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BIO 120 > LAB 1ST DEPEX SAMPLE QUESTIONS > Flashcards

LAB 1ST DEPEX SAMPLE QUESTIONS Flashcards

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1
Q

What is the study of organisms and agents too small to be seen by the naked eye called?
A. Botany
B. Microbiology
C. Virology
D. Parasitology

A

B. Microbiology

Microbiology is the study of organisms less than 1mm in size that require a microscope for visualization.

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2
Q

Which of the following is the smallest known microbe?
A. Epulopiscium
B. Circovirus
C. SARS-CoV-2
D. Escherichia coli

A

B. Circovirus

Circovirus is 20 nm in diameter, making it the smallest known microbe.

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3
Q

Who was the first person to observe microorganisms?
A. Louis Pasteur
B. Robert Koch
C. Anton Van Leeuwenhoek
D. Joseph Lister

A

C. Anton Van Leeuwenhoek

Leeuwenhoek first observed bacteria and protozoa using a microscope he designed.

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4
Q

Which of the following is NOT one of the five major groups of microorganisms?
A. Bacteria
B. Fungi
C. Viruses
D. Plants

A

D. Plants

Plants are macroscopic and not included in the five major groups of microorganisms.

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5
Q

What part of the microscope connects the base to the head and supports the eyepiece tube?
A. Base
B. Arm
C. Nosepiece
D. Condenser

A

B. Arm

The arm connects the base and head of the microscope and aids in carrying it.

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6
Q

Which of the following is used to adjust the focus for high-definition imaging on a microscope?
A. Coarse adjustment knob
B. Fine adjustment knob
C. Condenser adjustment knob
D. Aperture

A

B. Fine adjustment knob

The fine adjustment knob is used for precise focusing, especially under high magnification.

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7
Q

Which microscope feature allows users to switch between objective lenses?
A. Nosepiece
B. Stage
C. Aperture
D. Condenser

A

A. Nosepiece

The nosepiece holds and rotates the objective lenses, allowing for changes in magnification.

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8
Q

What is the main cause if you see a completely black field in the ocular lens?
A. Dirty objective lens
B. The slide is upside down
C. The microscope is unplugged
D. The condenser is too low

A

C. The microscope is unplugged

A lack of power would result in no light being transmitted to the ocular lens.

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9
Q

If the image is blurred while using a microscope, which of the following is a possible cause?
A. The slide is upside down
B. The condenser is too low
C. The objective lens is dirty
D. The microscope is unplugged

A

C. The objective lens is dirty

A dirty objective lens can blur the image observed through the microscope.

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10
Q

Which part of the microscope controls the width of the light beam?
A. Field diaphragm
B. Condenser
C. Iris diaphragm
D. Aperture

A

A. Field diaphragm

The field diaphragm controls the width of the light beam entering the condenser.

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11
Q

What is the total magnification if you are using an eyepiece with 10x magnification and an objective lens with 40x magnification?
A. 100x
B. 400x
C. 40x
D. 10x

A

B. 400x

Total magnification is calculated by multiplying the magnification of the eyepiece by the objective lens (10x * 40x = 400x).

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12
Q

Which of the following has the highest magnification power?
A. LPO
B. HPO
C. OIO
D. Ocular lens

A

C. OIO

The oil immersion objective (OIO) typically has a magnification of 100x, the highest among the objective lenses.

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13
Q

Which type of microscope is best for viewing live, unstained cells?
A. Brightfield microscope
B. Phase-contrast microscope
C. Fluorescent microscope
D. Electron microscope

A

B. Phase-contrast microscope

Phase-contrast microscopes enhance contrast in unstained, live specimens.

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14
Q

What is the primary use of a fluorescent microscope?
A. To visualize the 3D structure of tissues
B. To view live cells in real-time
C. To detect antigen-antibody reactions
D. To examine internal cellular structures

A

C. To detect antigen-antibody reactions

Fluorescent microscopes are commonly used in immunofluorescence to detect antigen-antibody interactions.

