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Microbiology Lab 2 Exam Practice Questions and Answers (100% Pass)
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Microbiology Lab 2 Exam Practice Questions and Answers (100% Pass)
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©PREP4EXAMS @2024 [REAL EXAM DUMPS] Wednesday, July 17, 2024 1:27 AMMicrobiology Lab 2 Exam Practice
Questions and Answers (100% Pass)
combinations of multiple microbial species in a lab setting - ✔️✔️mixed culture
cultures that contain only one species of microbe
are absolutely required when characterizing cell structure, biochemistry, physiology, growth
parameters, genetics, or other features - ✔️✔️pure culture
pure cultures can become ________ __________ when unwanted microbes are introduced
through sloppy aseptic technique, inadequate sterilization, improper storage, or mixed
microbial stocks - ✔️✔️contaminated cultures
In lab 6 we used which two methods to obtain pure cultures - ✔️✔️streak plate method and
pour plate method
isolated colonies can be identified as separate species based on _______________
_____________, such as colony, color, shape, texture, and margins. - ✔️✔️visible
characteristics
Pour Plate Method - ✔️✔️mixed culture is serially diluted using a series of liquified tryptic soy
agar tubes.
tubes are heated to 100 degrees Celsius and then cooled to 50 as not to kill the mixed in
bacteria
each tube contains a smaller amount of bacteria than the last so that by the end the bacteria
species are spread out and will hopefully grow separately on the petri dish and grow into
isolated colonies
takes less skill than a streak plate
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, ©PREP4EXAMS @2024 [REAL EXAM DUMPS] Wednesday, July 17, 2024 1:27 AM
uses more materials and time for set up and execution
streak plate method - ✔️✔️cells are physically spread out on the surface of a solid medium
single cells will ideally come to rest and grow in separate spots and form isolated colonies
which can be used to make pure colonies
uses less materials and time than pour plate method, but takes much more skill to complete
repeated practice needed to achieve desired results and mastery
aseptically stir contents of mixed broth before transfer of one loopful of bacteria onto area A
and do repetitive non overlapping streaks with inoculating loop. flame and cool loop in
between each streak. flame and cool loop after last streak
Which method (pour plate or streak plate) was more successful for you in achieving the
desired result in lab 6? Explain your answer. - ✔️✔️Answers will vary based on results. The
more successful method will be the one that produce the best separation and isolation of
colonies that allow for optimal subculturing.
Why are isolated colonies necessary as part of the process to establish pure culture
conditions? - ✔️✔️Isolated colonies are formed from a single cell (in theory) coming to rest at
one spot on the agar surface. Since all cells in the colony derive from the starting cell, the
colony should be made up of cells from only one species. Colonies that aren't isolated will
potentially still be mixtures of different species of cells.
Why are plates incubated upside down? - ✔️✔️To prevent condensation that collects on the lid
from dripping onto the agar surface and spreading and mixing cells that are growing on the
agar surface.
Is it possible that your original mixed culture contained more species than what you observed
on your streak and pour plates? e.g. maybe culture contained 3 species but only 2 showed up.
- ✔️✔️Yes. It is possible that the medium used for pour and streak plates was not ideal for the
growth of all species in the original mixed culture. If a particular species does not grow well
on this medium, then it may not show up as visible colony growth for several days (or at all)
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