FREE AND STUDY GAMES ABOUT MICRO LAB PART 1

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FREE AND STUDY GAMES ABOUT MICRO LAB PART 1

EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -30 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation

Question 1: Pseudomonas aeuruginosa after primary stain is added

Answer:

purple Question 2: Bacteria with a high lipid content contain what material that affects the staining properties of certain bacteria?

Answer:

mycolic acid

Question 3: What does the Gram Stain differentiate?

Answer:

Gram Positive and Gram Negative bacteria Question 4: How do gram positive and gram negative bacteria differ in cellular structure? How does this contribute to their differential staining properties?

Answer:

A gram + cell wall (thick) retains the crystal-violet iodine complex better in teh presence of decolorizer as compared to gram - cell, which has a thin cell wall

Question 5: The exosporium or endospore coast is composed of

Answer:

proteins Question 6: List the four staining techniques of gram-stain and the cell type and color after completion of stain

Answer:

Crystal Violet; iodine; alcohol-acetone, safarin results in Gram + Purple and Gram - Pink Question 7: How do you think the acid-fast nature of Mycobacterium contributes to its virulence?

Answer:

The waxy cell protects it against phagocytosis & some antibiotics while in the host (eg lungs for TB) so the pathogen has greater opportunity to cause disease.Question 8: Bacillus anthracis, the causative agent of anthrax, is an endospore-former. Why does this trait enhance its capabilities as a biological weapon?

Answer:

They are ideal because they are easily produced, can be dispersed in the air & are environmentally stable.Question 9: Why must smear thickness be considered before performing gram stain?

Answer:

Smears that are too thick will not stain properly bec the stains may not penetrate lower layers & thick clumps of cells may not easily decolorize

Question 10: What is the function of a mordant?

Answer:

A mordant causes the primary stain to adhere better or be taken up by the cell so that it is not removed during the de-colorizing step

Question 11: List the five steps of Gram stain in order;

Answer:

1)Heat fixed cells2)Crystal Violet (Primary Stain) 20 seconds3)Gram's Iodine (mordant) for 1 minute4) Ethyl Alcohol (decolorizing) 10-20 seconds5) Safranin (1 min)

Question 12: Bacillus megaterium after the mordant is added

Answer:

purple

Question 13: Bacillus megaterium after the counterstain is added

Answer:

purple Question 14: For differential staining, how does a counterstain differ from a primary stain?

Answer:

The counterstain must be a different color than the primary stain to aid in differentiaion Question 15: List the four staining techniques of Acid-Fast Stain and the cell type and color after

Answer:

Carbolfuchsin, heat, acid-alcohol, methylene blue. Results; Acid fast bacteria=RED and non-acid fast bacteria= Blue

Question 16: Endospores are produced by bacteria in the genus

Answer:

Bacillus and Mycobacterium

Question 17: How does culture age affect the results of a Gram-stain?

Answer:

Old cultures of gram+ cells may not retain stain as well as younger cultures and could give false negatives

Question 18: Acid fast staining is useful for identifying he causative agent of

Answer:

leprosy and tuberculosis

Question 19: A bacterial cell wall is composed of;

Answer:

peptidoglycan

Question 20: Which is the most critical step in the Gram-Stain procedure? Why? If this procedure is cone incorrectly, how might that affect the final results?

Answer:

The decolorizer step because it is the step in which the cells become differentiated (Gram+ are purple and Gram- are colorless)Too much & Gram+ lose primary & stain pink. Too little & Gran- will not lose primary & will remain purple.

Question 21: How does culture age affect the results of a spore stain?

Answer:

Old cultures of spore formers like bacillus are ideal bec under the conditions of nutrient depletion, sporulation is more likely to occur Question 22: What makes Mycobacterium particularly resistant to staining? How are the bacteria in this genus grouped in terms of Gram classification?

Answer:

It has a peptidoglycan layer filled w/mycolic acids that make the wall waxy & impenetrable to stains.Classified w/gram+ cell bec of cell wall thickness & genetic similarities

Question 23: The color of Staphylococcus aureus before primary stain is added

Answer:

colorless

Question 24: Pseudomonas aeruginosa after the counterstain is added

Answer:

pink

Question 25: Moraxella (Branhamella) catarrhalis after the decolorizer is used

Answer:

no color

Question 26: The Gram Stain is an example of what type of stain?

Answer:

Differential Stain