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15
Q

Which microscope can provide the highest magnification?
A. Phase-contrast microscope
B. Fluorescent microscope
C. Scanning electron microscope
D. Transmission electron microscope

A

D. Transmission electron microscope

Transmission electron microscopes (TEM) provide magnifications up to 1,000,000x, higher than other microscopes.

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16
Q

Which of the following describes the process of destroying all living cells, spores, and viruses?
A. Antisepsis
B. Disinfection
C. Sterilization
D. Pasteurization

A

C. Sterilization

Sterilization is the absolute destruction or removal of all microbial life forms, including spores and viruses.

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17
Q

Which method of sterilization uses high-temperature steam under pressure?
A. Dry heat
B. Filtration
C. Moist heat
D. Pasteurization

A

C. Moist heat

Moist heat sterilization uses steam under pressure to destroy resistant forms such as endospores.

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18
Q

Which method of sterilization is most appropriate for heat-sensitive fluids like antibiotics?
A. Filtration
B. Direct flaming
C. Dry heat
D. Pasteurization

A

A. Filtration

Filtration is suitable for sterilizing heat-sensitive substances by physically removing microorganisms from fluids.

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19
Q

Which of the following is NOT an absolute sterilization technique?
A. Direct heat
B. Filtration
C. Disinfection
D. Moist heat

A

C. Disinfection

Disinfection does not guarantee the complete elimination of all forms of life, as some spores and viruses may remain.

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20
Q

Which biosafety level is required for handling microbes like Mycobacterium tuberculosis?
A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

A

C. BSL-3

BSL-3 is required for handling microbes that can cause serious or potentially lethal diseases through respiratory transmission.

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21
Q

Which of the following media is both selective and differential for Staphylococcus species?
A. MacConkey Agar
B. Blood Agar
C. Mannitol Salt Agar
D. Nutrient Agar

A

C. Mannitol Salt Agar

Mannitol Salt Agar is selective for Staphylococcus due to its high salt concentration and differential due to mannitol fermentation.

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22
Q

What is the purpose of an enrichment media?
A. To suppress the growth of unwanted microbes
B. To promote the growth of most organisms
C. To increase the number of desired microorganisms
D. To differentiate between microbial species

A

C. To increase the number of desired microorganisms

Enrichment media are designed to increase the number of a particular microorganism to detectable levels.

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23
Q

Which of the following biosafety levels requires the use of a full body, air-supplied positive pressure suit?
A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

A

D. BSL-4

BSL-4 is the highest level of containment, requiring specialized facilities and personal protective equipment, including a positive pressure suit.

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24
Q

If the microscope’s light flickers while in use, what is the most probable cause?
A. Dirty objective lens
B. The slide is upside down
C. The wiring is damaged
D. The condenser is too low

A

C. The wiring is damaged

Flickering light often indicates a problem with the electrical wiring or a bulb nearing the end of its life.

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25
Q

Which of the following is a possible cause of partial illumination in a microscope?
A. The objective lens is dirty
B. The condenser is not centered correctly
C. The slide is upside down
D. The coarse adjustment knob is used

A

B. The condenser is not centered correctly

Partial illumination can happen if the condenser is not properly aligned to focus light onto the specimen.

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26
Q

If you encounter difficulty focusing the microscope, what could be a potential reason?
A. The slide is not seated properly on the stage
B. The objective lens is not clicked into place
C. The microscope is unplugged
D. The diaphragm is closed

A

A. The slide is not seated properly on the stage

If the slide is not correctly positioned on the stage, the image might be out of focus.

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27
Q

Which of the following is NOT a recommended practice in a microbiology laboratory?
A. Wearing gloves and lab coats while working
B. Storing personal items like journals in the lab
C. Reporting any spills or accidents immediately
D. Keeping the laboratory clean and organized

A

B. Storing personal items like journals in the lab

Personal items should be kept out of the lab to prevent contamination and maintain a sterile environment.

