Fungal Diseases is part of Biology. Below are notes on 6 sub-topics, followed by practice MCQs from State PSC and UPSC papers.
Antifungal Drugs: Mechanisms of Action, Classes, and Side Effects
- Antibiotics are primarily derived from microorganisms, including fungi and bacteria.
- Penicillin, a widely used antibiotic, is famously produced by the fungus Penicillium chrysogenum.
- Antifungal drugs selectively target unique fungal components or metabolic pathways to inhibit growth or kill fungal cells, minimizing host toxicity.
- Mechanisms of Action of Antifungal Drugs:
- Cell Membrane Disruption:
- Ergosterol Synthesis Inhibition: Azoles (e.g., Fluconazole, Ketoconazole) and Allylamines (e.g., Terbinafine) disrupt fungal cell membrane integrity by blocking ergosterol production.
- Ergosterol Binding & Pore Formation: Polyenes (e.g., Amphotericin B, Nystatin) directly bind to ergosterol, creating pores that lead to cell lysis.
- Cell Wall Synthesis Inhibition: Echinocandins (e.g., Caspofungin) inhibit the synthesis of β-(1,3)-D-glucan, a crucial component of the fungal cell wall.
- Nucleic Acid Synthesis Inhibition: Flucytosine is converted to fluorouracil within fungal cells, interfering with DNA and RNA synthesis.
- Microtubule Function Disruption: Griseofulvin interferes with mitotic spindle formation and fungal cell division.
- Major Classes of Antifungal Drugs: Polyenes, Azoles (Triazoles, Imidazoles), Allylamines, Echinocandins, Pyrimidine Analogues (Flucytosine), and Others (Griseofulvin).
- Common Side Effects:
- Nephrotoxicity (prominent with Amphotericin B).
- Hepatotoxicity (associated with Azoles, Terbinafine).
- Bone marrow suppression (Flucytosine).
- Gastrointestinal disturbances, skin rash, and infusion-related reactions.
Common Pathogenic Fungi and their Characteristics
- Fungi General Characteristics: Saprophytic mode of nutrition; some are parasitic. Reproduce via spore formation (e.g., Rhizopus).
- Mucormycosis (Black Fungus): Caused by fungi. An invasive, systemic, immune-metabolic infection. Previously known as Zygomycosis. Caused by multiple fungal species including Mucor, Rhizopus, and Rhizomucor. Humans are exposed to their spores daily.
- Yeast: A type of fungus. Reproduces asexually by budding. Is a facultative anaerobe. Can form pseudomycelium. Facilitates reactions in baking bread and brewing alcohol. Not all yeasts are dimorphic or pathogenic.
- Rhizopus: A common fungus that grows on bread (black bread mold). Reproduces by spore formation.
- Synchytrium: An endobiotic fungus (lives inside the host cell).
- Ustilago: A plant pathogen that exhibits "Clamp connection".
- Albugo: Forms zoospores inside vesicles during reproduction.
- Ophiocordyceps sinensis: Commonly known as Chinese Caterpillar Fungus or Himalayan Viagra. Included in the IUCN Red List.
- Lichens: A symbiotic association formed between algae and fungi.
Environmental Factors Influencing Fungal Disease Epidemiology
- Humidity: High relative humidity (moisture) is essential for fungal growth, spore germination, and proliferation.
- Temperature: Moderate temperatures (e.g., 20-40°C) are optimal for the growth of most fungi; temperatures above 60°C are generally fungicidal or inhibit growth.
- Air Circulation: Stagnant or poor air circulation allows localized accumulation of moisture and spores, favoring fungal growth.
- Nutrient Availability: Presence of organic matter (e.g., decaying plant/animal material, host tissues) provides necessary nutrients for fungal metabolism.
- pH: Most fungi prefer a slightly acidic to
- Light: Many fungi exhibit optimal growth in dark or low-light environments.
Fungal Diseases in Plants: Economic Importance and Management Strategies (e.g., Rusts, Smuts, Blights)
- Fungal diseases cause significant economic losses in agriculture, affecting crop yield and quality.
- Rusts and Smuts are two common fungal diseases affecting wheat crops.
- Black Rust of Wheat: Caused by the fungus Puccinia graminis.
- Karnal Bunt: A fungal disease predominantly affecting wheat crops.
