Media Tests Micro Lab Exam 2 Questions With Complete Solutions

Phenylethyl alcohol agar PAA correct answer: Selective media- used to isolate specific groups of bacteria Isolation of mostly Gram positive organisms ** Phenylethyl alcohol ** inhibits Gram negative organisms colonies may be visible , but smaller in number and size Phenylethyl alcohol agar Media Test Reading correct answer: Lab results: S. aureus : Amount of growth (1 + ) Appearance of growth ( light golden ) Appearance of medium (----------) E. faecalis : Amount of growth (1) Appearance of growth ( white ) Appearance of medium (------------) Phenylethyl alcohol agar Media Test Reading correct answer: Lab results : E. coli on PAA agar Amount of growth - 1+ Appearance of Growth - white Appearance of Medium ------------ (no change ) Crystal Violet Agar CVA correct answer: Selective media -used to isolate specific groups of bacteria Selective for Gram (-) negative organisms **Crystal violet dye ** exerts an inhibitory effect on Gram (+) positive organisms Crystal Violet Agar Media Test Reading correct answer: Lab Results : E. coli on CVA Amount of Growth - 1 Appearance of Growth - purple Appearance of Medium - ----------(no change) Crystal Violet Agar Media Test Reading correct answer: Lab results : E. faecalis on CVA Amount of Growth - 0 Appearance of Growth - ---------(none) Appearance of Medium -----------( no change ) Crystal Violet Agar Media Test Reading correct answer