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Gram Stain Method in Microbiology

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Questions and Answers

What is the purpose of the decolorizer in the Gram staining process?

To increase the affinity of crystal violet
To stain the gram-positive bacteria
To allow the crystal violet-iodine complex to wash out of gram-negative bacteria (correct)
To fix the material on the slide

What is the typical color of the counterstain used in the Gram staining process?

Green
Blue
Purple
Red (correct)

What is the purpose of rinsing the slide with tap water?

To remove excess stain (correct)
To add more stain to the material
To mix the stains together
To fix the stain to the material

Why is the iodine solution left on the slide for a longer period than the crystal violet?

Because iodine increases the affinity of crystal violet (B) Signup and view all the answers

What determines the optimal time for decolorization?

The concentration of the decolorizer (B) Signup and view all the answers

What is the main purpose of the Gram stain method in microbiology?

To provide rapid presumptive identification of pathogens (C) Signup and view all the answers

What is the primary function of Gram's Iodine Mordant in the Gram stain method?

To help the crystal violet stain penetrate deeper into the cell wall (C) Signup and view all the answers

What is the characteristic of the cell wall of gram-positive bacteria?

A thick peptidoglycan layer (C) Signup and view all the answers

What is the difference between gram-positive and gram-negative bacteria in terms of cell wall composition?

Gram-negative bacteria have a thin peptidoglycan layer sandwiched between an outer membrane and a lipopolysaccharide layer (C) Signup and view all the answers

What is the recommended method for drying delicate smears, such as certain body fluids?

Air drying (A) Signup and view all the answers

What is the importance of the Gram stain method in microbiology?

To provide rapid presumptive identification of pathogens (C) Signup and view all the answers

What is the primary purpose of the Gram stain method in diagnostic microbiology?

To differentiate bacteria into gram-positive and gram-negative groups (D) Signup and view all the answers

What magnification is recommended for examining the slide under an oil immersion lens?

1000x (B) Signup and view all the answers

What is an advantage of the Gram stain method over simpler staining techniques?

It offers a more specific identification of bacteria (D) Signup and view all the answers

What is a advantage of the Gram stain method in terms of cost?

It is a low-cost method (D) Signup and view all the answers

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