Micro lab
When completing a quadrant streak, when do you flame the loop?
- Before you pick up a loopful of organisms from the original culture - Before you streak quadrant two and three - Before you return the loop to the receptacle
Order the reagents used in the acid-fast staining procedure.
- Carbolfuchsin - Acid-alcohol - Methylene blue
Please order the following choices to reflect the appropriate sequence of materials used in the Gram staining procedure
- Crystal violet - Gram's Iodine - Alcohol/Acetone - Safranin
Which of the following are destroyed by alcohol?
- Enveloped viruses - Vegetative bacterial cells
Which parts of a cell are most affected by temperature?
- Enzymes - Ribosomes - membrane fluidity
Order the reagents used in an indirect ELISA for HIV detection.
- HIV antigen - patient serum - anti-IgG antibody linked to enzyme - colorless substrate
Which of the following statements best describes what you would expect to happen if a transfusion recipient had blood type 0 and a donor had blood type AB?
Agglutination would occur as the recipient's antibodies bind to the donors antigens
Indicate the sites where microorganisms are likely to be found:
Air Hands Computer keyboard Laboratory bench surface
Narrow spectrum antibiotics are effective against a wide range of both Gram positive and Gram negative bacteria.
False
The higher the concentration of alcohol, the more effective its antimicrobial activity, with 100% alcohol being the most effective
False ( 70 % is the most effective)
E.coli, S. aureus, Candida spp. and Klebsiella spp are all considered common causes of
Healthcare Associated Infections (HAIs)
Infectious organisms can follow which of the following patterns of transmission?
Indirect contact Vector transmission Correct! All choices are correct Direct contact Vehicle transmission
Which is incorrect about fermentation?
It generates oxygen.
What advantage does the pour-plate method have over the streak-plate method?
It requires less skill.
What is the first step in differentiating the Enterobacteriaceae?
Lactose fermentation
What is the best source of information regarding the potential hazards, proper handling, and disposal instructions for a particular chemical?
MSDS (Material Safety Data Sheet)
Please choose the answer that best completes the blanks of this sentence in the correct order. _______ is used to stain the endospore, and _______ is the stain used to stain the vegetative cell in the Schaeffer-Fulton method of spore staining.
Malachite green; safranin
What media is used for testing antibiotic susceptibility?
Mueller Hinton agar
If a population drops below the threshold percent for herd immunity, what will happen?
Outbreaks will occur and be more frequent
What is heat fixation?
Passing the slide through the flame of a burner several times after the smear has completely dried.
When a vaccine is administered the body produces which type of immune response?
Primary Immune Response
Which of the following infectious agents is least likely to be damaged by UV exposure?
Prions
What medium is commonly used when culturing molds on agar plates?
Sabouraud's agar
Which of the following would be appropriately sterilized using UV radiation?
Stainless steel surface in biological safety cabinet used for media preparation
Which organism causes serious problems with Methicillin and Vancomycin resistant strains?
Staphylococcus aureus
You have a human isolate unknown culture that appears as Gram-positive cocci. It demonstrates bubbling upon the addition of hydrogen peroxide. Which of the following is a likely candidate to suspect?
Staphylococcus epidermidis
What must occur before sucrose is used in cellular respiration? (Sucrose is fructose and glucose bonded together)
Sucrase enzyme breaks it down to glucose and fructose.
Why does the solid medium become liquified for an organism that produces gelatinase in the nutrient gelatin medium?
The gelatin serves as the solidifying agent
You have cultured several different objects and surfaces in the environment. Which of the following indicates a more abundant bacterial population?
The item with the greatest number of microbial colonies on an agar plate
How is air contamination prevented when an inoculating loop is used to introduce or remove organisms from an agar plate?
The plate lid is kept closed or lifted only slightly when inoculating.
What makes Mycobacterium particularly resistant to staining?
The presence of mycolic acid in their cell walls
You make a smear of E. coli and then simple stain the slide with methylene blue. If you failed to use correct aseptic technique by not sterilizing the loop before picking up the bacterial sample for the smear, what results may be seen under the microscope?
There may be cells of different shapes, sizes, and arrangements.
Why is antimicrobial sensitivity testing done?
