Deck 3: Tools of the Laboratory: Methods for the Culturing of Microscopic Analysis of Microorganisms

Question 1

The procedures for culturing a microorganism require the use of a microscope.

Answer 1

False

Question 2

Table 3.6 in your textbook uses Paramecium to illustrate several types of light microscopy.Each image is magnified 230X and measures about 4 cm.The actual size of a Paramecium is about ______.

A)920 $\mu$ m
B)0.2 $\mu$ m
C)175 $\mu$ m
D)57.5 $\mu$ m
E)4,000 $\mu$ m

Answer 2

175 $\mu$ m

Question 3

Humans can see objects as small as 0.1 mm.Leeuwenhoek's best microscope could magnify objects to 300X.Which of the following would be invisible using Leeuwenhoek's microscope?

A)Poliovirus, 30 nm
B)Red blood cell, 8 $\mu$ m
C)Escherichia coli, 1 $\mu$ m X 4 $\mu$ m
D)Pandora virus, 0.5 mm X 1 mm

Answer 3

Poliovirus, 30 nm

Question 4

Your microscope has a resolving power of 0.15 $\mu$ m.The specimen that you will be observing has bacterial cocci the size of 0.1 $\mu$ m in diameter.Which of the following statements is correct?

A)The cocci will appear much smaller than their actual size because of the low resolution.
B)The cocci will be fuzzy-looking and blend together.
C)The cocci will not be visible.
D)The cocci will be readily visible and distinct.

Question 5

Thioglycolate medium contains the following: yeast extract, pancreatic digest of casein, glucose, L-cysteine, sodium chloride, sodium thioglycolate, and agar.It is considered a complex medium because

A)depending on their oxygen utilization pattern, organisms will grow differently on it.
B)it has multiple ingredients for a broad range of nutrients.
C)both yeast extract and pancreatic digest of casein are not chemically defined.
D)thioglycolate has a carbon-sulfur bond that many microbes cannot break enzymatically.

Question 6

A pure culture contains

A)only bacteria.
B)only one identified species of microorganism.
C)a variety of species from the same genus.
D)microbes from a single source.

Question 7

A microbiologist inoculates Staphylococcus epidermidis and Escherichia coli into a culture medium. Following incubation, only the E. coli grows in the culture. What is the most likely explanation?

A) The culture medium was selective.
B) The culture medium was differential.
C) The microbiologist used too much inoculum.
D) The culture was contaminated.
E) The incubation temperature was incorrect.

Question 8

Robert Koch and his colleagues first used agar in bacteriological media.Why was this ingredient an improvement on previous materials used to culture bacteria?

A)Agar can convert from liquid to solid form, and back again, very easily.
B)Agar is a complete source of nutrients for most bacteria.
C)Bacteria growing on the solidified medium did not degrade or break down the agar.
D)Agar was less expensive than the nutrients that Koch was previously using in the lab.

Question 9

A microbiologist inoculates Staphylococcus aureus into a culture medium.Following incubation, both Staphylococcus aureus and Staphylococcus epidermidis are determined to be growing in this culture.What is the most likely explanation?

A)The microbiologist used too much inoculum.
B)The culture medium was selective.
C)The culture medium was differential.
D)The culture was contaminated.
E)The incubation temperature was incorrect.

Question 10

Newly inoculated cultures must be _____ at a specific temperature and time to encourage growth.

A)incubated
B)streaked
C)spread
D)poured

Question 11

The term that refers to the purposeful addition of microorganisms into a laboratory nutrient medium is ______.

A)inoculation
B)contamination
C)infection
D)immunization
E)isolation

Question 12

Some microbes are not capable of growing on artificial media as pure cultures.

Question 13

Which isolation technique is most effective for the majority of applications and is most commonly used for colony isolation in the laboratory?

A)Spread plate
B)Streak plate
C)Pour plate
D)Culture plate
E)Loop dilution

Question 14

The correct microbiological term for the sample of specimen that is put into a nutrient medium to produce a culture is ______.

