Lesson 23

Question 1

What is the study of fungi called?

Answer 1

Mycology.

Question 2

What type of organisms are fungi?

Answer 2

Eukaryotes.

Question 3

Are fungi unicellular or multicellular?

Answer 3

They can be either unicellular (e.g., yeasts) or multicellular (e.g., mushrooms, molds).

Question 4

How do fungi obtain nutrients?

Answer 4

They are heterotrophs; they absorb nutrients from the environment by secreting enzymes to break down complex molecules.

Question 5

What are the three main nutritional roles of fungi?

Answer 5

Decomposers, parasites, and mutualists.

Question 6

What are the filamentous structures of multicellular fungi called?

Answer 6

Hyphae (singular: hypha).

Question 7

What is a mass of hyphae called?

Answer 7

Mycelium (plural: mycelia).

Question 8

What are the cross-walls that divide hyphal cells called?

Answer 8

Septum (plural: septa).

Question 9

What is a key structural component of most fungal cell walls?

Answer 9

Chitin (a polymer of N-acetylglucosamine).

Question 10

What are asexual spores produced by molds called?

Answer 10

Conidia.

Question 11

What is the term for a fungal mycelium containing two or more genetically different haploid nuclei?

Answer 11

Heterokaryon.

Question 12

What is the union of cytoplasm from two parent mycelia called?

Answer 12

Plasmogamy.

Question 13

What is the fusion of haploid nuclei after plasmogamy called?

Answer 13

Karyogamy.

Question 14

What are spores produced via meiosis called?

Answer 14

Sexual spores.

Question 15

How do yeasts typically reproduce asexually?

Answer 15

By budding, where a small bud cell pinches off from the parent cell.

Question 16

Which fungal phylum includes members with motile zoospores?

Answer 16

Chytridiomycota.

Question 17

What disease is caused by Batrachochytrium, and what does it affect?

Answer 17

Chytridiomycosis, which affects amphibians and is linked to massive die-offs.

Question 18

Which phylum is known as ‘conjugation fungi’ and includes species like Rhizopus?

Answer 18

Zygomycota.

Question 19

What kind of symbiotic relationship do Glomeromycota form with plants?

Answer 19

Mycorrhizal relationships (specifically endomycorrhizal).

Question 20

What does ‘mycorrhizal’ mean?

Answer 20

‘Myco’ = fungus, ‘rhiza’ = root; a symbiotic association between fungi and plant roots.

Question 21

Which phylum includes mushrooms and toadstools?

Answer 21

Basidiomycota.

Question 22

What is the characteristic reproductive structure of Basidiomycota?

Answer 22

The basidium, a club-shaped structure that produces basidiospores.

Question 23

Which is the largest phylum of fungi?

Answer 23

Ascomycota (about 75% of known fungi).

Question 24

Name three important genera in Ascomycota.

Answer 24

Saccharomyces (yeast), Candida (pathogen), Aspergillus (mold).

Question 25

What is the common term for fungal infections?

Answer 25

Mycoses (singular: mycosis).

Question 26

What are the three main mechanisms by which fungi cause disease in humans?

Answer 26

1. Inappropriate immune/allergic response, 2. Mycotoxin production, 3. Mycosis (infection).

Question 27

What are mycotoxins?

Answer 27

Toxic secondary metabolites produced by fungi, e.g., aflatoxins from Aspergillus flavus.

Question 28

What are the three categories of mycoses based on tissue invasion?

Answer 28

Superficial, subcutaneous, and systemic.

Question 29

Give an example of a superficial mycosis.

Answer 29

Athlete's foot, ringworm, or thrush (caused by Trichophyton or Candida).

Question 30

What is sporotrichosis, and how is it acquired?

Answer 30

'Rose-gardener's disease'; a subcutaneous infection acquired through skin punctures from contaminated soil or plants.

Question 31

What are systemic mycoses, and who is most at risk?

Answer 31

Deep infections affecting internal organs; risk is highest in immunocompromised, elderly, or those with underlying conditions.

Question 32

Name four fungi that can cause systemic mycoses.

Answer 32

Histoplasma capsulatum, Cryptococcus neoformans, Candida albicans, Aspergillus fumigatus.

Question 33

What is the difference between fungicidal and fungistatic drugs?

Answer 33

Fungicidal drugs kill fungal cells; fungistatic drugs inhibit their growth and reproduction.

Question 34

Why are antibiotics ineffective against fungi?

Answer 34

Because fungi are eukaryotes with different cellular structures and processes than bacteria (prokaryotes).

Question 35

Name three common antifungal medicines.

Answer 35

Clotrimazole, fluconazole, amphotericin B.

Question 36

How do fungi cause disease in plants?

Answer 36

They act as pathogens, obtaining nutrients from plant tissues and causing diseases like powdery mildew.

Question 37

What is an example of host-specific fungal plant pathogen?

Answer 37

Blumeria graminis f. sp. hordei causes powdery mildew on barley but not wheat.