To determine what antimicrobials would be most effective for treating the infection
Why is the mouth of a culture tube passed through the Bunsen burner flame after removing and before replacing the cap?
To prevent the entry of ambient air which might introduce contaminants.
Watches, bracelets, and rings should be removed prior to washing hands.
True
long hair should always be tied back when working in the laboratory.
True
Which of the following statements apply to a host-to-host epidemic?
Vaccination, hygiene, and antibacterial/antiviral medications may help control the spread.
The rod shaped cells represent _______________ which stained pink/red due to the uptake of the _______________ dye.
Vegetative cells, Safranin
How does smear preparation of cells from a liquid medium differ from preparation of cells from a solid medium?
Water is applied to the slide before emulsifying cells from a solid medium.
When preparing a wet mount specimen for viewing, the specimen should be covered with
a coverslip
A positive reaction for motility in SIM medium would produce
a haze throughout the tube
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
What is the oxygen requirement for the organism in Tube "A"?
aerobe
Which of the following CANNOT serve as a nitrogen source?
agar
What type of medium provides the best opportunity for growing and observing the morphology of isolated colonies?
agar colonies
What type of medium provides the best opportunity for growing and observing the morphology of isolated colonies?
agar plates
The formation of visible clumps when antibodies react with whole cell antigens is specifically called __________.
agglutination
obligate anaerobe
alkaline
A compound such as cephalothin that is made by a species of mold and is able to kill or inhibit a number of different bacteria is correctly referred to as
an antibiotic.
Which organisms have centrioles?
animals
The plasma of a person with type A blood has:
anti-B antibodies.
The goal of ______ technique is to minimize the contamination of both original and newly inoculated cultures as well as protect the laboratory handler from contamination.
aseptic
What is used to sterilize infectious items prior to cleaning or disposal?
autoclave
Infectious laboratory waste is sterilized prior to disposal by
autoclaving (steam autoclave)
An agent that stops the growth of bacteria but does not kill them is described
bacteriostatic.
Which is the most appropriate disposal for a swab used to culture your throat during lab?
biohazard bag
Plant cells often have a large membrane-bound sac that is used for storing water and other substances called a:
central vacuole.
The __________ causes the stage to move upward or downward.
coarse adjustment knob
A ______ is a mound of cells on a solid medium that represents the progeny from one original bacterial cell.
colony
When determining the cell density of a sample by the standard plate count method, the final density of cells is reported as
colony forming units (CFU)/mL
Which of these items should be placed in the sharps container?
cover slips
Please choose the answer that best completes the blanks of this sentence in the correct order. After acid-fast staining, Mycobacterium tuberculosis would be _______ in color, whereas Proteus vulgaris would be ________ in color.
red; blue
You have just washed you hands after completing your lab work. Where should the paper towels used to dry your hands be discarded?
regular trash receptacle
The objective lenses of the compound light microscope are attached to the
rotating nosepiece
you are interested in studying the gram-negative bacteria that may be found in ground meat. You would like to use a medium that will enable the growth of most species of gram-negative bacteria, while inhibiting gram-positive bacteria. This would be a __________________ medium.
selective
An indirect method of estimating bacterial numbers is based on the turbidity of the sample. A ________ can be used to determine the turbidity by measuring absorbance.
spectrophotometer
Asexual spores that form within a thin-walled sac are referred to as ________.
sporangiospores
Please choose the answer that best completes the blanks of this sentence in the correct order. The ______ plate method involves spreading an inoculum onto the surface of a plate in a pattern that results in isolated colonies in some areas of the plate after incubation, whereas the ______ plate method involves diluting an inoculum into several melted agar tubes and then adding their contents into plates for solidification and incubation.
streak; pour
Respirometers were set up that contained yeast and 2% glucose solution. Each respirometer was placed at a different temperature. The height of the bubble contained in the respirometer was measured every 5 minutes for 20 minutes. What is the independent variable in this experiment?
temperature
The coagulase test detects
the ability to clot plasma
If the blood from an individual with type AB blood is mixed with anti-A serum in one well and anti-B serum in a second separate well
the anti-A serum well and the anti-B serum well will show agglutination.
