Chapter 2

The usual temperatures used in the laboratory to propagate microorganisms are between

20°C and 45°C

_____ makes a good solidifying agent for culturing medium because it is flexible and can hold moisture and nutrients while not acting as a nutrient for most microbes.

Agar

What is involved in making a smear?

Air drying a liquid application on a glass slide Spreading a thin film of suspended cells on a glass slide

______ media are used by drug manufacturers to assess the effect of disinfectants, antiseptics, cosmetics, and preservatives on the growth of microorganisms.

Assay

Which type(s) of organisms are usually observed with light microscopes?

Bacteria

Dyes with a positive charge are called _____ , whereas dyes with a negative charge are called ________

Blank 1: cationic or basic Blank 2: anionic or acidic

To simultaneously kill and secure a specimen to the glass slide, ______ ______ is used in smear preparation.

Blank 1: heat Blank 2: fixation, fixing, or fixed

The total power of magnification is calculated by the product of the separate powers of the _________ lens and the _______ lens.

Blank 1: objective Blank 2: ocular or eyepiece

A property used to classify media that refers to the medium's normal consistency is the

Blank 1: physical Blank 2: state

In Gram staining, purple cells are gram-_______ , whereas cells that appear pink/red are gram-_____

Blank 1: positive or + Blank 2: negative or -

Differential stains are general staining techniques that use a ________ dye followed by a _________ to distinguish between cell types and structures.

Blank 1: primary Blank 2: counterstain

The factor that most limits the clarity of a microscope's image is the

Blank 1: resolving Blank 2: power

Sabouraud's agar restricts the growth of bacteria and is an example of a ________ medium, whereas Mannitol salt agar can determine which species of Staphylococcus is present, making it an example of a ______ medium.

Blank 1: selective Blank 2: differential

Which types of media contain at least one ingredient that is not chemically defined?

Blood agar Complex

Which type of microscope forms its image when light is transmitted through a specimen?

Bright-field microscope

Which of the following are characteristics of an enriched medium?

Can be used to aid in the growth of fastidious organisms May contain special growth factors May contain organic substances such as blood, serum or hemoglobin

Which of the following pairs are correct?

Cationic dyes = Basic dyes Anionic dyes = Acidic dyes

Which of the following describe the medium whose recipe is shown here?

Chemically complex

Which term describes a once pure culture that has since had unwanted microbes of uncertain identity introduced into it?

Contaminated

Which of the following media can be described precisely as to its chemical content?

Defined

Semisolid media are used for ______.

Determining the motility of bacteria Localizing a reaction at a specific site

Which of the following staining procedures employ both a primary dye and a counterstain?

Differential stain

Which of the following does not describe selective media?

Display visible differences among microorganisms Select for growth of a broad spectrum of organisms

Media ingredients that cannot be chemically defined include which of the following?

Extracts of animals, plants, or yeasts Blood and serum Cell secretions

True or false: "Inspection" begins the process using the Five "I" procedure for culturing microorganisms.

False

True or false: A defined medium differs from a complex medium in that the chemical composition of the defined medium cannot be precisely determined.

False

True or false: Isolation of colonies usually requires a large number of cells to be inoculated over an expansive area of medium.

False

True or false: Selective media cannot be differential.

False

________ staining is done by coating and then staining the filament(s) used by bacteria for motility.

Flagellar

Differential stains include the ______ stain.

Gram acid-fast

In which of the five I's would a microbiologist adjust the temperature and atmospheric gases in a culture environment?

Incubation

Which of the following describes the process of placing a culture of microorganisms in a temperature-controlled chamber to encourage growth?

Incubation

Which of the following identifies the step in the Five I's of culturing microorganisms during which a culture is placed in a controlled environment to encourage growth?

Incubation

Which one of the following is NOT part of the 5 basic techniques used to grow, examine and manipulate microorganisms in the laboratory (recall the Five I's)? Infection Isolation Inspection Inoculation

Infection

Which of the following are required for proper isolation of microorganisms?

Inoculation tools Agar in a petri dish

is part of the Five I's of culturing microorganisms and is based on visual observations of microscopic and macroscopic growth characteristics.

Inspection

Which of the following attributes make agar an ideal solidifying agent for culturing media?

It holds moisture and nutrients. It is solid at room temperature.

A wet mount is suitable for observing ______.

Living, motile or non-motile cells

Which of the following are not general purpose media? MacConkey agar Mannitol salt agar Brain heart infusion broth Trypticase soy agar Nutrient agar and broth

MacConkey agar Mannitol salt agar

What is the type of staining method called where the dye does not stick to the specimen but settles around its outer boundary, forming a silhouette?

