Mycology Practice Questions

Q: What type of spore is produced by Ascomycota during sexual reproduction?

Ascospores. ***Ascospores*** - **Ascospores** are the sexual spores produced by fungi belonging to the phylum **Ascomycota** during their sexual reproductive cycle. - These spores are formed inside a sac-like structure called an **ascus** after **karyogamy (nuclear fusion)** and **meiosis**. - Each ascus typically contains **4-8 ascospores** arranged in a characteristic pattern. - Examples of Ascomycota include *Aspergillus*, *Penicillium*, *Candida*, and yeasts like *Saccharomyces*. *Asexual spores* - **Asexual spores** are produced during **asexual reproduction** without the fusion of gametes or meiosis. - Examples include **conidia** and **sporangiospores**, which allow for rapid proliferation and dispersal. *Conidia* - **Conidia** are a specific type of **asexual spore**, not sexual spores. - They are formed exogenously on specialized structures called **conidiophores**. - While Ascomycota can produce conidia asexually, the question asks specifically about sexual reproduction. *None of the options* - This option is incorrect because **ascospores** are indeed the sexual spores of Ascomycota.

Q: Which of the following is a cause of Valley fever (desert rheumatism)?

Coccidioides. ***Coccidioides*** - **Valley fever**, or desert rheumatism, is caused by infection with the dimorphic fungus **Coccidioides**, primarily **Coccidioides immitis** and **Coccidioides posadasii**. - This fungus is endemic to arid and semi-arid regions, especially the **southwestern United States** and parts of Central and South America. *Sporothrix* - **Sporothrix schenckii** causes sporotrichosis, a chronic fungal infection typically involving the skin, subcutaneous tissue, and adjacent lymphatics, often through skin trauma. - It does not cause Valley fever. *Cladosporium* - **Cladosporium** species are ubiquitous molds commonly found in outdoor and indoor environments, often associated with allergic reactions and occasionally superficial infections. - They are not a cause of Valley fever. *Phialophora* - **Phialophora** species are dematiaceous fungi that can cause phaeohyphomycosis, chromoblastomycosis, and eumycetoma, which are subcutaneous or systemic fungal infections. - They are not associated with Valley fever.

Q: A plant prick can produce sporotrichosis. Which of the following statements about sporotrichosis is false?

It is an occupational disease of butchers, doctors. ***It is an occupational disease of butchers, doctors*** - Sporotrichosis is an **occupational hazard for gardeners, florists, and agricultural workers** due to exposure to decaying plant matter, not typically for butchers or doctors. - The disease is caused by **direct inoculation** of the fungus *Sporothrix schenckii* into the skin, often through a thorn prick or minor trauma. *Most cases are acquired via cutaneous inoculation* - This statement is **true** as sporotrichosis is primarily caused by **traumatic implantation** of fungal spores into the skin. - Common sources include **thorns, splinters, sphagnum moss**, and other plant materials. *Enlarged lymph nodes extending centripetally as a beaded chain are a characteristic finding* - This statement is **true** and describes the classic **lymphocutaneous sporotrichosis**, where lesions and **nodular lymphangitis** track along lymphatic channels. - The "beaded chain" appearance refers to the multiple subcutaneous nodules formed along the lymphatic vessels. *Is a chronic mycotic disease that typically involves skin, subcutaneous tissue and regional lymphatics* - This statement is **true** because sporotrichosis is a **slow-progressing fungal infection** that primarily affects the skin, the tissue just beneath the skin, and the lymphatics draining the infected area. - While systemic dissemination can occur in immunocompromised individuals, the **cutaneous and lymphocutaneous forms** are most common.

Q: The fungus with septate hyphae and dichotomous branching is?

Aspergillus. ***Aspergillus*** - *Aspergillus* species are characterized by their **septate hyphae** and **acute-angle branching** (branching at approximately 45-degree angles), which are key distinguishing features in histopathology. - This branching pattern is sometimes referred to as "dichotomous branching" in medical literature, though true dichotomous branching is more characteristic of certain tissue forms. - This fungal morphology is often seen in infections such as **invasive aspergillosis** in immunocompromised patients. *Penicillium* - *Penicillium* also has **septate hyphae**, but its branching pattern is typically *not acute-angled or dichotomous*. - It is more commonly known for its **brush-like** conidiophores (penicillus) in culture rather than distinctive tissue branching patterns. *Mucor* - *Mucor* is a type of **zygomycete** (now classified under Mucorales) and is characterized by **aseptate or sparsely septate hyphae** with **irregular, right-angle branching**. - This is a key histological feature distinguishing it from *Aspergillus* in cases of **mucormycosis**. *Rhizopus* - Similar to *Mucor*, *Rhizopus* is also a zygomycete with **aseptate or sparsely septate hyphae** and **irregular, wide-angle branching**. - It is often identified in culture by the presence of **rhizoids** (root-like structures) and sporangiophores.

