Micro Lab exam #1

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1

Which part of the microscope condenses the light and focuses it on the specimen?

Condenser lens

2

What is the term used to state that microbes are found everywhere?

Ubiquitous

3

Which of the following is an incorrect way to aseptically transfer cultures?

A. Sterilize loop end until red hot in the bottom of the flame
B. Heat tube rim and stopper before inserting loop
C. Place stopper/lid on the table while transferring bacteria***
D. Let loop cool before touching cultures

4

Typically growth media is sterilized in an __________ which utilizes steam under pressure.

Autoclave

5

Name two out of the four differences between simple and negative stains.

Simple – basic, positive, stains cells, heat-fixed
Negative – negative, acidic, stains slide, not heat-fixed

6

True or False: Bacteria and fungi exist as resident flora and outnumber human cells by 10:1

True

7

Which safety guideline is not correct?

A. Wash your hands before and after your experiment
B. Be careful of lose clothing, long hair, and dangling jewelry
C. Do not use butane lighters to ignite the Bunsen burners
D. Throw broken glass into the trash can***

8

True or False: It is okay to mouth pipette substances and smell cultures

False

9

__________ means that the image should stay in focus when you change lenses

Parfocal

10

True or False: A danger of using heat to fix a specimen is that cells may become damaged or their cellular structures may become distorted.

True

11

Why is colony number more important than colony size?

Colony number gives you more of an indication of the number of species/organisms you started out with, while colony size just tells you that the colony is growing

12

What is the term that describes structural stains that detect specific physical and chemical characteristics of a cell?

Differential Stains

13

What are two differences between a gram positive and a gram negative cell?

Gram+ = Stains purple, peptidoglycan, thick cell walls, no lipopolysaccharide layer, teichoic acids

Gram- = Stains red, no peptidoglycan, thin cell walls, lipopolysaccharide layer, teichoic acids

14

What is the additional cell wall component in Mycobacterium and Norcardia?

A. Mycolic Acid**
B. Petidoglycan
C. Anionic Cells
D. Lipopolysaccharide Layer

15

A less common structure that can be detected through staining is the bacterial __________.

Endospore

16

True or False: Bacteria are complex single-celled organisms; therefore, many species do not share a common cell morphology and/or arrangement.

False

17

True or False: Determining the gram reaction for bacteria isolated from clinical specimens is vital in prescribing the appropriate antibiotic

True

18

What is the main cell wall component in gram positive bacteria?

Peptidoglycan

19

What does a capsule help a bacteria do?

A. Escape from phagocytic cells
B. Resist dessication
C. Aids them in attachment
D. All of the above**

20

__________ can even be used in some cases to distinguish between pathogenic and nonpathogenic strains of a particular bacterial species.

Capsules

21

What is the term for the following bacterial orientation: Chains of Cells?

Strepto

22

Antimicrobial chemical are typically classified as either __________ or disinfectants.

Antiseptics

23

What is the difference between disinfectants and antiseptics?

Disinfectants are for use on inanimate objects, while antiseptics are safe for use on living tissue

24

True or False: Antimicrobial chemicals are capable of eliminating all microbes.

False

25

What is the test most widely used for determining the sensitivity of microbes to antimicrobial drugs?

Kirby-Bauer Method

26

What is the term for the area with no bacterial growth?

A. Zone of diffusion
B. Zone of inhibition**
C. Zone of misery
D. Zone of selection

27

The _________ of the zone of inhibition indicates the level of effectiveness for a given compound against the organism.

Size

28

True or False: The efficacy of a compound may vary depending on the characteristics of the microbe it is being tested against.

True

29

Term used when a drug causes little to no damage to the host cells and tissues.

Selective Toxicity

30

A chemical that is produced by microbes that limits the growth of other microbes

A. Bactericide
B. Antiseptic
C. Antibiotic**
D. Disinfectant

31

What is the medical use for the toxin produced by Clostridium botulinum?

Botox

32

True or False: Water has great potential to serve as a vehicle for the transmission of pathogens.

