BIOS 280 Lab Quiz 2; Questions and Answers Already
Solved
a gram stain provides information about the bacterial cell ____ Correct Ans-wall
bacterial cell walls consist of a complex molecule called ____ Correct Ans-peptidoglycan
bacterial cells have either a ____ cell wall with very little peptidoglycan present, or a ____ cell
wall with a significant amount of peptidoglycan Correct Ans-thin
thick
the peptidoglycan of the ____ cell wall will hold crystal violet dye while the small amount of
peptidoglycan in the ____ cell wall will allow the crystal violet dye to rinse off with alcohol
Correct Ans-thick
thin
the first step in the gram-stain process is to apply ____ stain to a heat-fixed bacterial smear;
the stain is then rinsed off with _____ Correct Ans-crystal violet
water
, BIOS 280 Lab Quiz 2; Questions and Answers Already
Solved
the second step in the gram-stain process is that the ____ solution is added to the slide; this
acts as a ____, which binds the crystal violet dye to the peptidoglycan layer in the cell wall
Correct Ans-iodine
mordant
the third step in the gram-stain process is that the bacterial smear is ____ with alcohol; any
dye not firmly fixed into the cell wall will wash out; then safranin, a ____, is applied to the
smear Correct Ans-decolorized
counterstain
gram-positive organisms will retain the crystal violet in their thick cell walls with the help of
the mordant and appear ____ Correct Ans-purple
the alcohol removes the purple stain from gram-negative organisms, and the colorless cells
take up the safranin counterstain, which appear ____ Correct Ans-pink
____-fixing prevents the bacteria from washing off the slide Correct Ans-heat
, BIOS 280 Lab Quiz 2; Questions and Answers Already
Solved
the first step in heat-fixing the bacteria is to place 1-2 loopfuls of distilled water on a slide; be
sure to use an ____ loop; aseptically transfer a small amount of bacterial culture from a plate;
mix the culture with the distilled water on a slide; spread the liquid evenly over the slide
Correct Ans-incinerated
the second step in heat-fixing the bacteria is to allow the slide to ____-dry; it is dry when
there is no visible moisture or wetness on the slide Correct Ans-air
the third step in heat-fixing the bacteria is to heat-fix the slide by either leaving the slide on
the slide warmer for ____ minutes, or holding the slide (with a clothespin) against the outside
of a turned-on incinerator for ____ minutes Correct Ans-10
1-1.5
after the slide is heat-fixed, the slide is ready for ____ Correct Ans-staining
the first step to perform a gram-stain is to place the slide on the staining rack over the sink;
you may use a clothespin to hold the slide; add 2-3 drops of ____ stain to the slide for about
30 seconds Correct Ans-crystal violet
Solved
a gram stain provides information about the bacterial cell ____ Correct Ans-wall
bacterial cell walls consist of a complex molecule called ____ Correct Ans-peptidoglycan
bacterial cells have either a ____ cell wall with very little peptidoglycan present, or a ____ cell
wall with a significant amount of peptidoglycan Correct Ans-thin
thick
the peptidoglycan of the ____ cell wall will hold crystal violet dye while the small amount of
peptidoglycan in the ____ cell wall will allow the crystal violet dye to rinse off with alcohol
Correct Ans-thick
thin
the first step in the gram-stain process is to apply ____ stain to a heat-fixed bacterial smear;
the stain is then rinsed off with _____ Correct Ans-crystal violet
water
, BIOS 280 Lab Quiz 2; Questions and Answers Already
Solved
the second step in the gram-stain process is that the ____ solution is added to the slide; this
acts as a ____, which binds the crystal violet dye to the peptidoglycan layer in the cell wall
Correct Ans-iodine
mordant
the third step in the gram-stain process is that the bacterial smear is ____ with alcohol; any
dye not firmly fixed into the cell wall will wash out; then safranin, a ____, is applied to the
smear Correct Ans-decolorized
counterstain
gram-positive organisms will retain the crystal violet in their thick cell walls with the help of
the mordant and appear ____ Correct Ans-purple
the alcohol removes the purple stain from gram-negative organisms, and the colorless cells
take up the safranin counterstain, which appear ____ Correct Ans-pink
____-fixing prevents the bacteria from washing off the slide Correct Ans-heat
, BIOS 280 Lab Quiz 2; Questions and Answers Already
Solved
the first step in heat-fixing the bacteria is to place 1-2 loopfuls of distilled water on a slide; be
sure to use an ____ loop; aseptically transfer a small amount of bacterial culture from a plate;
mix the culture with the distilled water on a slide; spread the liquid evenly over the slide
Correct Ans-incinerated
the second step in heat-fixing the bacteria is to allow the slide to ____-dry; it is dry when
there is no visible moisture or wetness on the slide Correct Ans-air
the third step in heat-fixing the bacteria is to heat-fix the slide by either leaving the slide on
the slide warmer for ____ minutes, or holding the slide (with a clothespin) against the outside
of a turned-on incinerator for ____ minutes Correct Ans-10
1-1.5
after the slide is heat-fixed, the slide is ready for ____ Correct Ans-staining
the first step to perform a gram-stain is to place the slide on the staining rack over the sink;
you may use a clothespin to hold the slide; add 2-3 drops of ____ stain to the slide for about
30 seconds Correct Ans-crystal violet
