Lab Practical 1

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created 7 years ago by coleybugs
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Includes labs: 1 (laboratory safety), 2 (exercise 5 & 6), 3 (exercise 10, 11, and 14), 4 (exercise 8 & enzymes and laundry detergents), 5 (exercise 9, 12, & 17), and 6 (exercise 13 & 15)
updated 7 years ago by coleybugs
Grade levels:
12th grade, College: First year, College: Second year
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1

(true or false)
Never remove cultures, media, or equipment from the lab

True

2

What can be inserted into the Bacti-cinerator

loop, needles, and tweezers only

3

How must all plates be incubated (unless told otherwise)

in an inverted position

4

When is it necessary to wear eye protection in the lab?

when handling chemicals, stains, or cultures

5

(true or false)
It is ok to pipette by mouth

false

6

When do we flame inoculating loops and needles in the lab?

before and after use

7

the magnification written on the ocular lens (eyepiece) is

10 times

8

The magnification on the low power objective a)_____.
Medium power objectives b)_____.
High power pbjective c)_____.

a. 4 times
b. 10 times
c. 45 times

9

What is the TOTAL magnification for eac lens
a) low power
b) medium power
c) high power

a)40 times
b)100 times
c)450 times

10

What is the purpose of the diaphram

control amount of light on the slide

11

How would you control the lightness of darkness of the field of view?

open the diaphram

12

Why does the ocular lens have a pointer?

to point out specific objects

13

What happens if you do not have an objective fully clicked into place?

it goes black all you can see is darkness

14

In exercise 5 (protozoa, algae, and cyanobacteria), what is the purpose of this exercise?

to provide an opportunity for you to become familiar with common pond-dwelling microorganisms and to appreciate the vast diversity that existsin a drop of pond water

15

In exercise 5 (protozoa, algae, and cyanobacteria), you will also become familiar witn the differences among several groups by compairing what?

their major characteristics

16

In exercise 5 (protozoa, algae, and cyanobacteria), which type of slide would need to be made in order to study the microorganisms in pond water?

wet mound slides

17

When making a wet mount what type of of slide is used?

depression slide

18

What are the most widely distributed organisms in the biosphere?

bacteria

19

What are the two main characteristics that really define bacteria?

cellular structure & small size

20

Bacteria have a simple cell structure that lacks what?

a defined nucleus surrounded by a nuclear membrane

21

Describe bacterias nuclear genetic material and where is resides.

primarily supercoiled, circular DNA molecules that reside in the cell cytoplasm

22

For most bacteria, the cell is surrounded by a cell wall composed of a unique molecule called what?

peptidoglycan

23

Exercise 6 (ubiquity of bacteria), study figure 7.1

which illustrates the common shapes of bacteria

24

In what order do you focus using a microscope?

low, then medium, then high power

25

according to your lab book the first step in preparing a slide for exercise 5 (protozoa, algae, and cyanobacteria) is

to wash, rinse, and dry the slide

26

How is the sterile swab used in exercise 6 ( ubiquity of bacteria)?

with nutrient broth

27

The best region to take a sample of pond water is probably where?

from the bottom of the bottle of pond water

28

In exercise 6 (ubiquity of bacteria), the sterile swab is used

to collect microbes from various surfaces

29

Which microscope objective is always used first when attempting to focus a slide?

the low power objective

30

Give a general definition for the word ubiquity

presence wverywhere or in many places

31

(true or false)
Bacteria is the most widely distributed organisms in the biosphere

true

32

while viewing a slide prepared from pond water, you see a colorless (nonpigmented), fast-moving organism. This organism is likely what?

protozoa

33

The type of slide that will be produced while completing exercise 5, the viewing of pond water, is what

a wet mount

34

according to exercise 10 (smear preparation), the success for most staining procedures, depends upon the preparation of a good what?

smear

35

What is the first gaol in making a good smear

to cause the cells to adhere to the microscope slide so that they are not washe off during subsequent staining and washing procedures

36

What is the second goal in making a good smear?

it is imortant to insure that shrinkage of cells does not does not occur during staining, otherwise distortion and artifacts can result

37

What is the third goal in making a god smear?

to prepare thin smears because the thickness of the smear will determine if you can visualize individual cells, their arrangements, or detail regarding microstructures associated with cells

38

the first step in preparing a bacteriological smear differs according to what?

