Chapter 3 Tools of the Lab

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

Streak plate

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

incubated

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

isolation

inoculation

incubation

identification

Differential media result in which of the following observable characteristics?

Differently colored colonies,

Chemical precipitates,

Different media color after incubation,

Gas bubbles

What is the term for a culture made from a single isolated species?

Both axenic and pure are correct.

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.

objective; ocular

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

fastidious

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

They are differential stains.

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?

The culture medium was selective.

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

add contrast to see them better

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

True

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

differential

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

true

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

Resolution

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

defined

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

inoculation

Basic dyes are _______.

attracted to the negatively charged surface of bacterial cells

If a microbiologist is studying a specimen at a total magnification of 1000X, what is the magnifying power of the objective lens if the ocular lens is 10X?

100 X

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

complex

One technique for staining bacteria for viewing under the microscope is called the Gram stain. In this technique, alcohol is used as a decolorizer because it degrades the outer membrane found in some bacteria. What chemical component of the cell does alcohol affect?

Lipid

Agar is an important component of media because _______.

agar provides a solid surface for bacterial growth

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

false

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 ______.

simple staining

A pure culture contains _______.

only one identified species of microorganism

Ethyl alcohol is used in the Gram staining procedure as a decolorizer to degrade the outer membrane found in some bacteria. What chemical component of the cell does alcohol affect?

Lipid

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 ______.

0.1 µm

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

algae

All of the following are the benefits of agar as a solid medium,

Flexibility,

Can be inoculated and poured at a temperature that is not harmful,

Solid at room temperature,

Holds moisture

The three physical forms of laboratory media are ______.

solid,

semisolid,

liquid

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

immersion oil

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

inoculum

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

Staphylococcus

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

Differential

A common medium for culturing fastidious bacteria is ______.

blood agar

The term ____________________________ refers to the purposeful addition of a microbe to a new medium.

inoculation

Learning appropriate ____________________________ techniques is crucial when working in the lab to prevent the contamination of the samples that you are working with.

sterile

The addition of ____________________________, derived from a species of algae, is important to allowing microbiologists to create solid media that can act as a platform to grow our cultures.

agar

To prevent the refraction of light from obscuring the image of your specimen, it is important to always use ______________________________ when looking at microbes using the 100X objective lens.

immersion oil

To colorize the cells of a bacterial smear, we use a(n) ______________________________ dye that has a positive charge and is attracted to the surface of most cells.

basic

The ____________________________ stain is the most commonly used differential staining technique used in microbiology labs today and allows scientists to begin separating bacteria based on differences in their cell wall compositions.

gram

To visually confirm the presence of Mycobacterium leprae in a patient you suspect of having Hansen's Disease, which differential staining technique would prove most useful given its ability to identify the presence of mycolic acid/wax commonly found in species of Mycobacterium?

acid-fast stain

The primary reason to choose a negative stain over a traditional simple stain is to:

better see the true, unaltered shape of the cell

Which of the following types of media would be most appropriate to determine whether a cell can or cannot metabolize a specific amino acid?

differential

Which feature of Borrelia burgdorferi would be most influential in leading a microbiologist to perform a negative stain on it, as opposed to any other type?

it is a spirochete