Negative stain

Applications of bright-field microscopy include ______.

Observation of dark specimens in a white field Observation of live and preserved stained specimens

What is the type of stain method where the dye sticks to the specimen and gives it color?

Positive stain

Which type of culture contains only a single known species or type of microorganism?

Pure culture

Which of the following staining procedures requires the use of only a single dye?

Simple staining

A hanging drop slide is used to assess which of the following?

Size of cells Motility

Which of the following describe selective media?

Suppress unwanted organisms Encourage the growth of desired organisms

The purpose(s) of isolation in the culturing of microorganisms includes:

The ability to observe individual colony morphology Producing a discrete colony of just one species

Negative staining of a cell can yield results concerning:

The presence of a capsule Cell size Cell shape and arrangement

The techniques used to prepare specimens for optical microscopy depend on ______.

The type of microscopy available The aims of the examiner The condition of the specimen

True or false: The aims of the examiner, such as whether to observe overall structure or to observe motility, influence the manner in which specimen is prepared for optical microscopy.

True

Applications of a wet mount include which of the following?

True assessment of motility True assessment of size True assessment of morphology

how does a bright field microscope form its image?

When light is transmitted through a specimen

What type of plate is shown in this figure?

a streak plate

This medium, MacConkey agar, has colonies that appear either red or white based on their ______.

ability to ferment lactose

Resolving power is the ability of a microscope to ______.

accurately distinguish between two separate entities

A non-nutritive component of media that can be liquefied at high temperatures and cools to a solid that can hold moisture and nutrients is ______.

agar

The polysaccharide found in a sea alga that is commonly used to prepare solid culture media is called ______.

agar

General purpose media are characterized by ______.

allowing the growth of a broad range of microbes

Staining involves ______.

applying colored dyes to specimens

Media used by technologists to test the effectiveness of antimicrobial drugs are called

assay

Capsule staining is used to observe the unstructured protective layer surrounding some ______.

bacteria fungi

Which of the following are selective agents used in microbiological media?

bile salts antibiotics

After the Gram staining procedure, gram-positive cells appear ______.

blue/purple

This image of a Paramecium was obtained using _____ microscopy.

bright-field

This image shows the results of a Gram stain. The form of microscopy used to visualize this stain is _____ microscopy.

bright-field

The three types of visible-light microscopes include ______.

bright-field dark-field phase-contrast

The observation of live and preserved stained specimens in a white field involves the use of

bright-field microscope

A stain that is designed to observe the unstructured protective layer surrounding some bacteria and fungi is the

capsule, negative, or capsular stain

Microbial growth in a liquid broth medium is indicated by ______.

cloudiness sediment color change

Especially with bacteria and fungi, the most common manifestation of growth on solid media is the appearance of

colonies or colony

When adequately separated from other cells, an individual bacterial cell can grow into a discrete mound of cells called a(n)

colony or colonies

All of the following are properties used to classify media, except ______. functional type physical state color chemical composition

color

Media that contain at least one ingredient that is not chemically definable are called ________ or nonsynthetic.

complex

Media that contain at least one ingredient that is not chemically definable are called _________ or nonsynthetic.

complex

A ______ microscope uses a laser beam to provide three dimensional images of specimens that have been stained with a fluorescent dye.

confocal

A phase-contrast microscope uses visible light as its illuminating source, a fluorescence microscope uses ultraviolet radiation, and a ______ microscope uses a laser beam.

confocal

A phase-contrast microscope uses visible light as its illuminating source, a fluorescence microscope uses ultraviolet radiation, and a _________ microscope uses a laser beam.

confocal

A microscope that scans fluorescent-stained specimens with a laser beam is a(n)

confocal microscope

When a culture shows two or more microbes of uncertain identity that have been introduced into it, the culture is considered to be ______.

contaminated

Which of the following are necessary qualities of an effective microscope?

contrast resolution magnification

The most effective instrument for visualizing living cells that would be distorted by drying or heat or that cannot be stained with usual methods is a(n)

dark-field microscope

A medium that works by showing two reaction types, such as a color change in some colonies but not in others is called a(n) ______ medium.

differential

Dyes are frequently used as pH indicators in _____ media.

differential

Media that allow the growth of multiple types of microbes but are designed to distinguish characteristics among members of the culture are called ______ media.