the source of the organisms

39

from solid media such as nutrient agar, blood agar, or some part of the body, how does one start?

by placing one or two loopfulls of water on the slide and then using an inoculating loop to disperse the organisms in the water

40

What is the most difficult concept for students to understand when making slides from solid media?

it takes only a very small amount of material to make a good smear

41

Why is it important to be sure to cool the loop completely before inserting it into a medium?

a loop that is too hot will spatter the medium and move bacteria into the air

42

the use of a single stain to color a bacteria cell is commonly referred to as

simple staining

43

list three of the most commonly used dyes for simple staining

1. methylene blue
2. basic fuchsin
3. crystal violet

44

Why do the three dyes commonly used during simple staining work so well on bacteria?

because they have color-bearing ions (chromophores) that are positively charged (cationic)

45

The fact that bacteria are negatively charged produces what?

a pronounced attraction between these catioic chromophores and the organism)

46

pertains to irregularity of form: that is, demonstrating several different shapes

pleomorphism

47

a gram stain is an example of what

a differential stain

48

Gram staining reactions take advantage of what?

the fact that cells or structures within cells display dissimilar staining reactions that can be distinguished by the use of different dyes

49

Iodine is considered a _____ that complexes with the crystal violet and forms an insoluble complex in gram-positive cells

mordant

50

When viewed by electron micr;oscopy, gram-positive cells have a thick layer of ____ that comprises the cell wall of these organisms

peptidoglycan

51

one of the reasons that stains with positively charged chromophores tend to work well in staining bacteria is

that most bacteria are negatively charged and attract the chromophores of the stain

52

(true or false)
The two smears that you will produce for exercise 10 should be fixed (heat fixed)

true

53

after briefly rinsing a stain with water when preparing a simple stained slide for viewing, how should the water drops on the slide be dried?

by blotting with bibulous paper

54

The first step in preparing a smear from solid media is

to place 1 or 2 loopfuls of water in the center of a "target" circle

55

(true or false)
Before a smear can be heat fixed, it must air-dry

true

56

(true or false)
In Exercise 10, Smear Preparation, you will be preparing two smears. These smears will both be produced from solid media

false

57

the "best" smear is made from

a small amount of organisms

58

a gram stain is considered which type of stain

a differential stain

59

The use of aseptic technique insures what as far as organisms are concerned

that no contaminating organisms are introduced into culture materials when the latter are inoculated or handled in some manner

60

Aseptic technique also insure what as far as handling is concerned

that organisms that are being handled do not contaminate the handler or others who may be present

61

aseptic technique insure what as far as contamination remains are concerened

that no contamination remains after you have worked with cultures

62

work area disinfection does what

destroys vegetative cells and viruses but may not destroy endospores

63

How is a loop or needle sterilized

by inserting it into a Bunsen burner flame until it is red hot

64

as far as culture tube flaming and inoculation is concerned, prior to inserting a cooled loop or needle into a culture tube what needs to happen

the cap is removed and the mouth of the tube is flamed

65

What needs to happen after the culture is inoculated

the mouth of the tube is reflamed and the tube is recapped

66

as far as the loop and needle are concerned after the inoculation is complete

the loop or needle is flamed in the Bunsen burner to destroy any organisms that remain on these implements

67

After the loop or needle has been cleaned and sterilized what needs to occur

the loop or needle is then returned to its receptacle for storage DO NOT PLACE ON THE DESK SURFACE

68

(true or false)
loops are routinely used when streaking agar plates and slants. when used properly, a loop will not gouge or tear agar surfaces

true

69

needles are used in transfers involving what

stab cultures

70

media in plates must be protected against what

contamination

71

in order to prevent exposure to air contamination what needs to occur

covers should always be left closed

72

How should the cover be when organisms are removed from a plate culture

the cover should be only partially opened

73

(true or false)
Plates are flamed like loops and needles.

false

74

where are petri plates containing inoculated media labeled

on the bottom of the plate

75

Inoculated plates are almost always incubated how

upside down

76

When plates are incubated upside down this does whar

prevents moisture from condensing on the agar surface and spreading the inoculated organisms

77

digests protein based stains

proteases

78

digests starch based stains

amylase

79

digests fat or oil based stains

lipase

80

inhibits dye transfer

guardzyme (a peroxidase)