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28
Q

Which of the following best describes aseptic techniques?
A. Techniques to sterilize all equipment
B. Methods to prevent contamination of cultures
C. Methods to kill all microorganisms
D. Techniques to disinfect surfaces

A

B. Methods to prevent contamination of cultures

Aseptic techniques are used to prevent the introduction of unwanted microorganisms into a culture or sterile environment.

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29
Q

Which of the following is an example of a physical method of sterilization?
A. Antisepsis
B. Filtration
C. Use of disinfectants
D. Use of antibiotics

A

B. Filtration

Filtration is a physical method where microorganisms are physically removed from liquids or gases.

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30
Q

Which of the following forms of heat sterilization is most effective for sterilizing heat-sensitive liquids?
A. Dry heat sterilization
B. Flaming
C. Moist heat sterilization
D. Filtration

A

D. Filtration

Filtration is used for sterilizing heat-sensitive liquids such as enzymes and antibiotics that would be damaged by heat.

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31
Q

Which of the following is the correct definition of disinfection?
A. The complete elimination of all forms of microbial life
B. The reduction or inhibition of microbial growth
C. The process of removing all viruses
D. The destruction of spores

A

B. The reduction or inhibition of microbial growth

Disinfection reduces or inhibits microbial growth but does not necessarily kill all microorganisms or spores.

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32
Q

Which form of sterilization is commonly used to sterilize wire loops and needles in microbiology labs?
A. Dry heat in an oven
B. Direct flaming
C. Pasteurization
D. Filtration

A

B. Direct flaming

Direct flaming is commonly used to sterilize metal instruments like wire loops and needles by burning them in a flame.

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33
Q

What type of medium is MacConkey Agar?
A. Selective only
B. Differential only
C. Both selective and differential
D. General purpose

A

C. Both selective and differential

MacConkey Agar is selective for Gram-negative bacteria and differentiates lactose fermenters from non-lactose fermenters.

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34
Q

What is the primary purpose of using a semi-solid medium?
A. To grow a large number of microorganisms
B. To test for bacterial motility
C. To isolate pure colonies
D. To differentiate bacterial species

A

B. To test for bacterial motility

Semi-solid media have a lower concentration of agar and are used to observe bacterial motility.

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35
Q

Which of the following is a general-purpose medium used for growing most microorganisms?
A. Blood Agar
B. Nutrient Agar
C. Mannitol Salt Agar
D. Eosin Methylene Blue Agar

A

B. Nutrient Agar

Nutrient Agar supports the growth of a wide range of non-fastidious organisms and is used for general purposes.

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36
Q

A culture medium that contains exact concentrations of known chemicals is called a:
A. Complex medium
B. Defined medium
C. Selective medium
D. Differential medium

A

B. Defined medium

Chemically-defined media contain specific amounts of pure chemicals, unlike complex media where the exact composition is unknown.

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37
Q

Which of the following describes an enrichment medium?
A. Suppresses the growth of unwanted microorganisms
B. Increases the number of desired microorganisms
C. Differentiates microorganisms based on metabolic activity
D. Allows the growth of most non-fastidious organisms

A

B. Increases the number of desired microorganisms

Enrichment media enhance the growth of specific microorganisms by providing essential nutrients.

38
Q

Which biosafety level (BSL) is appropriate for work involving organisms that are not known to cause disease in healthy adults?
A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

A

A. BSL-1

BSL-1 is the lowest biosafety level, used for organisms that pose minimal risk to healthy individuals.

39
Q

Which of the following is an example of a BSL-3 organism?
A. Non-pathogenic Escherichia coli
B. Staphylococcus aureus
C. Mycobacterium tuberculosis
D. Ebola virus

A

C. Mycobacterium tuberculosis

Mycobacterium tuberculosis is handled in BSL-3 laboratories due to the potential for serious respiratory infections.

40
Q

Which biosafety level requires a full-body, air-supplied positive pressure suit?
A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

A

D. BSL-4

BSL-4 laboratories handle the most dangerous pathogens, requiring full-body suits and extensive containment.

