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Microbiology 20 Quiz #2; June 20, 2007
NAME: KEY
Procedure for the Gram Stain (write the answer below, 2 points each):
A. Add __1__ stain over the fixed culture. Let stand for 60 seconds. Pour off the stain.
B. Add the __2__ solution on the smear, enough to cover the fixed culture. Let stand for 30 to 60 seconds. #2
acts as a __3__ for #1.
C. Add a few drops of __4__ so the solution trickles down the slide until color no longer comes off.
D. __5__ with __6__ solution for 40 to 60 seconds. Wash off the solution with __7__. Blot with __8__ to
remove the excess __9__.
E. The Gram stain is best observed at __10__ objective.
1. Crystal Violet
2. Gram Iodine
3. Mordant
4. Ethanol/Alcohol
5. Counterstain
6. Safranin
7. Water
8. Bulbous Paper
9. Water
10. 100X
What color will the following bacteria be under the following conditions (Write the answer in the line provided,
2 point each):
_____11. E. coli Gram Stained: (A) Pink, (B) Purple, (C) Blue, (D) Green, (E) None of the above
_____12. Staphylococcus aureus Gram Stained: (A) Pink, (B) Purple, (C) Blue, (D) Green, (E) None of
the above
_____13. Mycobacterium tuberculosis Gram Stained: (A) Pink, (B) Purple, (C) Blue, (D) Green, (E) None
of the above
_____14. Human cell Gram Stained: (A) Pink, (B) Purple, (C) Blue, (D) Green, (E) None of the above
_____15. Plant cell Gram Stained: (A) Pink, (B) Purple, (C) Blue, (D) Green, (E) None of the above
_____16. Fungal cell Gram Stained: (A) Pink, (B) Purple, (C) Blue, (D) Green, (E) None of the above
What makes up the Outermost structure of a Gram positive cell? Peptidoglycan
What makes up the Outermost structure of a Gram negative cell? Phospholipid bilayer
What makes up the Outermost structure of a Acid Fast cell? Lipis
Endotoxic shock occurs upon bacteremia with what type of bacteria? Gram negative