81

removes the fuzz that builds up on cotton clothes

carezyme

82

better for ground in dirt

powder

83

better for oily stains

liquids

84

(true or false)
immersion oil is placed directly on top of the organism

false (it is placed on top of the cover slip)

85

(true or false)
It is ok to go back and forth between oil immersion and high power at any time

false
once you have put immersion oil on a specimen DO NOT go to any other objetive

86

what should you use to thoroughly clean the oil from the oil immersion objective

lens paper only

87

When we try to study the bacterial flora of the body, soil, water, or just about any environment, we realize, quickly that what

bacteria exist in natural environments as mixed populations

88

(true or false)
It is only in very rare instances that bacteria accur as a single species

true

89

two commonly used procedures for obtaining pure cultures

streak plate & pour plate

90

Both streak plate and pour plate procedures involve diluting the bacterial cells in a sample to an end point where a single cell divides giving rise to a single what

pure colony

91

For economy of materials and time, which method, the streak plate or pour plate, is best?

streak-plate

92

The important thing in using the streak-plate method is what

to produce good spacing between colonies

93

this stain is acidic and thus have a negatively charged chromophore that does not penetrate the cell but rather is repelled by the similarly charged bacterial cell

negative stains

94

the background surrounding the cell is colored by a negative stain resulting in what

a negative or indirect staining of the cell

95

Because heat fixation is not performed, no shrinkage of cells occurs and size determinations are what

more accurate than those determined on fixed material

96

avoiding heat fixation is also important if the capsule surrounding the cell is to be observed because why

heat fixation will severly shrink this structure

97

what are the major organelles of motility in bacteria

flagella

98

flagella allow cells to move toward nutrients in the environment or move away from harmful substances, such as acids, in a complicated process called what

chemotaxis

99

Motility and the arrangement of flagella around the cell are important _____ _____ characteristics that are useful in characterizing bacteria

taxonomic characteristics

100

Motility can be determined by several methods including which three that we talk about in exercise 17

1. wet mount
2. hanging drop technique
3. brownian motion

101

is movement due to molecular bombardment of cells causing cells to shake or "jiggle about" but not move in any vectorial way

brownian motion

102

some bacterial cells are surrounded by an extracellular slime layer called ____ or _____ which can play a protective role for certain pathogenic bacteria

capsule or glycocalyx

103

Evidence supports the view that probably all bacterial cells have some amount of _____ _____, but in most cases the amount is not enough to be readily discernible

slime layer

104

staining of the bacterial capsule (can/cannot) be accomplished by ordinary staining procedures

cannot

105

If smears are heat-fixed prioir to staining, whaty happens to the capsule

it shrinks or is destroyed and cannot be seen in stains

106

In the Anthony method of staining capsules what is the first step

smears are air dried and then stained with crystal violet for 2 minutes

107

The second step in the Anthony method is that the stain is washed off with what and blotted dry

aqueous solution of 20% copper sulfate

108

In the Anthony method, under oil immersion the capsule will appear as _____ _____ and the cells will appear as ____ ______.

light blue
dark purple

109

When species of bacteria belonging to the genera Bacillus and Clostridia exhaust essential nutrients, they undergo a complex developmental cycle that produces resting stages called what?

endospores

110

allows Bacillus and Clostridia to survive environmental conditions that are not favorable for growth

endospores

111

If nutrients once again become available, the endospores can go through a process of _____ to form a new vegetative cell and growth will resume

germination

112

very dehydrated structures that are not actively metabolizing

endospores

113

Are endospores easily destroyed by heat or chemicals?

no

114

(true or false)
There is no need to clean the oil immersion objective after using immersion oil

false

115

(true or false)
endospores are easily destroyed by heat

false

116

When focusing with the oil immersion lens, which is the correct order of objective lens?

low power, medium power, high power, oil immersion

117

When using immersion oil, where is the drop of oil placed?

on the top of the coverslip after focusing with low power, medium power, and high power objectives

118

Your lab book states that probably _____ bacterial cells have some amount of glycocalyx

all

119

(true or false)
Most capsules are composed of polysaccharides

true

120

How should a preparation stained with a capsule stain appear when viewed with a microscope?

halo-like structures around purple cells with a dark background

121

Endospores are not easily penetrated by stains. We must stain the endospores so that we will be able to view them. What will we attempt in the lab to force the stain into the endospores?

using heat