41
Q

In a BSL-2 laboratory, what precaution is taken to prevent infection from aerosol-generating activities?
A. Work is done on an open bench
B. Use of a biological safety cabinet (BSC)
C. Use of gloves only
D. Use of full-body protective suits

A

B. Use of a biological safety cabinet (BSC)

In BSL-2 labs, procedures that generate aerosols are performed inside a biological safety cabinet to reduce exposure.

42
Q

What is the relationship between magnification and focal point in microscopy?
A. They are directly proportional
B. They are inversely related
C. They are unrelated
D. Magnification increases focal point

A

B. They are inversely related

As magnification increases, the focal point decreases.

43
Q

Which of the following enhances the resolution of a microscope?
A. Decreasing the numerical aperture
B. Increasing the working distance
C. Increasing the numerical aperture
D. Decreasing light intensity

A

C. Increasing the numerical aperture

A higher numerical aperture increases the resolving power of a microscope, improving the clarity of fine details.

44
Q

What is the smallest distance that the lens is able to distinguish two points as separate called?
A. Magnification
B. Working distance
C. Limit of resolution
D. Numerical aperture

A

C. Limit of resolution

The limit of resolution defines the smallest distance at which two points can be distinguished as separate.

45
Q

What is the correct order for setting up Köhler illumination?
A. Focus the specimen, close the field diaphragm, center the light
B. Open the field diaphragm, focus the condenser, adjust the light
C. Adjust the light intensity, close the aperture diaphragm, focus the condenser
D. Close the field diaphragm, focus the specimen, adjust the condenser

A

A. Focus the specimen, close the field diaphragm, center the light

Proper Köhler illumination setup involves focusing the specimen, adjusting the field diaphragm, and centering the light.

46
Q

Which type of electron microscope is used to observe the 3D surface of a specimen?
A. Transmission electron microscope (TEM)
B. Scanning electron microscope (SEM)
C. Phase-contrast microscope
D. Fluorescent microscope

A

B. Scanning electron microscope (SEM)

SEM provides detailed 3D images of the surface of specimens.

47
Q

What is the source of illumination in an electron microscope?
A. Tungsten light
B. Laser beam
C. Beam of electrons
D. Fluorescent dye

A

C. Beam of electrons

Electron microscopes use a beam of electrons instead of light to illuminate the specimen.

48
Q

If the bulb in a microscope is getting ready to burn out, what symptom might you observe?
A. A black field in the ocular
B. Light flickering
C. Blurred image
D. Partial illumination

A

B. Light flickering

Flickering light is a common sign that the microscope bulb is nearing the end of its life.

49
Q

Which of the following is a cause of a blurred image during microscopy?
A. Oil on the stage
B. The objective lens is dirty
C. The slide is upside down
D. The microscope is unplugged

A

B. The objective lens is dirty

A dirty objective lens can result in a blurred image, as it obstructs the passage of light.

50
Q

Which of the following is a key feature of a parfocal microscope?
A. It requires refocusing each time the objective lens is changed
B. It maintains focus when switching between objectives
C. It automatically adjusts light intensity
D. It uses electron beams for illumination

A

B. It maintains focus when switching between objectives

Parfocal microscopes are designed so that the image remains in focus when changing objective lenses.

51
Q

What is a pure culture in microbiology?
A. A culture with multiple types of microorganisms
B. A culture with only one type of microorganism
C. A culture containing fungi and bacteria
D. A culture with mixed colonies

A

B. A culture with only one type of microorganism

A pure culture arises from a single cell and is composed of only one type of microorganism.

52
Q

Which of the following is a method for isolating pure colonies?
A. Gram staining
B. Serial dilution
C. Hanging drop technique
D. Catalase test

A

B. Serial dilution

Serial dilution is used to thin out microbial populations, allowing for the isolation of single colonies.