The number of serial dilutions that are necessary for a standard plate count assay will depend on
the estimated density of cells in the original sample
Blood is a biohazard that requires special safety precautions.
true
Disease incidence can be reduced in a population through the use of vaccines.
true
The majority of heterotrophic microorganisms are chemoheterotrophs that derive both energy and carbon from organic compounds.
true
For each blood type, match the antibodies found in the plasma.
type A serum: anti-B antibodies type B serum: Anti-A antibodies type AB serum: neither Type O serum: both
Bacteria are _______, meaning that they are distributed everywhere.
ubiquitous
Microorganisms are found in nearly every environment and are said to be ____________________.
ubiquitous
The enzyme necessary to hydrolyze urea into ammonia and carbon dioxide is
urease
Soap should be applied to __________ hands.
wet
Which of the following items can be washed in the sink after use in the laboratory?
- dissection tools - glassware that was not used with hazardous chemicals - dissection trays
Which of the following activities should never take place in the laboratory?
- eating and/or drinking - handling contact lenses - applying make-up
Select all of the following pathways that produce ATP during cellular respiration.
- electron transport chain - Krebs cycle - glycolysis
Which of the following items should be autoclaved?
- glass culture tubes - biohazard bag
Select all of the following that are substrates lactic acid fermentation.
- glucose -
Which of the following are appropriate tools for making bacterial transfers from one medium to another? (Check all that apply)
- inoculating loop - inoculating wire
Which of the following are found in both plant and animal cells?
- mitochondria - Golgi complexes - endoplasmic reticulum
Which of the following steps are part of a thorough hand washing protocol?
- removal of bracelets, watches, and rings - lathering with soap, rubbing hands together for at least 20 seconds - using a brush and wooden stick, clean well under finger nails
Match each item with its most appropriate means of disposal.
- sharps container: broken glass slide - normal trash receptacle: paper towels used to dry hands after hand washing - rack for autoclaving: glass culture tubes containing broth cultures of Staphylococcus epidermidis - biohazard bag: used culture plates
Which types of culture media are solid?
- slants - agar plates
Which of the following terms are used to describe the appearance of the edge or margin of a colony growing on an agar surface?
- smooth - wavy - irregular
Match the names of the microscope parts in column A with the descriptions in column B. Place the letter of your choice in the space provided.
- stage(slide) clip: holds a microscope slide in position - arm: serves as a handle for carrying the microscope - eyepiece (ocular): contains a sense at the top of the body tube - nosepiece: Part to which the objective lenses are attached - field of view: Circular area seen through the eyepiece
Who and/or what is protected by lab safety protocols?
- students doing lab activities - lab instructors and technical assistants - anyone who walks into the lab - the physical lab spaced and he equipment housed within the lab
Endospores are less susceptible to UV damage because ________. (Check all that apply.)
- the DNA of endospores is protected by small proteins that protect it from photochemical damage - UV light generates a product in endospores that functions in the enzymatic repair of damaged DNA
Which groups within the population typically benefit the most from the principle of herd immunity? (choose all that apply)
- young children - infants - elderly - immunocompromised
Which carbohydrate is the primary or preferred starting compound for glycolysis and the fermentation pathway?
glucose
Which of the following substrates is fermented most easily by yeast?
glucose
A process common to all living organisms, whether aerobic or anaerobic, is
glycolysis
The principle where most of the population is immune to a particular pathogen thus protecting those who are not from encountering the pathogen is known as _____.
herd immunity
Detergents are
low-level germicides
The function of the iodine in the starch hydrolysis test is to
make starch visible
SIM medium will assay for
motility sulfur reduction Correct! all of the above indole production
In which circumstance is food and/or beverage allowed in the laboratory?
never
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
Which objective lens provides the highest total magnification?
oil immersion
Using oil immersion is useful because
oil immersion increases the resolving power of the specimen.
How does pH negatively affect the metabolism of microorganisms?
pH changes can denature enzymes
Which structure surrounds the cytoplasm of the cell and separates the interior of the cell from the external environment?
plasma membrane
If the addition of Kovac's reagent produces a floating red layer on a SIM medium culture, this indicates the organism is
positive for tryptophanase
Please choose the answer that best fills in the blanks of this sentence in the correct order. Gram-________ cells stain purple whereas gram-_______ cells stain pink or red when using the Gram stain technique.
positive; negative
Yeast cells under anaerobic conditions
produce ethyl alcohol (ethanol).
