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

Question 1

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

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

Answer 1

inoculation

Question 2

Which of the following is not an inoculating tool?

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

Answer 2

Petri dish

Question 3

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

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

Answer 3

Bacteria growing on the solidi?ed medium did not degrade or break down the agar.

Question 4

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

A) isolation
B) incubation
C) infection
D) identi?cation
E) inoculation

Question 5

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

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

Question 6

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/an ______.

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

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

Question 8

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

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

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

Question 10

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) Escherichia coli, 1 ?m X 4 ?m
C) Pandora virus, 0.5 mm X 1 mm
D) Red blood cell, 8 ?m

Question 11

Agar is an important component of media because _______.

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

Question 12

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

Question 13

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

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

Question 14

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

Question 15

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

Question 16

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

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

Question 17

A pure culture contains _______.

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

Question 18

Cells of Staphylococcus aureus are cocci measuring about 1 ?m in diameter. In a textbook image of S. aureus, each cell measures about 1 cm. The magni?cation of the image on the page is ______.

A) 10,000X
B) 1,000X
C) 100X
D) 0.01X
E) 0.001X
F)0.0001X

Question 19

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 20

A textbook uses Paramecium to illustrate several types of light microscopy. Each image is magni?ed 230X and measures about 4 cm. The actual size of a Paramecium is about ______.

A) 920 ?m
B) 4,000 ?m
C) 0.2 ?m
D) 57.5 ?m
E) 175 ?m

Question 21

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

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

Question 22

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

Question 23

Mixed cultures are also referred to as contaminated cultures.

Question 24

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

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

Question 25

The three physical forms of laboratory media are ______.

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

Question 26

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

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

Question 27

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

Question 28

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

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

Question 29

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 30

Bacterial cultures are easily identified from their microscopic appearance.

Question 31

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

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

Question 32

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

Question 33

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 34

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

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

Question 35

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

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

Question 36

A common medium for culturing fastidious bacteria is ______.

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

Question 37

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

Question 38

A reducing medium is used to culture ______ organisms.

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

Question 39

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

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

Question 40

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

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

Question 41

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

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

Question 42

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

A) size of the ?eld
B) illumination
C) resolution
D) contrast
E) magni?cation

Question 43

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

Question 44

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

A) Refraction
B) Magni?cation
C) Resolution
D) Contrast

Question 45

Magni?cation is achieved in a compound microscope through the initial magni?cation 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) objective; ocular
B) ocular; objective
C) ocular; oil immersion
D) scanning; objective

Question 46

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) Bright-?eld
C) Fluorescence
D) Confocal
E) Phase-contrast

Question 47

Who invented the ?rst crude microscope by grinding glass?

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

Question 48

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

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

Question 49

Which type of microscope shows cells against a white background?

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

Question 50

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

A) phase-contrast
B) dark-?eld
C) confocal
D) electron
E) ?uorescence

Question 51

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

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

Question 52

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) differential and selective
C) for enrichment
D) selective
E) differential

Question 53

All of the following pertain to the ?uorescence microscope except _______.

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

Question 54

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

A) enriched
B) de?ned
C) reducing
D) complex

Question 55

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

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

Question 56

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

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

Question 57

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

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

Question 58

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) 2.0 µm
B) 0.1 µm
C) 0.2 µm
D) 0.2 mm

Question 59

A nutrient medium that contains at least one ingredient that is not chemically de?ned is termed ______.

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

Question 60

A scanning confocal microscope _______.

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

Question 61

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

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

Question 62

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

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

Question 63

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

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

Question 64

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

Question 65

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

Question 66

Which type of microscope achieves the greatest resolution and highest magni?cation?

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

Question 67

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 can provide good images of bacteria but not viruses.
C) Transmission EM requires dyes.
D) Transmission EM gives detail of the external architecture of cells.

Question 68

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

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

Question 69

Which type of microscope cannot image live specimens?

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

Question 70

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

A) hanging drop
B) ?agellar stain
C) Gram stain
D) ?xed, stained smear
E) negative stain

Question 71

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

Question 72

A microbiologist makes a ?xed 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) capsule staining
B) the acid-fast stain
C) negative staining
D) simple staining
E) using an acidic dye

Question 73

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

Question 74

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

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

Question 75

Basic dyes are _______.

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