MCB 100 Exam 2 iClicker Questions and Correct Answers
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Course
MCB 100
Institution
MCB 100
During treatment of waste water to make it potable, about 90% of the microbes are removed
A. by preliminary fermentation B. in the sedimentation step C. by treatment with alum D. by treatment with chlorine or ozone E. in the filtration step E. in the filtration step
Which statement regarding the ...
MCB 100 Exam 2 iClicker Questions and
Correct Answers
During treatment of waste water to make it potable, about 90% of the microbes are
removed
A. by preliminary fermentation
B. in the sedimentation step
C. by treatment with alum
D. by treatment with chlorine or ozone
E. in the filtration step ✅E. in the filtration step
Which statement regarding the quality of drinking water is MOST accurate?
A. Permissible levels of contaminants vary from state to state
B. There are federal laws that dictate standards for drinking water quality
C. Drinking water is safe only if there are no microbes or chemicals present
D. There are no standards for the quality of drinking water
E. Drinking water is potable when there are no pathogens present ✅A. Permissible
levels of contaminants vary from state to state
Which of the following statements is false?
A. The grouping of microorganisms in a phylogenetic scheme that is based on nucleic
acid sequence data is not always the same as the grouping of microorganisms in a
taxonomic scheme based on morphological traits
B. The cells of prokaryotic organisms are divided into compartments by internal
membranes, which is efficient for energy purposes
C. In the most popular current phylogenetic scheme, prokaryotic organisms are divided
into two domains called Bacteria and Archaea
D. Most chemoautotrophic organisms on Earth are prokaryotes and can use inorganic
energy sources to make organic compounds from carbon dioxide
E. The cells of prokaryotic microorganisms contain 70S ribosomes, and most have
circular chromosomes, but some have linear chromosomes. ✅B. The cells of
prokaryotic organisms are divided into compartments by internal membranes, which is
efficient for energy purposes
The bacterial arrangement illustrated here is known as
A. Staphylococcus
B. Palisades
C. Pleomorphic
D. Tetrad
, E. Streptobacillus ✅B. Palisades
When Pseudomonas aeruginosa is grown in LB under aerobic conditions and then
stained for biofilm formation the results area ring as shown for the left tube. When the
bacteria are grown anaerobically in the presence of arginine (Arg), the results on the
right are obtained. Which statement best explains the observed results?
A. Arg caused the P . aeruginosa bacteria to lyse under anaerobic conditions and all the
polysaccharide slime coated the tube wall
B. Arg stimulated the P . aeruginosa bacteria to make much more polysaccharide slime
that coated the tube wall
C. The Arg dissolved the polysaccharide into hydrophobic layers that coated the tube
wall
D. The P.aeruginosa bacteria used Arg to grow anaerobically, so that it no longer had to
grow at the air-liquid interface, which allowed it to form a biofilm all over the tube wall
E. The hydrophobic Arg in the medium coated the tube wall and was stained with crystal
viol ✅D. The P. aeruginosa bacteria used Arg to grow anaerobically, so that it no
longer had to grow at the air-liquid interface, which allowed it to form a biofilm all over
the tube wall
Why do doctors caution patients who are pregnant to avoid deli meats, cold cuts, and
soft cheeses?
A. Fermentation of those foods by Listeria will cause nausea
B. Listeria bacteria can make these foods taste sour
C. The Listeria bacteria can degrade the nutrients of the food
D. These foods are soft and easy for the bacteria to spread throughout
E. The Listeria bacteria can easily grow in the uncooked food stored in the refrigerator
✅E. The Listeria bacteria can easily grow in the uncooked food stored in the
refrigerator
Listeria virulence is directly related to the ability to:
A. produce powerful toxins that lyse eukaryotic cells
B. form resistant endospores that can withstand harsh chemical environments
C. live within cells and thus avoid exposure to the immune system of its host
D. move rapidly through the body using multiple flagella called comet tails
E. resist most antimicrobial agents due to resistant cell walls. ✅C. live within cells and
thus avoid exposure to the immune system of its host
Why do male teenagers typically have more acne than male adults?
A. sebum production is decreased by testosterone, which is more in adult males
B. The P. acnes bacteria overgrow during puberty when sebum is abundant due to high
levels of testosterone, particularly in males
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