MIC 205 Exam 1 Study Guide UPDATED
ACTUAL QUESTIONS AND CORRECT
ANSWERS
Simple stain - CORRECT ANSWER Uses one dye to color all cells the same way.
Differential stain - CORRECT ANSWER Uses multiple dyes to distinguish between different
types of cells or cellular components.
Gram stain - CORRECT ANSWER Detects peptidoglycan in bacterial cell walls and
differentiates based on cell wall thickness.
Gram-positive organism color - CORRECT ANSWER Blue/purple.
Gram-negative organism color - CORRECT ANSWER Red/pink.
Gram-positive bacterial cells - CORRECT ANSWER Have a thick peptidoglycan layer,
teichoic acids, and a single cell membrane.
Gram-negative bacterial cells - CORRECT ANSWER Have a thin peptidoglycan layer, an
outer membrane with LPS, a periplasmic space, and murein lipoprotein.
Penicillin antibiotics - CORRECT ANSWER Act on peptidoglycan synthesis.
Susceptibility of gram-positive bacteria to penicillin - CORRECT ANSWER More susceptible
due to thicker peptidoglycan layer.
Eukaryotes and penicillin - CORRECT ANSWER Eukaryotes are not harmed because they
lack peptidoglycan.
Acid-fast stain - CORRECT ANSWER Detects mycolic acid in waxy cell walls.
, Acid-fast organisms color after staining - CORRECT ANSWER Appear red.
Example of an acid-fast organism - CORRECT ANSWER Mycobacterium.
Schaeffer-Fulton stain - CORRECT ANSWER A differential stain, colored green.
Driving primary stain into endospore - CORRECT ANSWER Heat must be used because
endospore walls are practically impermeable to chemicals.
Endospore - CORRECT ANSWER A dormant, non-reproductive resting structure for survival.
Purpose of bacteria making endospores - CORRECT ANSWER To survive 'tough times.'
Characteristics of endospores - CORRECT ANSWER Resistant to radiation, desiccation, heat,
and chemicals; can survive millions of years; need no nutrients.
Medically important bacterial group that forms endospores - CORRECT ANSWER Bacillus.
C. difficile and endospores - CORRECT ANSWER C. difficile forms endospores, making it
highly resistant to treatment.
Selective growth medium - CORRECT ANSWER Contains chemicals that inhibit growth of
certain bacteria while allowing others to grow.
Differential growth medium - CORRECT ANSWER Contains indicators that allow distinction
between different types of bacteria based on their metabolic activities.
MacConkey's agar (MAC) - CORRECT ANSWER Selective: Bile salts and crystal violet
inhibit Gram+ bacteria; Differential: Contains lactose and pH indicator (neutral red); Information:
Isolates Gram- bacteria; lactose fermenters turn pink, non-fermenters remain white.
ACTUAL QUESTIONS AND CORRECT
ANSWERS
Simple stain - CORRECT ANSWER Uses one dye to color all cells the same way.
Differential stain - CORRECT ANSWER Uses multiple dyes to distinguish between different
types of cells or cellular components.
Gram stain - CORRECT ANSWER Detects peptidoglycan in bacterial cell walls and
differentiates based on cell wall thickness.
Gram-positive organism color - CORRECT ANSWER Blue/purple.
Gram-negative organism color - CORRECT ANSWER Red/pink.
Gram-positive bacterial cells - CORRECT ANSWER Have a thick peptidoglycan layer,
teichoic acids, and a single cell membrane.
Gram-negative bacterial cells - CORRECT ANSWER Have a thin peptidoglycan layer, an
outer membrane with LPS, a periplasmic space, and murein lipoprotein.
Penicillin antibiotics - CORRECT ANSWER Act on peptidoglycan synthesis.
Susceptibility of gram-positive bacteria to penicillin - CORRECT ANSWER More susceptible
due to thicker peptidoglycan layer.
Eukaryotes and penicillin - CORRECT ANSWER Eukaryotes are not harmed because they
lack peptidoglycan.
Acid-fast stain - CORRECT ANSWER Detects mycolic acid in waxy cell walls.
, Acid-fast organisms color after staining - CORRECT ANSWER Appear red.
Example of an acid-fast organism - CORRECT ANSWER Mycobacterium.
Schaeffer-Fulton stain - CORRECT ANSWER A differential stain, colored green.
Driving primary stain into endospore - CORRECT ANSWER Heat must be used because
endospore walls are practically impermeable to chemicals.
Endospore - CORRECT ANSWER A dormant, non-reproductive resting structure for survival.
Purpose of bacteria making endospores - CORRECT ANSWER To survive 'tough times.'
Characteristics of endospores - CORRECT ANSWER Resistant to radiation, desiccation, heat,
and chemicals; can survive millions of years; need no nutrients.
Medically important bacterial group that forms endospores - CORRECT ANSWER Bacillus.
C. difficile and endospores - CORRECT ANSWER C. difficile forms endospores, making it
highly resistant to treatment.
Selective growth medium - CORRECT ANSWER Contains chemicals that inhibit growth of
certain bacteria while allowing others to grow.
Differential growth medium - CORRECT ANSWER Contains indicators that allow distinction
between different types of bacteria based on their metabolic activities.
MacConkey's agar (MAC) - CORRECT ANSWER Selective: Bile salts and crystal violet
inhibit Gram+ bacteria; Differential: Contains lactose and pH indicator (neutral red); Information:
Isolates Gram- bacteria; lactose fermenters turn pink, non-fermenters remain white.
