BIO 250 Exam 1 V1 | BIO 250 Microbiology | Actual
Q&A with Rationale (BIO250 Exam 1) |
StraighterLine
1. A scientist who uses logical steps to establish a relationship between a specific microbe
and a specific disease is applying which of the following principles?
A. Spontaneous generation theory
B. Tyndallization protocol
C. Koch’s postulates
D. Pasteur’s germ theory
Correct Answer: C
Explanation: Koch’s postulates are a series of four criteria designed to establish a
causative relationship between a microbe and a disease. These postulates were developed
in the late 19th century and remain a gold standard in medical microbiology. By isolating
the pathogen and re-infecting a healthy host, the researcher confirms the specific etiology
of the illness.
2. Which of the following represents the correct sequence of the ‘Five I’s’ used in the
microbiology laboratory?
A. Inoculation, Incubation, Isolation, Inspection, Identification
B. Incubation, Inoculation, Inspection, Isolation, Identification
,C. Isolation, Inoculation, Incubation, Inspection, Identification
D. Identification, Inspection, Inoculation, Incubation, Isolation
Correct Answer: A
Explanation: The Five I’s represent the basic procedures used by microbiologists to
examine and characterize microbes. Inoculation involves placing a sample into a medium,
followed by incubation to allow for growth. Isolation, inspection, and identification follow
to ensure a pure culture is obtained and correctly named based on its characteristics.
3. What is the primary function of the bacterial cell wall composed of peptidoglycan?
A. Regulating the transport of nutrients into the cell
B. Providing structural support and preventing osmotic lysis
C. Facilitating motility through aqueous environments
D. Serving as a storage site for high-energy phosphates
Correct Answer: B
Explanation: The peptidoglycan layer is a rigid mesh-like structure that gives bacteria
their shape and protects them from high internal osmotic pressure. Without this structural
integrity, the cell would likely burst in hypotonic environments. This wall is also a primary
target for several classes of antibiotics, such as penicillins.
, 4. Which of the following features are common to all living cells, including both prokaryotes
and eukaryotes? (Select all that apply)
A. Membrane-bound organelles
B. Peptidoglycan cell wall
C. Cell membrane, ribosomes, and DNA
D. Linear chromosomes
E. 80S Ribosomes
F. Mitochondria and Chloroplasts
Correct Answer: C
Explanation: All living cells, regardless of their domain, must possess a cytoplasmic
membrane to define their boundaries. They also require ribosomes for protein synthesis
and DNA as their hereditary material to guide cellular functions. While other structures
vary between prokaryotes and eukaryotes, these three components are universally
essential for cellular life.
5. In the Gram stain procedure, what is the specific role of the iodine solution?
A. Primary stain
B. Counterstain
C. Decolorizer
D. Mordant
Q&A with Rationale (BIO250 Exam 1) |
StraighterLine
1. A scientist who uses logical steps to establish a relationship between a specific microbe
and a specific disease is applying which of the following principles?
A. Spontaneous generation theory
B. Tyndallization protocol
C. Koch’s postulates
D. Pasteur’s germ theory
Correct Answer: C
Explanation: Koch’s postulates are a series of four criteria designed to establish a
causative relationship between a microbe and a disease. These postulates were developed
in the late 19th century and remain a gold standard in medical microbiology. By isolating
the pathogen and re-infecting a healthy host, the researcher confirms the specific etiology
of the illness.
2. Which of the following represents the correct sequence of the ‘Five I’s’ used in the
microbiology laboratory?
A. Inoculation, Incubation, Isolation, Inspection, Identification
B. Incubation, Inoculation, Inspection, Isolation, Identification
,C. Isolation, Inoculation, Incubation, Inspection, Identification
D. Identification, Inspection, Inoculation, Incubation, Isolation
Correct Answer: A
Explanation: The Five I’s represent the basic procedures used by microbiologists to
examine and characterize microbes. Inoculation involves placing a sample into a medium,
followed by incubation to allow for growth. Isolation, inspection, and identification follow
to ensure a pure culture is obtained and correctly named based on its characteristics.
3. What is the primary function of the bacterial cell wall composed of peptidoglycan?
A. Regulating the transport of nutrients into the cell
B. Providing structural support and preventing osmotic lysis
C. Facilitating motility through aqueous environments
D. Serving as a storage site for high-energy phosphates
Correct Answer: B
Explanation: The peptidoglycan layer is a rigid mesh-like structure that gives bacteria
their shape and protects them from high internal osmotic pressure. Without this structural
integrity, the cell would likely burst in hypotonic environments. This wall is also a primary
target for several classes of antibiotics, such as penicillins.
, 4. Which of the following features are common to all living cells, including both prokaryotes
and eukaryotes? (Select all that apply)
A. Membrane-bound organelles
B. Peptidoglycan cell wall
C. Cell membrane, ribosomes, and DNA
D. Linear chromosomes
E. 80S Ribosomes
F. Mitochondria and Chloroplasts
Correct Answer: C
Explanation: All living cells, regardless of their domain, must possess a cytoplasmic
membrane to define their boundaries. They also require ribosomes for protein synthesis
and DNA as their hereditary material to guide cellular functions. While other structures
vary between prokaryotes and eukaryotes, these three components are universally
essential for cellular life.
5. In the Gram stain procedure, what is the specific role of the iodine solution?
A. Primary stain
B. Counterstain
C. Decolorizer
D. Mordant
