsed with deionized water
• d) They are placed in the broken glass container

11. You spill a bacterial culture on your lab bench. Which actions are part of the correct protocol? Select all that apply.

• a) Cover the spill with paper towels
• b) Soak the towels with disinfectant and allow them to stand for 20 minutes
• c) Report the spill to your instructor
• d) Place the used paper towels in the container marked for autoclaving
• e) Rinse the area with water and continue working

12. Which precautions must be taken when working with open flames in the laboratory? Select all that apply.

• a) Secure loose hair and dangling jewelry
• b) Secure loose clothing and nearby paper
• c) Never leave a hot plate or Bunsen burner unattended
• d) Keep containers of alcohol or acetone at a safe distance from flames
• e) Lay the hot inoculating loop on the bench to cool

13. How should any microorganism handled in a microbiology laboratory be regarded?

• a) As harmless, provided it was purchased from a commercial supplier
• b) As a potential pathogen
• c) As a BSL-3 organism
• d) As harmless unless it is labeled with a biohazard symbol

14. Bright-field microscopy uses white light to visualize the specimen. Because the specimen absorbs the light, it appears ______ than the surrounding background.

• a) Darker
• b) Brighter
• c) More magnified
• d) Colorless

15. Which term refers to the ability to distinguish two objects from one another?

• a) Magnification
• b) Contrast
• c) Resolution
• d) Refraction

16. Which term refers to the difference in light intensity between the specimen and the background?

• a) Resolution
• b) Contrast
• c) Total magnification
• d) Working distance

17. Magnification alone will not produce a quality image. What else must be achieved? Select all that apply.

• a) Resolution
• b) Contrast
• c) A higher ocular lens power
• d) A thicker specimen

18. Why are biological specimens generally stained before they are observed?

• a) They usually lack the contrast needed to observe details
• b) Staining increases the total magnification
• c) Staining prevents the slide from breaking
• d) Staining is required before the coarse focus knob can be used

19. Immersion oil is used with the oil immersion objective lens because it:

• a) Increases the magnifying power of the lens
• b) Prevents the loss of light due to refraction, thereby preserving resolution
• c) Cleans the surface of the lens
• d) Kills bacteria present on the slide

20. Which objective lenses are dry objectives, meaning they do not require immersion oil to maintain good resolution? Select all that apply.

• a) Scanning
• b) Low power
• c) High power
• d) Oil immersion

21. The coarse focus (adjustment) knob should be used only with which objective lens?

• a) The 4x scanning objective
• b) The 10x low-power objective
• c) The 40x high-power objective
• d) The 100x oil immersion objective

22. A compound microscope has a 10x ocular lens. What is the total magnification when the 40x high-power objective is in use?

• a) 40x
• b) 50x
• c) 400x
• d) 4000x

23. Your microscope objectives are parfocal. What does this mean?

• a) All objective lenses provide the same total magnification
• b) When the specimen is in focus with one objective, it should stay in focus when you move to another objective
• c) The objectives can be used without adding immersion oil
• d) The condenser automatically adjusts the light for each objective

24. As you increase objective magnification power, what adjustment becomes necessary, and which component is used to make it?

• a) Less light is needed; the coarse focus knob is used
• b) More light is needed; the iris diaphragm aperture lever is used
• c) Less light is needed; the revolving nose-piece is used
• d) More light is needed; the stage control knobs are used

25. What is the correct way to bring the oil immersion objective lens into use?

• a) Place a drop of oil on the slide while the high-power lens is in position, then rotate to the oil lens
• b) Rotate the nose-piece so the space between the high-power and oil immersion lenses is over the slide, place a small drop of oil on the slide, then slowly rotate the oil lens into place
• c) Rotate the oil immersion lens into place first, then add oil to the top of the lens
• d) Add oil to the condenser before rotating the oil immersion lens into place

