BIOD 171 Essential Microbiology Module 4: Cultivation
and Sensitivity 2026/2027 UPDATE UPDATED ACTUAL
Exam Questions and CORRECT Answers
1. What is the primary purpose of using a growth medium in microbiology?
A. To provide nutrients for microbial growth
B. To kill unwanted bacteria
C. To observe viral replication only
D. To prevent any bacterial growth
Answer: A
Rationale: Growth media provide the necessary nutrients, such as carbon and nitrogen
sources, to support the multiplication of microorganisms.
2. Which of the following is a liquid growth medium?
A. Agar plate
B. Agar slant
C. Broth
D. Agar deep
Answer: C
Rationale: Broth is a liquid medium used for growing large quantities of bacteria in a
suspension.
,3. Agar is derived from which of the following sources?
A. Beef extract
B. Peptone
C. Yeast
D. Red algae
Answer: D
Rationale: Agar is a polysaccharide derived from red algae and is used as a solidifying
agent because most bacteria cannot digest it.
4. Which type of medium inhibits the growth of certain microbes while allowing
others to grow?
A. Enriched media
B. Differential media
C. Selective media
D. General purpose media
Answer: C
Rationale: Selective media contain components that inhibit the growth of specific groups
of microbes while encouraging the growth of others.
5. Which medium is used to distinguish between different groups of
microorganisms based on their biological characteristics?
A. Selective media
B. Differential media
C. Reducing media
D. Enriched media
Answer: B
Rationale: Differential media contain indicators (like dyes or blood) that allow one to
distinguish between different types of bacteria based on their metabolic activities.
, 6. What is the purpose of the ‘streak plate’ method?
A. To count the total number of cells
B. To encourage the growth of anaerobic bacteria
C. To test for antibiotic sensitivity
D. To isolate individual colonies to obtain a pure culture
Answer: D
Rationale: The streak plate method dilutes a sample across the surface of an agar plate to
isolate individual cells that grow into distinct, pure colonies.
7. A ‘pure culture’ is defined as:
A. A culture containing only a single species of microorganism
B. A culture that has been sterilized
C. A culture containing multiple species of bacteria
D. A culture found in a natural environment
Answer: A
Rationale: A pure culture consists of only one species or strain of microorganism, which is
essential for studying specific characteristics.
8. LB (Lysogeny Broth) agar is classified as what type of medium?
A. Selective only
B. Differential only
C. Enriched for fastidious organisms
D. General purpose/Non-selective
Answer: D
Rationale: LB agar is a multi-purpose, non-selective, and non-differential medium used for
the growth of a wide variety of non-fastidious bacteria.
and Sensitivity 2026/2027 UPDATE UPDATED ACTUAL
Exam Questions and CORRECT Answers
1. What is the primary purpose of using a growth medium in microbiology?
A. To provide nutrients for microbial growth
B. To kill unwanted bacteria
C. To observe viral replication only
D. To prevent any bacterial growth
Answer: A
Rationale: Growth media provide the necessary nutrients, such as carbon and nitrogen
sources, to support the multiplication of microorganisms.
2. Which of the following is a liquid growth medium?
A. Agar plate
B. Agar slant
C. Broth
D. Agar deep
Answer: C
Rationale: Broth is a liquid medium used for growing large quantities of bacteria in a
suspension.
,3. Agar is derived from which of the following sources?
A. Beef extract
B. Peptone
C. Yeast
D. Red algae
Answer: D
Rationale: Agar is a polysaccharide derived from red algae and is used as a solidifying
agent because most bacteria cannot digest it.
4. Which type of medium inhibits the growth of certain microbes while allowing
others to grow?
A. Enriched media
B. Differential media
C. Selective media
D. General purpose media
Answer: C
Rationale: Selective media contain components that inhibit the growth of specific groups
of microbes while encouraging the growth of others.
5. Which medium is used to distinguish between different groups of
microorganisms based on their biological characteristics?
A. Selective media
B. Differential media
C. Reducing media
D. Enriched media
Answer: B
Rationale: Differential media contain indicators (like dyes or blood) that allow one to
distinguish between different types of bacteria based on their metabolic activities.
, 6. What is the purpose of the ‘streak plate’ method?
A. To count the total number of cells
B. To encourage the growth of anaerobic bacteria
C. To test for antibiotic sensitivity
D. To isolate individual colonies to obtain a pure culture
Answer: D
Rationale: The streak plate method dilutes a sample across the surface of an agar plate to
isolate individual cells that grow into distinct, pure colonies.
7. A ‘pure culture’ is defined as:
A. A culture containing only a single species of microorganism
B. A culture that has been sterilized
C. A culture containing multiple species of bacteria
D. A culture found in a natural environment
Answer: A
Rationale: A pure culture consists of only one species or strain of microorganism, which is
essential for studying specific characteristics.
8. LB (Lysogeny Broth) agar is classified as what type of medium?
A. Selective only
B. Differential only
C. Enriched for fastidious organisms
D. General purpose/Non-selective
Answer: D
Rationale: LB agar is a multi-purpose, non-selective, and non-differential medium used for
the growth of a wide variety of non-fastidious bacteria.
