1
BIOD 171 FINAL EXAM (4 VERSIONS, LATEST-2026/2027): ESSENTIAL
MICROBIOLOGY W/ LAB: PORTAGE LEARNING
1.
Which statement best describes the role of enzymes in microbial metabolism?
A. Enzymes provide the activation energy required for all reactions.
B. Enzymes act as catalysts that lower activation energy and speed up reactions.
C. Enzymes permanently alter the structure of substrates.
D. Enzymes are consumed during chemical reactions.
Answer: B
Rationale: Enzymes accelerate biochemical reactions by lowering activation
energy; they are not consumed in the process.
2.
A scientist isolates a prokaryotic cell with peptidoglycan in its cell wall but no
membrane-bound organelles. Which group does this organism most likely belong
, 2
to?
A. Bacteria
B. Fungi
C. Archaea
D. Protozoa
Answer: A
Rationale: Bacteria are prokaryotes characterized by peptidoglycan cell walls and
absence of membrane-bound organelles.
3.
During a Gram stain, a bacterial sample remains purple after decolorization. What
does this indicate?
A. The bacteria are Gram-negative.
B. The bacteria are Gram-positive with thick peptidoglycan walls.
C. The bacteria lack a cell wall.
D. The bacteria are endospore formers.
Answer: B
Rationale: Gram-positive bacteria retain crystal violet dye due to their thick
peptidoglycan layers.
, 3
4.
Which phase of bacterial growth is characterized by rapid cell division and
maximum metabolic activity?
A. Lag phase
B. Log (exponential) phase
C. Stationary phase
D. Death phase
Answer: B
Rationale: The log phase represents exponential growth where cells divide rapidly
under optimal conditions.
5.
A researcher uses a nutrient agar plate to isolate single bacterial colonies. Which
technique is most appropriate?
A. Streak plate method
B. Spread plate method
C. Serial dilution broth
D. Pour plate without dilution
Answer: A
, 4
Rationale: The streak plate technique isolates pure colonies by mechanically
spreading bacteria to separate individual cells.
6.
Which statement correctly describes facultative anaerobes?
A. They require oxygen to survive.
B. They grow only in the absence of oxygen.
C. They can survive with or without oxygen.
D. They die when exposed to oxygen.
Answer: C
Rationale: Facultative anaerobes can adapt to both aerobic and anaerobic
conditions, using oxygen when available.
7.
A nurse explains that endospores are difficult to destroy because:
A. They lack nucleic acids.
B. They are metabolically active and divide rapidly.
C. They have tough protective coats and are dormant.
D. They contain high levels of RNA.
Answer: C
BIOD 171 FINAL EXAM (4 VERSIONS, LATEST-2026/2027): ESSENTIAL
MICROBIOLOGY W/ LAB: PORTAGE LEARNING
1.
Which statement best describes the role of enzymes in microbial metabolism?
A. Enzymes provide the activation energy required for all reactions.
B. Enzymes act as catalysts that lower activation energy and speed up reactions.
C. Enzymes permanently alter the structure of substrates.
D. Enzymes are consumed during chemical reactions.
Answer: B
Rationale: Enzymes accelerate biochemical reactions by lowering activation
energy; they are not consumed in the process.
2.
A scientist isolates a prokaryotic cell with peptidoglycan in its cell wall but no
membrane-bound organelles. Which group does this organism most likely belong
, 2
to?
A. Bacteria
B. Fungi
C. Archaea
D. Protozoa
Answer: A
Rationale: Bacteria are prokaryotes characterized by peptidoglycan cell walls and
absence of membrane-bound organelles.
3.
During a Gram stain, a bacterial sample remains purple after decolorization. What
does this indicate?
A. The bacteria are Gram-negative.
B. The bacteria are Gram-positive with thick peptidoglycan walls.
C. The bacteria lack a cell wall.
D. The bacteria are endospore formers.
Answer: B
Rationale: Gram-positive bacteria retain crystal violet dye due to their thick
peptidoglycan layers.
, 3
4.
Which phase of bacterial growth is characterized by rapid cell division and
maximum metabolic activity?
A. Lag phase
B. Log (exponential) phase
C. Stationary phase
D. Death phase
Answer: B
Rationale: The log phase represents exponential growth where cells divide rapidly
under optimal conditions.
5.
A researcher uses a nutrient agar plate to isolate single bacterial colonies. Which
technique is most appropriate?
A. Streak plate method
B. Spread plate method
C. Serial dilution broth
D. Pour plate without dilution
Answer: A
, 4
Rationale: The streak plate technique isolates pure colonies by mechanically
spreading bacteria to separate individual cells.
6.
Which statement correctly describes facultative anaerobes?
A. They require oxygen to survive.
B. They grow only in the absence of oxygen.
C. They can survive with or without oxygen.
D. They die when exposed to oxygen.
Answer: C
Rationale: Facultative anaerobes can adapt to both aerobic and anaerobic
conditions, using oxygen when available.
7.
A nurse explains that endospores are difficult to destroy because:
A. They lack nucleic acids.
B. They are metabolically active and divide rapidly.
C. They have tough protective coats and are dormant.
D. They contain high levels of RNA.
Answer: C