- Karnal Bunt infected wheat fields exhibit a characteristic foul smell due to the presence of the volatile compound Trimethylamine.
- Captafol is an example of a fungicide used for the management of various plant fungal diseases.
Key Human Fungal Diseases: Candidiasis, Aspergillosis, Cryptococcosis, Dermatophytosis
- Candidiasis:
- Cause: Candida species (e.g., C. albicans), a yeast.
- Manifestations: Oral thrush, vaginal yeast infection, diaper rash, systemic infections.
- Aspergillosis:
- Cause: Aspergillus species (e.g., A. fumigatus), a mold.
- Manifestations: Allergic bronchopulmonary aspergillosis (ABPA), aspergilloma (fungal ball), invasive aspergillosis (severe in immunocompromised).
- Cryptococcosis:
- Cause: Cryptococcus neoformans / C. gattii, an encapsulated yeast.
- Manifestations: Primarily pulmonary infection, can disseminate to CNS (meningitis, common in HIV/AIDS).
- Dermatophytosis (Ringworm infections):
- Cause: Dermatophytes (e.g., Trichophyton, Microsporum, Epidermophyton) – fungi that feed on keratin.
- Manifestations: Tinea infections affecting skin, hair, nails.
- Key examples (all caused by fungus):
- Athlete's foot (Tinea pedis): Fungal infection of the feet.
- Ringworm (Tinea corporis): Fungal infection of body skin.
- Jock itch (Tinea cruris): Fungal infection of groin area.
Mycotoxins: Aflatoxins, Ergotism, and their Public Health Impact
- Mycotoxins are toxic secondary metabolites produced by various fungi (moulds).
- Aflatoxins:
- Produced by specific species of fungi, primarily Aspergillus (e.g., Aspergillus flavus, Aspergillus parasiticus).
- Contaminate agricultural products like cereal grains (maize, wheat), oilseeds (groundnuts/peanuts), tree nuts, and spices.
- Production is favored by warm, humid conditions and improper handling/ storage.
- Highly toxic, potent carcinogens (especially liver cancer), mutagenic, teratogenic, and immunosuppressive.
- Generally not destroyed by normal cooking processes.
- Public Health Impact: Major food safety concern globally, contributing to liver disease and cancer in humans and animals.
- Ergotism:
- Caused by consuming grains (primarily rye, but also wheat, barley) contaminated with ergot fungi, mainly Claviceps purpurea.
- The fungi produce ergot alkaloids, which are toxic.
- Symptoms:
- Gangrenous Ergotism (St. Anthony's Fire): Caused by vasoconstriction, leading to numbness, tingling, severe burning pain, and eventual dry gangrene and limb loss.
- Convulsive Ergotism: Affects the central nervous system, causing painful spasms, tremors, convulsions, hallucinations, and psychological disturbances.
- Public Health Impact: Historically responsible for major epidemics of mass poisoning due to contaminated staple grains.
27. Other Parasitic Diseases
Practice MCQs: Fungal Diseases
Antifungal Drugs: Mechanisms of Action, Classes, and Side Effects
Antibiotics are mostly obtained from -
Asked in: Assistant Engineer (AE) Exam 2013
- Fungi
- Viruses
- Mycobacterium Tuberculosis
- Trypamosoma
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Answer: A. Fungi
The question specifically asks for the causative agent of typhoid fever. Salmonella typhi is the pathogen responsible for this infectious disease.
Typhoid disease is caused by
Asked in: law officier 2025
- Protozoan animal
- Bacteriophage
- Bacteria
- Virus
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Answer: C. Bacteria
Typhoid is a bacterial disease.
Typhoid is caused by which vector?
Asked in: J.E (Electrical 2020) 2020 · RO ARO Mains 2021
- Trichinosis
- Brucellosis
- West Nile Virus
- Salmonella typhi bacteria
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Answer: D. Salmonella typhi bacteria
Typhoid fever is a bacterial infection caused by the bacterium Salmonella enterica serotype Typhi (often shortened to Salmonella typhi). It is typically transmitted through contaminated food or water. C. Bacteria D. Angiosperms Ans: A This question is from biology, specifically about the origin of antibiotics, a crucial class of drugs. It tests knowledge of microbial sources of medicines.
