Ch 32: Fungi Flashcards
Fungi
An abundant and diverse group of heterotrophic eukaryotic organisms, principally responsible for the decomposition of plant and animal tissues.
Hyphae
In fungi, highly branched multicellular filaments that provide a large surface area for absorbing nutrients.
Mycelium
A network of branching hyphae.
Chitin
A modified polysaccharide containing nitrogen that makes up the cell walls of fungi and the hard exoskeletons of arthropods.
Septa
In fungal hyphae, a wall that partially divides the cytoplasm into separate cells.
Yeast
A single-celled fungus found in moist, nutrient-rich environments. Many yeasts can metabolize sugar by means of fermentation.
Ectomycorrhizae
One of the two main types of mycorrhizae; ectomycorrhizae produce a thick sheath of fungal cells (hyphae) that surround the root tip, as well as hyphae that grow between, but do not penetrate, cells in the interior of the root.
Endomycorrhizal
One of the two main types of mycorrhizae; endomycorrhizal hyphae penetrate into root cells, where they produce highly branched structures (arbuscules) that provide a large surface area for nutrient exchange.
Endophyte
A fungus that lives within leaves and that may help the host plant by producing chemicals that deter pathogens and herbivores.
Lichen
Stable associations between a fungus and a photosynthetic microorganism, usually a green alga but sometimes a cyanobacterium.
Fruiting Body
A multicellular structure in some fungi that facilitates the dispersal of sexually produced spores.
Plasmogamy
The cytoplasmic union of two cells.
Karyogamy
The fusion of two nuclei following plasmogamy.
Heterokaryotic
Describes a stage in the life cycle of some fungi, in which plasmogamy is not followed immediately by karyogamy and the cells have unfused haploid nuclei from both parents.
Dikaryotic
Having two haploid nuclei, one from each parent, in each cell.
Mating types
Genetically distinct forms of individuals of a fungus species that, by enabling fertilization only between different types, prevent self-fertilization and promote out-crossing.
Parasexual
Describes asexual species that generate genetic diversity by the crossing over of DNA during mitosis.
Chytrid
Primarily aquatic fungi that have simple, often unicellular bodies and that produce flagellated gametes and spores.
Zygomycota
Fungi that produce hyphae undivided by septa and do not form multicellular fruiting bodies; they make up less than 1% of known fungal diversity.
Glomeromycota
A monophyletic fungal group of apparently low diversity but tremendous ecological importance that occurs in association with plant roots.
Dikarya
A fungal group that includes about 98% of all described fungal species and in which dikaryotic cells are formed.
Ascomycetes
A monophyletic fungal subgroup of the Dikarya in which nuclear fusion and meiosis take place in an elongated saclike cell called an ascus; also called sac fungi.
Basidiomycetes
A monophyletic fungal subgroup of the Dikarya, including smuts, rusts, and mushrooms, in which nuclear fusion and meiosis take place in a club-shaped cell called a basidium; also called club fungi.
T/F: Fungi are the most important decomposers of wood in the ecosystem.
True
To what group do aquatic fungi with flagellated spores belong?
chytrids
How do endophytes differ from endomycorrhizal fungi?
Endophytes live within leaves, whereas endomycorrhizal fungi live within roots.
In what ways are mycelia and fruiting bodies similar?
Both are composed of hyphae.
T/F: Ascomycete yeasts evolved from multicellular ancestors.
True
T/F: Lichens are symbiotic relationships between a fungus and a plant.
False
In fungi, _____ cells are cells composed of the cytoplasm of two or more cells, but they retain distinct sets of chromosomes contained in separate nuclei.
heterokaryotic
A scientist collects a spore from a new species of fungus and observes that this spore has a flagellum. What does the presence of a flagellum suggest about the lifestyle of this species?
The species is aquatic.
Fungi are most closely related to:
arthropods, which are organisms that also produce chitin.
What is the advantage of a fungal body being composed of numerous thin hyphae instead of one or two very thick hyphae?
A greater surface area is available for absorption of nutrients.
What is the primary advantage of having multiple mating type alleles?
There is an increased probability that two fungi encountering each other will have compatible mating types.
The stage of the fungal life cycle during which two or more genetically distinct nuclei are found in the same cell is referred to as the:
heterokaryotic stage.
Crossing over during mitosis increases genetic diversity during:
parasexuality.
When a fungus encounters a particularly rich food source, what is the expected result?
Hyphae branch and extend rapidly from their tips to form a mycelium.
T/F: One of the greatest advantages of sexual reproduction is the generation of variability.
True
_____ and _____ are structures formed in the fruiting bodies of dikaryotic (n + n) fungi that produce spores.
Basidia; asci
Toadstools are mushrooms with a central stalk and a cap with gills. Which type of fungus are toadstools?
basidiomycetes
How is karyogamy different from plasmogamy?
Karyogamy is the fusion of nuclei, whereas plasmogamy is the fusion of cytoplasm.
Within the fungal body, nutrients are transported from the _____ to the _____ by the process of _____.
mycelium; fruiting body; bulk flow
What is the primary reason that fungi are important in the carbon cycle?
Fungi are able to reach incredibly large sizes. Their high ratio of surface area to volume allows them to decompose large amounts of dead and decaying material, thereby returning carbon to the atmosphere.
How are the spores of zygomycetes such as Rhizopus dispersed?
By the wind
Fungi produce fruiting bodies to:
enhance spore dispersal
In many groups of fungi, karyogamy and plasmogamy are separated in time and space. One potential advantage of this arrangement is that:
mating and spore production can occur in different environments.