A)loop
B)inoculum
C)streak
D)colony

Question 15

A microbiology student with a visual disability is viewing a sample of Bacillus endospores in a phase contrast microscope that is linked to an iPad.By "stretching" the image on the iPad screen, the student can increase the apparent size of the endospores.How does this manipulation affect resolution and contrast? (No software is being used to alter the image!)

A)Only the magnification can be increased; resolution and contrast are unchanged.
B)Contrast will improve because the microscope is phase-contrast.
C)Both magnification and resolution increase; contrast is unchanged.
D)Resolution and magnification will decrease because the screen is not as good as the human eye.

Question 16

What is the term for a culture made from one isolated colony?

A)Axenic
B)Mixed
C)Pure
D)Both axenic and mixed are correct.
E)Both axenic and pure are correct.

Question 17

Which of the following is not an inoculating tool?

A)Pipette
B)Swab
C)Petri dish
D)Loop
E)Needle

Question 18

The Five I's of studying microorganisms include all of the following except ______.

A)identification
B)isolation
C)incubation
D)infection
E)inoculation

Question 19

Agar is an important component of media because

A)agar provides a solid surface for bacterial growth.
B)bacteria require agar as a source of carbon.
C)agar inhibits mold growth.
D)agar prevents contamination.

Question 20

The bacterium Neisseria gonorrhoeae causes the sexually-transmitted infection gonorrhea.Although it can be isolated from the vagina, there are numerous normal biota in that location as well.To generate a pure culture of this pathogenic bacterium, the best choice is a(n) ______.

A)differential medium
B)enrichment medium
C)selective medium
D)liquid medium

Question 21

A reducing medium is used to culture ______ organisms.

A)fastidious
B)pathogenic
C)anaerobic
D)aerobic

Question 22

A medium that is gel-like has less agar in it compared to a solid medium.

Question 23

All of the following are examples of different types of microbiological media except ______.

A)agar
B)enriched
C)broth
D)Petri dish
E)semisolid

Question 24

A common medium for culturing fastidious bacteria is ______.

A)trypticase soy agar
B)reducing medium
C)mannitol salt agar
D)blood agar
E)MacConkey medium

Question 25

A reducing medium contains

A)sugars that can be fermented.
B)extra oxygen.
C)hemoglobin, vitamins, or other growth factors.
D)substances that remove oxygen.
E)inhibiting agents.

Question 26

Mixed cultures are also referred to as contaminated cultures.

Question 27

Which type of medium distinguishes different types of microorganisms based on an observable change in the colonies or in the medium?

A)Enriched
B)Enumeration
C)Selective
D)Reducing
E)Differential

Question 28

Which of the following is essential for the development of discrete, isolated colonies?

A)Solid medium
B)Differential medium
C)Broth medium
D)Assay medium
E)Selective medium

Question 29

Which method often results in colonies developing down throughout the agar along with some colonies on the surface?

A)Spread plate
B)Pour plate
C)Replica plate
D)Streak plate

Question 30

A selective medium contains one or more substances that inhibit growth of some microbes to facilitate the growth of other desired microbes.

Question 31

The three physical forms of laboratory media are ______.

A)solid, semisolid, and liquid
B)reducing, transport, and enumeration
C)a streak plate, a pour plate, and a broth
D)solid, liquid, and gas

Question 32

Mannitol salt agar is selective for organisms in which bacterial genus?

A)Salmonella
B)Staphylococcus
C)Escherichia
D)Neisseria
E)Streptococcus

Question 33

Bacteria that require special growth factors and complex nutrients are termed ______.

A)fermentative
B)hemolytic
C)fastidious
D)aerobic
E)anaerobic

Question 34

Which of the following is not a benefit of agar as a solid medium?

