Using a back and forth mo on to create confluent

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Using a back and forth mo " on to create confluent growth A dilu ! on gradient is formed. The resul ! ng gradient should always contain within it the growth of individual colonies. Your Answer: 5 / 5 pts Ques ! on 23 In what phase of a dilu " on streak would you expect to find the lowest concentra " on of bacteria, P2 or P4? P4 because when you get to zone 4 the bacteria has been thinned and diluted and this is where you may find clonal isolates P4 (Phase 4) would contain the lowest concentra ! on of bacteria. The phases rank (from highest to lowest), P1 > P2 > P3 > P4. 2 / 2 pts Ques ! on 24 True or False. When performing a dilu " on streak a new (or sterilized) loop is not required for each phase as long as the bacterial culture is pure. True False Correct! Correct! A new or sterilized loop is absolutely required for each phase. Failure to do so would prevent the establishment of a dilu " on gradient, as the same bacterial concentra " on would be spread across both phase regions, regardless of whether or not the culture is pure. Your Answer: 5 / 5 pts Ques ! on 25 The number of phases (3 vs. 4) and/or the number of " mes a loop passes through a previous phase (once vs. mul " ple " mes) is acceptable provided what happens? Provided that it is documented and the resul " ng gradient holds the growth of the invidual colonies, if not the experiement needs to be rerun. Either devia ! on is acceptable in prac ! ce provided the resul ! ng gradient contains within it the growth of individual colonies—if not, the experiment must be repeated. 2 / 2 pts Ques ! on 26 True or False. To restrict the growth of a pathogenic microbe a researcher might decrease an incubator from 37°C to 25°C. True Correct! Correct! Pathogenic strains of bacteria tend to grow faster than non-pathogenic strains at 37°C, so researchers may set incubators at 25°C to restrict its growth. False Your Answer: 5 / 5 pts Ques ! on 27 When given an unknown bacterial sample the first step is to expand the current bacterial popula " on. Which form of media best suites this need? Why? 1. MSA agar 2. LB media 3. MacConkey agar 4. Columbia CNA agar LB Media because it is a nutri " onally rich liquid and it is popular and frequently used due to its ability to grow various di ff erent microbes. Correct Answer LB media. All other op ! ons (A, C and D) are all forms of selec ! ve media, meaning they may poten ! ally inhibit the growth of the unknown sample. The culture should be first expanded and then place onto selec ! ve/di ff eren ! al agar plates. 0 / 2 pts Ques ! on 28 True or False. Only directly inges " ng the pre-formed clostridium toxin (neither the bacteria nor its spores) will cause disease in adults. True Correct Answer Correct Answer False You Answered 2 / 2 pts Ques ! on 29 True or False. There are currently no cures for tetanus. True Correct! Although the symptoms can be treated it is only to manage the discomfort not to cure.

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