Chamberlain University
BAL • 242 SOIB
★ ★
C College of Nursing & Public Health
J O U R N E Y T O E X T R A O R D I N A R Y CO M PA S S I O N AT E C A R E
EST. 1889
BIOS 242 — Lab Practicum Examination
F U N D A M E N TA LS O F M I C R O B I O LO G Y L A B O R ATO R Y T E C H N I Q U E S & A P P L I C AT I O N S
INSTITUTION Chamberlain University COURSE CODE BIOS 242
PROGRAM Bachelor of Science in Nursing (BSN) ACADEMIC YEAR
EXAM TITLE Lab Practicum – Microbiology Laboratory TOTAL QUESTIONS 40 Questions
COURSE TITLE Fundamentals of Microbiology FORMAT Multiple Choice / Select All That Apply — Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer or all correct answers for each question as specified.
▸ This lab practicum covers aseptic technique, media types, bacterial colonies, Gram staining, growth curves, biosafety levels, immunological concepts, sterilization, biochemical
testing, and organism identification.
▸ Questions are drawn from the complete BIOS 242 Lab Practicum review content.
▸ Correct answers and detailed rationales appear below each question for comprehensive review.
▸ All content reflects Chamberlain University BIOS 242 laboratory competencies.
MICROBIOLOGY LABORATORY TECHNIQUES & APPLICATIONS Questions 1 – 40
1. Which of the following are examples of GOOD aseptic technique? (Select all that apply)
A. Sterilizing the inoculating loop before using it but not afterwards
B. Decontaminating the lab bench both before and after use
C. Sterilizing the inoculating loop both before and after using it
D. Flaming your loop for at least 10 seconds but then sitting it on the bench before doing your bacterial transfer
E. Waving your inoculating loop around in the air to cool it faster
F. Flaming the top of your tube to generate upwards air currents before and after inoculating your culture
G. Flaming your inoculating loop, dropping it on the floor, but picking it up immediately to use again
CORRECT ANSWER B, C, and F — Decontaminate bench before and after; sterilize loop before and after; flame tube tops to generate upward air currents
RATIONALE Good aseptic technique requires: decontaminating the work surface before and after use (B), sterilizing the inoculating loop both before AND after use (C), and
flaming tube tops to create upward convection currents that prevent airborne contaminants from entering (F). Sterilizing only before but not after (A) leaves live
organisms on the loop. Setting a sterile loop on the bench (D) contaminates it. Waving the loop in air (E) exposes it to airborne microbes. Using a dropped loop (G)
introduces floor contaminants.
2. Scientists use various types of media to grow microorganisms. The process of introducing microbes into media is called:
A. Incubation
B. Inoculation
C. Isolation
D. Inspection
CORRECT ANSWER B — Inoculation
RATIONALE Inoculation is the process of introducing microorganisms into culture media. After inoculation (B), incubation (A) provides optimal growth conditions. Bacteria
then grow in colonies on solid surfaces. Isolation (C) is obtaining pure cultures. Inspection (D) is observing colony characteristics.
3. Which of the following statements about a bacterial colony are TRUE? (Select all that apply)
A. Is Macroscopic
B. Is Microscopic
C. Contains fewer than 100 cells
D. Likely contains more than one million cells
E. Comes from a single bacterial cell
F. Comes from many different bacterial cells all growing together
G. Can be seen with the naked eye
CORRECT ANSWER A, D, E, and G — Macroscopic; >1 million cells; from a single cell; visible to naked eye
RATIONALE A bacterial colony is macroscopic (visible to naked eye) and arises from a single bacterial cell that divides repeatedly, typically containing millions of cells. It is not
microscopic (B), does not contain fewer than 100 cells (C), and is not a mixture of different bacterial types (F). Cell shape (microscopic) and colony shape
(macroscopic) are not the same.
