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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.

E) A) and C)
F) B) and C)

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An irregular cluster of spherical bacterial cells is termed ______.


A) staphylospirillum
B) streptobacillus
C) staphylobacillus
D) streptococcus
E) staphylococcus

F) D) and E)
G) A) and C)

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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) Mycobacterium tuberculosis
C) Borrelia burgdorferi
D) Staphylococcus aureus
E) Mycoplasma pneumoniae

F) B) and D)
G) A) and D)

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The division of microbes termed the Mendosicutes have a cell wall type best described as ______.


A) lacking a cell wall
B) archaeal
C) gram-positive
D) gram-negative

E) B) and C)
F) A) and B)

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Bacterial endospores are produced by ______.


A) Entamoeba
B) Bacillus
C) Mycoplasma
D) Staphylococcus

E) A) and C)
F) All of the above

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The short, numerous appendages used by some bacterial cells for adhering to surfaces are called ______.


A) periplasmic flagella (axial filaments)
B) flagella
C) fimbriae
D) cilia
E) pili

F) C) and D)
G) A) and D)

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The division of microbes termed the Firmicutes have a cell wall type best described as ______.


A) gram-positive
B) archaeal
C) lacking a cell wall
D) gram-negative

E) C) and D)
F) None of the above

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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.

E) B) and C)
F) A) and B)

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All of the following occur during endospore germination except


A) the cell grows out of its protein coats.
B) binding of a small organic molecule to initiate germination.
C) dehydration of the cell components.
D) enzymes digest the endospore cortex.

E) B) and D)
F) C) and D)

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Which of the following bacterial structures is incorrectly matched with a function?


A) Nucleoid - hereditary material
B) Plasmids - contain genes essential for growth and metabolism
C) Cytoplasm - dense, gelatinous solution
D) Ribosomes - protein synthesis
E) Inclusions - excess cell nutrients and materials

F) B) and C)
G) A) and D)

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Lysozyme is most effective against ______.


A) gram-positive organisms
B) archaea
C) mycoplasmas
D) cyanobacteria
E) gram-negative organisms

F) C) and D)
G) A) and B)

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Which of the following bacteria is not closely related to the others?


A) Salmonella enterica subsp.enterica
B) Salmonella enterica subsp.indica
C) Salmonella bongori
D) Salmonella enterica subsp.Arizonae

E) B) and C)
F) A) and C)

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Which of the following is not a phenotypic trait of bacteria?


A) Cell shape
B) Biochemical reactions
C) rRNA sequence
D) Nutrient requirements

E) A) and B)
F) A) and C)

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The macromolecule containing alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) chains cross-linked by short peptide fragments is ______.


A) lysozyme
B) lipopolysaccharide
C) mycolic acid
D) peptidoglycan
E) teichoic acid

F) A) and B)
G) D) and E)

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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. 2-20-13

A) True
B) False

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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) The mice will get a severe case of pneumonia and recover.
B) The mice will remain healthy.
C) The mice will die of pneumonia.
D) The infection will respond to antiviral medication.

E) C) and D)
F) B) and C)

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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

F) A) and E)
G) D) and E)

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The cell envelope of gram-positive bacteria has two layers: a thick cell wall and the cell membrane.

A) True
B) False

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Spirochetes are able to move due to ______.


A) cilia serving as walking feet
B) a membrane-bound flagellum
C) glycocalyx for gliding motility
D) a periplasmic flagellum
E) pseudopods

F) A) and B)
G) A) and C)

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A nutrient binds to receptors near the flagellar basal body.This will result in


A) inhibition of flagella rotation.
B) numerous tumbles.
C) clockwise rotation of flagella.
D) counterclockwise rotation of flagella.

E) A) and D)
F) A) and C)

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