Prince George Community College » Biology » Bio 2010 - Microbiology » Summer 2023

Question #1

What cellular structure cause the different results after Gram staining?

A. Mycolic acid

B. Cell membrane

C. Cytoplasm

D. Cell wall

E. Flagella

Question #2

You forgot to use the safranin in your Gram staining. Which of the following would be a possible consequence?

A. Both gram positive and Gram negative will appear purple

B. Gram negative will not be stained

C. Gram positive will turn purple

D. Both Gram positive and Gram Negative will appear pink

Question #3

Which of the following are the correct order of chemicals used in Gram staining?

A. Iodine, Acetone-alcohol, crystal violet, safranin

B. Safranin, crystal violet, iodine, acetone-alcohol

C. Crystal violet, iodine, safranin, acetone-alcohol

D. Crystal violet, iodine, acetone-alcohol, safranin

Question #4

Which of the following is the most probable genus and species of bacteria indicated in the image above??

A. Staphylococcus epidermidis

B. Neisseria sicca

C. Bacillus subtilis

D. Escherichia coli

Question #5

Which of the following is the Gram's destain or bleaching reagent?

A. Crystal violet

B. Safranin

C. Carbolfuchsin

D. Acetone- Alcohol

E. Loeffler's methylene blue