A)Holds moisture
B)Flexibility
C)Solid at room temperature
D)Can be inoculated and poured at a temperature that is not harmful
E)Easily digested by most microbes

Question 35

Which type of medium would be the best choice when shipping a sample of bacteria from a clinic to a laboratory for testing?

A)Thioglycolate medium
B)Eosin-methylene blue agar
C)Transport medium
D)Blood agar

Question 36

Bacterial cultures are easily identified from their microscopic appearance.

Question 37

A microbiologist must culture a patient's feces for intestinal pathogens.Which of the following components would likely be present in a selective medium for this purpose?

A)Thioglycolic acid
B)Sheep red blood cells
C)Bile salts
D)Peptone
E)NaCl

Question 38

Agar is a complex polysaccharide that comes from a/an ______.

A)bacterium
B)algae
C)fungus
D)marine invertebrate
E)green plant

Question 39

Differential media result in which of the following observable characteristics?

A)Differently colored colonies
B)Different media color after incubation
C)Chemical precipitates
D)Gas bubbles
E)All of the choices are correct.

Question 40

Which of the following is produced by adding 1% to 5% agar to nutrient broth that is then boiled and cooled?

A)A pure culture
B)A contaminated medium
C)A liquid medium
D)A mixed culture
E)A solid medium

Question 41

Which type of microscope shows cells against a white background?

A)Confocal
B)Electron
C)Bright-field
D)Fluorescence
E)Phase-contrast

Question 42

Which of the following parts of a microscope magnifies the specimen to produce a real image of the specimen?

A)Body
B)Condenser
C)Objective lens
D)Ocular lens
E)Nosepiece

Question 43

A nutrient medium that contains at least one ingredient that is not chemically defined is termed ______.

A)enriched
B)complex
C)reducing
D)synthetic

Question 44

All of the following are diameters of cells that would be resolved in a microscope with a limit of resolution of 0.2 µm except ______.

A)0.2 mm
B)0.1 µm
C)2.0 µm
D)0.2 µm

Question 45

Which term refers to the microscope's ability to show two separate objects as discrete and distinct?

A)Contrast
B)Magnification
C)Refraction
D)Resolution

Question 46

Scattering of peripheral light rays through the glass slide under very high magnification can be prevented by ______.

A)the condenser
B)the ocular
C)immersion oil
D)the cover slip

Question 47

If a microbiologist is studying a specimen at a total magnification of 950X, what is the magnifying power of the objective lens if the ocular lens is 10X?

A)95X
B)940X
C)950X
D)9500X

Question 48

A nutrient medium that has all of its chemical components identified and their precise concentrations known and reproducible is termed ______.

A)reducing
B)enriched
C)complex
D)defined

Question 49

Which of the following parts of the microscope magnifies the specimen to produce the virtual image of the specimen?

A)Ocular lens
B)Objective lens
C)Condenser
D)Body

Question 50

The simple microscopes used by the earliest practitioners of microscopy contained which of the following?

A)Magnifying lens
B)Oil-immersion lens
C)Lamp
D)Ocular
E)Condenser

Question 51

The specimen preparation technique that is best for viewing cell motility is the ______.

A)flagellar stain
B)Gram stain
C)negative stain
D)hanging drop
E)fixed, stained smear

Question 52

The _____ of the microscope holds and allows selection of the objective lenses.

A)ocular
B)condenser
C)stage
D)nosepiece

Question 53

The type of microscopy in which you would observe brightly illuminated specimens against a black background is ______.

A)dark-field
B)confocal
C)fluorescence
D)phase-contrast
E)electron

Question 54

Who invented the first crude microscope by grinding glass?

A)Lister
B)Schultz and Schwann
C)Leeuwenhoek
D)Redi
E)Pasteur

Question 55

Eosin-methylene blue agar, or EMB, is a commonly used bacteriological medium for growing gram-negative bacteria from complex environments.It contains two dyes, eosin and methylene blue, as well as the sugar lactose.Eosin is a pH indicator that changes color when the medium is acidic, while methylene blue inhibits the growth of most gram-positive bacteria.If an organism consumes lactose, acid will be produced, causing the bacterial colonies to change color. Based upon this description, this medium is ______.

