MCB Chapter 3

Most student laboratory microscopes magnify to 1000X. If the human eye has a limit of resolution of 0.1 mm, what is the size of the smallest object that could be detected at 1000X in such a microscope? Multiple choice question. 0.1 μm

0.1 UM 0.1 μm x 1000 = 100 μm = 0.1 mm

Most student laboratory microscopes magnify to 1000X. If the human eye has a limit of resolution of 0.1 mm, what is the size of the smallest object that could be detected at 1000X in such a microscope?

0.1 μm Reason: 0.1 μm x 1000 = 100 μm = 0.1 mm

Using a microscope with a 10X ocular lens and an oil immersion lens of 100X, a cell of Staphylococcus that is about 1 μm in diameter will appear as _____ in diameter.

1 mm

Which are examples of differential stains? Multiple select question. Simple stain Acid-fast stain Negative stain Gram stain

Acid-fast stain Gram stain

What is involved in making a smear? Applying a liquid suspension to a cover slip Staining the slide background and then applying cells Air drying a liquid application on a glass slide Spreading a thin film of suspended cells on a glass slide

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

Which tests can be used to identify cultured microorganisms? Biochemical tests Microscopic examination Immunological tests Turbidity measurements of broth DNA analysis

Biochemical tests Microscopic examination Immunological tests DNA analysis

Which types of media contain at least one ingredient that is not chemically defined? Blood agar Synthetic Complex

Blood agar Complex Blood agar: This is a type of complex medium whose exact composition is undefined. Synthetic: Media type is known Synthetic can be chemicaly defined because you can say what it is made of. With blood or complex you cant say what it is definetly made of

A microbial ___________ is defined as the accumulation of microorganisms in or on a nutrient medium; it is observed as turbidity in a broth or colonies on solid media.

CULTURE

Which of the following are characteristics of an enriched medium? Its components are always chemically defined Can be used to aid in the growth of fastidious organisms May contain organic substances such as blood, serum or hemoglobin Contains antibiotics to assist in keeping cultures pure May contain special growth factors

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

Which of the following characteristics can be assessed by simple stains? Cell arrangement Cell size Cell shape Motility Cell color

Cell arrangement Cell size Cell shape

Media ingredients that cannot be chemically defined include which of the following? Cell secretions Disodium hydrogen phosphate Sodium chloride Blood and serum Extracts of animals, plants, or yeasts

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

The ability to be distinguished from the surroundings

Contrast

The four types of visible-light microscopes include ______.

Dark-field Bright-field Phase-contrast Interference

Select the characteristics of complex media used in microbial culturing. (Check all that apply.) The chemical composition is precisely known. They provide a rich mixture of nutrients for microbial growth. They may contain blood, serum, or meat extracts. They are also referred to as synthetic media. Examples include chocolate agar and MacConkey agar.

Examples include chocolate agar and MacConkey agar. They provide a rich mixture of nutrients for microbial growth. They may contain blood, serum, or meat extracts.

True or false: Selective media cannot be differential.

False Some selective media can also be differential (MacConkey medium, for example).

True or false: Characteristics that can be assessed with differential stains include the presence of internal organelles, such as ribosomes.

False: The viewing of internal structures such as organelles requires more sophisticated microscopy than that provided by stained specimens and a light microscope.

Bacteria that require growth factors and complex nutrients are termed

Fastidious

Require growth factors and/or complex nutrients

Fastidious organisms:

Give a reason why a microbiologist would use a flagellar stain. Only pathogens have flagella, and safety measures must be initiated if flagella are found. Different types of flagella would stain different colors. Flagella are so narrow that they cannot be visualized without a special stain. Flagella can be so numerous that individuals can't be resolved without a special stain.

Flagella are so narrow that they cannot be visualized without a special stain.

______is placing a culture in a temperature-controlled chamber to encourage multiplication.

Incubation

Which of the following represents inoculation of a microbial sample? Multiple select question. Injecting sample into a bird embryo Sequencing of the microbial DNA Placing a sample in sterile medium Examining a microbe under the microscope Streaking a sample on an agar plate Maintaining a sample at body temperature

Injecting sample into a bird embryo Placing a sample in sterile medium Streaking a sample on an agar plate

Which of the Five I's deals with the evaluation of cultures both macroscopically and microscopically?

Inspection Not identification because Identification involves much more than microscopic and macroscopic inspection. It involves extensive biochemical and physiological testing as well.

Which of the following are correct about immersion oil and its properties? It has the same optical qualities as air It increases the numerical aperture It decreases the numerical aperture It prevents refractive loss as peripheral light passes from slide to air It has the same optical qualities as glass

It increases the numerical aperture It prevents refractive loss as peripheral light passes from slide to air It has the same optical qualities as glass

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

Liquid Liquefiable Semisolid

General purpose media are designed to grow a broad spectrum of microbes and include ______.

Nutrient agar and broth Brain heart infusion broth Trypticase soy agar Slide 18

Choose the three basic ways that media are classified. Chemical composition Purpose Temperature of incubation Physical state Ease of preparation

Physical state Chemical composition Purpose

While both methods are used to isolate bacteria, what is the difference between the results of streak plating and pour plating? Pour plating results in isolated colonies on the surface and within the medium. Pour plating results in isolated colonies only within the medium. Streak plating results in isolated colonies on the surface and in the medium. Streak plating results in isolated colonies only within the medium.