The antibiotic penicillin is produced by
Asked in: Government Polytechnic Lecturer Group B Exam 2015 16 2015
- Bacteria
- Fungus
- Algae
- Lichens
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Answer: B. Fungus
Fungi have been a rich source of antibiotics. Penicillium mold secretes penicillin, which inhibits the growth of bacteria, making it a potent antibacterial agent.
Common Pathogenic Fungi and their Characteristics
Which of the following statements are correct regarding Mucormycosis? 1. It is an invasive systemic, immune- metabolic infection. 2. This is a very common human infection also earlier called zygomycosis. 3. Mucormycosis is caused by multiple different fungal species including Mucor, Rhizopus and Rhizomucor. 4. All humans are exposed to their spores on almost daily basis.
Asked in: GPSC Prelims CSP 2 2022
- 1 and 2 only
- 1, 3 and 4 only
- 1 and 3 only
- 2, 3 and 4 only
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Answer: B. 1, 3 and 4 only
Mucormycosis is an invasive fungal infection (1) caused by various fungi in the order Mucorales, including Mucor, Rhizopus, and Rhizomucor (3). The spores of these fungi are ubiquitous in the environment, and most humans are exposed daily without consequence (4). It is an uncommon infection that primarily affects individuals with weakened immune systems or certain underlying conditions like uncontrolled diabetes (hence not a 'very common human infection' as stated in 2).
Consider the following statements about Yeast: 1. 2. Yeast can make pseudomycelium. 3. Yeast reproduces asexually by budding. 4. Yeast is a facultative anaerobe. 5. All yeasts are dimorphic. 6. All yeasts are pathogenic. Which of the above statements are correct?
Asked in: HAS Prelims 2021
- 1, 2, 3, 4
- 1, 2, 3, 6
- 3, 4, 5, 6
- 2, 3, 4, 5
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Answer: A. 1, 2, 3, 4
Based on known biological facts about yeast: Statement 2: Yeast can form pseudomycelium (pseudohyphae), especially under stress conditions. True. Statement 3: Yeast commonly reproduces asexually by budding. True. Statement 4: Yeast is a facultative anaerobe, capable of both aerobic respiration and anaerobic fermentation. True.
46 Consider the following statements about Yeast : 1. Yeast are fungi. 2. Yeast can form pseudomycelium. 3. Yeast reproduce asexually by budding. 4. Yeasts are facultative anaerobes. 5. All Yeasts are dimorphic. 6. All Yeasts are pathogenic. Which of the above are correct ?
Asked in: HAS Prelims 2021
- 1, 2, 3, 4
- 1, 2, 3, 6
- 3, 4, 5, 6
- 2, 3, 4, 5
Show answer
Answer: A. 1, 2, 3, 4
- Statement 1: Yeast are fungi. Correct. Yeast are single-celled eukaryotic microorganisms belonging to the Kingdom Fungi. - Statement 2: Yeast can form pseudomycelium. Correct. Under certain conditions, particularly in environments with limited nutrients or high sugar concentration, some yeasts (like Candida) form pseudohyphae or pseudomycelium, which are elongated budding cells that fail to detach. - Statement 3: Yeast reproduce asexually by budding. Correct. Budding is the most common mode of asexual reproduction in yeasts, where a small outgrowth (bud) forms on the parent cell, matures, and then detaches. - Statement 4: Yeasts are facultative anaerobes. Correct. Yeasts can live in the presence of oxygen (aerobic respiration) or in the absence of oxygen (anaerobic fermentation, producing ethanol and carbon dioxide). This makes them facultative anaerobes. - Statement 5: All Yeasts are dimorphic. Incorrect. Dimorphism in fungi refers to the ability to grow as yeast (single cells) or as filamentous hyphae/pseudohyphae. While some yeasts are dimorphic (e.g., Candida albicans), many common yeasts are not. - Statement 6: All Yeasts are pathogenic. Incorrect. The vast majority of yeast species are not pathogenic. Many are beneficial (e.g., Saccharomyces cerevisiae used in baking and brewing), and some are part of the normal human microbiota. Only a small number are opportunistic pathogens.
An endobiotic fungus is
Asked in: WBCS Main Paper 4 2022
- Agaricus
- Morchella
- Synchytrium
- Polyporus
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Answer: C. Synchytrium
Chytrids are a group of simple fungi, many of which are aquatic or live as parasites inside other organisms. Synchytrium endobioticum is known for causing potato wart disease.