True

33

Milk contains __________, fats, and sugars in addition to many __________ and minerals necessary for microbial growth.

Proteins;Vitamins

34

Coliforms are gram __________ bacteria commonly found in the intestines of vertebrates.

Negative

35

A common method for detecting and enumerating coliforms in water

A. EMB Agar
B. Most Probable Number**
C. Disk Diffusion Test
D. Gram-Staining

36

What is the term for the process that removes both potential spoilage organisms and pathogens?

Pasteurization

37

What are the four test involved in a IMViC test?

Indole production, Methyl-red test, Voges-Proskauer test, citrate utilization

38

True or False: Standard methods of pasteurization are to completely sterilize milk

False

39

Colonies are referred to instead as a __________ that allows for the more likely possibility of a colony originating from a small clump of cells.

Colony Forming Unit (CFU)

40

What is an example of an acidic dye?

India ink

41

Acid-fast staining is useful for identifying the causative agent of _______.

Tuberculosis

42

The working distance is the distance between ________.

The slide and the objective lenses

43

Agents that inhibit the growth of bacterial cells are referred to as:

Bacteriostatic

44

Which of the following structures can prevent bacteria from phagocytic cells?

Capsule

45

Mycobacterial will be stained with _____ color in the acid-fast staining?

Red

46

Which test is effective in determining the effectiveness of antimicrobial drugs?

Kirby-Bauer test

47

E. coli, which are commonly used indicators of water quality are Gram ____, and _______ bacteria.

Negative, rod-like

48

Streptococcus refers to bacteria with which kind of morphology?

Chain/Round

49

The total magnification when viewing the specimen under the high dry lens is _____.

400x

50

Compound lifht microscopes constain a series of lenses that allow for magnification of a specimen up to _______.

1,000x

51

Magnification is limited by the resolving_______.

Power of lenses

52

What does resolution indicate?

The clarity a microscope is able to achieve.

53

For most light microscopes, the limit of the resolution is ______.

0.2 Um

54

What does immersion oil do?

Reduce refraction or bending of light and increase resolution

55

Light is passed through a condensor lens that _______.

Concentrates the light and focuses it on the specimen

56

What does the diaphragm do?

Regulates the amount of light passing through the condenser to the specimen.

57

What happens when the light passes through the objective lens?

It refracts, and creates a magnified image

58

The light is further magnified through the ______ known as the eyepiece.

ocular lens

59

What is working distance?

Distance between the specimen and the objective

60

What is the field of view?

The amount of the specimen you can visualize

61

As magnification increases the working distance, your field of view and the intensity of light all ______.

Decrease

62

___________ may be required to the fine focus and the condenser in order to sharpen the image.

small adjustments

63

How do you determine the total magnification of a specimen?

Multiply the magnification of the objective lens by the magnification of the ocular lens.

64

The objective lenses on most lab-grade compound microscopes will have magnifications of _____,_______,and _______.

10X (low power), 40X (high dry), and 100X (oil immersion)

65

What are aseptic techniques?

Any technique employed to avoid contamination

66

What happens initially in order to prevent contaimination? How is this achieved?

All inoculating instruments (loops and needles) should be sterilized prior to use. Flaming the objects.

67

All growth media should be sterilized to ensure an ______.

Axenic culture

68

What is an axenic culture?

Pure culture of organism of interest

69

Typically, growth media is sterilized in an _________.

Autoclave

70

What does an autoclave do?

Utilizes steam under pressure

71

Microbes play important roles in ___________________.

Agriculture, nutrient recycling, sewage processing, commercial food production, and industry, normal function of the human body.

72

Bacteria and fungi exist as _________, and outnumber human cells by 10:1.

Resident flora

73

Colonies can be described as ____, _______,_______,_______, and ______.

shape, margin, elevation, texture and pigment.

