ch 4 Flashcards
(94 cards)
E. coli has been isolated and cultured from three different individuals. Upon biochemical testing of these three cultures, you find that there are differences in some reactions. What is the best explanation of these differences?
A. TheserepresentthreedifferentspeciesofE.coli.
B. This is normal genetic variation seen among strains of E. coli.
C. Two of the cultures are mutants of the other.
D. The other two cultures are not really E. coli.
E. Mistakes have been made in the test interpretation.
B
In which situation would a bacterium most likely have cytoplasmic inclusions?
A. Whenproducinganendospore
B. When the cell is synthesizing flagella
C. When the cell is starved for nutrients
D. In a habitat abundant in nutrients
d
If you observe rod-shaped, pink cells on a slide that had just been Gram stained, you can assume that their cell envelope contains endotoxin.
T/F
T
You apply the acid-fast stain method to a patient’s specimen, an aspirate from the lungs. Microscopic examination reveals a large number of bright pink-red bacillus-shaped bacteria in the smear. Which statement is true?
A. This is the expected outcome for normal sputum.
B. Thepatienthaspneumonia.
C. The patient has tuberculosis.
D. The patient has an HIV infection.
C
A patient has a serious respiratory infection. A sputum sample yielded a bacterium that did not have any peptidoglycan. You hypothesize that the identity of this microbe could possibly be \_\_\_\_\_\_. A. Streptococcus pneumoniae B. Mycobacteriumtuberculosis C. Borrelia burgdorferi D. Staphylococcus aureus E. Mycoplasmapneumoniae
E
You have made a smear of a bacterial culture and have performed the Gram stain on it. Looking at the organism under the microscope, you notice that the cells do not seem to be the dark blue-purple of a gram-positive reaction, but instead are light purple. Your staining procedure was performed correctly. What is your best explanation as to why the bacteria have stained this way?
A. The bacteria were taken from an inappropriate medium, and a chemical is interfering with proper staining of the cells.
B. There is something in the wall of the bacteria that has affected the uptake of the crystal violet into the cell wall, thereby staining it improperly.
C. The specimen did not undergo heat fixation before staining; therefore, the primary dye does not stick properly to the wall.
D. These are mutant bacteria which cannot be stained like other bacteria.
B
You have found a mutant of Streptococcus pneumoniae that has lost the ability to produce a capsule. If you inject this strain into a population of healthy mice, what prediction can you make about the consequences?
A. Themicewillgetaseverecaseofpneumoniaandrecover.
B. The mice will remain healthy.
C. The mice will die of pneumonia.
D. The infection will respond to antiviral medication.
B
- You’ve just isolated a new bacterium in pure culture, and you culture it on a general purpose medium where its cells have a coccobacillus morphology. When you examine the cells after culturing on a variety of differential media, you find that in some cases, the cells appear as coccobacillus, but in others, they can be filamentous, cocci, or club-shaped. The best explanation for this observation is that
A. themediawereincubatedatanincorrecttemperature.
B. the differential media are contaminated.
C. the microscope is out of adjustment.
D. the bacterium is pleomorphic.
E. yourculturehasbecomecontaminated.
B. the differential media are contaminated.
You’ve just isolated a new bacterium in pure culture, and you culture it on a general purpose medium where its cells have a rod-shape (bacillus) morphology. In addition to culturing it on solid media, you inoculate a slide to grow it as a biofilm. When you use confocal microscopy to image the biofilm, you observe that there are several cellular morphologies, ranging from coccus to coccobacillus to long bacillus. The best explanation for this observation is that
A. the confocal microscope is out of adjustment.
B. the biofilm is no longer a pure culture of the microbe.
C. the biofilm culture was not incubated under the appropriate conditions.
D. the microenvironments within a biofilm promote structural variation.
D
A new drug is found to act by blocking the incorporation of subunits into sterol molecules for the cell membrane. Which statement is true?