Q: Which of the following statements about Penicillium marneffei is incorrect?

Forms black colonies. ***Forms black colonies*** - *Penicillium marneffei* typically forms colonies that are often **reddish-beige** or **pigmented red-diffusible**, not black. - The production of a characteristic **red-to-burgundy pigment** is a key identifying feature of this fungus, especially in culture. *Is a dimorphic fungus* - This statement is correct. *Penicillium marneffei* is a **thermally dimorphic fungus**, meaning it grows as a mould at 25°C (room temperature) and as yeast-like cells at 37°C (body temperature). - This dimorphism is crucial for its pathogenesis and identification. *Amphotericin B is used for treatment* - This statement is correct. **Amphotericin B** is a commonly used antifungal agent for the treatment of severe *Penicillium marneffei* infections, particularly in immunocompromised patients. - It is often followed by a maintenance regimen with an azole antifungal like itraconazole. *Causes severe infections in immunocompromised patients* - This statement is correct. *Penicillium marneffei* is an **opportunistic pathogen** that primarily causes severe, disseminated infections in individuals with compromised immune systems, especially those with HIV/AIDS. - Endemic regions include Southeast Asia, where it is a leading cause of systemic mycosis in HIV-positive patients.

Q: In a patient presenting with respiratory symptoms, acute angled septate hyphae are seen in which of the following fungi?

Aspergillus. ***Aspergillus*** - *Aspergillus* species are characterized by their distinctive **acute-angled (dichotomous) septate hyphae** when observed microscopically in tissue sections or clinical samples. - This morphological feature is crucial for differentiating *Aspergillus* infections, such as **aspergillosis**, from other fungal infections. *Mucor* - *Mucor* (along with *Rhizopus* and *Lichtheimia*) belongs to the Zygomycetes class, which are characterized by **broad, non-septate, ribbon-like hyphae** with irregular branching, not acute-angled septate hyphae. - These fungi are associated with **mucormycosis**, often seen in immunocompromised patients, particularly those with diabetes. *Penicillium* - *Penicillium* is a common mold known for producing penicillin and typically appears as **septate hyphae** but is more often recognized by its branching, brush-like conidiophores (penicilli) in culture rather than a distinct acute-angled septate hyphal morphology in clinical samples causing invasive disease. - While it can cause opportunistic infections, its hyphae are less commonly described as having uniquely acute angles compared to *Aspergillus*. *Candida* - *Candida* species are typically observed as **yeast cells (oval budding forms)**, often forming **pseudohyphae** (elongated yeast cells that remain attached) or true hyphae under specific conditions, but not as acute-angled septate hyphae. - *Candida* is a common cause of superficial and invasive candidiasis, and its microscopic appearance is distinct from filamentous fungi.

Q: Which fungus is commonly known as golden yellow jelly fungus?

Tremella mesenterica. ***Tremella mesenterica*** - This fungus is commonly referred to as **golden yellow jelly fungus** or **witch's butter** due to its distinctive golden-yellow, gelatinous, and brain-like appearance. - It is a **jelly fungus** that typically grows on dead hardwood branches, especially after rain, and is known for its pliable, quivering texture. *T. tonsurans* - This refers to **Trichophyton tonsurans**, a dermatophytic fungus primarily known for causing **tinea capitis** (ringworm of the scalp). - Its common name relates to its effect on hair, causing breakage and a "black dot" appearance, rather than a golden yellow, jelly-like form. *Epidermophyton floccosum* - This is a dermatophytic fungus that specifically causes infections of the **skin and nails**, particularly **tinea pedis** (athlete's foot) and **tinea cruris** (jock itch). - It does not produce a fruiting body and is not described as a jelly-like fungus. *T. mentagrophytes* - This refers to **Trichophyton mentagrophytes**, another common dermatophyte responsible for various superficial fungal infections, including **tinea pedis**, **tinea corporis**, and **tinea unguium**. - Its clinical presentation is not that of a golden yellow jelly fungus.