A)reducing
B)for enrichment
C)selective
D)differential and selective
E)differential

Question 56

The wavelength of light used and the numerical aperture governs ______.

A)resolution
B)contrast
C)illumination
D)size of the field
E)magnification

Question 57

A scanning confocal microscope

A)produces specimen images on electron micrographs.
B)uses dyes that emit visible light when excited by ultraviolet radiation.
C)uses ultraviolet light to form a specimen image.
D)scans narrow planes and can build a three-dimensional image of the specimen.

Question 58

Magnification is achieved in a compound microscope through the initial magnification of the specimen by the _____ lens.This image is then projected to the _____ lens that will further magnify the specimen to form a virtual image received by the eye.

A)ocular; oil immersion
B)scanning; objective
C)ocular; objective
D)objective; ocular

Question 59

All of the following pertain to the fluorescence microscope except

A)it is a type of compound microscope.
B)it is used to diagnose certain infections.
C)it uses electrons to produce a specimen image.
D)it requires the use of dyes like acridine or fluorescein.
E)it requires an ultraviolet radiation source.

Question 60

Which type of microscopy transforms the subtle variations in cell density into differences in light intensity, allowing for increased internal detail without staining?

A)Electron
B)Fluorescence
C)Bright-field
D)Confocal
E)Phase-contrast

Question 61

Which type of microscope does not use light in forming the specimen image?

A)Electron
B)Dark-field
C)Phase-contrast
D)Bright-field
E)Fluorescence

Question 62

Fixed smears of specimens are required to perform the Gram stain or the endospore stain.

Question 63

Comparing transmission electron microscopy with scanning electron microscopy, the following statement is true.

A)Transmission EM is used for internal detail of cells and subcellular structures.
B)Transmission EM gives detail of the external architecture of cells.
C)Transmission EM requires dyes.
D)Transmission EM can provide good images of bacteria but not viruses.

Question 64

Which type of microscope achieves the greatest resolution and highest magnification?

A)Bright-field
B)Fluorescence
C)Electron
D)Dark-field
E)Phase-contrast

Question 65

The Gram staining procedure is best described as a ______ staining technique.

A)negative
B)simple
C)selective
D)differential

Question 66

Which type of microscope cannot image live specimens?

A)Differential interference
B)Bright-field
C)Electron
D)Dark-field
E)Phase-contrast

Question 67

Following a properly-performed Gram stain, gram-positive bacteria will appear as pink or red cells.

Question 68

A differential interference contrast microscope uses dyes to give colored, three-dimensional images.

Question 69

Basic dyes are

A)repelled by cells.
B)attracted to the acidic surface of bacterial cells.
C)used in negative staining.
D)dyes such as India ink and nigrosin.
E)anionic.

Question 70

The bending of light rays as they pass from one medium to another is called refraction.

Question 71

The purpose of staining cells on a microscope slide is to ______.

A)secure them to the slide
B)kill them
C)observe motility
D)enlarge the cells
E)add contrast to see them better

Question 72

Which type of microscope bombards a whole, metal-coated specimen with electrons moving back and forth over it?

A)Transmission electron
B)Differential interference contrast
C)Scanning electron
D)Phase-contrast
E)Fluorescence

Question 73

A microbiologist makes a fixed smear of bacterial cells and stains it with methylene blue.All cells appear blue under the oil immersion lens.This is an example of ______.

A)simple staining
B)negative staining
C)capsule staining
D)the acid-fast stain
E)using an acidic dye

Question 74

What do the Gram stain, the acid-fast stain, and the endospore stain have in common?

A)They use heat to force the dye into cell structures.
B)The staining outcome varies with the charge of the cell wall.
C)They are used on a wet mount of the specimen.
D)They are differential stains.
E)They use a negative stain technique.