53
Q

In streak plating, what is the primary purpose?
A. To quantify bacteria
B. To isolate single bacterial colonies
C. To test for antibiotic resistance
D. To grow anaerobic bacteria

A

B. To isolate single bacterial colonies

Streak plating is used to separate individual bacteria from a mixed population for the purpose of isolating pure colonies.

54
Q

What is the purpose of autoclaving media before use?
A. To warm the media
B. To sterilize the media
C. To dry the media
D. To cool the media

A

B. To sterilize the media

Autoclaving is used to sterilize media by subjecting it to high-pressure saturated steam to eliminate all microorganisms.

55
Q

Selective media are used to:
A. Inhibit the growth of certain microorganisms
B. Support the growth of all microorganisms
C. Differentiate between types of microorganisms based on chemical reactions
D. Maintain the life of microorganisms for long periods

A

A. Inhibit the growth of certain microorganisms

Selective media contain compounds that inhibit the growth of certain organisms while allowing others to grow.

56
Q

Which medium is both selective and differential?
A. Nutrient agar
B. MacConkey agar
C. Mannitol salt agar
D. Blood agar

A

B. MacConkey agar

MacConkey agar is selective for Gram-negative bacteria and differentiates them based on lactose fermentation.

57
Q

In the short-term preservation method, subculturing is prone to:
A. Reduce the metabolic rate of microorganisms
B. Generate spontaneous mutants
C. Prevent contamination
D. Increase the metabolic rate of microorganisms

A

B. Generate spontaneous mutants

Frequent subculturing can lead to the selection of mutants due to the replication of organisms over time.

58
Q

What is the preferred temperature for storing bacterial cultures in short-term preservation?
A. -20°C
B. 37°C
C. 4°C to 8°C
D. Room temperature

A

C. 4°C to 8°C

Refrigeration at 4°C to 8°C slows down the metabolic rate of the organisms, extending their viability for up to 2 months.

59
Q

Which of the following is a cryoprotective agent used in freezing at -20°C?
A. Agar
B. Glycerol
C. Ethanol
D. Glucose

A

B. Glycerol

Glycerol is a cryoprotective agent that protects cells during freezing by preventing ice crystal formation.

60
Q

Which of the following long-term preservation techniques can sustain cells for more than 50 years?
A. Subculturing
B. Storage in distilled water
C. Ultralow-temperature freezing
D. Immersing in oil

A

C. Ultralow-temperature freezing

Microorganisms can be maintained for more than 50 years at temperatures of −70°C or lower.

61
Q

The wet mount technique is primarily used to observe:
A. Stained bacterial cells
B. Living microorganisms
C. Bacterial spores
D. Gram-positive bacteria

A

B. Living microorganisms

Wet mounts allow for the observation of live microorganisms, including their motility and natural behavior.

62
Q

Which slide preparation technique is best for continuous observation of motility?
A. Wet mount
B. Hanging drop technique
C. Heat fixing
D. Simple staining

A

B. Hanging drop technique

The hanging drop technique is ideal for continuous observation of true motility in microorganisms.

63
Q

Which of the following is true about Brownian motion?
A. It represents true motility
B. It occurs due to the self-movement of bacteria
C. It is the random movement caused by collisions with water molecules
D. It is directional movement across larger areas

A

C. It is the random movement caused by collisions with water molecules

Brownian motion is caused by water molecules colliding with the organism, resulting in random movement.

64
Q

Which stain is used in Gram staining to color Gram-positive bacteria?
A. Safranin
B. Methylene blue
C. Crystal violet
D. Malachite green

A

C. Crystal violet

In Gram staining, crystal violet is the primary stain that colors Gram-positive bacteria purple.

65
Q

Which of the following can be stained by using acidic dyes?
A. Bacterial cells
B. Cell walls
C. The background of the slide
D. Spores

A

C. The background of the slide

Acidic dyes stain the background in negative staining, leaving the cells colorless.

