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Absorption
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Fungi are heterotrophs that acquire their nutrients by ----.
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Absorption
Fungi are heterotrophs that acquire their nutrients by ----.
Exoenzymes
---- decompose complex molecules to the simpler compounds that the fungus can absorb and use.
Saprobic
---- fungi absorb nutrients from nonliving organic material, such as fallen logs, animal corpses, or the wastes of live organisms.
Parasitic
---- fungi absorb nutrients from the cells of living hosts.
Pathogenic
---- fungi cause about %80 of plant diseases.
Mutualistic
---- fungi absorb nutrients from a host organism, but they reciprocate with functions beneficial to their partners in some way, such as aiding a plant in the uptake of minerals from the soil.
Vegetative
The ---- (nutritonally active) bodies of most fungi are usually hidden, being diffusely organized around and within the tissues of their food sources.
Yeasts, hyphae
Except for ----, which are unicellular, the bodies of fungi are constructed of tiny filaments called ----.
Hyphae, mycelium
---- are composed of tubular walls surrounding plasma membranes and cytoplasm. They form an interwove mat called a ----, the 'feeding' network of a fungus.
Septa
Most fungi are multicellular with hyphae divided into cells by cross-walls, or ----.
Chitin
Most fungi build their cell walls mainly of ----.
Aseptate, coenocytic
Some fungi are ---, that is, their hyphae are not divided into cells by cross-walls. Known as ---- fungi, they consist of a continuous cytoplasmic mass with hundreds or thousands of nuclei.
Haustoria
Parasitic fungi usually have some of their hyphae modified as ----, nutrient-absorbing hyphal tips that penetrate the tissues of the host.
Filamentous
The ---- structure of the mycelium provides an extensive surface area that suits the absorptive nutrition of fungi.
Haploid, Diploid
The nuclei of fungal hyphae and spores of species are ----, except for transient ---- stages that form during sexual life cycles.
Heterogenous, heterokaryon
Some mycelia may become genetically ---- through the fusion of two hyphae that have genetically different nuclei. Such a mycelium is said to be a ----, meaning 'different nuclei.'
Nuclei, heterokaryon
In some heterokaryons, the different nuclei stay in separate parts of the same mycelium, which is then a mosaic in terms of genotype and phenotype. In other cases, the different ---- mingle and may even exchange chromosomes and genes in a process similar to crossing over. This ---- condition has some of the advantages of diploidy; one haploid genome may be able to compensate for harmful mutations in the other nucleus, and vice versa.
Plasmogamy, karyogamy
In many fungi with sexual life cycles, the union of partners occurs in two distinct stages called ---- and ----.
Plasmogamy
---- is the fusion of the two parent's cytoplasm when their mycelia come together.
Karyogamy
---- is the fusion of the haploid nuclei contributed by the two parents.
Haploid
Plasmogamy and karyogamy may be separated in time by hours or even centuries. During the interim, the hybrid mycelium exists as a heterokaryon, its ---- nuclei still separate.
Dikaryotic, karyogamy
In some fungi, the haploid nuclei pair off, two to a cell, one from each parent. Such a mycelium, a special case of heterokaryon, is said to be ----, meaning 'two nuclei.' Without fusing, the two nuclei in each cell divide in tandem as the mycelium grows, until ---- finally occurs.
Zygotes, meiosis
In most fungi, the ---- or transient structures formed by karyogamy are the only diploid stages in the life cycle. ---- restores the haploid condition before specialized reproductive structures of the mycelium produce and disperse spores.
Chytrids, zoospores
The ---- are mainly aquatic. They form uniflagellated spores called ----. The parasitic ones may be contributing to a worldwide decline in the number of amphibians.
Coenocytic
Most chytrids form ---- hyphae, although some are unicellular. They are often considered the most primitive fungi.
Zygote, decaying
---- fungi form resistant structures during sexual reproduction. These fungi are mostly terrestrial and live in soil or on ---- plant and animal material.
Mycorrhizae
One Zygomycota group of major importance forms ----, mutualistic associations with the roots of plants.
Reproductive
Zygomycete hyphae are coenocytic, with septa found only where ---- cells are formed.
zygomycete, hyphae
A common ---- is black bread mold, Rhizopus stolonifer. Horizontal ---- spread out of over the food, penetrate it, and absorb nutrients.
Zygosporangium, meiosis
Plasmogamy (in black bread mold) produces a resistant structure called a -----, in which karyogamy and then ---- occur.
Multinucleate, heterokaryotic
A zygosporangium, while representing the zygote (2n) stage in the life cycle, is not a zygote in the usual sense of a cell with one diploid nucleus. Rather, the zygosporangium is a ---- structure, first ---- with many nuclei from the two parents, then with many diploid nuclei after karyogamy.
Zygosporangia
The ----, for which zygomycetes are named, are resistant to freezing and drying and are metabolically inactive. When conditions improve, the zygosporangia release genetically diverse haploid spores that colonize the new substrate.
Spores
Some zygomycetes, such as Pilobolus, can actually aim their ----.
Hyphal extensions, gametangia
(Bread Mold Life Cycle) 1. Neighboring mycelia of opposite mating types form ---- ---- called ----, each walled off around several haploid nuclei by a septum.
plasmogamy, zygosporangium
(Bread Mold Life Cycle) 2. The gametangia undergo ---- (fusion of cytoplasm), forming a heterokaryotic ---- containing multiple haploid nuclei from the two parents.
Karyogamy, meiosis
(Bread Mold Life Cycle) 3. This cell develops a rough, thick-walled coating that can resist dry conditions and other harsh environments for months. When conditions are favorable again ---- occurs. Paired nuclei fuse, followed by ----.
sporangium, haploid
(Bread Mold Life Cycle) 4. The zygosporangium then breaks dormancy, germinating into a short ---- that disperse genetically diverse, ---- spores.
mycelia, asexually
(Bread Mold Life Cycle) 5. These spores germinate and grow into new ----. Mycelia of Rhizopus can also reproduce ---- by forming sporangia that produce genetically identical haploid spores.
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