differential

The name given to media that work by showing two reaction types, such as a color change in some colonies but not in others, is

differential media

The name given to media which allow different types of microbes to grow but are designed to display visible morphological or chemical differences among those microbes is

differential media

Because it distinguishes bacteria based on their cell wall structure, the Gram stain is an example of a(n)

differential stain

Specimens prepared for transmission electron microscopy must be sectioned into extremely thin slices because ______.

electrons cannot readily penetrate thick specimens

A stain that is designed to distinguish between spores stained with malachite green and the vegetative cells from which they are produced is called the

endospore or spore

Culturing pathogens that are present in low numbers is a good application for _____ media.

enriched

A nutrient medium supplemented with blood, serum, or some growth factor to promote the multiplication of fastidious microorganisms is called a(n)

enriched medium

A medium that would be used to count the number of microbes in a sample is called a(n)

enumeration

Bacteria that require growth factors and complex nutrients are termed

fastidious

The entire circular area of view that is seen through the ocular lens is referred to as the ______.

field

When viewing a specimen through a microscope, the entire circular area that is seen through the ocular lens is called the

field of view

To visualize the filaments used by bacteria for locomotion, __________ staining is used.

flagella, flagellar, or flagellum

This image of a eukaryotic cell was obtained using _____ microscopy.

fluorescence

A specially modified compound microscope that uses an ultraviolet radiation source is the

fluorescence or fluorescent

The most universal differential staining technique that differentiates between bacteria based on their cell envelope structure is the

gram stain

These colonies growing on MacConkey agar are all ______ bacteria.

gram-negative

General purpose media ______.

grow a broad spectrum of microbes usually contain a mixture of nutrients are usually non-synthetic include nutrient agar and broth

A ______ is an organic compound such as a vitamin or amino acid that must be provided in the diet to facilitate survival of certain bacteria.

growth factor

Which of the following are defined as organic compounds that must be provided in the medium to facilitate growth (essential nutrients)?

growth factors

To simultaneously kill and secure a specimen to the glass slide, ________ _________ is used in smear preparation.

heat fixation

The endospore stain is similar to the acid-fast stain in that ______.

heat is applied to force the dye in

Which one of the Five I's involves placing an inoculated container of medium in a termperature-controlled chamber to encourage multiplication of the microbes?

incubation

A temperature-controlled chamber that provides the proper temperature conditions for microbial multiplication in the culturing process is called a(n)

incubator

The temperature-controlled chamber operated in the range of 20°C to 45°C to encourage the multiplication of bacterial cultures is called a(n)

incubator

The medium whose recipe appears here is a chemically complex medium because

ingredients like brain heart extract may vary from batch to batch

The introduction of microorganisms into an environment in which they will multiply is called

inoculation

Which term describes the introduction of microorganisms into an environment in which they will multiply?

inoculation

Selective media with bile salts can be used to isolate ______.

intestinal pathogens

Following the Five I's used for culturing microorganisms, inoculation, incubation, and _______ must occur prior to inspection.

isolation

The ______ microscope is used to visualize most types of bacteria.

light

The visualization of bacteria requires the use of a compound

light or optical microscope

The most effective use of dark-field microscopy is to visualize ______.

living cells that cannot be stained by usual methods

DNA detection technologies have shown that there are ______ microbes that we don't know how to cultivate in the lab than those we do.

many more

If a culture contains two or more identified, easily differentiated microbe species, it is called a ______ culture.

mixed

This image shows the results of a Gram stain. The culture sample for the stain was a _____ culture.

mixed

A container that holds two or more identified, easily differentiated species of microbes is called a

mixed culture.

Like fixed, stained preparations, wet mounts can provide a true assessment of cell size and morphology; however, unlike fixed preparations, wet mounts can also provide an assessment of the organism's ________ generated by the action of flagella or other structures.

motility, locomotion, or movement

A specimen for optical microscopy is generally prepared first by ______.

mounting the sample on a glass slide

A general type of staining that does not disrupt the cell structure with heat fixation and can indicate the presence of a capsule is called

negative stain

If a dye settles around the boundary of a specimen rather than sticking to it, forming a bright silhouette of the microbe on a dark background, the image has been formed by

negative stain

For a light microscope, the lens that is normally located directly above the stage is called the

objective lens

To which part of the microscope is the arrow pointing?

objective lens

An image's total magnification is determined by multiplying the individual power of both the ______.

objective lens and the ocular lens

The total power of magnification of the final image is a product of the separate powers of which two microscope components?