74

Edge of the colony

margin

75

side view

elevation

76

texture

wet, shiny, opaque

77

color

pigment

78

Bacterial cells typically reproduce through _______, and asexual production.

binary fission

79

___________ tend to be larger with different colors from top or bottom view and may be fuzzy due to spore forming structures.

Fungal colonies

80

The abililty to determine the causative agents of a specific infectious disease hinges on _______.

isolating the suspected culprit in a pure culture.

81

One of the most commonly used methods for generating a pure single species culture is ______.

streak plate method

82

What does the streak plate method assume?

Each cell in a mixed culture will give ruse to a single pure colony when grown on a semi-solid medium.

83

Bacteria can be distinguished based on what 2 things?

Cell morphology (shape) and arrangement

84

What are the three common bacterial shapes?

coccus (round), bacillus (rod), or spiral (spirillum, spirochete, or vibrio)

85

What is a pair of bacterial cells referred to as?

diplo arrangement
ex) diplococci and diplobacilli

86

In order to visualize the morphology and arrangements of tiny transparent bacterial cells, a thin _________is prepared and then ______.

smear, stained

87

__________Involves heat-fixing a bacterial sample to a microscope slide.

Smear preparation

88

What does the addition of heat in a smear preparation do?

It kills the cells, causing them to adhere to the surface of the slide and so they are not dislodged during the staining process.

89

What is a danger of using heat to fix a specimen?

Cells may become damaged or their cellular structures may become distorted

90

Single color stains used to illustrate morphology and arrangement

Simple stains

91

Simple stains are what charge?

cationic, positively charged, and basic

92

These dyes are attracted to the negative nature of the bacterial cell and bind to the cell so that it takes on the color of the dye and becomes visible using microscopy

Basic dyes, that are positive and cationic (simple stains)

93

___________ employ acidic dyes that are anionic, negatively charged.

Negative stain techniques

94

These dyes are repelled by the negative nature of the bacterial cell and will bind to and stain the slide instead.

Acidic dyes

95

In ______ smears are not heat-fixed so the bacterial cell size and structural components are more accurate.

Negative stain techniques

96

Why may many species of bacterial cells share a common morphology and/or arrangement?

They are simplistic single-celled organisms

97

__________ Detect specific physical and chemical characteristics of a cell. Why may this be useful?

structural stains; removes some of the ambiguity of bacterial identification

98

Structural stains are also referred to as _________.

differential stains

99

_______ is a form of glycocalyx; typically composed of extracellular layers of sticky _______.

Bacterial capsule; polysaccharides

100

What does the bacterial capsule help with?

Allows bacteria to escape from phagocytic cells, resist desiccation, and aids them in attachment. Help distinguish between pathogenic and nonpathogenic strains

101

How can Capsules be observed? What does it involve

Modified negative stain; Staining both the background and the cell while the capsule itself remains unstained.

102

Dormant structures that provide production for cells exposed to harsh environmental conditions

bacterial endospore

103

What do the "resting bodies"/bacterial endospore protect from?

excessive heat, cold, changes in pH, radiation, and various chemicals

104

____________ is steamed into bacterial endospores, and then the vegatative cells are counterstained with __________ which will replace the primary _______stain.

Malachite green;safranin

105

Endospores are typically characterized by shape as ___, ____,or _____ and common shapes are _____,_______,________.

terminal, subterminal, central; round, oval,or cylindrical

106

One of the most commonly used differential bacterial stains = ________.

Gram stain

107

Gram positive bacterial cells stain _____ and gram negative bacterial cells stain ___.

purple;pinkish red

108

Characterisics of gram positive cell walls = _______.

thick, rigid, with many layers of the complex polysaccharide peptidoglycan with interwoven teichoic acids.

109

Characteristics of gram negative cell walls = ________.

Little or no peptidoglycan and lack teichoic acids, but possess an outer lipopolysaccharide membrane.

110

The thick layer of peptidoglycan are less susceptible to the organic solvent _______, than the ethanol soluble layers of the gram negative outer membrane.

ethyl alcohol

111

What does it mean to be gram variable?