, 4. The streak plate method is commonly used to obtain:
A. Mixed colonies for diversity studies
B. Isolated (pure) colonies
C. Broth cultures only
D. Anaerobic growth conditions
CORRECT ANSWER B — Isolated (pure) colonies
RATIONALE The streak plate method uses progressive dilution across an agar surface to separate individual bacterial cells, each of which grows into an isolated colony. This
produces pure cultures—colonies derived from a single bacterial species. It does not produce mixed colonies (A) or require broth (C).
5. General-purpose (nonselective) media are designed to:
A. Grow only one specific bacterial species
B. Grow as many different types of microbes as possible
C. Differentiate between Gram-positive and Gram-negative bacteria
D. Select for antibiotic-resistant organisms only
CORRECT ANSWER B — Grow as many different types of microbes as possible
RATIONALE General-purpose (nonselective) media contain a mixture of nutrients supporting a wide variety of microbial life. They do not select for or against specific
organisms. Selective media (A) grow only one species or group. Differential media (C) distinguish between types. Enriched media contain blood or special growth
factors for fastidious bacteria.
6. Enriched media contain complex organic substances such as blood, serum, or hemoglobin and are used for:
A. Inhibiting Gram-positive bacteria
B. Growing fastidious bacteria that require special growth factors
C. Differentiating lactose fermenters from non-fermenters
D. Sterilizing laboratory equipment
CORRECT ANSWER B — Growing fastidious bacteria that require special growth factors
RATIONALE Enriched media (e.g., blood agar) contain complex nutrients (blood, serum, hemoglobin, growth factors) required by fastidious organisms that cannot grow on
basic media. Blood agar also demonstrates hemolysis patterns: alpha (partial), beta (complete), and gamma (no lysis).
7. A selective medium is designed to:
A. Grow all species equally without discrimination
B. Grow specific types of microorganisms while inhibiting others
C. Differentiate between organisms based on biochemical reactions
D. Enrich all organisms with additional growth factors
CORRECT ANSWER B — Grow specific types of microorganisms while inhibiting others
RATIONALE Selective media contain agents (antibiotics, bile salts, dyes) that inhibit certain organisms while permitting others to grow. MacConkey agar is selective against
Gram-positive bacteria (bile salts/crystal violet) and differential based on lactose fermentation (pink = fermenter, off-white = non-fermenter).
8. A differential medium allows:
A. Only one species to grow
B. All species to grow but may show different reactions, distinguishing them visually
C. No growth of any organisms
D. Growth without any visible differences between species
CORRECT ANSWER B — All species to grow but may show different reactions, distinguishing them visually
RATIONALE Differential media contain indicators that reveal metabolic differences. All species grow, but they produce visibly different reactions (e.g., color changes). On a
general-purpose differential medium, all species may have similar appearance (no differentiation). MacConkey agar is both selective AND differential.
9. MacConkey agar is both selective and differential. It selects against Gram-positive bacteria and differentiates based on:
A. Catalase production
B. Lactose fermentation (pink = positive; off-white = negative)
C. Motility
D. Hemolysis patterns
CORRECT ANSWER B — Lactose fermentation (pink = positive; off-white = negative)
RATIONALE MacConkey agar contains lactose and neutral red pH indicator. Lactose fermenters produce acid, lowering pH and appearing pink. Non-fermenters remain off-
white/colorless. It also contains bile salts and crystal violet that inhibit Gram-positive bacteria, making it selective as well.
10. Staining is used to help visualize cells. A simple stain shows:
A. Differences between Gram-positive and Gram-negative cell walls
B. Cell size, shape, and arrangement
C. Acid-fast properties of mycobacteria
D. Presence of endospores
CORRECT ANSWER B — Cell size, shape, and arrangement
RATIONALE Simple stains use a single dye and reveal basic morphology: cell size, shape (coccus, bacillus, spirillum), and arrangement (chains, clusters, pairs). Differential
stains (A) like the Gram stain distinguish between bacterial types based on cell wall structure. Acid-fast and endospore stains are specialized differential stains.
