Question

gram positive bacteria retain the crystal violet stain after the decolorization step because they have a thicker layer of what?
○ peptidoglycan
○ outer membrane
○ cellulose
○ lipopolysaccharides

question 6 (1 point)
you complete a gram stain and observe small pink cells that are longer than they are wide. what classification of cells do you have?
○ acid fast cocci
○ gram negative rod
○ gram negative cocci
○ gram positive rod

Explanation:

First Question (Gram - positive bacteria stain):

Gram - positive bacteria have a thick peptidoglycan layer in their cell wall. During Gram staining, the crystal violet - iodine complex is trapped in this thick peptidoglycan layer, so they retain the stain after decolorization. Outer membrane is a feature of Gram - negative bacteria. Cellulose is a component of plant cell walls, not bacterial cell walls. Lipopolysaccharides are part of the outer membrane of Gram - negative bacteria.

Gram - negative bacteria appear pink after Gram staining (because they lose the crystal violet stain and take up the safranin counterstain). Rod - shaped bacteria are longer than they are wide, while cocci are spherical. So, small pink (Gram - negative) cells that are longer than they are wide are Gram - negative rods. Acid - fast staining is different from Gram staining, and Gram - positive rods would be purple, Gram - negative cocci are spherical and pink.

Answer:

Peptidoglycan

Second Question (Gram - stain cell classification):