BIOD 171 | BIOD 171 Microbiology Module 6 Exam
| Questions with Correct Answers and Expert
Explanation for Each Question | Portage Learning
1. What is the primary structural component of the fungal cell wall that distinguishes
it from plants?
A. Chitin
B. Cellulose
C. Peptidoglycan
D. Ergosterol
Correct Answer: A
Expert Explanation: The primary component of the fungal cell wall is chitin, a
durable polysaccharide that provides structural support. Unlike plants which use
cellulose, fungi utilize chitin to maintain the integrity of their cell boundaries. Chitin
is composed of N-acetylglucosamine units and is highly resistant to environmental
stress. This specific molecular structure is a key target for certain antifungal
treatments. Understanding this difference is fundamental to identifying fungal
pathogens in a laboratory setting.
2. Fungi that live on dead or decaying organic matter are specifically referred to as:
A. Autotrophs
,B. Phototrophs
C. Obligate parasites
D. Saprophytes
Correct Answer: D
Expert Explanation: Saprophytes are organisms that obtain their nutrients by
decomposing dead or decaying organic material. This ecological role is vital for
nutrient cycling within various ecosystems. Fungi secrete extracellular enzymes to
break down complex organic polymers into simpler forms they can absorb. While
some fungi are parasitic, the majority of the fungal kingdom consists of these
essential decomposers. Their ability to recycle carbon and minerals makes them
indispensable to the biosphere.
3. Which of the following describes the morphology of a yeast?
A. Multicellular with hyphae
B. Forming complex fruiting bodies
C. Unicellular and typically oval-shaped
D. Acellular and requiring a host cell
Correct Answer: C
,Expert Explanation: Yeasts are unicellular fungi that are typically oval or spherical
in shape. They reproduce primarily through an asexual process known as budding.
Unlike molds, they do not form long, branching filaments called hyphae under
standard conditions. Some yeasts are opportunistic pathogens, such as Candida
albicans, which can cause infections in humans. Their simple cellular structure
allows them to inhabit moist, nutrient-rich environments like mucosal surfaces.
4. Which sterol is found in fungal cell membranes and is a common target for
antifungal drugs?
A. Cholesterol
B. Stigmasterol
C. Ergosterol
D. Phytosterol
Correct Answer: C
Expert Explanation: Ergosterol is the primary sterol found in the cell membranes
of fungi, serving a similar function to cholesterol in animal cells. Because human
cells do not produce ergosterol, it serves as an excellent target for selective toxicity
in medicine. Antifungal agents like amphotericin B and the azole class work by
disrupting ergosterol synthesis or its function. This disruption leads to increased
, membrane permeability and eventual cell death. Monitoring ergosterol levels can
also be a method for quantifying fungal biomass in research.
5. A fungal infection that affects the skin, hair, or nails is clinically classified as a:
A. Systemic mycosis
B. Cutaneous mycosis
C. Subcutaneous mycosis
D. Opportunistic mycosis
Correct Answer: B
Expert Explanation: Cutaneous mycoses are fungal infections restricted to the
keratinized layers of the skin, hair, and nails. These infections are often caused by
dermatophytes, which have the ability to break down keratin for nutrition.
Examples include common conditions like athlete’s foot, ringworm, and jock itch.
Unlike systemic infections, these are usually superficial and do not spread to
internal organs. Treatment typically involves topical antifungal creams or oral
medications for more persistent cases.
6. What is the term for a fungus that can exist as both a yeast and a mold depending
on environmental conditions?
A. Dimorphic
B. Biphasic
| Questions with Correct Answers and Expert
Explanation for Each Question | Portage Learning
1. What is the primary structural component of the fungal cell wall that distinguishes
it from plants?
A. Chitin
B. Cellulose
C. Peptidoglycan
D. Ergosterol
Correct Answer: A
Expert Explanation: The primary component of the fungal cell wall is chitin, a
durable polysaccharide that provides structural support. Unlike plants which use
cellulose, fungi utilize chitin to maintain the integrity of their cell boundaries. Chitin
is composed of N-acetylglucosamine units and is highly resistant to environmental
stress. This specific molecular structure is a key target for certain antifungal
treatments. Understanding this difference is fundamental to identifying fungal
pathogens in a laboratory setting.
2. Fungi that live on dead or decaying organic matter are specifically referred to as:
A. Autotrophs
,B. Phototrophs
C. Obligate parasites
D. Saprophytes
Correct Answer: D
Expert Explanation: Saprophytes are organisms that obtain their nutrients by
decomposing dead or decaying organic material. This ecological role is vital for
nutrient cycling within various ecosystems. Fungi secrete extracellular enzymes to
break down complex organic polymers into simpler forms they can absorb. While
some fungi are parasitic, the majority of the fungal kingdom consists of these
essential decomposers. Their ability to recycle carbon and minerals makes them
indispensable to the biosphere.
3. Which of the following describes the morphology of a yeast?
A. Multicellular with hyphae
B. Forming complex fruiting bodies
C. Unicellular and typically oval-shaped
D. Acellular and requiring a host cell
Correct Answer: C
,Expert Explanation: Yeasts are unicellular fungi that are typically oval or spherical
in shape. They reproduce primarily through an asexual process known as budding.
Unlike molds, they do not form long, branching filaments called hyphae under
standard conditions. Some yeasts are opportunistic pathogens, such as Candida
albicans, which can cause infections in humans. Their simple cellular structure
allows them to inhabit moist, nutrient-rich environments like mucosal surfaces.
4. Which sterol is found in fungal cell membranes and is a common target for
antifungal drugs?
A. Cholesterol
B. Stigmasterol
C. Ergosterol
D. Phytosterol
Correct Answer: C
Expert Explanation: Ergosterol is the primary sterol found in the cell membranes
of fungi, serving a similar function to cholesterol in animal cells. Because human
cells do not produce ergosterol, it serves as an excellent target for selective toxicity
in medicine. Antifungal agents like amphotericin B and the azole class work by
disrupting ergosterol synthesis or its function. This disruption leads to increased
, membrane permeability and eventual cell death. Monitoring ergosterol levels can
also be a method for quantifying fungal biomass in research.
5. A fungal infection that affects the skin, hair, or nails is clinically classified as a:
A. Systemic mycosis
B. Cutaneous mycosis
C. Subcutaneous mycosis
D. Opportunistic mycosis
Correct Answer: B
Expert Explanation: Cutaneous mycoses are fungal infections restricted to the
keratinized layers of the skin, hair, and nails. These infections are often caused by
dermatophytes, which have the ability to break down keratin for nutrition.
Examples include common conditions like athlete’s foot, ringworm, and jock itch.
Unlike systemic infections, these are usually superficial and do not spread to
internal organs. Treatment typically involves topical antifungal creams or oral
medications for more persistent cases.
6. What is the term for a fungus that can exist as both a yeast and a mold depending
on environmental conditions?
A. Dimorphic
B. Biphasic
