BIOL 331 EXAM 1: FUNDAMENTALS OF
MICROBIOLOGY QUESTIONS &
VERIFIED ANSWERS 2026/2027 UPDATE
1. Which of the following scientists was the first to visualize and describe micro-fungi
(specifically Mucor) using a compound microscope, predating the work of Leeuwenhoek?
A. Robert Koch
B. Robert Hooke
C. Antonie van Leeuwenhoek
D. Louis Pasteur
Answer: B
Conceptual Explanation: Robert Hooke published Micrographia in 1665, where he
described the fruiting structures of molds, which were the first microbes to be visualized.
2. A strain of bacteria is found to lack the gene for MreB. What would be the most likely
morphological consequence for this organism?
A. It would be unable to divide.
B. It would lose its ability to move.
C. It would lose its rod shape and become coccoid.
D. It would fail to form a septum during cytokinesis.
,Answer: C
Conceptual Explanation: MreB is an actin-like protein in bacteria that directs the
synthesis of peptidoglycan along the longitudinal axis, maintaining rod shape; without it,
cells default to a coccus shape.
3. In the Phosphotransferase System (PTS), which component is responsible for providing the
phosphate group that eventually phosphorylates the sugar?
A. ATP
B. GTP
C. Pyruvate
D. Phosphoenolpyruvate (PEP)
Answer: D
Conceptual Explanation: Group translocation via PTS uses PEP as the high-energy
phosphate donor rather than ATP.
4. Which specific component of the Lipopolysaccharide (LPS) is responsible for its toxic effects
in the human bloodstream (endotoxin activity)?
A. Lipid A
B. Core polysaccharide
C. O-antigen
D. Braun’s lipoprotein
, Answer: A
Conceptual Explanation: Lipid A is the hydrophobic anchor of LPS and acts as a potent
endotoxin that triggers a massive immune response.
5. An organism is isolated from a hot spring at 90°C. You observe that its membrane contains
C40 isoprenoid chains linked to glycerol via ether bonds, forming a monolayer. This organism
is likely:
A. A Gram-negative bacterium
B. A hyperthermophilic Archaeon
C. A thermophilic Eukaryote
D. A Gram-positive bacterium
Answer: B
Conceptual Explanation: Archaeal membranes use ether linkages and isoprenoid chains;
hyperthermophiles often form tetraether monolayers for increased stability at high
temperatures.
6. During the process of endospore formation, what is the role of dipicolinic acid complexed
with calcium ions?
A. It dehydrates the core and stabilizes DNA against heat.
B. It catalyzes the formation of the cortex.
C. It provides energy for germination.
MICROBIOLOGY QUESTIONS &
VERIFIED ANSWERS 2026/2027 UPDATE
1. Which of the following scientists was the first to visualize and describe micro-fungi
(specifically Mucor) using a compound microscope, predating the work of Leeuwenhoek?
A. Robert Koch
B. Robert Hooke
C. Antonie van Leeuwenhoek
D. Louis Pasteur
Answer: B
Conceptual Explanation: Robert Hooke published Micrographia in 1665, where he
described the fruiting structures of molds, which were the first microbes to be visualized.
2. A strain of bacteria is found to lack the gene for MreB. What would be the most likely
morphological consequence for this organism?
A. It would be unable to divide.
B. It would lose its ability to move.
C. It would lose its rod shape and become coccoid.
D. It would fail to form a septum during cytokinesis.
,Answer: C
Conceptual Explanation: MreB is an actin-like protein in bacteria that directs the
synthesis of peptidoglycan along the longitudinal axis, maintaining rod shape; without it,
cells default to a coccus shape.
3. In the Phosphotransferase System (PTS), which component is responsible for providing the
phosphate group that eventually phosphorylates the sugar?
A. ATP
B. GTP
C. Pyruvate
D. Phosphoenolpyruvate (PEP)
Answer: D
Conceptual Explanation: Group translocation via PTS uses PEP as the high-energy
phosphate donor rather than ATP.
4. Which specific component of the Lipopolysaccharide (LPS) is responsible for its toxic effects
in the human bloodstream (endotoxin activity)?
A. Lipid A
B. Core polysaccharide
C. O-antigen
D. Braun’s lipoprotein
, Answer: A
Conceptual Explanation: Lipid A is the hydrophobic anchor of LPS and acts as a potent
endotoxin that triggers a massive immune response.
5. An organism is isolated from a hot spring at 90°C. You observe that its membrane contains
C40 isoprenoid chains linked to glycerol via ether bonds, forming a monolayer. This organism
is likely:
A. A Gram-negative bacterium
B. A hyperthermophilic Archaeon
C. A thermophilic Eukaryote
D. A Gram-positive bacterium
Answer: B
Conceptual Explanation: Archaeal membranes use ether linkages and isoprenoid chains;
hyperthermophiles often form tetraether monolayers for increased stability at high
temperatures.
6. During the process of endospore formation, what is the role of dipicolinic acid complexed
with calcium ions?
A. It dehydrates the core and stabilizes DNA against heat.
B. It catalyzes the formation of the cortex.
C. It provides energy for germination.
