PORTAGE LEARNING: MICROBIOLOGY,
MODULE 3 2026/2027 ACTUAL
QUESTIONS WITH VERIFIED ANSWERS.
gram-negative bacteria - correct answer-have a relatively thin
peptidoglycan layer followed by an outer membrane composed
of lipopolysaccharides (LPS)
decolorization wash - correct answer-gram-negative bacteria
will initially retain the crystal violet dye; however, by next
washing the cells with alcohol, a step referred to as the
________________, the LPS and thin peptidoglycan layers of
gram-negative bacteria are unable to retain the dye and the
outer membrane is depleted of its color
safranin - correct answer-added after decolorization in order to
visualize gram-negative bacteria
pink - correct answer-by counterstaining with positively charged
safranin, gram-negative bacteria appears....
, differential stain - correct answer-a generalized term used for
any staining technique that separates specimens into further
subgroups/most often utilizes at least two dyes
tightly adherent cells - correct answer-required to prevent
sample loss during the staining and wash steps
heat fixation - correct answer-most common method to fix a
sample
chemical fixation - correct answer-includes the use of
paraformaldehyde, ethanol or methanol/this process kills the
microorganism and as such, characteristics related to motility
(movement) are not possible
wet mount - correct answer-small liquid culture containing a
microorganism of interest is prepared, added to a slide and
then covered with a glass coverslip/ heat fixing is not performed
simple staining - correct answer-uses a solution of a positively
charged dye such as methylene blue, crystal violet, safranin or
MODULE 3 2026/2027 ACTUAL
QUESTIONS WITH VERIFIED ANSWERS.
gram-negative bacteria - correct answer-have a relatively thin
peptidoglycan layer followed by an outer membrane composed
of lipopolysaccharides (LPS)
decolorization wash - correct answer-gram-negative bacteria
will initially retain the crystal violet dye; however, by next
washing the cells with alcohol, a step referred to as the
________________, the LPS and thin peptidoglycan layers of
gram-negative bacteria are unable to retain the dye and the
outer membrane is depleted of its color
safranin - correct answer-added after decolorization in order to
visualize gram-negative bacteria
pink - correct answer-by counterstaining with positively charged
safranin, gram-negative bacteria appears....
, differential stain - correct answer-a generalized term used for
any staining technique that separates specimens into further
subgroups/most often utilizes at least two dyes
tightly adherent cells - correct answer-required to prevent
sample loss during the staining and wash steps
heat fixation - correct answer-most common method to fix a
sample
chemical fixation - correct answer-includes the use of
paraformaldehyde, ethanol or methanol/this process kills the
microorganism and as such, characteristics related to motility
(movement) are not possible
wet mount - correct answer-small liquid culture containing a
microorganism of interest is prepared, added to a slide and
then covered with a glass coverslip/ heat fixing is not performed
simple staining - correct answer-uses a solution of a positively
charged dye such as methylene blue, crystal violet, safranin or
