BIOD 171 Exam 5 study set questions with complete solution

BIOD 171 Exam 5 study set questions with complete solution Define the concept of universal precautions. - CORRECT ANS-Universal precautions means any and all samples, whether known or unknown, are to be treated as potentially hazardous (or pathogenic) materials. List at least 3 observations a researcher would be sure to note while assessing an unknown microbial sample. - CORRECT ANS-A lab researcher would be certain to note: 1. Size and shape 2. Any observable motility 3. Gram status (positive or negative) 4. The presence of any chemical reactions 5. Changes in color localized to the organism or the surrounding media 6. Capture (or draw) images of any of the characteristics described above While observing an unknown sample of limited amounts, a researcher must determine the following observations: (1) the presence of any motility and (2) its Gram status using the same sample—the liquid sample cannot be divided. Which would you determine first and why? - CORRECT ANS-You must determine motility before determining the Gram status. Motility requires a wet mount, while Gram staining requires heat fixing the sample. If one were to begin with the Gram stain the heat fixation process would kill the organism, making any observations regarding motility impossible. The correct approach would be to place the liquid culture on a glass slide and determine its motility status. Next, the same liquid culture can be heat fixed and Gram stained. A facultative anaerobe is a microorganism capable of growth under what conditions? - CORRECT ANS-A facultative anaerobe is capable of growth under aerobic (with oxygen) and anaerobic (without oxygen) conditions. As Streptococcus is catalase negative would it thrive or die in the presence of peroxides? Why? - CORRECT ANS-Streptococcus would not survive in the presence of peroxides—it is unable to breakdown peroxides (catalase negative). Left unchecked, peroxides would damage the cellular integrity of Strep causing lysis/cell death. Streptococcus is most often streaked onto: - CORRECT ANS-Blood agar True or False. The Lancefield groups are used to subdivide antigenic groups of gamma-hemolytic Streptococcus. - CORRECT ANS-False Greater than 90% of all human streptococcal infections belong to: - CORRECT ANS-Group A Left untreated, strep throat can progress to ______ , which displays _____ hemolytic activity. - CORRECT ANS-R