“Clamp connection” is found in which genera of plant pathogen ?
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- Pythium
- Phytophthora
- Erysiphe
- Ustilago
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Answer: B. Phytophthora
Clamp connections are characteristic features found in the hyphae of Phytophthora, an oomycete plant pathogen.
In which of the following fungi zoospore are formed inside vesicles ?
Asked in: Agri. Officer 2020
- Pythium
- Phytophthora
- Alternaria
- Albugo
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Answer: A. Pythium
Pythium is known for its characteristic zoospore formation. While Phytophthora also produces zoospores, the formation of zoospores within vesicles is more pronounced and a typical feature of Pythium. Alternaria produces conidia, not zoospores. Albugo produces sporangia that release zoospores, but the characteristic vesicular formation is more typical of Pythium.
Chinese Caterpillar Fungus (also known as Himalayan Viagra) has been included in the Red List of 'International Union for Conservation of Nature'. What is its scientific name?
Asked in: acf 2019
- Ophiocordyceps sinensis
- Agrocybe molesta
- Xylaria longipes
- Cortinarius traganus
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Answer: A. Ophiocordyceps sinensis
Ophiocordyceps sinensis is the scientific name for the Chinese Caterpillar Fungus.
Lichens are formed due to the symbiotic association of A) moss and fungi B) bacteria and fungi C) algae and fungi D) None of these
Asked in: ASSISTANT AUDIT OFFICER 2017 18 2017
- moss and fungi
- bacteria and fungi
- algae and fungi
- None of these
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Answer: C. algae and fungi
Lichens are a classic example of symbiosis, where algae provide food through photosynthesis, and fungi provide structure, protection, and absorb water and minerals.
Which fungus grows on a bread?
Asked in: Assistant Engineer (AE) Exam 2013
- Aspergillus
- Rhizopus
- Yeast
- Synchyrium
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Answer: B. Rhizopus
Rhizopus is a genus of saprophytic fungi that are common decomposers. They are characterized by their fuzzy appearance and the formation of dark sporangiospores.
The reaction involved in baking bread and brewing alcohol is facilitated by :
Asked in: lower devision clerk 2025
- Bacteria
- Yeast
- Mold
- Virus
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Answer: B. Yeast
Yeast performs alcoholic fermentation, converting sugars into ethanol and carbon dioxide, which is the basis for baking bread and brewing alcohol.
The method of reproduction in Rhizopus (a fungus) is :
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- Binary fission
- Budding
- Fragmentation
- Spore formation
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Answer: D. Spore formation
Rhizopus, a common fungus, reproduces asexually primarily through spore formation.
Mode of nutrition in fungi:
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- Autotrophic
- Parasitic
- Saprophytic
- Chemosynthetic
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Answer: C. Saprophytic
Fungi are heterotrophic organisms. Saprophytic mode of nutrition is characterized by absorbing nutrients from dead and decaying organic matter.
Mucormycosis disease is caused by the :
Asked in: Forest Range Officer Exam 2021
- Fungus
- Bacterium
- Virus
- Protozoan
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Answer: A. Fungus
Mucormycosis is a fungal infection. It is also known as 'black fungus'. It primarily affects immunocompromised individuals.
Environmental Factors Influencing Fungal Disease Epidemiology
Fungus growth on organic object taken place in the presence of - - (A) High humidity - (B) High temperature above 60°C - (C) Moderate temperature (30°C - 40°C) - (D) Stagnant air Code -
Asked in: Department Recruitment 2024 (Chemist) 2024
- (1) A, C & D
- (2) A, B
- (3) A, C
- (4) B, D
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Answer: A. (1) A, C & D
Fungal growth, which leads to the deterioration of organic objects, thrives in environments with high humidity, moderate temperatures (optimal growth is typically between 20°C and 30°C, but it can occur at slightly higher ranges like 30-40°C), and stagnant air, which helps to maintain moisture levels. High temperatures above 60°C generally inhibit fungal growth.
