Page |1
Murray’s Microbiology Midterm Exam
2025 |Actual Exam Questions and
Correct Detailed Answers |Already
Graded A+.
MULTPLE CHOICES
Bacteria with a pH growth optimum between pH 8.5 and pH 11.5 are considered?
a. Alkaliphiles
b. Acidophiles
c. Neutrophiles
d. None of the above
a. Alkaliphiles
Explanation (brief):
Alkaliphiles are microorganisms that grow best in basic (alkaline) environments, typically
with optimal growth at pH ≥ 8.5 (often up to ~11). Acidophiles prefer acidic conditions (pH <
5), while neutrophiles thrive near neutral pH (~6.5-7.5).
Fermentation generates ATP through
a. oxidative phosphorylation
b. Photophosphorylation
c. Substrate level phosphorylation
d. None of the above
c. Substrate level phosphorylation
Why:
During fermentation, ATP is formed directly in the glycolytic reactions when a high-energy
phosphate group is transferred from an intermediate (such as phosphoenolpyruvate) to ADP.
, Page |2
This enzyme-catalyzed transfer is called substrate-level phosphorylation. Fermentation does
not involve an electron-transport chain, so oxidative phosphorylation is impossible, and it is
unrelated to light-driven photophosphorylation.
Sterilization is
a. destruction or removal of all viable organisms
b. removal of disease causing organisms
c. reduction of microbial population to levels deemed safe
d. None of the above
a. destruction or removal of all viable organisms
Explanation (quick recap)
Sterilization = eliminating every form of microbial life (bacteria, fungi, viruses, spores, etc.)
on or in an object or medium.
Disinfection (Choice b) targets only pathogens.
Sanitization (Choice c) lowers overall counts to "safe" levels but doesn't guarantee total
elimination.
Facultative anaerobes die in the presence of oxygen (True or False)
False
Explanation:
Facultative anaerobes can grow with or without oxygen; they actually use oxygen for aerobic
respiration when it's available and switch to anaerobic pathways when it's not, so they
certainly don't die in its presence.
Circular DNA in mitochondria and chloroplast is evidence of endosymbiosis (True or
False)
True
Explanation:
, Page |3
Both mitochondria and chloroplasts contain their own circular DNA—resembling bacterial
chromosomes—which supports the endosymbiotic theory that these organelles originated as
free-living bacteria engulfed by ancestral eukaryotic cells.
What does the scientific debate about spontaneous generation vs. biogenesis tell us
about the process of science?
A. Science is composed of theories based on personal beliefs
B. Science is simply the collection of facts about nature over time
C. Science is the process of refining ideas through vigorous debate and the challenging of old
ideas with new data collection
D. None of the above
C. Science is the process of refining ideas through vigorous debate and the challenging of old
ideas with new data collection
Explanation:
The spontaneous-generation vs. biogenesis controversy shows that science advances by
continually testing, debating, and revising ideas in light of new evidence rather than relying
on fixed belief or mere fact-collecting.
In the name Esherichia coli, Escherichia is the
A. Specific epithet
B. Genus
C. Kingdom
D. Family
E. Order
B. Genus
Explanation:
Escherichia is the genus name, while coli is the specific epithet; together they form the
species name Escherichia coli.
Murray’s Microbiology Midterm Exam
2025 |Actual Exam Questions and
Correct Detailed Answers |Already
Graded A+.
MULTPLE CHOICES
Bacteria with a pH growth optimum between pH 8.5 and pH 11.5 are considered?
a. Alkaliphiles
b. Acidophiles
c. Neutrophiles
d. None of the above
a. Alkaliphiles
Explanation (brief):
Alkaliphiles are microorganisms that grow best in basic (alkaline) environments, typically
with optimal growth at pH ≥ 8.5 (often up to ~11). Acidophiles prefer acidic conditions (pH <
5), while neutrophiles thrive near neutral pH (~6.5-7.5).
Fermentation generates ATP through
a. oxidative phosphorylation
b. Photophosphorylation
c. Substrate level phosphorylation
d. None of the above
c. Substrate level phosphorylation
Why:
During fermentation, ATP is formed directly in the glycolytic reactions when a high-energy
phosphate group is transferred from an intermediate (such as phosphoenolpyruvate) to ADP.
, Page |2
This enzyme-catalyzed transfer is called substrate-level phosphorylation. Fermentation does
not involve an electron-transport chain, so oxidative phosphorylation is impossible, and it is
unrelated to light-driven photophosphorylation.
Sterilization is
a. destruction or removal of all viable organisms
b. removal of disease causing organisms
c. reduction of microbial population to levels deemed safe
d. None of the above
a. destruction or removal of all viable organisms
Explanation (quick recap)
Sterilization = eliminating every form of microbial life (bacteria, fungi, viruses, spores, etc.)
on or in an object or medium.
Disinfection (Choice b) targets only pathogens.
Sanitization (Choice c) lowers overall counts to "safe" levels but doesn't guarantee total
elimination.
Facultative anaerobes die in the presence of oxygen (True or False)
False
Explanation:
Facultative anaerobes can grow with or without oxygen; they actually use oxygen for aerobic
respiration when it's available and switch to anaerobic pathways when it's not, so they
certainly don't die in its presence.
Circular DNA in mitochondria and chloroplast is evidence of endosymbiosis (True or
False)
True
Explanation:
, Page |3
Both mitochondria and chloroplasts contain their own circular DNA—resembling bacterial
chromosomes—which supports the endosymbiotic theory that these organelles originated as
free-living bacteria engulfed by ancestral eukaryotic cells.
What does the scientific debate about spontaneous generation vs. biogenesis tell us
about the process of science?
A. Science is composed of theories based on personal beliefs
B. Science is simply the collection of facts about nature over time
C. Science is the process of refining ideas through vigorous debate and the challenging of old
ideas with new data collection
D. None of the above
C. Science is the process of refining ideas through vigorous debate and the challenging of old
ideas with new data collection
Explanation:
The spontaneous-generation vs. biogenesis controversy shows that science advances by
continually testing, debating, and revising ideas in light of new evidence rather than relying
on fixed belief or mere fact-collecting.
In the name Esherichia coli, Escherichia is the
A. Specific epithet
B. Genus
C. Kingdom
D. Family
E. Order
B. Genus
Explanation:
Escherichia is the genus name, while coli is the specific epithet; together they form the
species name Escherichia coli.