A. Only archaeal cells would be affected by this drug.
B. Only biofilms would be affected by this drug.
C. Most bacteria would be unaffected by this drug.
D. A drug with this mechanism would be an excellent antibiotic.
E. This kind of drug would destroy viruses only.
c
- You need to determine if a pure culture of bacteria is gram-positive or gram-negative, but you’ve just spilled your only solution of crystal violet so you can’t do a Gram stain. You decide to try a lysozyme treatment on a sample of each culture and then examine the samples under the microscope. The expected result is
A. gram-positives will lyse and appears as debris; gram-negatives will lyse but more slowly.
B. gram-positives will lyse and appears as debris; gram-negatives will be unaffected.
C. gram-positives will lyse and appears as debris; gram-negatives will lose cellular morphology and appear as
cocci.
D. gram-negatives will lyse and appears as debris; gram-positives will lose cellular morphology and cocci
E.
gram-negatives will lyse and appears as debris; gram-positives will be unaffected.
B
Researchers studying the rigidity and flexibility of the cell envelope used chemotaxis to measure the ability of microbes to squeeze through tight spaces. E. coli, a gram-negative bacterium, was able to traverse narrower channels than B. subtilis, a gram-positive microbe, even though both cells are the same size when grown without restriction. E. coli has the more flexible cell envelope because
A. lipopolysaccharide has no charge.
B. it has fewer flagella.
C. it has only a single membrane.
D. there is less structural carbohydrate.
E. therearefewerproteinreceptors.
d
The process of sporangium formation and endospore maturation requires 6-8 hours. What is most likely to result if the temperature of the environment was raised to 100°C about 2 hours after the process started?
A. The chromosome in the endospore would likely carry mutations.
B. The endospore would form more slowly and be heat resistant.
C. The endospore would form properly but would be unable to germinate.
D. The organism would be termed a hyperthermophile.
E. The endospore would not form properly because it is not yet heat resistant.
E
Archaea have been found in many microenvironments in the human body. Which of the following microenvironments is most likely to fit with the designation of Archaea as “extremophiles?”
A. Theinnerearcanwithstandincreasedpressure.
B. The surface of the tongue has salt receptors.
C. The gingiva and the gut are anaerobic.
D. The temperature of the testes is less than 37°C.
c
At present, the most accurate indicator of evolutionary relatedness among organisms is the
A. size of the bacterial chromosome.
B. similaritiesofcellmembraneproteins.
C. sequence of the ribosomal small subunit RNA.
D. size of the ribosomes.
E. size of the periplasmic space.
C
Serological analysis for bacterial identification typically involves using
A. specific antibodies to the bacterial cell antigens.
B. amicroscopetodeterminecellmorphology.
C. the determination of guanine + cytosine base concentrations.
D. methods to identify cell enzymes.
E. the analysis of the appearance of colonies.
a
Which of the following bacteria is not closely related to the others?
A. Salmonella enterica subsp. enterica B. Salmonellaentericasubsp.indica
C. Salmonella bongori
D. Salmonella enterica subsp. Arizonae
c
Which of the following is mismatched? A. Tenericutes - waxy, acid-fast cell walls B. Gracilicutes-gram-negativecellwalls C. Mendosicutes - archaea cell walls D. Firmicutes - gram-positive cell walls
a
A research laboratory that identifies the subspecies of bacterial isolates from a recent Salmonella epidemic would refer to Bergey's Manual of \_\_\_\_\_\_ Bacteriology for guidance in identification. A. Systematic B. Classical C. Evolutionary D. Determinative
a
A clinical laboratory that identifies the bacterial agents that cause human disease would refer to Bergey’s
Manual of ______ Bacteriology for guidance in identification.
A. Systematic B. Determinative C. Classical
D. Evolutionar
b
The reference for bacterial descriptions and classifications is \_\_\_\_\_ Manual of Systematic Bacteriology. A. Leeuwenhoek's B. Lister's C. Koch's D. Bergey's E. Pasteur's
d
Which of the following is not a phenotypic trait of bacteria? A. Cell shape B. Biochemical reactions C. rRNA sequence D. Nutrient requirement
c
Archaea do not have the typical peptidoglycan structure found in bacterial cell walls.
t/f
t
- Which of the following is mismatched?
A. Psychrophiles - adapted to very low temperatures
B. Extreme halophiles - adapted to salty habitats
C. Methanogens-convertCO2andH2intomethane
D. Hyperthermophiles - adapted to high temperatures
E. Thermoplasmas - adapted to warm-blooded animal environments
e
