BIOD 171 ESSENTIAL MICROBIOLOGY QUESTIONS WITH CORRECT ANSWERS EXAM 1

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BIOD 171 ESSENTIAL MICROBIOLOGY QUESTIONS AND ANSWERS TRUE OR FALSE Growth bacteria is best suited for distinguishing between two similar species of bacteria. - ANS - FALSE - GROWTH MEDIA IS DESIGN... ED TO SUPPORT MICROBIAL GROWTH. IT IS NOT DESIGNED TO RESTRICT IT. A researcher is asked to determine which of two vials contains E. Coli and which contains Salmonella. Knowing both are Gram-Negative while only one of them is capable of fermenting lactose, which type of media would be best suited: - ANS - DIFFERENTIAL MEDIA What are the requirements of fastidious microbe? - ANS - THEY REQUIRE ESSENTIAL NUTRIENTS TO GROW AND WITHOUT THESE ESSENTIAL NUTRIENTS THEY WILL NOT GROW. TRUE OR FALSE: LB agar is classified as a selective, non-differential media. - ANS - FALSE. LB AGAR IS THE MOST BASIC TYPE OF AGAR AND IT SUPPORTS THE GROWTH OF ALL MICROBES WITHOUT RESTRICTION. What is agar used for in microbiology? - ANS - TO CREATE A SOLID, SMOOTH SURFACE ON WHICH MICROBES CAN GROW. What are the three hemolytic classes and there description of activity? - ANS - 1. ALPHA (GREEN) HEMOLYSIS - INCOMPLETE HEMOLYTIC (B) 2. BETA (CLEAR ZONES) HEMOLYSIS - COMPLETE HEMOLYTIC ACTIVITY (C) GAMMA (WHITE/TAN) HEMOLYSIS- NO HEMOLYTIC ACTIVITY (A) Columbia CNA agar is most closely related to which media: - ANS - BAP. IT IS ALSO ENRICHED WITH BLOOD AND ALLOWS DIFFERENTIATION BASED ON HEMOLYTIC PATTERNS. True or False: Chocolate agar gets its brown color from cocoa to produce enriched media. - ANS - FALSE. CHOCOLATE COCOA IS NEVER ADDED TO THE MEDIA. THE NAME IS DERIVED SIMPLY BASED ON THE COLOR THAT COMES FROM THE PRESENCE OF 'COOKED' (LYSED) RED BLOOD CELLS IN THE MEDIA. A researcher is studying a strain of E. Coli currently growing on a MacConkey plate. However, the researcher can't remember if E. coli is Gram-Positive or Gram-Negative. Would a Gram stain be necessary to confirm? Why or why not? - ANS - NO. A GRAM STAIN WOULD NOT BE NECESSARY, AS ONLY GRAM-NEGATIVE MICROBES WILL GROW ON MACCONKEY AGAR. E. COLI IS A GRAM-NEGATIVE MICROBE. In an attempt to detect the presence of the pathogenic strain of E. coli O157: H7, a researcher spread a culture onto a MacConkey agar with failed results. What type of agar should they (correctly) try next? Why? - ANS - THE MICROBE SHOULD BE PLATED ON SMAC (SORBITOL-MACCONKEY AGAR) AS IT IS SPECIFICALLY FORMULATED TO DETECT O157:H7. PATHOGENIC E. COLI (O157:H7) CANNOT FERMENT SORBITOL WHITE NON-PATHOGENIC E. COLI CAN FERMENT BOTH SORBITOL AND LACTOSE. THEREFORE, COLONIES THAT FERMENT (ACIDIC CONDITIONS; NON-PATHOGENIC) CAN BE DIFFERENTIATED FROM NON-FERMENTERS (NEUTRAL TO BASIC CONDITIONS; PATHOGENIC). [Show More]

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