lab 2 pt 1

Which biochemical test would be most appropriate for determining whether an organism uses oxidative or fermentative metabolism?

O/F glucose

Why are young cultures (24-48 hr) preferred for Gram staining?

Older cultures of a gram-positive bacteria may stain as gram-negative.

Please choose the statement that explains why patient specimens have to be plated and cultured using differential and selective media for laboratory diagnosis of staphylococcal infections.

Staphylococcus grows in areas of the body that are highly populated with normal biota, so these media inhibit other microorganisms so that it is easier to find the staphylococci.

Acetobacter aceti is a bacterial species involved in the production of acetic acid during vinegar production. Which category would this bacteria be classified within?

acidophile

Some organisms don't require oxygen for growth since they use fermentation to harvest energy, but are able to grow in the presence of oxygen even if they don't use it. These organisms are classified as

aerotolerant aerobes

Which type of bacteria would you expect to find when surveying the microorganisms in a soda lake?

alkalinophile

Partial lysis of the red blood cells surrounding a bacterial colony indicate that the colony is ______.

alpha hemolytic

An organism that hydrolyzes starch possesses the enzyme ________.

amylase

The presence of urease is detected by

an increase in pH causing a color change of a phenol red indicator to bright pink.

When examining your culture, the colonies appear to be quite uniform in appearance and the culture appears to be pure. Upon observation of a Gram stained slide, you see what looks like cocci and short bacilli. What is the most likely morphology of these microorganisms?

bacillli

The terms, granular, flaky, flocculent, turbid, and pellicle, would be used to describe growth in or on

broth media

How does pH negatively affect the metabolism of microorganisms?

can denature enzymes

Which of the following would be most useful for differentiating a colony of staphylococcus from a colony of streptococcus?

catalase test

An infectious disease which is transmitted from one person to another, such as influenza, is specifically referred to as a(n) _______ infectious disease.

communicable

The steep decrease seen in the temperature range growth curve after the optimum is related to the _____________ of enzymes.

denaturation

At temperatures above the maximum in a bacterium's temperature range, its enzymes will ______.

denature

Which of the following will produce colonies with a metallic green sheen on eosin methylene blue agar (EMB)?

e coli

The terms crateriform, umbonate, convex, flat, and raised are all used to describe the _______ of a colony.

elevation

An infectious disease, such as Lyme disease, that is always present in a particular region at a steady frequency is known as a(n) ________ disease.

endemic

The study of the frequency and distribution of disease in defined human populations is known as __________.

epidemiology

Some organisms exhibit flexibility in terms of their energy harvesting reactions. If provided with oxygen, they will obtain energy through aerobic respiration. If in an environment without oxygen, they will turn to fermentation to satisfy their energy needs. These organisms are classified as

facultative anaerobes

T o F All bacteria that ferment make lactic acid as the end product.

false

T o F Transformation is a mode of genetic recombination in which a plasmid is transferred from a donor cell to a recipient cell via a direct connection.

false

Colonies that do not affect the red blood cells in the surrounding medium are ______.

gamma hemolytic

Which of the following is most critical to perform an acid-fast stain on?

gram positive bacilli

endospore stains need only be done on

gram positive bacilli

What is the substrate for the catalase enzyme?

hydrogen peroxide

The first incident or case in a given outbreak of a disease is the __________ case.

index

Which of the following is detected by the methyl red (MR) test?

low pH

The "M" in the IMViC reaction set refers to

methyl red test

Some organisms require oxygen in significantly reduced amounts, such as 5% oxygen. These organisms are classified as

microaeophiles

Organisms such as Pseudomonas spp. and Bacillus spp. need oxygen as the final electron acceptor in the electron transport chain and must have adequate oxygen in their immediate atmosphere in order to grow. These organisms are classified as

obligate aerobes

A bacterial species that cannot tolerate the presence of oxygen and will only grow in the absence of oxygen is classified as a(n)

obligate anaerobe

You have inoculated a tube of SIM (sulfide-indole-motility) medium and after incubation, the medium remained clear and you can only see growth right along the inoculation stab. What does this indicate?

organism is nonmotile

An epidemic that spreads across multiple continents, such as influenza in 1918, is known as a(n) _________.

pandemic

Any liquefaction of the gelatin medium by an organism indicates the presence of

proteases

Listeria monocytogenes is a human pathogen, growing readily in the human body. It poses a problem in food storage because of its ability to grow in refrigerated foods, such as unpasteurized milk or deli meats. A mesophilic organism that is capable of growth at refrigerator temperatures is known as a ______.

psychotroph

How should the reserve stock culture be stored over the several weeks that you are working on your "unknown?"

slant should be refrigerated

How is the gelatin medium inoculated?

stabbed with an inoculating needle

The ATP generated during fermentation reactions is generated by

substrate level phosphorylation

A phenol red glucose broth with a Durham tube has been inoculated and incubated. After 48 hours, the broth is turbid and bright yellow, and approximately half of the contents of the Durham tube have been displaced with gas. Interpret these results.

the organic is fermenting glucose

Predict how the pH of a medium might change if triglycerides are hydrolyzed.

the pH would decrease

After 48 hours of incubation, the surface of a starch agar plate growing a test bacterium is flooded with iodine. The entire plate turns into a blue-black color. This indicates that

the test organism did NOT hydrolyze starch

Taq polymerase is a DNA polymerase enzyme that demonstrates maximal activity around 72° C. The organism from which this enzyme was isolated would most likely be classified as a

thermophile

You inoculate a plate of general-purpose medium with Clostridium sporogenes, and you incubate it for 48 hours at its optimum temperature. When you remove the plate from the incubator, you notice that there is no growth on the plate. Besides errors made in inoculation, what else could explain this lack of growth?

this organism is an obligate anaerobes and requires the absence of O2 for growth

The acquisition of genetic material through the uptake of "naked" DNA molecules from the environment by bacteria is called ______.

transformation

Helicobacter pylori, a neutrophile, is able to survive in the acidic environment of the stomach due to its ability to hydrolyze urea. How does the hydrolysis of urea contribute to the survival of Helicobacter in this acidic environment?

urea hydrolysis results in end products that raise pH

You are studying a bacterium found in the normal intestinal biota of humans and most other mammals, and you are doing an experiment to determine the optimum growth rate of this bacteria. You have inoculated five nutrient broths, and are incubating one broth at each of the following temperatures: 5° C, 25° C, 38° C, 42° C, and 55° C. At which temperature would you predict to see the optimum growth rate?

38 C

T o F The presence of catalase and superoxide dismutase enzymes is what causes obligate anaerobes to be killed by the presence of oxygen.

False

Please select the pathogen from the genus Streptococcus that correctly represents the most serious pathogen of this group.

Group A beta hemolytic S. pyogenes