Fungal Diseases in Plants: Economic Importance and Management Strategies (e.g., Rusts, Smuts, Blights)
Two common gungal diseases of wheat are:
Asked in: RPSC RAS Prelims 1996
- Black rust and smut
- White rust and smut
- Smut and leaf curl
- Black rust and white rust
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Answer: A. Black rust and smut
Black rust and smut are prevalent fungal diseases affecting wheat.
Captafol is a/an
Asked in: Food Safety Officer 2019
- Algaecide
- Fungicide
- Protein
- Food colour
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Answer: B. Fungicide
Captafol is classified as a fungicide.
Karnal bunt disease of wheat gives foul smell in the field due to presence of volatile compound
Asked in: Food Safety Officer 2022
- Tetramethyl amine
- Trimethyl amine
- Diallyl propyl sulphide
- Allyl propyl disulphide
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Answer: B. Trimethyl amine
The foul smell associated with Karnal bunt disease of wheat is caused by the volatile compound trimethyl amine.
The Black rust disease of wheat is caused by
Asked in: Assistant Prosecuting Officer (APO) Exam 2009
- Puccinia graminis
- Xanthomonas graminis
- Puccinia recondita
- None of the above
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Answer: A. Puccinia graminis
This question pertains to plant pathology and identifies the causative agent of a specific disease affecting a major crop.
Kamal Bunt is a disease of
Asked in: RO ARO pre 2016
- Barley crop
- Wheat crop
- Bajra crop
- Jowar crop
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Answer: B. Wheat crop
Kamal Bunt is a disease specific to wheat.
Key Human Fungal Diseases: Candidiasis, Aspergillosis, Cryptococcosis, Dermatophytosis
"Athlete's foot" is a skin disease caused by
Asked in: UPSC Geoscientist 2023
- virus
- fungus
- alga
- bacterium
Show answer
Answer: B. fungus
- Athlete's foot is a skin infection. - Caused by a type of fungus. - Medically known as tinea pedis. - Fungi that cause it are called dermatophytes.
“Athlete’s Foot” is a disease caused by
Asked in: UPPCS Prelims 2001
- Bacteria
- Fungus
- Protozoan
- Nematode
Show answer
Answer: B. Fungus
- Athlete's foot is a dermatophyte infection. - Dermatophytes are parasitic fungi that infect skin, hair, and nails. - Common causative fungi include species of Trichophyton, Epidermophyton, and Microsporum.
Athlete's foot is a dangerous disease caused by: A) Fungus B) Mosquito bite C) Virus D) Vitamin deficiency
Asked in: ASSISTANT AUDIT OFFICER 2017 18 2017
- Fungus
- Mosquito bite
- Virus
- Vitamin deficiency
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Answer: A. Fungus
Athlete's foot is a fungal infection.
'Athelete's foot' is a disease caused by -
Asked in: Civil Judge 2018
- Bacteria
- Fungi
- Protozoa
- Nematode
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Answer: B. Fungi
Athlete's foot is a fungal infection.
Mycotoxins: Aflatoxins, Ergotism, and their Public Health Impact
Aflatoxins are produced by which of the following ?
Asked in: PPSC CS Prelims 2013
- Bacterium
- Fungus
- Algae
- Virus
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Answer: B. Fungus
Aflatoxins are potent toxins produced by certain species of the fungi Aspergillus, particularly Aspergillus flavus and Aspergillus parasiticus. These fungi are commonly found in soil, decaying vegetation, hay, and grains. They can contaminate food crops like corn, peanuts, cottonseed, and tree nuts, especially under warm and humid conditions.
Improper handling and storage of cereal grains and oilseeds result in the production of toxins known as aflatoxins which are not generally destroyed by normal cooking process. Aflatoxins are produced by
Asked in: UPSC IAS 2013
- bacteria
- protozoa
- moulds
- viruses
Show answer
Answer: C. moulds
Aflatoxins are naturally occurring mycotoxins that are produced by certain molds, specifically species of Aspergillus, most notably Aspergillus flavus and Aspergillus parasiticus. These molds grow on various food crops, such as maize, peanuts, cottonseed, and tree nuts, often under conditions of high humidity and temperature and improper storage. Aflatoxins are highly toxic and carcinogenic, and are not typically destroyed by normal cooking temperatures.
Ergotism is due to consumption of
Asked in: UPPCS Prelims 1998
- contaminated grains
- rotting vegetables
- contaminated water
- stale cooked food
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Answer: A. contaminated grains