66
Q

What is the primary purpose of heat-fixing a bacterial smear?
A. To stain the bacteria
B. To kill the bacteria and fix them to the slide
C. To apply the mordant to the bacteria
D. To increase the contrast of the bacteria

A

B. To kill the bacteria and fix them to the slide

Heat-fixing kills the bacteria and adheres them to the slide so that they are not washed away during staining.

67
Q

Which of the following stains is used to visualize bacterial endospores?
A. Crystal violet
B. Safranin
C. Malachite green
D. Methylene blue

A

C. Malachite green

Malachite green is used to stain endospores, which are resistant structures that require a primary stain under heat.

68
Q

What is the purpose of a mordant in flagella staining?
A. To bind the primary stain to the cell wall
B. To increase the diameter of the flagella
C. To fix the dye to the bacterial capsule
D. To differentiate Gram-positive from Gram-negative bacteria

A

B. To increase the diameter of the flagella

The mordant in flagella staining thickens the flagella, making them visible under a microscope.

69
Q

A positive result in the Simmon’s citrate test is indicated by:
A. A color change from green to blue
B. Bubbles forming in the medium
C. A black precipitate forming
D. No color change in the medium

A

A. A color change from green to blue

In Simmon’s citrate test, a color change from green to blue indicates citrate utilization by the organism.

70
Q

The Triple Sugar Iron (TSI) test differentiates bacteria based on all of the following EXCEPT:
A. Glucose fermentation
B. Hydrogen sulfide production
C. Lactose fermentation
D. Urease production

A

D. Urease production

TSI test differentiates bacteria based on their ability to ferment sugars and produce hydrogen sulfide, but not urease.

71
Q

What does the presence of a black precipitate in the SIM test indicate?
A. Citrate utilization
B. Indole production
C. Hydrogen sulfide production
D. Catalase activity

A

C. Hydrogen sulfide production

The black precipitate in the SIM test indicates the production of hydrogen sulfide, which reacts with iron salts.

72
Q

Which biochemical test is used to detect the enzyme catalase?
A. SIM test
B. TSI test
C. Catalase test
D. Citrate test

A

C. Catalase test

The catalase test detects the enzyme catalase by the formation of bubbles when hydrogen peroxide is added to the culture.

73
Q

A positive catalase test result is observed as:
A. A color change to blue
B. The formation of bubbles
C. The appearance of a black precipitate
D. A red ring forming at the top of the tube

A

B. The formation of bubbles

The formation of bubbles indicates the breakdown of hydrogen peroxide by catalase into water and oxygen.

74
Q

Which reagent is added to detect indole production in the SIM test?
A. Methylene blue
B. Crystal violet
C. Kovac’s reagent
D. Safranin

A

C. Kovac’s reagent

Kovac’s reagent reacts with indole to produce a red color, indicating positive indole production.

75
Q

Which of the following bacteria retain the crystal violet stain in Gram staining?
A. Gram-negative bacteria
B. Gram-positive bacteria
C. Acid-fast bacteria
D. Endospore-forming bacteria

A

B. Gram-positive bacteria

Gram-positive bacteria retain the crystal violet stain due to their thick peptidoglycan cell walls.

76
Q

What color do Gram-negative bacteria appear after Gram staining?
A. Purple
B. Blue
C. Red or pink
D. Green

A

C. Red or pink

Gram-negative bacteria appear red or pink after Gram staining due to the counterstain (safranin) used after decolorization.

77
Q

What is the purpose of the decolorizer in Gram staining?
A. To fix the crystal violet stain
B. To wash off the primary stain from Gram-negative cells
C. To enhance the color of Gram-positive cells
D. To stain the background

A

B. To wash off the primary stain from Gram-negative cells

The decolorizer, usually alcohol or acetone, removes the crystal violet stain from Gram-negative cells, allowing them to take up the counterstain.

78
Q

Acid-fast staining is used to identify:
A. Gram-positive organisms
B. Gram-negative organisms
C. Mycobacterium species
D. Spore-forming bacteria

A

C. Mycobacterium species

Acid-fast staining is used to differentiate acid-fast bacteria, such as Mycobacterium, due to their waxy cell walls.