Pour plating results in isolated colonies on the surface and within the medium. Streak plate method is just on the surface

Match the type of hemolysis with its appearance on an inoculated blood agar plate.

Refer to chart

The ability to distinguish between two separate structures that are very close to one another

Resolution

Mannitol salt agar is a type of ---- medium due to its ability to suppress growth of some organisms but this medium is also --------- because it produces a visual distinction among the microbes that grow.

SELECTIVE DIFFERENTIAL

A __________ medium means that the medium does not contain any viable microbes.

Sterile

Select the type of microscope that allows for the visualization of intracellular organelles and viruses in thinly sliced specimen preparations.

Transmission electron microscopy

Which are two general forms of electron microscopy?

Transmission electron microscopy Scanning electron microscopy

True or false: A broth can be defined as being liquid, water based, and not able to solidify at temperatures above freezing.

True

True or false: The factor that most limits the clarity of a microscope's image is the resolving power.

True

Which types of differences can be displayed by using differential media?

Variations in colony color Media color changes Variations in colony size Formation of gas bubbles

Resolving power is the ability of a microscope to ______.

accurately distinguish between two separate entities

General purpose media:

are usually complex support the growth of many types of microbes

On a blood agar plate,____________ -hemolysis is demonstrated by a complete clearing around a bacterial colony.

beta

he observation of live and preserved stained specimens in a white field involves the use of ________ - ___________ microscopy.

bright field

General characteristics that can be assessed with differential stains include ______. cell shape cell arrangement cell structures cell motility

cell shape cell arrangement cell structures

A _______ is the term used for a macroscopic cluster of cells appearing on a solid medium, arising from the multiplication of a single cell.

colony

A sterile medium is characterized by ______.

complete absence of viable microbes

___________ media contain at least one ingredient that is not chemically definable.

complex

A _________ culture results when a microbe of uncertain identity has been introduced into it.

contaminated

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

contaminated

a visible accumulation of microorganisms in or on nutrient medium.

culture

The Gram stain is an example of a ________ stain because it distinguishes bacteria based on their cell wall structure.

differential

______ stains are more complicated than _________ stains because they utilize a primary dye and a counterstain.

differential simple

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

enriched or complex

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

enriched or complex

_______ __________ is used in microscopy to simultaneously kill and secure the specimen to the glass slide.

heat fixation

To study microorganisms, microbiologists must separate different species from one another because ______.

in most habitats, microbes are in complex associations

____________ is the part of the Five I's process for culturing microorganisms that deals with the examination and evaluation of a culture both macroscopically and microscopically.

inspection

Broths are characterized by being ______.

liquid, water based, and not able to solidify at temperatures above freezing

Applications of bright-field microscopy include observation of ______.

live and preserved stained specimens dark specimens in a white field

making an object bigger

magnification

Heat fixing a sample in microscopy is used for ______. making a more permanent mount for long-term study simultaneously killing and securing the sample to the slide drying the liquid used to make the smear preserving various cellular components in a natural state highlighting cell structure for observation

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

Which two types of media are both selective and differential?

mannitol salt agar MacConkey agar

A container that holds two or more identified, easily differentiated species of microorganisms

mixed culture

Applications of a wet mount include which of the following? True assessment of size True assessment of morphology True assessment of motility

motility size morphology

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/movement

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

mounting the sample on a glass slide

In ______ staining, the dye settles around the boundary of the specimen rather than sticking to it, forming a bright silhouette of the microbe on a dark background.

negative

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

negative

Which dyes are commonly used in negative staining?

nigrosin and india ink

What substance prevents the refractive loss of light when using the highest powered lens of a light microscope?

oil

pink staining= purple staining =

pink = neg purple = pos

Loop dilution or _________ plating differs from streak plating in that isolated colonies will develop both on the surface of and within the agar medium.

pour

When a container of medium grows only a single known species or type of microorganism, that culture is considered to be ______.

pure or axenic

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

resolving

The two general forms of electron microscopy are _________ electron microscopy (SEM) and _________ electron microscopy (TEM).

scanning transmission

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

selective differential

Choose the term that describes motility media.

semisolid

______ stains will help the observer identify cell shape and arrangement, but they do not usually show differences in cell wall or structural components.

simple

_______ stains require only a single dye and _____stains use two different dyes in a more complicated

simple differential

To prepare a specimen for optical microscopy, the sample is generally placed on a glass __________ that sits on the stage between the condenser and objective lens of the microscope.

slide

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

smear

A microbiologist would use a flagellar stain because ______. only pathogens have flagella, and safety measures must be initiated if flagella are found this provides information about the antibiotic susceptibility of an organism some microbes can be identified by their arrangement of flagella

some microbes can be identified by their arrangement of flagella

The procedure that involves applying colored chemicals (dyes) to specimens is called

staining

A ________ is made by taking a sample from an isolated colony and inoculating a separate medium to obtain a pure culture.

subculture

Taking a sample from an isolated colony and inoculating a separate medium is known as ______.

subculturing Taking a sample from an isolated colony is isolation, but inoculating a separate medium is "subculturing."

A _____ medium is used to preserve specimens that have to be held before analysis.

transport

Microbial growth in a broth culture may be detected by changes in ______. turbidity volume color sediment

turbidity color sediment

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

visible light