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Microbiology Lab Study 1-13 Questions with Solutions 2024
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Microbiology Lab Study 1-13
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Microbiology Lab Study 1-13As the staff biologist for the public health department, you examine the pond water
under the microscope and notice high levels of algae. (Case file 1) What do you tell the
members of the community about the safety of their water? What information do you
need? - answer The community would need to know the type of algae and what caused
the overgrowth. The pond is stagnant, making it a place for algae to cultivate. It is
unsafe for people to use or swim in.
What is the purpose of using immersion oil with the 100x objective? - answerSince light
bends, at higher magnifications the light becomes scattered, making the specimen
blurry. The oil has the same refractive index as glass which makes the light less
scattered and the image becomes more clear under high magnification.
You are examining a prepared slide with the 40x objective in place over the microscope.
You rotate the 100x objective over the slide. When you look into the eyepiece, the
specimen is gone. What happened? - answerThe specimen was not in the field of view
once zoomed in, the fine adjustment and stage adjustment knobs should be used to
locate the specimen at higher magnification.
What is the difference between magnification and resolution? - answerMagnification:
makes small objects appear larger
Resolution: the ability of a lens system to distinguish separate entities objects that are
very small and very close together. Resolution is determined by the quality of the lens
and the wavelength used.
Bacteria are... - answersingle-celled organisms that lack a nucleus; prokaryotes
Bacillus cereus - answerBacillus cereus is a Gram-positive, rod-shaped, facultatively
anaerobic, motile, beta-hemolytic, spore forming bacterium commonly found in soil and
food. The specific name, cereus, meaning "waxy" in Latin, refers to the appearance of
colonies grown on blood agar.
Bacillus subtilis - answerBacillus subtilis, known also as the hay bacillus or grass
bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the
gastrointestinal tract of ruminants and humans
Staphylococcus aureus - answerStaphylococcus aureus is a Gram-positive round-
shaped bacterium, a member of the Firmicutes, and is a usual member of the
microbiota of the body, frequently found in the upper respiratory tract and on the skin.
, Spirillum volutans - answerSpirillum volutans is a gram-negative, bacterium from the
genus of Spirillum which occurs in freshwater. It has an amphitrichous flagellar
arrangement. Spirillum volutans is one of the largest bacteria species.
Saccharomyces cerevisiae - answerSaccharomyces cerevisiae is a species of yeast.
The species has been instrumental in winemaking, baking, and brewing since ancient
times. It is believed to have been originally isolated from the skin of grapes.
aseptic technique - answerA procedure performed under sterile conditions. Prevents
contamination of specimen
would culture characteristics like colony morphology be of value to a clinical
microbiologist? How could they be used? - answercharacteristics such as colony
morphology would be valuable for a clinical microbiologist because he would be able to
identify a microbe based off of color, moment, shape, arrangement, etc.
How do you confirm if a culture is a pure culture? - answerA culture is pure if it contains
only one type of microorganism. This is clear when the streak cultivates microorganisms
of the same color, size, shape, and arrangement.
Jane was very careful in performing her petri dish inoculation. When she examined her
plate during the lab period, a white colony was growing on her plate, but not along her
inoculation streak what happened? - answerIf contamination occurred elsewhere of her
streak, it is possible that the lid was open too much during inoculation and airborne
microbes entered the plate.
Jeffrey, Jane's partner, inoculated a tryptone broth tube with E.coli. When he examined
his broth tube during the next lab period, there was no growth at all. What could have
gone wrong with his experiment? - answerIt is possible that growth did not occur
because he did not swirl the tube of e.coli before taking some out, this would affect
growth because these microbes settle at the bottom of the tube. Also, if they did not
allow the loop to cool long enough after sterilization, the hot loop could have killed the
bacteria.
In the case file, the organism responsible for the patients health is a normal member of
the human microbiota. How do you explain it causing the death of this patient? -
answerIt was introduced into an area where the microbiota is not found. The microbiota
is normally found in the oral cavity and intestinal tract
List a least three examples of how microbial phototrophs are important clinically and
environmentally - answerthey are beneficial to the health of soils by restoring nitrogen
levels through nitrogen fixation, involved in symbiotic relationships,
Phototrophs - answerorganisms that get energy from light (ex: cyanobacteria)
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