Gram positive cells that do not contain consistent amounts of teichoic acids in their cells walls and may give a gram negative reaction
Due to genetics or age of culture*

112

Bacteria of the mycobacterium and norcardia genera may have an additional cell wall component called __________.

mycolic acid

113

This thick, waxy layer of lipids makes these bacteria resistant to water-based stains like those used in a gram stain

mycolic acid

114

__________, which contains phenol, is used to penetrate through mycolic acid.

carbolfuchsin

115

____utilizes heat to facilitate the penetration of carbolfuchsin into the cells.

Ziehl-Neelsen Method

116

_____Uses a stain with an increased concentration of both carbolfuchsin and phenol to eliminate the need for heat.

Kinyoun Method

117

__________ are the causative agents of tuberculosis and leprosy.

Mycobacterium

118

___________is responsible for a tissue-destroying disease of the hands and feet in addition to polmonary disease.

Norcardia

119

Gram negative bacteria commonly found in the intestines of vertebrates.

coliforms

120

__________are the most widely used to monitor water quality.

Coliform bacteria

121

Coliform indicators are members of the ________ family.

enterobacteriaceaeae.

122

Enterics are non-endospore forming, ________ that ferment _____ producing both acid and gas.

facultative; lactose

123

Enterics include members of the following genera:

Escherichia, Enterobacter, klebsiella, shigella, citrobacter, and many others.

124

Many dangerous pathogens in water are due to ____________.

fecal contamination

125

__________ are indicative of intestinal pathogens.

fecal coliforms

126

One of the most commonly used fecal coliforms in assessing the potability of water.

E-coli

127

A common method for detecting and enumerating coliforms in water involves a ______test.

Most Probable Number

128

_________Involves inoculating lactose broths with a water sample and monitoring the tubes for fermentation.

MPN: if acid and gas are observed, coliforms are present

129

Suspected coliforms are inoculated on a selective media like ______ and ____.

Levin's eosin methylene blue agar (EMB) or endo agar
They inhibit growth of gram + and differentiate between lactose fermenting or not.

130

_______ is a series of tests that can be used to differentiate between members of the Enteric family.

IMViC

131

How do you incubate an inoculated agar plate and why?

You incubate it upside down so no air gets in and the bacteria will grow properly

132

Mention one reason why you would use the aseptic technique.

To keep things sterile and free from contamination

133

What is the purpose of heat-fixing a bacterial sample?

It kills the organisms without serious distortion, and they adhere better to the slide, taking up the dye more easily

134

Bacillus anthracis, the organism that causes anthrax is a ____ shaped bacterium.

rod

135

The fact that milk makes an ideal growth medium for microbes increases the risk of both ______ and ______.

spoilage and the transmission of disease

136

Many dangerous pathogens in milk are due to _____.

fecal contamination

137

_________Removes both the potential for spoilage organisms and pathogens.

pasteurization

138

Standard methods of pasteurization to not truly sterilize but....

Increase shelf life and reduce the ability to be used as a transmission for disease

139

________Involves dilutions of milkbeingplatedwith growth media.

standard plate count

140

Colonies are reffered to instead as a ________ that allows for the more likely possibility of a colony originating from a small clump of cells.

CFU

141

Antimicrobial chemicals are typically classified as either __________or________.

antiseptics or disinfectants

142

Antimicrobial chemicals meant for use on inanimate surfaces

disinfectants

143

Considered safe for use on living tissues

antiseptics

144

Reduce microbial numbers to an acceptable level

Sanitizing agent

145

this test involves exposing bacterial inoculated agar to a filter disk impregnated with the chemical in question, incubating the plate, then looking for an effect on the bacterial growth pattern

disk-diffusion test

146

Area with no microbial growth

zone of inhibition

147

__________are chemical compound that are used internally to interfere with the growth of microorganisms.

Antimicrobial drugs

148

causing little or no damage to the host cells and tissues

selective toxicity

149

A chemical that is produced by microorganisms that will inhibit the growth of other microbes

antibiotic