The cell wall is a common feature to
prokaryotic and plant cells.
You are looking at a drop of pond water and in the field of view, you observe a moving unicellular organism with short hairlike structures surrounding the outside surface of the cell. You are most likely observing an example of a/an ________.
protozoan
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. An organism that prefers moderate temperatures, such as 25 - 40C but is capable of growth at refrigerator temperatures is known as a:
psychrotroph
Which organism is typically grown in a candle jar? And what environment is obtained within the candle jar?
- decrease oxygen, increased carbon dioxide - Streptococcus pneumoniae
Which of the following may indicate that you have correctly subcultured an organism from a plate to a slant?
- After Gram staining a smear prepared from the slant, all of the cells have similar color and morphology under the microscope. - The slant shows only one color of growth.
Indicate which of the following observations can be made when observing growth on nutrient agar.
- Amount of growth - Opacity/clarity of colonies - Color of colonies - Shape and /or pattern of growth
Flame the loop red-hot before setting aside.
- Bacterial endospores are highly resistant to heat, drying and radiation. - Endospores can exist in the environment for indefinite periods of time. - Endospores resist boiling and therefore steam must be used to destroy endospores present in food.
Which of the following are reasons for washing hands before and after lab activities?
- Hands may be a source of contamination of lab experiments. - Hands may become contaminated with infectious bacteria during lab experiments. - Hands may become stained during lab. - Hands may be contaminated with irritating chemicals during experiments.
Order these statements to indicate correct aseptic procedure for removing organisms from a culture for application to a slide
- Heat inoculating loop and wire to red-hot. - Remove the cap of the culture tube and flame the mouth of the tube. - Remove a loopful of organisms from the culture. - Flame the mouth of the culture tube. - Return the cap to the culture tube. - Place organisms onto the slide in the center of the target circle. - Flame the loop red-hot before setting aside.
Which are advantages of the streak-plate method when compared to the pour-plate method?
- It requires less materials. - It is a very quick process.
Identify the correct statements about lab coats
- Lab coats provide some protection against contamination with infectious microorganisms. - Lab coats provide some protection against exposure to corrosive chemicals
Place the following steps in order to demonstrate your understanding of the pour plate method.
- Liquefy nutrient agar tubes and maintain at 50 degrees Celsius. - Remove loopful of organisms from culture using aseptic technique. - Add loopful of organisms to an agar tube. - Transfer one loopful from one agar tube into another agar tube, and repeat this again with a third agar tube. - Pour liquefied agar tubes into empty plates. - Incubate for 24-48 hours.
Which parts of a cell are most affected by temperature?
- Membrane fluidity - Ribosomes - Enzymes
Which Gram negative organisms are unable to ferment lactose? (select all that apply)
- Proteus sp. - Shigella sp. - Salmonella sp. - Yersinia sp.
Testing for the Rh antigen differs from testing for the A and B antigens in which of the following ways?
- Rh testing should be done on whole blood or plasma-suspended red blood cells - NOT saline-suspended red blood cells - Rh testing should be done at higher temperatures, 37 °Celsius for the tube test and 45 °Celsius for the slide test.
Select the statements that represent goals in correct smear preparation.
- The cells must be heat fixed to the slide to prevent removal when stain is washed off the slide. - It is important to minimize any artifacts or distortion of the cells for accurate viewing after staining. - Smears must be thin to allow for observation of single cells
Which of the following are destroyed by alcohol?
- Vegetative bacterial cells - Enveloped viruses
Which of the following represent important safety procedures for microbiology students?
- Wash your hands before and after laboratory procedures. - Disinfect your lab bench at the beginning and end of the lab period. - Take extra care around the flame of a Bunsen burner by tying up hair and keeping it from combustibles.
Complete the calculations for total magnification produced by various combinations of the eyepiece and objective lenses. Remember, to calculate the total magnification achieved when using a particular objective, multiply the power of the eyepiece by the power of the objective used.
