Chapter 31 - Fungi

Question 1

Fungi that are decomposers -

Answer 1

break down and absorb nutrients from nonliving organic material, such as fallen logs, animal corpses, and the wastes of organisms

Question 2

Parasitic fungi -

Answer 2

absorb nutrients from the cells of living hosts. Some are pathogenic, including many species that cause diseases in plants and others that cause diseases in animals

Question 3

Mutualistic fungi -

Answer 3

absorb nutrients from a host, but they reciprocate with actions that benefit the host. For example, those that live within the digestive tracts of certain termite species use their enzymes to break down wood

Question 4

Yeasts -

Answer 4

multicellular filaments and single cells that often inhabit moist environments, including plant sap and animal tissues, where there is a ready supply of soluble nutrients, such as sugars and amino acids.

Question 5

Hyphae -

Answer 5

a network of tiny filaments consisting of tubular cell walls surrounding the plasma membrane and cytoplasm of the cells

Question 6

Chitin -

Answer 6

a strong but flexible polysaccharide. Chitin-rich walls can enhance feeding by absorption and strength

Question 7

Septa -

Answer 7

hyphae are divided into cells by cross-walls which generally have pores large enough to allow ribosomes, mitochondria, and even nuclei to flow from cell to cell

Question 8

Coenocytic fungi -

Answer 8

fungi that lack septa and consist of a continuous cytoplasmic mass having hundreds or thousands of nuclei resulting from the repeated division of nuclei without cytokinesis

Question 9

Mycelium -

Answer 9

fungal hyphae form an interwoven mass that infiltrates the material on which the fungus feeds maximizing its surface-to-volume ratio, making feeding very efficient

Question 10

Haustoria -

Answer 10

modified hyphae that enable them to extract nutrients from plants.

Question 11

Arbuscules -

Answer 11

specialized branching hyphae which fungi exchange nutrients with their plant hosts

Question 12

Mycorrhizae -

Answer 12

mutually beneficial relationships between fungi and plant roots

Question 13

Ectomycorrhizal fungi -

Answer 13

form sheaths of hyphae over the surface of a root and typically grow into the extracellular spaces of the root cortex.

Question 14

Arbuscular mycorrhizal -

Answer 14

fungi extend arbuscules through the root cell wall and into tubes formed by invagination (pushing inward) of the root cell plasma membrane.

Question 15

Pheromones -

Answer 15

signaling molecules that often start sexual reproduction when the hyphae from two mycelia release

Question 16

Plasmogamy -

Answer 16

the union of the cytoplasms of two parent mycelia

Question 17

Heterokaryon -

Answer 17

a mycelium where parts of the fused mycelium contain coexisting, genetically different nuclei

Question 18

Dikaryotic -

Answer 18

some species where the haploid nuclei pair off, two to a cell, one from each parent. As the mycelium grows, the two nuclei in each cell divide in tandem without fusing

Question 19

Karyogamy -

Answer 19

the next stage in the sexual cycle during which the haploid nuclei contributed by the two parents fuse, producing diploid cells

Question 20

“Sexual spores” -

Answer 20

the genetically diverse spores produced when meiosis restores the haploid condition

Question 21

Molds (filamentous fungi) -

Answer 21

fungi that reproduce asexually by growing as filamentous fungi that produce (haploid) spores by mitosis and often form visible mycelia

Question 22

Yeasts -

Answer 22

fungi that reproduce asexually by growing single-celled and instead of producing spores, asexual reproduction occurs by ordinary cell division or by the pinching of small “bud cells” off a parent cell

Question 23

Deuteromycetes -

Answer 23

group of all fungi lacking sexual reproduction

Question 24

Opisthokonts -

Answer 24

clade that includes fungi with flagellum

Question 25

Nucleariids -

Answer 25

group of unicellular protists consisting of amoebas that feed on algae and bacteria

Question 26

Cryptomycetes -

Answer 26

found in both marine and freshwater communities, aerobic and anaerobic environments, are unicellular, and have flagellated spores. and also can synthesize a chitin-rich cell wall

Question 27

Microsporidians -

Answer 27

1,300 species of microsporidians are unicellular parasites of protists and animals, can synthesize a chitin-rich cell wall, have highly reduced mitochondria and small genomes, lack flagellated spores; instead, they produce unique spores that infect host cells via a harpoon-like organelle

Question 28

Chytrids -

Answer 28

ubiquitous in lakes and soil, have cell walls made of chitin, also share certain key enzymes and metabolic pathways with other fungal groups. Some form colonies with hyphae, while others exist as single spherical cells

Question 29

Zoospores -

Answer 29

flagellated spores

Question 30

Zoopagomycetes -

Answer 30

fungi in the phylum Zoopagomycota, live as parasites or as commensal (neutral) symbionts of animals; some are parasites of other fungi or protists. Zoopagomycetes form filamentous hyphae and reproduce asexually by producing nonflagellated spores

Question 31

Mucoromycetes -

Answer 31

fungi in the phylum Mucoromycota, includes species of fast-growing molds responsible for causing foods such as bread, peaches, strawberries, and sweet potatoes to rot during storage. Although some mucoromycetes are decomposers, most are associated with plants. Many mucoromycetes live as parasites or pathogens of plants, while others live as mutualists

Question 32

A zygosporangium -

Answer 32

represents the zygote (2n) stage in the life cycle, it is not a zygote in the usual sense, it is a multinucleate structure, first heterokaryotic with many haploid nuclei from the two parents, then with many diploid nuclei after karyogamy.

Question 33

Ascomycetes -

Answer 33

species that produce spores in saclike asci and are commonly called sac fungi. During their sexual stage, most ascomycetes develop fruiting bodies, called ascocarps, which range in size from microscopic to macroscopic

Question 34

Ascocarps -

Answer 34

fruiting bodies that contain the spore-forming asci.

Question 35

Basidiomycetes -

Answer 35

the phylum includes mutualists that form mycorrhizae and two groups of destructive plant parasites: rusts and smuts. The name of the phylum derives from the basidium (plural, basidia; Latin for “little pedestals”), a cell in which karyogamy occurs, followed immediately by meiosis. The club-like shape of the basidium also gives rise to the common name club fungus

Question 36

Basidiocarps -

Answer 36

Basidiomycetes periodically, in response to environmental stimuli, the mycelium reproduces sexually by producing elaborate fruiting bodies

Question 36

Endophytes -

Answer 36

symbiotic fungi (or bacteria) that live inside leaves or other plant parts without causing harm

Question 37

A lichen -

Answer 37

a symbiotic association between a photosynthetic microorganism and a fungus in which millions of photosynthetic cells are held in a mass of fungal hyphae

Question 38

Soredia -

Answer 38

small clusters of hyphae with embedded algae