Which staining technique is used to determine the thickness of the peptidoglycan layer based
on the cell wall composition? - correct answer gram stain
Where would you properly dispose of the following items?
A. contaminated slides
B. pipettes
C. used test tubes
D. uncontaminated glass - correct answer A. slide trays on the student benches
B. Nalgene buckets on student benches
C. trash cart at front of lab
D. broken glass box @ front of lab (notify TA)
In exercise 1 part 2 phase contrast microscopy _________ ___________ was used to visualize
bacteria at 100X total magnificationw/ oil immersion - correct answer Bacillus megaterium
Brightfield microscopy was used to view - correct answer dead, stained microorganisms
Phase contrast microscopy is used to view - correct answer live, unstained microorganisms
purpose of isolation streak - correct answer purify one species of bacteria
,BIO205L Practical Review and BIO 205L
Practical 2
3 main functions for a good image in microscopy - correct answer -resolution, contrast,
magnification
magnification - correct answer the distance from lens at the focal plane must be grater than
from lens of object
resolution - correct answer the ability to separate two points as distinct
contrast - correct answer enhancing contrast
-optics of the microscope may be altered various ways
-specimen may be altered by the addition of staining
Which staining technique is the quickest way to determine the cell morphology of bacteria? -
correct answer simple stain
steps to simple stain:
-control organism
-steps - correct answer Bacillus megaterium
1. prepare dry mount
2. heat fix cells
3. add 3-4 drops of methylene blue for 1 minute
4. blot dry
, BIO205L Practical Review and BIO 205L
Practical 2
Which of the following stains are used to determine the Gram reaction of bacterial cells? -
correct answer safranin & crystal violet
What is the definition of a control organism? - correct answer A control organism is known to
have a positive or negative reaction to a specific test and is used as a comparison to determine
the test result of an unknown organism.
What is the cellular morphology of spherical-shaped bacterial cells? - correct answer cocci
When staining bacterial cells, what is the purpose of a mordant? - correct answer The
mordant and the primary stain form an insoluble complex that is attached to a substrate of
interest.
How do bacteria benefit from the production of endospores? - correct answer Endospores
allow bacteria to survive stressful environmental conditions.
When differentially staining bacterial cells, what is the purpose of the steaming step?:
A. Endospore stain
B. Acid-fast stain
C. Capsule stain
D. Gram stain - correct answer A. The steaming step drives the primary stain into keratin
proteins.
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