MCB 100 Exam 2 Study Set with Questions and Correct Answers
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Course
MCB 100
Institution
MCB 100
How do pseudohyphae in yeasts differ from vegetative hyphae in mold? Yeasts use pseudohyphae to invade host tissue, whereas mold use their vegetative hyphae for obtaining nutrients.
Based on its Gram status, why are penicillin and other beta-lactam antibiotics effective against Streptococcus pneum...
MCB 100 Exam 2 Study Set with
Questions and Correct Answers
How do pseudohyphae in yeasts differ from vegetative hyphae in mold? ✅Yeasts use
pseudohyphae to invade host tissue, whereas mold use their vegetative hyphae for
obtaining nutrients.
Based on its Gram status, why are penicillin and other beta-lactam antibiotics effective
against Streptococcus pneumoniae? ✅Penicillin and Beta lactam antibiotics are
effective against Streptococcus pneumoniae because it is a Gram positive organism
and does not have a protein layer surrounding it's cell wall
Choose from the following statements the ones that correctly discuss reproduction using
binary fission (regeneration of parts) in a bacterial cell. ✅Due to the stretching of the
cytoplasmic membrane, both cells will contain a complete genome
Each daughter cell is a complete copy of the other, both genetically and morphologically
Which of the following is not true of aflatoxins? ✅They are produced from Penicillium.
Aflatoxin: poisonous substances produced by certain kinds of fungi (molds) that are
found naturally all over the world; they can contaminate food crops and pose a serious
health threat to humans and livestock.
Most mycoses (disease caused by fungus) are difficult to treat because __________
✅Fungi are biochemically similar to humans cells
Which of the following statements is false?
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.
The cells of prokaryotic organisms are divided into compartments by internal
membranes, which is efficient for energy purposes.
In the most popular current phylogenetic scheme, prokaryotic organisms are divided
into two domains called Bacteria and Archaea
Most chemoautotrophic organisms on Earth are prokaryotes and can use inorganic
energy sources to make organic compounds from carbon dioxide.
The cells of prokaryotic microorganisms contain 70S ribosomes, and most have circular
chromosomes, but some have linear chromosomes. ✅The cells of prokaryotic
,organisms are divided into compartments by internal membranes, which is efficient for
energy purposes (prokaryotes don't have internal membranes)
When Pseudomonas aeruginosa is grown in LB under aerobic conditions and then
stained for biofilm formation the results are a ring as shown for he 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? ✅The P.
aeruginosa bacteria used Arg to grow anaerobically, so that it no longer had to grow at
the air-liquid interface(didn't need direct oxygen), which allowed it to form a biofilm all
over the tube
Listeria virulence is directly related to its ability to ✅live within cells and thus avoid
exposure to the immune system of its host
Why do doctors caution patients who are pregnant to avoid deli meats, cold cuts, and
soft cheeses? ✅The listeria bacteria can easily grow in the uncooked food stored in
the refrigerator
Which statement regarding drinking water is MOST accurate? ✅There are federal laws
that dictate standards for drinking water quality
Why do male teenagers typically have more acne than male adults? ✅The P. acnes
bacteria overgrow during puberty when sebum is abundant due to higher testosterone
levels, particularly in males
Which of the following is an advantage for a bacterium having the ability to invade and
reside inside host cells: ✅The host cytosol is rich in nutrients, if access can be gained
by the bacteria
Suppose you have two A-B type toxins, A-B and A'-B'.
A-B binds specifically to neurons and blocks protein synthesis to kill the nerve cells. A'-
B' binds specifically to intestinal epithelial cells and blocks Na2+ uptake to cause
diarrhea.
What would injection of a hybrid toxin, A'-B, into an animal do to its muscle cells?
✅Nothing
Although the proteins they transfer may be different, the type 3 secretion systems of
Escherichia coli, Salmonella, Shigella, and Yersinia function similarly in that they
_______. ✅Transfer bacterial proteins from the bacterium into the host cell
Suppose you have two A-B type toxins, A-B and A'-B'.
, A-B binds specifically to muscle cells and blocks protein synthesis to kill the muscle cell.
A'-B' binds specifically to intestinal epithelial cells and blocks Na2+ uptake to cause
diarrhea.
What would injection of a hybrid toxin, A'-B, into an animal do to its muscle cells?
✅Cause tissue swelling- Na2+ uptake gets blocked causing cells to swell instead of
shrink
How do archaeal ribosomes differ the most from bacterial ribosomes? ✅Ribosomal
RNA content
Which of the following statements about archaea is true? ✅Archaea lack true
peptidoglycan in their cell walls
Which of the following is NOT a reason archaea thrive in extreme environments?
✅Nuclear Composition- archaea don't have a nucleus
All truly pathogenic fungi exist in the environment as molds but grow in the body as
spherical yeasts. This trait is known as? ✅dimorphism
Which of the following statements about Candida is FALSE? ✅Candida can be easily
treated with topical antifungals in immunocompromised individuals
Ringworm is caused by ________ ✅Dermatophytes growing in the outer dead tissue
layers of the skin
Most common source of tinea cruris (jock itch) is _________ ✅Spread from feet
The deadliest mushroom toxin is produced by _____________ ✅Amanita phalloides
_____________ are the environmental reservoir for infection with Cryptococcus
neoformans ✅Birds
Opportunistic fungi that can be pathogens in some people ___________ ✅are part of
the normal microbiota for many individuals
Healthy humans typically become infected with Toxoplasma gondii by ______.
✅Ingesting undercooked meat containing T. gondii
The fever that is associated with malaria is primarily a result of ______.
✅Reproduction of Plasmodium inside erythrocytes
Are viruses good or bad? ✅Depends on point of view
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