BIOS 242 WEEK 3 QUIZ MCQS EXAM SCRIPT
2026 QUESTIONS WITH SOLUTIONS GRADED
A+
◉ Considering that they require an oxygen-free environment, how
do obligate anaerobes survive in the human body?
A) They live inside of organelles, such as peroxisomes.
B) They are able to use enzymes to convert reactive oxygen species
to harmless molecules.
C) They are able to survive in places where aerobic organisms
quickly use the available oxygen. They can also survive in areas with
impaired blood flow (reducing oxygen availability).
D) Obligate anaerobes are unable to survive in the human body.
Answer: C) They are able to survive in places where aerobic
organisms quickly use the available oxygen. They can also survive in
areas with impaired blood flow (reducing oxygen availability).
◉ Based upon microbiome projects, the most dominant microbial
species in sebaceous gland system is
A) Propionibacterium species.
B) Streptococcus species.
C) Staphylococcus species.
D) Corynebacterium species. Answer: A) Propionibacterium species.
,◉ Clostridium difficile infections most often occur
A) following a dietary change.
B) following antibiotic treatment.
C) following a fecal transplant.
D) following the use of a new probiotic. Answer: B) following
antibiotic treatment.
◉ The male urogenital tract is generally sterile except for the distal
portion of the urethra.
True OR False Answer: True
◉ The most heavily colonized human organ by bacteria is the
________, containing 1011-1012 bacterial cells per gram.
A) large intestine
B) small intestine
C) mouth
D) skin Answer: A) large intestine
◉ Which of the following is NOT a major question in the Human
Microbiome Project?
A) Do differences in the human microbiome correlate with
differences in human health?
,B) Is there a correlation between microbial population structure and
host genotype?
C) How can we reduce the number of microbes on the human body?
D) Are differences in the relative abundance of different bacteria
important? Answer: C) How can we reduce the number of microbes
on the human body?
◉ The human microbiome contains all
A) organisms present in and on the body.
B) organisms within the digestive system.
C) organisms present on the skin.
D) organisms present on the skin or in the digestive system only.
Answer: A) organisms present in and on the body.
◉ C. difficile infections are on the rise, both in elderly hospitalized
patients receiving antibiotics and in younger populations having no
previous contact either with a hospital environment or antibiotics.
What is the most effective treatment for chronic C. difficile
infections?
A) high doses of antibiotics
B) surgical removal of the colon if antibiotic therapy fails
C) fecal transplants from a healthy donor
, D) medical management with intravenous fluids to prevent
dehydration and shock Answer: C) fecal transplants from a healthy
donor
◉ The colonization of a newborn's gut is influenced by __________.
A) method of delivery and source of nutrition
B) source of nutrients
C) method of delivery
D) gender Answer: A) method of delivery and source of nutrition
◉ Vaginal acidity in the adult female is due to acid production by
Lactobacillus acidophilus.
True OR False Answer: True
◉ Following antibiotic therapy, patients are often administered
________ to facilitate recolonization of normal microbiota in the
intestines.
A) probiotics
B) iron
C) antivirals
D) fluoride Answer: A) probiotics
2026 QUESTIONS WITH SOLUTIONS GRADED
A+
◉ Considering that they require an oxygen-free environment, how
do obligate anaerobes survive in the human body?
A) They live inside of organelles, such as peroxisomes.
B) They are able to use enzymes to convert reactive oxygen species
to harmless molecules.
C) They are able to survive in places where aerobic organisms
quickly use the available oxygen. They can also survive in areas with
impaired blood flow (reducing oxygen availability).
D) Obligate anaerobes are unable to survive in the human body.
Answer: C) They are able to survive in places where aerobic
organisms quickly use the available oxygen. They can also survive in
areas with impaired blood flow (reducing oxygen availability).
◉ Based upon microbiome projects, the most dominant microbial
species in sebaceous gland system is
A) Propionibacterium species.
B) Streptococcus species.
C) Staphylococcus species.
D) Corynebacterium species. Answer: A) Propionibacterium species.
,◉ Clostridium difficile infections most often occur
A) following a dietary change.
B) following antibiotic treatment.
C) following a fecal transplant.
D) following the use of a new probiotic. Answer: B) following
antibiotic treatment.
◉ The male urogenital tract is generally sterile except for the distal
portion of the urethra.
True OR False Answer: True
◉ The most heavily colonized human organ by bacteria is the
________, containing 1011-1012 bacterial cells per gram.
A) large intestine
B) small intestine
C) mouth
D) skin Answer: A) large intestine
◉ Which of the following is NOT a major question in the Human
Microbiome Project?
A) Do differences in the human microbiome correlate with
differences in human health?
,B) Is there a correlation between microbial population structure and
host genotype?
C) How can we reduce the number of microbes on the human body?
D) Are differences in the relative abundance of different bacteria
important? Answer: C) How can we reduce the number of microbes
on the human body?
◉ The human microbiome contains all
A) organisms present in and on the body.
B) organisms within the digestive system.
C) organisms present on the skin.
D) organisms present on the skin or in the digestive system only.
Answer: A) organisms present in and on the body.
◉ C. difficile infections are on the rise, both in elderly hospitalized
patients receiving antibiotics and in younger populations having no
previous contact either with a hospital environment or antibiotics.
What is the most effective treatment for chronic C. difficile
infections?
A) high doses of antibiotics
B) surgical removal of the colon if antibiotic therapy fails
C) fecal transplants from a healthy donor
, D) medical management with intravenous fluids to prevent
dehydration and shock Answer: C) fecal transplants from a healthy
donor
◉ The colonization of a newborn's gut is influenced by __________.
A) method of delivery and source of nutrition
B) source of nutrients
C) method of delivery
D) gender Answer: A) method of delivery and source of nutrition
◉ Vaginal acidity in the adult female is due to acid production by
Lactobacillus acidophilus.
True OR False Answer: True
◉ Following antibiotic therapy, patients are often administered
________ to facilitate recolonization of normal microbiota in the
intestines.
A) probiotics
B) iron
C) antivirals
D) fluoride Answer: A) probiotics