Question 38

Name three biotechnological uses of fungi.

Answer 38

Food production (bread, beer, cheese), antibiotic production (penicillin), and industrial chemical synthesis.

Question 39

Which fungus is used to produce penicillin?

Answer 39

Penicillium chrysogenum (formerly Penicillium notatum).

Question 40

Which yeast is commonly used in baking and brewing?

Answer 40

Saccharomyces cerevisiae.

Question 41

What is a key evolutionary advantage of sexual reproduction in fungi?

Answer 41

It introduces genetic variation through meiosis and recombination.

Question 42

What is a fruiting body?

Answer 42

A macroscopic reproductive structure (e.g., mushroom) that produces and disperses spores.

Question 43

What are the dusty, pigmented structures on molds that are asexual spores?

Answer 43

Conidia.

Question 44

What is the term for fungi that can live both as yeasts and as filamentous forms?

Answer 44

Dimorphic fungi.

Question 45

Which fungal phylum forms arbuscular mycorrhizae?

Answer 45

Glomeromycota.

Question 46

What major role do decomposer fungi play in ecosystems?

Answer 46

They break down dead organic matter, recycling nutrients.

Question 47

Which fungal infection is a common component of normal human flora but can become pathogenic?

Answer 47

Candida albicans (causes thrush and systemic candidiasis).

Question 48

Which fungus produces aflatoxins, and what is their danger?

Answer 48

Aspergillus flavus; aflatoxins are highly toxic and carcinogenic, causing liver damage and cancer.

Question 49

What is a common antifungal drug target in fungal cells?

Answer 49

The cell wall (e.g., chitin synthesis inhibitors) or cell membrane (e.g., ergosterol disruptors like azoles).

Question 50

What is the main storage carbohydrate in fungi?

Answer 50

Glycogen.

Question 51

What is the ecological significance of mycorrhizal fungi?

Answer 51

They enhance plant nutrient and water uptake, and plants supply the fungi with organic compounds.

Question 52

What does 'heterothallic' mean in fungal reproduction?

Answer 52

Requiring two different, compatible mating types for sexual reproduction.

Question 53

What is the function of pheromones in fungal sexual reproduction?

Answer 53

They act as signaling molecules to attract compatible mating hyphae.

Question 54

Which fungal disease is known as 'rose-gardener's disease' and why?

Answer 54

Sporotrichosis, because it often infects gardeners through prick wounds from roses or soil.

Question 55

What is chromoblastomycosis?

Answer 55

A chronic subcutaneous mycosis causing crusty, wart-like lesions, typically in tropical regions.

Question 56

What is histoplasmosis, and where is it commonly found?

Answer 56

A systemic mycosis caused by Histoplasma capsulatum, often associated with bird or bat droppings.

Question 57

How are fungal spores typically dispersed in the environment?

Answer 57

By wind, water, or animals.

Question 58

What is a key structural difference between fungal and plant cell walls?

Answer 58

Fungal walls contain chitin, while plant walls contain cellulose.

Question 59

What is the term for the rapid, asexual growth of molds producing many spores?

Answer 59

Mold growth; they are often called 'molds' when they produce visible mycelia and conidia.

Question 60

What are ergots, and what medicinal use do they have?

Answer 60

Hard structures produced by Claviceps fungi on rye; ergot alkaloids are used to treat migraines and postpartum bleeding.

Question 61

What is the significance of genetically modified yeast in biotechnology?

Answer 61

It can be engineered to produce pharmaceuticals, biofuels, and other industrial chemicals.

Question 62

What is a major global threat to amphibians caused by a fungus?

Answer 62

Chytridiomycosis caused by Batrachochytrium dendrobatidis.

Question 63

What is the term for fungi that live on the surface of a host without causing disease?

Answer 63

Commensals (part of normal microbiota).

Question 64

What is a common allergic response to fungal exposure?

Answer 64

Asthma or hypersensitivity reactions to fungal allergens (e.g., from Aspergillus).

Question 65

What does 'opportunistic pathogen' mean in mycology?

Answer 65

A fungus that normally does not cause disease but can infect individuals with weakened immune systems.

Question 66

How are subcutaneous mycoses typically treated?

Answer 66

With oral antifungal drugs such as azoles (e.g., itraconazole).

Question 67

What is a key feature of Zygomycota reproduction?

Answer 67

They produce resistant zygospores through sexual conjugation.

Question 68

What is a basidiocarp?

Answer 68

The fruiting body of Basidiomycota (e.g., a mushroom).

Question 69

What is the main role of conidia in fungal life cycles?

Answer 69

Asexual dispersal to new habitats.

Question 70

What is a common method for identifying fungi in the laboratory?

Answer 70

Microscopic examination of spores and hyphal structures, and culture characteristics.

Question 71

What is the economic impact of plant-pathogenic fungi?

Answer 71

They cause significant crop losses, affecting food security and agriculture.