Q: Regarding fungal cell wall, all are true except:

Azoles act on them. ***Azoles act on them*** - **Azole antifungals** primarily target the **ergosterol synthesis** pathway, specifically inhibiting the **lanosterol 14-alpha-demethylase** enzyme, which is located in the fungal cell membrane, not the cell wall. - While the cell wall is crucial for fungal viability, agents targeting it (e.g., **echinocandins**) are distinct from azoles. *Contains chitin* - The fungal cell wall is indeed a complex structure composed of various carbohydrates, with **chitin** being a major structural polysaccharide that provides rigidity. - Chitin is a **beta-(1,4)-linked polymer of N-acetylglucosamine** and is a unique component distinguishing fungal cells from animal cells. *Prevent osmotic damage* - The rigid fungal cell wall provides structural support and protects the cell from **environmental stresses**, particularly **osmotic lysis** in hypotonic environments. - It maintains the cell's integrity against internal **turgor pressure**, which is essential for fungal growth and survival. *Does not contain peptidoglycan* - Fungal cell walls are distinct from bacterial cell walls in their composition; they **do not contain peptidoglycan**. - **Peptidoglycan** is a characteristic component of bacterial cell walls, which is targeted by antibiotics like penicillins.

Q: Aseptate hyphae is not seen in which of the following fungi?

Aspergillus. ***Correct: Aspergillus*** - *Aspergillus* species are characterized by **septate hyphae** and **acute angle branching**, distinguishing them from zygomycetes. - They cause diseases such as **allergic bronchopulmonary aspergillosis (ABPA)**, aspergilloma, and invasive aspergillosis. - Since Aspergillus has septate hyphae, **aseptate hyphae are NOT seen** in Aspergillus. *Incorrect: Rhizopus* - *Rhizopus* is a zygomycete with **broad, ribbon-like, aseptate hyphae** and **right-angle/irregular branching**. - Common cause of **mucormycosis (zygomycosis)**, especially in immunocompromised individuals. *Incorrect: Mucor* - *Mucor* is another zygomycete with **aseptate hyphae** and **wide-angle branching**. - Causes mucormycosis, leading to severe infections primarily in patients with **diabetic ketoacidosis** or **hematologic malignancies**. *Incorrect: Penicillium* - *Penicillium* species possess **septate hyphae** with characteristic **brush-like (penicillus-shaped)** fruiting bodies. - While some produce antibiotics, certain species like *Talaromyces marneffei* can cause systemic infections in immunocompromised patients.

Question 1

What type of spore is produced by Ascomycota during sexual reproduction?

Accepted Answer

Ascospores

Answer

Asexual spores

Answer

Conidia

Answer

None of the options

Question 2

Which of the following is a cause of Valley fever (desert rheumatism)?

Accepted Answer

Coccidioides

Answer

Sporothrix

Answer

Cladosporium

Answer

Phialophora

Question 3

A plant prick can produce sporotrichosis. Which of the following statements about sporotrichosis is false?

Accepted Answer

It is an occupational disease of butchers, doctors

Answer

Enlarged lymph nodes extending centripetally as a beaded chain are a characteristic finding

Answer

Most cases are acquired via cutaneous inoculation

Answer

Is a chronic mycotic disease that typically involves skin, subcutaneous tissue and regional lymphatics

Question 4

The fungus with septate hyphae and dichotomous branching is?

Accepted Answer

Aspergillus

Answer

Penicillium

Answer

Mucor

Answer

Rhizopus

Question 5

Which of the following statements about Penicillium marneffei is incorrect?

Accepted Answer

Forms black colonies

Answer

Is a dimorphic fungus

Answer

Amphotericin B is used for treatment

Answer

Causes severe infections in immunocompromised patients

Question 6

In a patient presenting with respiratory symptoms, acute angled septate hyphae are seen in which of the following fungi?

Accepted Answer

Aspergillus

Answer

Mucor

Answer

Penicillium

Answer

Candida

Question 7

Which of the following statements is true regarding dimorphic fungi?

Accepted Answer

Transforms between yeast and mold forms at different temperatures

Answer

Exists in two distinct morphological forms

Answer

All dimorphic fungi are highly pathogenic to immunocompetent hosts

Answer

Primarily found in tropical and subtropical regions

Question 8

Which fungus is commonly known as golden yellow jelly fungus?

Accepted Answer

Tremella mesenterica

Answer

T. tonsurans

Answer

Epidermophyton floccosum

Answer

T. mentagrophytes

Question 9

Regarding fungal cell wall, all are true except:

Accepted Answer

Azoles act on them

Answer

Contains chitin

Answer

Prevent osmotic damage

Answer

Does not contain peptidoglycan

Question 10

Aseptate hyphae is not seen in which of the following fungi?

Accepted Answer

Aspergillus

Answer

Rhizopus

Answer

Mucor

Answer

Penicillium

Mycology — MCQs

Mycology — MCQs

On this page

Practice by Chapter

Want unlimited practice?