StraighterLine
LANIF · ORCIM
μ College of Science — Microbiology
MICROBIOLOGY
STRAIGHTERLINE
AFFORDABLE · FLEXIBLE · ACCREDITED
Straighterline Microbiology
B ACT E R I O LO G Y · V I R O LO G Y · I M M U N O LO G Y · A N T I M I C R O B I A L T H E RA PY · G E N E T I CS
INSTITUTION StraighterLine COURSE CODE BIO 250 / MICRO
PROGRAM Bachelor of Science — Pre-Nursing ACADEMIC YEAR
/ Health Sciences
EXAM TITLE Straighterline Microbiology TOTAL QUESTIONS 217 Questions
COURSE TITLE General Microbiology FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Questions cover bacteriology, virology, mycology, parasitology, immunology, antimicrobial therapy, and
microbial genetics.
▸ Understanding key terminology, mechanisms, and classification is emphasized.
▸ Correct answers and rationales appear below each question for self-assessment.
▸ All content reflects standard microbiology curriculum.
, SECTION I — MICROBIOLOGY COMPREHENSIVE REVIEW Questions 1 – 217
1. Which stain is used to distinguish differences between the cell walls of medically
important bacteria?
A. simple stain
B. acridine orange stain
C. Gram stain
D. negative stain
CORRECT ANSWER C
RATIONALE The Gram stain differentiates bacteria based on cell wall structure — gram-
positive (thick peptidoglycan, purple) vs. gram-negative (thin peptidoglycan +
outer membrane, pink). It is the most important differential stain in medical
microbiology.
2. Under ________ conditions, the solute concentration of the external environment is
lower than that of the cell's internal environment.
A. hypertonic
B. isotonic
C. hypotonic
D. osmotic
CORRECT ANSWER C
RATIONALE In hypotonic environments, water moves into the cell by osmosis because solute
concentration is higher inside. Hypertonic (A) has higher external solute
concentration, causing water to leave the cell.
,3. The prodromal stage is a period of 1 to 2 days where the earliest notable symptoms of
infection appear as:
A. severe organ failure
B. a vague feeling of discomfort, such as headache, muscle aches, fatigue, and upset
stomach
C. complete absence of symptoms
D. full recovery
CORRECT ANSWER B
RATIONALE The prodromal stage features vague, generalized symptoms — the pathogen is
multiplying but has not yet caused specific, localized disease manifestations. It
precedes the period of invasion.
4. DNA Polymerase I removes RNA primers used to initiate DNA synthesis and:
A. replaces them with DNA; can also proofread
B. replaces them with RNA
C. only proofreads without replacing
D. synthesizes new RNA primers
CORRECT ANSWER A
RATIONALE DNA Polymerase I has exonuclease activity — it removes RNA primers and fills the
gaps with DNA. It also proofreads. DNA Polymerase III is the primary synthesizing
enzyme.
, 5. Which microscope produces its image by transmitting electrons through the specimen
and is ideal for viewing detailed cell structures and viruses?
A. SEM
B. TEM
C. Phase-contrast
D. Confocal
CORRECT ANSWER B
RATIONALE Transmission Electron Microscopy (TEM) transmits electrons through ultra-thin
specimens, revealing internal ultrastructure. SEM (A) scans the surface. Phase-
contrast (C) and confocal (D) are light microscopy techniques.
6. Semisolid media is used to show what characteristic of bacteria?
A. Gram reaction
B. motility
C. capsule formation
D. spore formation
CORRECT ANSWER B
RATIONALE Semisolid media (with reduced agar concentration) allows motile bacteria to
swim away from the inoculation line, creating diffuse growth. Non-motile bacteria
grow only along the stab line. It is a standard method for assessing bacterial
motility.
LANIF · ORCIM
μ College of Science — Microbiology
MICROBIOLOGY
STRAIGHTERLINE
AFFORDABLE · FLEXIBLE · ACCREDITED
Straighterline Microbiology
B ACT E R I O LO G Y · V I R O LO G Y · I M M U N O LO G Y · A N T I M I C R O B I A L T H E RA PY · G E N E T I CS
INSTITUTION StraighterLine COURSE CODE BIO 250 / MICRO
PROGRAM Bachelor of Science — Pre-Nursing ACADEMIC YEAR
/ Health Sciences
EXAM TITLE Straighterline Microbiology TOTAL QUESTIONS 217 Questions
COURSE TITLE General Microbiology FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Questions cover bacteriology, virology, mycology, parasitology, immunology, antimicrobial therapy, and
microbial genetics.
▸ Understanding key terminology, mechanisms, and classification is emphasized.
▸ Correct answers and rationales appear below each question for self-assessment.
▸ All content reflects standard microbiology curriculum.
, SECTION I — MICROBIOLOGY COMPREHENSIVE REVIEW Questions 1 – 217
1. Which stain is used to distinguish differences between the cell walls of medically
important bacteria?
A. simple stain
B. acridine orange stain
C. Gram stain
D. negative stain
CORRECT ANSWER C
RATIONALE The Gram stain differentiates bacteria based on cell wall structure — gram-
positive (thick peptidoglycan, purple) vs. gram-negative (thin peptidoglycan +
outer membrane, pink). It is the most important differential stain in medical
microbiology.
2. Under ________ conditions, the solute concentration of the external environment is
lower than that of the cell's internal environment.
A. hypertonic
B. isotonic
C. hypotonic
D. osmotic
CORRECT ANSWER C
RATIONALE In hypotonic environments, water moves into the cell by osmosis because solute
concentration is higher inside. Hypertonic (A) has higher external solute
concentration, causing water to leave the cell.
,3. The prodromal stage is a period of 1 to 2 days where the earliest notable symptoms of
infection appear as:
A. severe organ failure
B. a vague feeling of discomfort, such as headache, muscle aches, fatigue, and upset
stomach
C. complete absence of symptoms
D. full recovery
CORRECT ANSWER B
RATIONALE The prodromal stage features vague, generalized symptoms — the pathogen is
multiplying but has not yet caused specific, localized disease manifestations. It
precedes the period of invasion.
4. DNA Polymerase I removes RNA primers used to initiate DNA synthesis and:
A. replaces them with DNA; can also proofread
B. replaces them with RNA
C. only proofreads without replacing
D. synthesizes new RNA primers
CORRECT ANSWER A
RATIONALE DNA Polymerase I has exonuclease activity — it removes RNA primers and fills the
gaps with DNA. It also proofreads. DNA Polymerase III is the primary synthesizing
enzyme.
, 5. Which microscope produces its image by transmitting electrons through the specimen
and is ideal for viewing detailed cell structures and viruses?
A. SEM
B. TEM
C. Phase-contrast
D. Confocal
CORRECT ANSWER B
RATIONALE Transmission Electron Microscopy (TEM) transmits electrons through ultra-thin
specimens, revealing internal ultrastructure. SEM (A) scans the surface. Phase-
contrast (C) and confocal (D) are light microscopy techniques.
6. Semisolid media is used to show what characteristic of bacteria?
A. Gram reaction
B. motility
C. capsule formation
D. spore formation
CORRECT ANSWER B
RATIONALE Semisolid media (with reduced agar concentration) allows motile bacteria to
swim away from the inoculation line, creating diffuse growth. Non-motile bacteria
grow only along the stab line. It is a standard method for assessing bacterial
motility.
