BIO 171 Module 4 Exam WITH COMPLETE SOLUTIONS GRADED A+ 2023|2024 UPDATED

True or False: Differential media is best suited for distinguishing between two similar species ofbacteria. True. Growth media does not contain restrictive factors, while selective media is best used toencourage the growth of one microbe while simultaneously discouraging the growth of the other. Since two similar species of microbes are being studied they must be differentiated under similar but just slightly different conditions (differential media). 2. A researcher is asked to determine if a sample contains Neisseria meningitides. Knowing Neisseria meningitides is slow growing and other foreign microbes may also be present in theculture, which type of media would be best suited: A. Growth media B. Differential media C. Selective media D. Selective and Differential media C. Selective media. If additional foreign microbes may be present in your sample and you know Neisseria meningitides is slow growing, you must restrict the unwanted microbes whilesupporting the growth of Neisseria meningitides. Thus, you are selectively encouraging one microbes growth, while selectively restricting others. 1. True or False: LB agar is classified as a selective, non-differential media. False. LB agar is the most basic type of agar and like LB media supports the growth ofvirtually all microbes without restriction. 2. What is agar used for in microbiology? 1. Alpha hemolysis B A. No hemolytic activity 2. Beta hemolysis C B. Incomplete hemolytic activity 3. Gamma hemolysis A C. Complete hemolytic activity Agar is used to create a solid, smooth surface on which microbes can grow. 1. Match the following hemolytic class with its description of activity. 1. Columbia CNA agar is most closely related to which media: A. Trypticase Soy Agar B. MacConkey Agar C. Blood agar D. EMB agar C. CNA agar is similar to BAP as it is also enriched with blood and allows for differentiation based on hemolytic patterns. 2. True or False: Chocolate agar gets its brown color from cocoa to produce an enriched media. False. Chocolate (cocoa) is never added to the media. The name is derived simply based on the color that actually comes from the presence of ‘cooked’ (lysed) red blood cells in the media. 3. 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? No. A Gram stain would not be necessary, as only Gram-Negative microbes will grow on MacConkey agar. Thus, E. coli is a Gram-Negative microbe. 1. In an attempt to detect the presence of the pathogenic strain of E. coli O157:H7, a researcherspread a culture onto a MacConkey agar with failed results. What type of agar should they (correctly) try next? Why? They should try Sorbitol MacConkey agar which is a variant of MacConkey agar specifically formulated to detect the presence of the pathogenic strain E. coli O157:H7. SMAC plates containsorbitol instead of lactose in order to differentiate non- pathogenic (red colonies, acid conditions)strains from pathogenic O157:H7 strain (white colonies with neutral to basic conditions). 1. In Eosin Methylene Blue (EMB) agar, what color indicates the presence of E. coli? Metallic Green. 2. Which type of agar media is best suited to support the growth of Staphylococcus? A. MacConkey agar B. Blood agar C. Columbia CNA agar D. Mannitol salt agar E. Chocolate agar. D. Mannitol salt agar 1. What is the process of spreading a bacterial culture onto a petri dish? Plating. 2. In order to visual individual colonies of bacteria would you culture your sample in a liquid media or on a solid (agar) media? Why? Solid (agar) media. The primary advantage is that cells are held into place. When grown in a nutrient broth, bacterial cells can multiply but are free to move around in solution. When grown on agar within a petri dish the fixed in such as way as to form colonies. 3. True or False? The visualization of colonies on a petri dish represents bacterial cells that haveoften multiplied a million times ove