BAL • 242 SOIB
★ ★
C College of Nursing & Public Health
J O U R N E Y T O E X T R A O R D I N A R Y CO M PA S S I O N AT E C A R E
EST. 1889
BIOS 242 — Lab Practicum Examination
F U N D A M E N TA LS O F M I C R O B I O LO G Y L A B O R ATO R Y T E C H N I Q U E S & A P P L I C AT I O N S
INSTITUTION Chamberlain University COURSE CODE BIOS 242
PROGRAM Bachelor of Science in Nursing (BSN) ACADEMIC YEAR
EXAM TITLE Lab Practicum – Microbiology Laboratory TOTAL QUESTIONS 40 Questions
COURSE TITLE Fundamentals of Microbiology FORMAT Multiple Choice / Select All That Apply — Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer or all correct answers for each question as specified.
▸ This lab practicum covers aseptic technique, media types, bacterial colonies, Gram staining, growth curves, biosafety levels, immunological concepts, sterilization, biochemical
testing, and organism identification.
▸ Questions are drawn from the complete BIOS 242 Lab Practicum review content.
▸ Correct answers and detailed rationales appear below each question for comprehensive review.
▸ All content reflects Chamberlain University BIOS 242 laboratory competencies.
MICROBIOLOGY LABORATORY TECHNIQUES & APPLICATIONS Questions 1 – 40
1. Which of the following are examples of GOOD aseptic technique? (Select all that apply)
A. Sterilizing the inoculating loop before using it but not afterwards
B. Decontaminating the lab bench both before and after use
C. Sterilizing the inoculating loop both before and after using it
D. Flaming your loop for at least 10 seconds but then sitting it on the bench before doing your bacterial transfer
E. Waving your inoculating loop around in the air to cool it faster
F. Flaming the top of your tube to generate upwards air currents before and after inoculating your culture
G. Flaming your inoculating loop, dropping it on the floor, but picking it up immediately to use again
CORRECT ANSWER B, C, and F — Decontaminate bench before and after; sterilize loop before and after; flame tube tops to generate upward air currents
RATIONALE Good aseptic technique requires: decontaminating the work surface before and after use (B), sterilizing the inoculating loop both before AND after use (C), and
flaming tube tops to create upward convection currents that prevent airborne contaminants from entering (F). Sterilizing only before but not after (A) leaves live
organisms on the loop. Setting a sterile loop on the bench (D) contaminates it. Waving the loop in air (E) exposes it to airborne microbes. Using a dropped loop (G)
introduces floor contaminants.
2. Scientists use various types of media to grow microorganisms. The process of introducing microbes into media is called:
A. Incubation
B. Inoculation
C. Isolation
D. Inspection
CORRECT ANSWER B — Inoculation
RATIONALE Inoculation is the process of introducing microorganisms into culture media. After inoculation (B), incubation (A) provides optimal growth conditions. Bacteria
then grow in colonies on solid surfaces. Isolation (C) is obtaining pure cultures. Inspection (D) is observing colony characteristics.
3. Which of the following statements about a bacterial colony are TRUE? (Select all that apply)
A. Is Macroscopic
B. Is Microscopic
C. Contains fewer than 100 cells
D. Likely contains more than one million cells
E. Comes from a single bacterial cell
F. Comes from many different bacterial cells all growing together
G. Can be seen with the naked eye
CORRECT ANSWER A, D, E, and G — Macroscopic; >1 million cells; from a single cell; visible to naked eye
RATIONALE A bacterial colony is macroscopic (visible to naked eye) and arises from a single bacterial cell that divides repeatedly, typically containing millions of cells. It is not
microscopic (B), does not contain fewer than 100 cells (C), and is not a mixture of different bacterial types (F). Cell shape (microscopic) and colony shape
(macroscopic) are not the same.
