30 Questions
Which of the following is a defining characteristic of fungi?
They have a cell wall made of chitin and polysaccharides
Fungi are heterotrophs, which means they:
Obtain energy by degrading complex organic molecules
How do fungi reproduce?
Sexually and asexually
What is the usual chromosome count in fungi?
Haploid (one set of chromosomes)
What is the main difference between plants and fungi?
Plants are photo-autotrophs, while fungi obtain energy by degrading organic material
What is the term for fungi that derive nutrients from dead remains?
Saprophytes
What is the term for fungi that derive nutrients from organisms they have killed?
Necrophytes
What is the term for fungi that derive nutrients from living hosts?
Biotrophs
What is a key characteristic of fungi in terms of their ecological niche?
They occupy a diverse array of ecological niches
What is the main component of the cell wall in fungi?
Chitin
Which of the following is a characteristic of yeasts?
They form a colony or 'pseudohyphae'
What triggers the transition between yeast and filamentous forms in dimorphic yeasts/fungi?
Temperature
Which of the following is a characteristic of filamentous fungi (molds)?
All of the above
What is the advantage of homothallism in fungi?
Allows self-fertilization
Which division (phylum) of fungi contains the largest number of species?
Ascomycota (Ascomycetes)
Which division (phylum) of fungi includes the model organism Saccharomyces cerevisiae?
Ascomycota (Ascomycetes)
Which division (phylum) of fungi is characterized by septate hyphae?
Basidiomycota (Basidiomycetes)
What is the main mode of reproduction in Deuteromycetes?
Asexual spore formation
Which division (phylum) of fungi includes important plant pathogens like rusts?
Basidiomycota (Basidiomycetes)
What is another name for Deuteromycetes?
Fungi imperfecti
True or false: Fungi are plants.
False
True or false: Fungi have the ability to use a diverse range of carbon sources.
True
True or false: Fungi can fix nitrogen.
False
True or false: Fungi have the ability to derive nutrients from dead remains.
True
True or false: Fungi have the ability to derive nutrients from living hosts.
True
True or false: Fungi and animals are each other's closest relatives.
True
True or false: Yeasts reproduce asexually by producing an identical but separate daughter cell.
True
True or false: Filamentous fungi (molds) reproduce via spores.
True
True or false: Dimorphic yeasts/fungi can transition between yeast and filamentous forms triggered by environmental cues.
True
True or false: Sexual spores in fungi are usually more hardy structures allowing survival in adverse conditions.
True
Study Notes
Defining Characteristics of Fungi
- Eukaryotes with cell walls made of chitin and polysaccharides
- Reproduce sexually and asexually
- Nuclei are usually haploid (one set of chromosomes)
- Heterotrophs, obtaining energy by degrading complex organic molecules
- Contain no chlorophyll and cannot utilize CO2 as a single carbon source
- Cannot fix N2
Types of Fungal Nutrient Acquisition
- Saprophytes: derive nutrients from dead remains
- Necrophytes: derive nutrients from organisms they have killed
- Biotrophs: derive nutrients from living hosts
- Parasites: astonishingly successful heterotrophs
Key Differences between Plants and Fungi
- Plants are photo-autotrophs (photosynthesizers), whereas fungi secrete enzymes and absorb organic material
- Fungi are usually filamentous in form, whereas plants are made up of box-like cells
- Fundamental differences in cell wall composition
- Nuclear mitosis occurs within the nucleus in fungi, unlike other eukaryotes
Classification of Fungi
- Historical perspective: five-kingdom classification (1969) and modern molecular approaches (1990s)
- Fungi and animals are each other's closest relatives
Fungal Growth and Reproduction
- Yeasts (e.g., Saccharomyces cerevisiae): single cell, oval or spherical, reproduces asexually
- Filamentous fungi (molds): multicellular, long thread-like filaments (hyphae), reproduce via spores
- Dimorphic yeasts/fungi: environmental cues trigger transition between yeast and filamentous forms
Reproduction in Fungi
- Asexual: yeasts bud a daughter cell, filamentous fungi generate lightweight spores for effective dispersion
- Sexual: union of compatible nuclei to form diploid state, usually when nutrients are in poor supply
- Heterothallism: requires two different mating types (+, -), homothallism: some fungi self-fertilize and produce sexual spores
Major Divisions of Fungi
- Chytridiomycota (Chytrids): 1000 species
- Zygomycota (Zygomycetes): 1000 species, aseptate hyphae, saprophytes, and mycorrhizal fungi
- Ascomycota (Ascomycetes): 65,000 species, septate hyphae, model organisms, plant pathogens, and food spoilage
- Basidiomycota (Basidiomycetes): 30,000 species, septate hyphae, dikaryons, saprophytes, plant pathogens, and edible mushrooms
- Deuteromycota (Deuteromycetes): fungi imperfecti, asexual spores formed in various ways, includes important food spoilers and industrial workhorses
Test your knowledge on fungi and learn about their unique characteristics and diversity. Explore topics such as unicellular yeasts, humongous fungi, and defining characteristics like eukaryotes and cell wall composition.
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