1. Hyphae are slender filaments. A mass of hyphae is a mycelium. As it applies to fungi, a septum is a cross wall that may divide the hyphae into cells. The septum is complete when it separates the reproductive structures from the rest of the mycelium. Incomplete septa permit the movement of reproductive materials between cells.
2. The fungal wall is composed of polysaccharide and chitin, which is an advantage because it renders the wall more resistant to degradation bacteria.
3. The fungal nuclei that are diploid are those of the zygote. All the rest are haploid. The event that occurs during sexual reproduction is that the hyphae of two genetically different mating types fuse. This affects the other nuclei because the nuclei do not fuse but coexist as separate entities. Heterokaryotic and dikaryotic hyphae contain two genetically distinct types of nuclei; homokaryotic and monokaryotic hyphae contain nuclei that are all genetically similar.
4. The three reproductive structures are sporangia, which form spores; gametangia, in which gametes form; and conidia, mostly multinucleate asexual spores not produced in sporangia.
5. Most fungi produce spores, often in prodigious amounts. These spores are typically "flung" some distance by the fungus or picked up and dispersed by the wind.
6. The three phyla of the kingdom Fungi are Zygomycota, Ascomycota, and Basidiomycota. They are differentiated by their sexual reproductive structures. Zygomycota are different because they have fusion of hyphae, which leads to zygote formation, and meiosis occurs only on spore germination. The Ascomycota and Basidiomycota have extensive dikaryotic hyphae where nuclear fusion does not take place except in structures that immediately undergo meiosis, and they produce haploid spores.
7. The Zygomycota are different from the Ascomycota and Basidiomycota in that they produce dormant structures called zygospores. The zygospore is a component of sexual reproduction. Asexual reproduction is more common, and occurs through the production of haploid spores in sporangia which are later shed and distributed by wind. Nonreproductive hyphae do not have septa.
8. These asexual spores are called conidia and are multinucleate. They are carried by conidiophores, and the nonreproductive hyphae of this division are incompletely septate.
9. Ascogonia and antheridia are female and male gametangia. The trichogyne grows from the ascogonia; its function is to allow migration of nuclei from the antheridium to the ascogonium. The hyphae that arise are heterokaryotic with paired nuclei.
10. The yeasts belong mostly to the Ascomycota; they differ from other fungi because they are unicellular. It is more likely that this characteristic is degenerate-derived from multicellular ancestors. The yeasts' primary mode of reproduction is by cell fission or budding. They are becoming more popular in research because they are the first eukaryotes used in genetic engineering and are the E. coli of the eukaryotic world.
11. Primary mycelium in this context is mycelium made up of only monokaryotic hyphae. Secondary mycelia are hyphae containing nuclei of both mating types-dikaryotic mycelium. A basidiocarp is the structure on which basidia are found. The basidiomycetes are generally only dikaryotic and are usually found on the surface of the gills of a common mushroom.
12. The Fungi Imperfecti are those fungi in which sexual reproduction has not been observed; the best represented of this group is the Ascomycota. Individuals in the phylum Deuteromycota are classified by examination of hyphal structure and similarities in asexual reproduction.
13. Lichens are symbiotic associations between a fungus and a green alga and/or cyanobacterium. The best represented of this group is the Ascomycota. These species are not able to grow independently; the fungus directs the photosynthetic component to produce certain special metabolic substances.
14. Mycorrhizae are fungi that live in association with plant roots. Endomycorrhizae hyphae penetrate the outer cells of the plant root, whereas ectomycorrhizae surround but do not penetrate the roots. The most prominent mycorrhizal fungi are the Zygomycota. The plant supplies food to the fungi, while the fungi serve as extensions of root surface area, allowing the roots of the plant to better absorb materials from the soil.