26. After you finish viewing a specimen with the oil immersion lens, the oil is removed using:

• a) Deionized water and a paper towel
• b) Lens cleaner and a lens cleaning cloth or lens paper
• c) Disinfectant solution and a Kim wipe
• d) Immersion oil and a dustpan brush

27. Agar is derived from the cell walls of algal cells. Why is it useful as a solidifying agent in microbiology?

• a) It provides essential nutrients for all bacteria
• b) Microorganisms are unable to digest it
• c) It removes oxygen from the media
• d) It causes bacteria to produce a distinct color change

28. Which of the following are examples of complex media? Select all that apply.

• a) Tryptic soy media
• b) Brain heart media
• c) Nutrient media
• d) A medium in which the exact chemical composition and quantities are known

29. Semi-solid media contain what amount of agar, and for which test are they commonly used?

• a) 1.5%-2% agar; isolation on petri plates
• b) 0.5% or less agar; motility tests
• c) No agar; serial dilutions
• d) 2% or more agar; long-term cold storage

30. Which media are BOTH selective and differential? Select all that apply.

• a) Mannitol salt agar
• b) MacConkey agar
• c) Eosin methylene blue agar
• d) Sterile nutrient broth

31. Anaerobic media are made using an ingredient that binds to and reduces oxygen in the media. Which ingredient serves this purpose?

• a) Agar
• b) Sodium thioglycolate
• c) Immersion oil
• d) Methylene blue

32. How can you tell that bacteria are growing in a broth culture?

• a) The broth becomes cloudy
• b) The broth remains clear
• c) The broth solidifies
• d) The broth separates into layers

33. One advantage of broth media is the ability to grow organisms at various concentrations of oxygen. Where are oxygen levels highest in a broth tube?

• a) At the surface of the liquid
• b) At the bottom of the tube
• c) Evenly distributed throughout the tube
• d) Oxygen is absent from all broth media

34. What is the purpose of transport media?

• a) To encourage rapid multiplication of the sample during transport
• b) To maintain the microorganism being transported without permitting its multiplication
• c) To differentiate organisms based on color changes during transport
• d) To remove oxygen from the sample during transport

35. Enriched media such as blood agar and chocolate agar are used to grow:

• a) Only anaerobic organisms
• b) Fastidious microorganisms requiring additional nutrients and growth factors
• c) Organisms that cannot digest agar
• d) Organisms being held for transport to a clinical laboratory

36. A glass spreading rod is bent into an L-shape and is used to:

• a) Stab semi-solid media during a motility test
• b) Spread an inoculum over the surface of a solid medium
• c) Transfer a loopful of broth culture to a slant
• d) Remove broken glass from the laboratory bench

37. For which tasks is an inoculating loop used? Select all that apply.

• a) Transferring bacteria from one type of media to another
• b) Performing the streak plate isolation method
• c) Transferring a sample to a microscope slide to create a smear
• d) Stabbing media during a motility test

38. What advantage is gained when solid media is poured into a petri plate rather than a test tube?

• a) It produces a large surface area, allowing isolation and observation of colony morphology
• b) It allows bacteria to be stored longer in cold storage
• c) It permits the growth of motile bacteria only
• d) It removes the need to use aseptic technique

39. To say that microorganisms are ubiquitous means that they are:

• a) Present everywhere, including the air, on and in our bodies, and on laboratory benches
• b) Found only in clinical specimens
• c) Able to grow only on enriched media
• d) Harmless to healthy individuals

40. Aseptic technique aims to prevent contamination of which of the following? Select all that apply.

• a) Your sample
• b) Your work space
• c) Yourself
• d) The microscopes stored in the cabinet

41. Which of the following are examples of aseptic techniques? Select all that apply.

• a) Washing hands properly
• b) Disinfecting work surfaces
• c) Sterilizing inoculating tools
• d) Incubating plates in an inverted position

42. When adjusting the Bunsen burner, why is the inner blue cone important?

• a) It is the hottest portion of the flame, and is where the inoculating tool is sterilized
• b) It indicates the gas shut-off valve is closed
• c) It is the coolest portion of the flame, and is where the loop is allowed to cool
• d) It shows that the burner is safe to leave unattended