ocular lens objective lens

The microscope lens that gives the greatest magnification is the ______.

oil immersion lens

Which microscope lens gives the greatest magnification?

oil immersion lens

A specimen for ________ microscopy is generally prepared first by placing a sample on a glass slide.

optical or light

Dyes are often used in microbiological media as differential agents because they are used to detect ______.

pH changes

Liquid is one of the ______ states which is used to classify microbial media.

physical

The arrow is pointing to a cell that has stained Gram-_____.

positive

Any staining technique in which the dye actually sticks to the specimen and gives it color, instead of staining the background, is called

positive stain

Heat fixing a sample in microscopy is used for ______.

preserving various cellular components in a natural state simultaneously killing and securing the sample to the slide making a more permanent mount for long-term study

Selective media are used for the ______.

primary isolation of a specific microbe

A culture that contains only ONE species of microorganism is called a(n)

pure culture

Fastidious organisms ______.

require growth factors and/or complex nutrients

Which term describes the ability of an optical system to distinguish two adjacent points from one another?

resolution

To be effective, a microscope should provide magnification, contrast, and

resolution or resolving power

The capacity of an optical system to distinguish two separate objects from one another is called _____ power, also known as resolution.

resolving

The capacity of an optical system to distinguish two separate objects from one another is called ______ power, also known as resolution.

resolving

Which is the factor that most limits the clarity of a microscope's image?

resolving power

This image of algae cells was obtained using _____ microscopy.

scanning electron

Media that are important in the initial stages of isolating a specific type of microorganism from samples containing many other species, such as saliva or feces, are called

selective media

Media with a firmness midway between that of a broth (a liquid medium) and an ordinary solid medium are called ______ media.

semisolid

Media that have a fairly gelatinous or clot-like consistency that allows microbiologists to observe motility in some microorganisms are called

semisolid media

Media that are used to determine the motility of bacteria and to localize a reaction at a specific site are called

semisolid or motility media

This sample of Corynebacterium has been stained with a _____ stain.

simple

A stain that requires the use of only one dye is a(n)

simple stain

Spreading a thin film made from a liquid suspension of cells on a slide and air drying it are steps involved in making a

smear, smear-prep, or fixed smear

Microbial media can be classified as which of the following physical states?

solid liquid semisolid

Given the vast diversity of microbes in nature, _____ microbes can be cultured on artificial medium.

some

These bacteria have been stained to illustrate their flagella. This is an example of a _____ stain.

special

The plate illustrated in this figure is an example of a _______ plate, created by an isolation method.

spread

Any procedure that applies colored chemicals to specimens is called ______.

staining

The isolation technique that works by applying a bacterial sample to an agar plate and diluting the sample using an inoculating loop that is sterilized at each step of the dilution pattern on the plate is called the _______ plate technique.

streak

The technique that involves spreading a small droplet of culture or sample over a solid medium with a sterile inoculating loop, resulting in a gradual dilution of the sample over the surface of the medium yielding isolated colonies, is known as the ______ plate method.

streak

The method of spreading a small culture sample over a medium in a pattern that gradually thins out the sample resulting in isolated colonies is called the ______ method.

streak plate

Which method begins with placing a small drop of culture on solid medium and involves a series of thinning steps with a sterile inoculation loop to allow the growth of individual colonies?

streak plating

Which of the following factors that affect the growth of microbes can be controlled by incubators?

temperature atmospheric gas

Enriched media are useful for ______.

the growth of fastidious organisms growing pathogens that are present in low numbers

The streak plate technique works by using an inoculating loop to spread the bacterial sample in a pattern that thins it out but this only works if ______.

the inoculating loop is re-sterilized at each thinning step of the pattern

Microbial growth on a solid medium is indicated by ______.

the presence of colonies

The Gram stain is the most universal differential staining technique for bacteria, and it differentiates bacteria based on ______.

their cell envelope

What is the purpose of enumeration media?

to count the number of organisms in a sample

When preparing a sample for _____ microscopy, specimens are sectioned into extremely thin slices and stained or coated with metals to increase contrast.

transmission electron

General purpose media are designed to grow a broad spectrum of microbes. Which of the following are general purpose media?

trypticase soy agar brain heart infusion broth nutrient agar and broth

A fluorescent microscope uses ______ to view a specimen.

ultraviolet light

The bright-field, dark-field, and phase contrast microscopes all use ______ to allow viewing of a specimen.

visible light

Visualization of living, motile cells can be achieved using a(n)

wet or hanging-drop