, 4. The streak plate method is commonly used to obtain:
A. Mixed colonies for diversity studies
B. Isolated (pure) colonies
C. Broth cultures only
D. Anaerobic growth conditions
CORRECT ANSWER B — Isolated (pure) colonies
RATIONALE The streak plate method uses progressive dilution across an agar surface to separate individual bacterial cells, each of which grows into an isolated colony. This
produces pure cultures—colonies derived from a single bacterial species. It does not produce mixed colonies (A) or require broth (C).
5. General-purpose (nonselective) media are designed to:
A. Grow only one specific bacterial species
B. Grow as many different types of microbes as possible
C. Differentiate between Gram-positive and Gram-negative bacteria
D. Select for antibiotic-resistant organisms only
CORRECT ANSWER B — Grow as many different types of microbes as possible
RATIONALE General-purpose (nonselective) media contain a mixture of nutrients supporting a wide variety of microbial life. They do not select for or against specific
organisms. Selective media (A) grow only one species or group. Differential media (C) distinguish between types. Enriched media contain blood or special growth
factors for fastidious bacteria.
6. Enriched media contain complex organic substances such as blood, serum, or hemoglobin and are used for:
A. Inhibiting Gram-positive bacteria
B. Growing fastidious bacteria that require special growth factors
C. Differentiating lactose fermenters from non-fermenters
D. Sterilizing laboratory equipment
CORRECT ANSWER B — Growing fastidious bacteria that require special growth factors
RATIONALE Enriched media (e.g., blood agar) contain complex nutrients (blood, serum, hemoglobin, growth factors) required by fastidious organisms that cannot grow on
basic media. Blood agar also demonstrates hemolysis patterns: alpha (partial), beta (complete), and gamma (no lysis).
7. A selective medium is designed to:
A. Grow all species equally without discrimination
B. Grow specific types of microorganisms while inhibiting others
C. Differentiate between organisms based on biochemical reactions
D. Enrich all organisms with additional growth factors
CORRECT ANSWER B — Grow specific types of microorganisms while inhibiting others
RATIONALE Selective media contain agents (antibiotics, bile salts, dyes) that inhibit certain organisms while permitting others to grow. MacConkey agar is selective against
Gram-positive bacteria (bile salts/crystal violet) and differential based on lactose fermentation (pink = fermenter, off-white = non-fermenter).
8. A differential medium allows:
A. Only one species to grow
B. All species to grow but may show different reactions, distinguishing them visually
C. No growth of any organisms
D. Growth without any visible differences between species
CORRECT ANSWER B — All species to grow but may show different reactions, distinguishing them visually
RATIONALE Differential media contain indicators that reveal metabolic differences. All species grow, but they produce visibly different reactions (e.g., color changes). On a
general-purpose differential medium, all species may have similar appearance (no differentiation). MacConkey agar is both selective AND differential.
9. MacConkey agar is both selective and differential. It selects against Gram-positive bacteria and differentiates based on:
A. Catalase production
B. Lactose fermentation (pink = positive; off-white = negative)
C. Motility
D. Hemolysis patterns
CORRECT ANSWER B — Lactose fermentation (pink = positive; off-white = negative)
RATIONALE MacConkey agar contains lactose and neutral red pH indicator. Lactose fermenters produce acid, lowering pH and appearing pink. Non-fermenters remain off-
white/colorless. It also contains bile salts and crystal violet that inhibit Gram-positive bacteria, making it selective as well.
10. Staining is used to help visualize cells. A simple stain shows:
A. Differences between Gram-positive and Gram-negative cell walls
B. Cell size, shape, and arrangement
C. Acid-fast properties of mycobacteria
D. Presence of endospores
CORRECT ANSWER B — Cell size, shape, and arrangement
RATIONALE Simple stains use a single dye and reveal basic morphology: cell size, shape (coccus, bacillus, spirillum), and arrangement (chains, clusters, pairs). Differential
stains (A) like the Gram stain distinguish between bacterial types based on cell wall structure. Acid-fast and endospore stains are specialized differential stains.