43. After flaming an inoculating loop until it is red hot, you should:

• a) Use it immediately while it is still hot
• b) Let it cool approximately 15-30 seconds without laying it down or letting it bump anything
• c) Lay it on the lab bench for 1 minute to cool
• d) Rinse it with deionized water to cool it quickly

44. How is the cap of a culture tube handled during an aseptic transfer?

• a) It is set on the lab bench beside the tube
• b) It is removed using the last two fingers of the dominant hand and is never set down on the bench
• c) It is removed with the non-dominant hand and placed in a test tube rack
• d) It is left on the tube and the loop is inserted alongside it

45. Why is a broth culture tube flicked before a sample is removed?

• a) To warm the culture to incubation temperature
• b) Because bacteria settle in the tube and need to be suspended for transfer
• c) To force air into the bottom of the tube for aerobic growth
• d) To check the cap for a tight seal

46. What information must be written on media you have inoculated? Select all that apply.

• a) Your initials
• b) Your lab section
• c) The date
• d) The initials of the bacteria provided by your instructor
• e) The total magnification you will use to view it

47. When labeling a petri dish, where should the information be placed?

• a) On the lid, so it can be read without disturbing the plate
• b) On the bottom, the portion containing the agar
• c) On a piece of tape placed across the seam of the plate
• d) On the side of the plate using a China marker

48. When inoculating a petri plate, why is only one side of the lid lifted rather than removing it completely?

• a) Microbes present in the air would fall into the plate and contaminate the sample
• b) The agar would dry out too quickly
• c) The lid is difficult to reseat once removed
• d) Removing the lid would cool the media below growth temperature

49. Under what conditions are inoculated petri plates incubated?

• a) Inverted, at 37°C, for 24-48 hours
• b) Upright, at room temperature, for 24-48 hours
• c) Inverted, at 37°C, for 15-30 minutes
• d) Upright, at 37°C, for at least one week

50. Inoculated petri plates are incubated in an inverted position primarily to:

• a) Prevent condensation from raining down onto the sample
• b) Increase the oxygen available to the culture
• c) Speed up bacterial growth
• d) Keep the labeling visible from above

51. A pure culture is a culture that contains:

• a) A single species
• b) Two or more species
• c) Only motile organisms
• d) Only organisms that can be grown on enriched media

52. Identification procedures and protocols performed in the microbiology laboratory are dependent upon the use of:

• a) Mixed cultures
• b) Pure cultures
• c) Broth cultures only
• d) Transport media

53. The sample that is introduced to a growth medium is known as the:

• a) Inoculum
• b) Subculture
• c) Slant
• d) Pure culture

54. Samples sent to a microbiology laboratory for identification and analysis are typically:

• a) Pure samples containing a single organism
• b) Mixed samples, meaning more than one microorganism is present
• c) Sterile samples containing no organisms
• d) Samples that have already been streaked for isolation

55. From which of the following clinical sources might a microbial sample be taken? Select all that apply.

• a) Sputum
• b) Fecal material
• c) Urine
• d) Blood

56. The streak plate technique produces isolated colonies because the sample is:

• a) Progressively diluted as it is streaked across the surface of the solid media
• b) Stabbed into the depth of the agar
• c) Suspended evenly throughout a liquid broth
• d) Spread across the plate with a glass spreading rod

57. During the streak plate procedure, why is the inoculating loop flamed and allowed to cool between quadrants?

• a) To continue diluting the sample so that isolated colonies can develop
• b) To keep the agar surface from melting
• c) To warm the loop before it touches the next quadrant
• d) To prevent the petri plate lid from becoming contaminated

58. Besides the streak plate technique, which of the following are isolation techniques employed in the laboratory? Select all that apply.

• a) The pour plate technique
• b) The spread plate technique
• c) The aseptic transfer technique
• d) The motility stab technique