MCAT Question A Day - 5/31/14 - Answer!
The lipopolysaccharide layer outside the peptidoglycan cell wall of a gram negative bacterium:
A. absorbs and holds gram stain.
B. protects the bacterium against certain antibiotics.
C. does not contain phospholipids.
D. allows the bacterium to attach to solid objects.
B is correct. You should arrive at this answer by process of elimination. You should know that gram negative bacteria do not retain gram stain, so 'A' is wrong. You should know that the membrane is made from phospholipids, so C is wrong. (Remember, archaebacteria are not on the MCAT.) D is wrong because fimbriae allow a bacterium to hold to solid objects. Finally, you should know that a bacterium with an outer membrane is gram negative and protected against certain antibiotics such as penicillin.
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B is correct. You should arrive at this answer by process of elimination. You should know that gram negative bacteria do not retain gram stain, so 'A' is wrong. You should know that the membrane is made from phospholipids, so C is wrong. (Remember, archaebacteria are not on the MCAT.) D is wrong because fimbriae allow a bacterium to hold to solid objects. Finally, you should know that a bacterium with an outer membrane is gram negative and protected against certain antibiotics such as penicillin.
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