79
Q

Which of the following is true about acid-fast bacteria?
A. They have thick peptidoglycan layers
B. Their cell walls contain mycolic acid
C. They are stained by basic dyes
D. They are resistant to crystal violet

A

B. Their cell walls contain mycolic acid

Acid-fast bacteria have a wax-like cell wall rich in mycolic acid, which makes them resistant to decolorization by acid-alcohol.

80
Q

Which stain is used as the primary stain in endospore staining?
A. Crystal violet
B. Safranin
C. Malachite green
D. Nigrosin

A

C. Malachite green

Malachite green is used as the primary stain in endospore staining, with heat applied to help the dye penetrate the endospores.

81
Q

In capsule staining, what is stained by acidic dyes?
A. The capsule
B. The bacterial cell
C. The background
D. The cell wall

A

C. The background

In capsule staining, the background is stained with acidic dyes, while the capsule remains unstained.

82
Q

Which of the following is NOT true about flagella staining?
A. It uses a mordant to increase the diameter of the flagella
B. Flagella are typically too thin to be seen without staining
C. Flagella can be visualized without any staining
D. The mordant helps the stain adhere to the flagella

A

C. Flagella can be visualized without any staining

Flagella are too thin to be seen under a light microscope without the use of a mordant and special staining.

83
Q

Which of the following accurately describes true motility?
A. Movement caused by water molecules colliding with cells
B. Random movement without direction
C. Directional movement across larger areas
D. Movement only in a circular pattern

A

C. Directional movement across larger areas

True motility refers to purposeful, directional movement as opposed to random Brownian motion.

84
Q

Which technique is most appropriate for observing bacterial motility over a prolonged period?
A. Gram staining
B. Hanging drop technique
C. Wet mount
D. Simple staining

A

B. Hanging drop technique

The hanging drop technique allows for extended observation of motility without drying out the sample.

85
Q

Which of the following is a differential medium used to distinguish bacteria based on hemolysis?
A. Blood agar
B. Nutrient agar
C. Sabouraud agar
D. MacConkey agar

A

A. Blood agar

Blood agar is a differential medium that distinguishes bacteria based on their hemolytic activity.

86
Q

Triple Sugar Iron (TSI) agar differentiates bacteria based on their ability to ferment:
A. Lactose, sucrose, and maltose
B. Glucose, sucrose, and lactose
C. Glucose, fructose, and sucrose
D. Lactose, maltose, and galactose

A

B. Glucose, sucrose, and lactose

TSI agar differentiates bacteria based on their ability to ferment glucose, sucrose, and lactose.

87
Q

Which of the following is a short-term preservation method?
A. Lyophilization
B. Subculturing
C. Freezing at -70°C
D. Ultralow freezing

A

B. Subculturing

Subculturing is a short-term preservation method where cultures are periodically transferred to fresh medium.

88
Q

What is the main disadvantage of subculturing as a preservation method?
A. It is expensive
B. It requires cryoprotective agents
C. It can lead to spontaneous mutants
D. It is a long-term method

A

C. It can lead to spontaneous mutants

Subculturing over time can result in the selection of spontaneous mutants, altering the original characteristics of the culture.

89
Q

Which of the following cryoprotective agents is commonly added to protect cells during freezing?
A. Agar
B. Glycerol
C. Ethanol
D. Sodium chloride

A

B. Glycerol

Glycerol is a commonly used cryoprotective agent that protects cells during freezing by preventing ice crystal formation.

90
Q

Freeze-drying (lyophilization) is effective because it:
A. Uses high temperatures to kill bacteria
B. Removes water from cells without forming ice crystals
C. Stains bacteria for long-term storage
D. Requires anaerobic conditions

A

B. Removes water from cells without forming ice crystals

Freeze-drying removes water from cells under reduced pressure, preventing ice crystal formation and preserving cell viability.

BIO 120 (12 decks)

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