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Microbiology Lab Test, Micro lab 1 Questions and Answers (100% Pass)
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Microbiology Lab Test, Micro lab 1 Questions and Answers (100% Pass)
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©PREP4EXAMS@2024 [REAL-EXAM-DUMPS] Monday, July 29, 2024 12:15 PMMicrobiology Lab Test, Micro lab 1
Questions and Answers (100% Pass)
Why are thick or dense smears less likely to provide a good smear preparation for
microscopic evaluation? - ✔️✔️It will diminish the amount o flight that can pass through
making it difficult to see under the microscope.
Why is it essential that smears be air-dried? Why can't they be gently heated over the
flame to speed up the drying process? - ✔️✔️1. Overheat will denature and rupture the
cell wall. 2. excess water on the slides will boil during fixation
Why should you be careful not to overheat the smear during the heat-fixing process? -
✔️✔️Overheating will distort the morphology through plasmolysis of the cell wall
Why do you think the presence of grease or dirt on a glass slide will result in a poor
smear preparations? - ✔️✔️1. Bacteria will attach to the grease or dirt and wash away
when staining. 2. It can also diminish the microscopic light making it hard to see the
cells.
Why are basic dyes more effective for bacterial staining than acidic dyes? - ✔️✔️Basic
stains with a positively charge chromogen are preferred because bacterial nucleic acid
and certain cell wall components carry a negative charge that strongly attract and binds
to the cationic chromogen.
Can simple staining technique be used to identify more than the morphological
characteristics of microorganisms? Explain - ✔️✔️Yes, the purpose of simple staining is
to elucidate the morphology and also arrangement of bacteria cells.
During the performance of the simple staining procedure, you failed to heat fix your E.
coli smear preparation. Upon microscopic examination, how would you expect this slide
1
, ©PREP4EXAMS@2024 [REAL-EXAM-DUMPS] Monday, July 29, 2024 12:15 PM
to differ from the correctly prepared slides? - ✔️✔️When heat fixing the bacteria, the
bacterial proteins are coagulated and fixed to the glass surface. If fail to heat fix, the
bacteria will wash away when staining.
During a coffee break, your friend spills coffee on your lab coat and the fabric is
discovered. Is this a true biological stain or simply a compound capable of imparting
color? Explain your rationale. - ✔️✔️Coffee does not contain an auxochrome group which
conveys the property of ionization to the chromogen, enabling it to form salts and bind
to fibers or tissues.
What are the advantages of differential staining procedure over the simple staining
techniques? - ✔️✔️The differential staining determine the shape, arrangement, and gram
reaction while the simple staining only determine the morphology
Cite the purpose of each following reagents in the differential staining procedure:
Primary stain, counterstain, decolorizing agent, mordant. - ✔️✔️Primary stain: to impart
its color to all cells
Counterstain: Determine gram-positive (retain the purple primary color) or gram-
negative (undergo decolorization).
Decolorizing agent: remove excess dye of cell and may or may not remove the primary
stain from entire cell or only certain cell structure
Mordant: Increases the cells' affinity for a stain
Why is it essential that the primary stain and the counterstain be of contrasting color? -
✔️✔️So it can be distinguished from each other.
Which is the most crucial step in the performance of the Gram staining procedures? -
✔️✔️Decolorizing.
Over-decolorizing will result in the lost of primary stain, causing gram positive to appear
negative. Under-dhttp://quizlet.com/create-set#add-rowecolorizing will not completely
remove the crystal violet, causing the gram negative to appear gram positive.
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