Microbio Lab Unit 2

Front 1

A chromophore is the:
A) transparent component of the dye
B) the part of the dye that does not bind.
C) the colored portion to the dye.
D) part of the dye that is not seen.
E) the part of the dye that is not used up.

Back 1

C) the colored portion to the dye.

Front 2

Which of the following would use the stain eosin?
A) acid-fast staining
B) endospore staining
C) negative staining
D) Gram staining
E) flagellar staining

Back 2

C) negative staining

Front 3

Which of the following staining procedures is matched with the principal use for that particular stain?
A) flagella stain used to detect capsules
B) The endospore stain is used to detect hard-to-stain endospores, which are formed during adverse conditions to ensure the organism's survival.
C) negative stain used to differentiate cell wall components
D) acid-fast stain for microbes with capsules

Back 3

B) The endospore stain is used to detect hard-to-stain endospores, which are formed during adverse conditions to ensure the organism's survival.

Front 4

Before cells are stained, the specimen must be fixed. Fixing a specimen accomplishes all of the following EXCEPT which one?
A) Fixation attaches cells to the slide so they will not wash off during the staining process.
B) Fixation differentiates the various cells being observed.
C) Fixation kills the cells that are being stained for observation.
D) Fixation preserves cellular structure in the natural state with minimum distortion.

Back 4

B) Fixation differentiates the various cells being observed.

Front 5

Which type of staining method would you use to determine endospore-forming cells from non-endospore-forming cells?
A) regular stain
B) simple stain
C) differential stain
D) specialized stain

Back 5

C) differential stain

Front 6

An acidic dye is:
A) a dye the carries no charge.
B) a dye the carries a negative charged chromophore.
C) a dye that carries no chromophore.
D) a dye that carries a positive charged chromophore.
E) a dye the carries both positive and negative charged chromophores

Back 6

B) a dye the carries a negative charged chromophore.

Front 7

What is the purpose of staining samples?
A) To increase the contrast and visibility of the specimen
B) To kill the specimen
C) To see the specimen without the aid of a microscope
D) To make the specimen appear larger in the microscope

Back 7

A) To increase the contrast and visibility of the specimen

Front 8

Which of the following is a characteristic of simple stains?
A) They stain specific structures of a bacterial cell AND can be rinsed with water.
B) They are a basic stain AND can be rinsed with water.
C) They can be rinsed with water.
D) They stain specific structures of a bacterial cell.
E) They are a basic stain.

Back 8

B) They are a basic stain AND can be rinsed with water.

Front 9

Consider the following situations, and determine when a simple stain should be used instead of a Gram stain.
A) A specimen is being examined in which the presence of multiple species of bacteria is suspected.
B) An unknown species of bacteria is being characterized and identified.
C) A wound specimen is being examined.
D) A microbiologist is trying to determine whether an organism has flagella.

Back 9

D) A microbiologist is trying to determine whether an organism has flagella.

Front 10

What are the common arrangements of bacteria? (Select all that are correct. Be sure to select the appropriate scientific name. You lose points for choosing incorrectly or for not choosing a correct choice.)
A) Strepto
B) Cocci
C) Vibrios
D) Diplo
E) Staphylo
F) Bacillus
G) Spirillum

Back 10

A) Strepto
D) Diplo
E) Staphylo

Front 11

A basic dye
A) is a dye that carries no charge.
B) is a dye that carries a positively charged chromophore.
C) is a dye that carries a negatively charged chromophore.
D) is a dye that carries both a positively and negatively charged chromophore.

Back 11

B) is a dye that carries a positively charged chromophore.

Front 12

Which of the following are bacterial SHAPES? (Select all that are correct. Be sure to select the appropriate scientific name. You lose points for choosing incorrectly or for not choosing a correct choice.)
A) Vibrio
B) Strepto
C) Spirillum
D) Staphylo
E) Cocci
F) Bacillus
G) Diplo

Back 12

A) Vibrio
C) Spirillum
E) Cocci
F) Bacillus

Front 13

This is a multiple select question. Choose all of the following that are apprioprate:
A) Most microorganisms are transparent and staining allows the microbes to be visualized.
B) Staining allows the shape and size to be visualized.
C) Staining helps individual characteristics of a microorganism to be seen.
D) Staining allows the cell arrangements to be visualized.

Back 13

A) Most microorganisms are transparent and staining allows the microbes to be visualized.
B) Staining allows the shape and size to be visualized.
C) Staining helps individual characteristics of a microorganism to be seen.
D) Staining allows the cell arrangements to be visualized.

Front 14

Why is it important that crystal violet be a contrasting color to safranin?
A) The contrast allows you to differentiate between gram-negative and gram-positive cells by observing the color of the organism.
B) Crystal violet is attracted to the negatively-charged components of the cell wall; safranin is attracted to the positively-charged components of the cell wall.
C) Contrast allows the cells to stand out from the background.
D) Only safranin binds to the cell wall components of gram-negative cells.

Back 14

A) The contrast allows you to differentiate between gram-negative and gram-positive cells by observing the color of the organism.

Front 15

What is the most critical step in the Gram staining procedure?
A) The decolorization step
B) The application of the mordant
C) The counterstain
D) The primary stain

Back 15

A) The decolorization step

Front 16

Spherical shaped bacteria that divide and remain attached in chainlike patterns are called ________.
A) tetrads
B) streptococci
C) staphylococci
D) spirochetes

Back 16

B) streptococci

Front 17

Why is it recommended that Gram staining be performed on young bacterial cultures (not older than 24 hours)?
A) Increased incubation times lead to increased risk of contamination.
B) Over time, gram-negative cells gain the ability to retain the crystal violet stain after decolorization.
C) Over time, gram-positive cells lose their ability to retain the crystal violet stain after decolorization.
D) Over time, gram-negative cells lose their ability to retain the crystal violet stain after decolorization.

Back 17

C) Over time, gram-positive cells lose their ability to retain the crystal violet stain after decolorization.

Front 18

Gram-negative cells contain a periplasmic space that is ________.
A) abundant in photosynthetic pigments
B) a site of endocytosis
C) the site of protein synthesis
D) filled with lysozyme
E) rich in degradative enzymes

Back 18

E) rich in degradative enzymes

Front 19

Which of the following statements about a gram-negative cell wall is not true?
A) It has teichoic acids.
B) It maintains the shape of the cell.
C) It includes a thin layer of peptidoglycan.
D) It contains endotoxin.

Back 19

A) It has teichoic acids.

Front 20

If you forgot to add the counterstain to the mixed culture sample at the end of the staining procedure, gram-negative cells would appear __________ and gram-positive cells would appear __________.
A) colorless; purple
B) purple; red or pink
C) red or pink; colorless
D) red or pink; purple

Back 20

A) colorless; purple

Front 21

Were the cell types the same in all three specimen sets: yeast, plaque, and cheek?
How were they similar? How were they different?

Back 21

Response in graded quiz