- When the scanning (4x) objective is used the total magnification will be 40x - When the low power (10x) objective is used the total magnification will be 100x - When the high power (40x) objective is used the total magnification will be 400x - When the oil immersion (100x) objective is used the total magnification will be 1000x
Mitochondria can be found in the cells of:
- animals - plants
Select all of the following antibodies found in the blood of a person with blood type O.
- anti-A antibodies - anti-B antibodies
Examples of prokaryotes include:
- bacteria - archaea
Which of the following items may be on the laboratory bench top while doing lab work?
- cultures (broth, agar plates, agar slants) - equipment items specifically needed to complete the lab activity - pencil or pen
A total of 145 colonies were counted on the plate that received 1.0 mL of the 1:10,000 dilution of a specimen. What is the bacterial count for the original specimen?
1,450,000 colonies/mL
Which objective lens requires oil to be applied?
100x
What is the zone of inhibition for Vancomycin (VA) in this Kirby-Bauer test? (mark is at the 2nd line to the right of the line for number 2 on a metric ruler)
18 mm
A total of 75 colonies were counted on the plate that received 1 mL of a diluted specimen. After calculating, it is determined that the total bacterial count in the original specimen was 75,000,000 colonies per mL. What was the dilution factor for the plated sample?
1:1,000,000
When performing a Standard Plate Count, plates that contain __________________ colonies are selected for counting with the Quebec Colony Counter.
30-300 colonies
If you wanted to prepare a 1:10,000 dilution of your sample and cannot measure out quantities of less than 1 mL, and have dilution blanks that can hold only 10 mL, how many dilution blanks will you need?
4
0.1 mL of an original sample is diluted into 9.9 mL of water and then 0.1 mL of this is spread on a plate. 54 colonies grew. What was the original cell density of the sample?
5.4 X 10^4 CFU/mL
You exposed this TSA plate to the air of the laboratory for 30 minutes, and then you incubated the plate for 24 hours at 37 degrees Celsius. What would be the correct quantitative evaluation of the degree of contamination on this plate?
50-100 colonies
A disinfectant is used on your work surface
All of the choices are correct. (this one) after any spill of live microorganisms. after all work is complete. before the beginning of laboratory procedures.
What enzyme do bacteria produce to detoxify hydrogen peroxide?
Catalase
What were previously known as "blue-green algae?"
Cyanobacteria
What is one limitation to the usefulness of UV radiation?
Direct contact only
What is a major limitation to a simple stain technique?
Does not differentiate cellular structures
Predict the effect of endospores on preservation of a bacterial culture.
Endospores will promote and enable culture preservation.
The ovoid bodies are _______________ which stained green due to the uptake of __________ dye.
Endospores, Malachite green
Please choose the answer that best fills in the blanks of this sentence in the correct order. Algae and protozoa are in Domain ______ and cyanobacteria are in Domain _______
Eukarya; Bacteria
The terms crateriform, umbonate, convex, flat, and raised are all used to describe the _______ of a colony.
elevation
The study of the frequency and distribution of disease and health-related factors in human populations is called
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 aerobes
After capsular staining, the cells are clear and the capsule is a dark purple ring.
false
An Rh negative individual typically has anti-Rh antibodies in their plasma.
false
As the concentration of solutes in a solution increases, the water concentration increases.
false
For every bacterial cell that undergoes sporulation, there are two resulting bacterial cells.
false
It is important that the smear is thick in order to ensure that the stain will be retained on the slide.
false
Observation of a broth after transfer can show whether or not contamination has occurred.
false
Paper towels should be discarded in a biohazard container after washing hands.
false
The differential ingredient in EMB is bile salts.
false
The higher the concentration of alcohol, the more effective its antimicrobial activity, with 100% alcohol being the most effective
false
The selective ingredient in EMB media is lactose.
false
The total magnification achieved using a 10× objective lens with a 10× eyepiece lens is 20×
false
The total magnification achieved using a 10× objective lens with a 10× eyepiece lens is 20×.
false
True or False: When performing a standard plate count, the bacterial count reached is a reflection of the total count NOT the viable count.
false
Using a cell phone in lab is permissible since it can be used for timing experiments.
false
