Chapter 31

an ascomycete

A dramatic example of the pathogenicity of certain fungi is the dramatic decrease of the American chestnut tree by _____. a rust truffles a shelf fungus an ascomycete ergots

heterokaryon

A fungal mycelium that contains two or more haploid nuclei per cell.

coenocytic

A fungus that lacks septa and hence whose body is made up of a continuous cytoplasmic mass that may contain hundreds or thousands of nuclei.

conidium

A haploid spore produced at the tip of a specialized hypha in ascomycetes during asexual reproduction.

endophyte

A harmless fungus, or occasionally another organism, that lives between cells of a plant part or multicellular alga.

blastula

A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals.

nucleariid

A member of a group of unicellular, amoeboid protists that are more closely related to fungi than they are to other protists.

opisthokont

A member of an extremely diverse clade of eukaryotes that includes fungi, animals, and several closely related groups of protists.

ascomycete

A member of the fungal phylum Ascomycota, commonly called sac fungus. The name comes from the saclike structure in which the spores develop.

basidiomycete

A member of the fungal phylum Basidiomycota, commonly called club fungus. The name comes from the club-like shape of the basidium.

chytrid

A member of the fungal phylum Chytridiomycota, mostly aquatic fungi with flagellated zoospores that represent an early-diverging fungal lineage.

glomeromycete

A member of the fungal phylum Glomeromycota, characterized by a distinct branching form of mycorrhizae called arbuscular mycorrhizae.

zygomycete

A member of the fungal phylum Zygomycota, characterized by the formation of a sturdy structure called a zygosporangium during sexual reproduction.

mycorrhiza

A mutualistic association of plant roots and fungus.

ergot

A parasitic fungus that attacks rye plants produces a structure called a(n) ________. ergot mycosis canker lichen smut

basidium

A reproductive appendage that produces sexual spores on the gills of mushrooms (club fungi).

ascus

A saclike spore capsule located at the tip of a dikaryotic hypha of a sac fungus.

chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.

ectomycorrhizal fungus

A symbiotic fungus that forms sheaths of hyphae over the surface of plant roots and also grows into extracellular spaces of the root cortex.

Arbuscular mychorrhizal fungi

A symbiotic fungus whose hyphae grow through the cell wall of plant roots and extend into the root cell (enclosed in tubes formed by invagination of the root cell plasma membrane).

Glomeromycota

Almost all of the members of this phylum form arbuscular mycorrhizae in a mutualistic partnership with plants. Basidiomycota Zygomycota Chytridiomycota Ascomycota Glomeromycota

a saclike structure containing spores

An ascus is _____. a club-shaped cell with spores on its outer surface the sexual structure of chytrids a cup-shaped structure containing many spore-producing cells on the gill of a mushroom an asexual spore-producing structure on a stalk a saclike structure containing spores

gastrula

An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.

help plants take up nutrients and water Mycorrhizae are mutualistic associations with the roots of plants, which enhance the absorption of nutrients.

An important example of interaction between fungi and certain other organisms is mycorrhizae, in which the fungal partners _____. sicken herbivores that attempt to feed on plants control soil nematodes cause the decay of cellulose and lignin provide carbohydrates to the plant partner help plants take up nutrients and water

form branching hyphae by invaginating through the cell wall of the roots

Arbuscular mycorrhizal fungi ___________. form sheaths of hyphae over the surface of plant shoots and extracellular spaces of the shoot cortex are parasitic fungi form sheaths of hyphae over the surface of plant roots and extracellular spaces of the root cortex form branching hyphae by invaginating through the cell wall of the shoots form branching hyphae by invaginating through the cell wall of the roots

protein-coding genes, genes for membrane transporters, and genes for small secreted proteins

Based on a genomic analysis of a mycorrhizal fungus and four nonmycorrhizal fungi, researchers were able to identify ___________. how researchers inoculate pine seedlings with mycorrhizal fungi how the mycorrhizal fungus and the nonmycorrhizal fungi compete for tree roots trees that need mycorrhizal fungi protein-coding genes, genes for membrane transporters, and genes for small secreted proteins how the mycorrhizal fungus and the nonmycorrhizal fungi are grown in a laboratory

Ascomycota

Cup fungi are in the phylum _____. Zygomycota Chytridomycota Ascomycota Chordata Basidiomycota

eight; meiosis followed by mitosis

During sexual reproduction of Neurospora, you observe asci that contain _________ ascospores that resulted from _________. eight; two consecutive rounds of mitosis four; mitosis eight; mitosis followed by meiosis four; meiosis eight; meiosis followed by mitosis

Karyogamy

During what stage of fungal reproduction are diploid cells produced? Karyogamy Binary fission Dikaryotic stage Plasmogamy Meiosis

form sheaths of hyphae over the surface of a plant's roots and extracellular spaces of the root cortex

Ectomycorrhizal fungi __________. form branching hyphae by invaginating through the cell wall of the roots form sheaths of hyphae over the surface of a plant's roots and extracellular spaces of the root cortex are parasitic fungi form sheaths of hyphae over the surface of a plant shoots and extracellular spaces of the shoot cortex form branching hyphae by invaginating through the cell wall of the shoots

basidiocarp

Elaborate fruiting body of a dikaryotic mycelium of a club fungus.

fossils

Evidence that mycorrhizae, the mutualistic relationship between plants and fungi, existed from the beginning of the colonization of land comes from _____. fossils microsporidia phylogenetics molecular clock studies comparisons of DNA sequences

zoospore

Flagellated spore found in chytrid fungi and some protists.

rusts Rusts include destructive plant parasites.

From the human perspective, which of the following kinds of fungi would be considered the least useful or beneficial? mycorrhizal fungi yeasts truffles rusts decomposers

the type of sexual structure they form

Fungal species are classified in a particular phylum based on __________. the type of sexual structure they form whether they produce sexually or asexually whether they are mutualistic or parasitic their mode of nutrition their type of motility

secreting digestive enzymes into the environment and then absorbing the smaller compounds into their bodies

Fungi "eat" their food by ___________. through phagocytosis ingesting large molecules from the environment and digesting the material within their bodies secreting digestive enzymes into the environment and then absorbing the smaller compounds into their bodies absorbing large molecules from the environment and digesting the material within their bodies

chemoheterotrophic

Fungi are __________ organisms. chemoautotrophic photoheterotrophic photoautotrophic chemoheterotrophic mixotrophic

opisthokonts

Fungi belong to the clade ___________. opisthokonts nucleariids chytrids glomeromycetes deuteromycetes

All of the above.

Fungi form mutualistic relationships with plants and animals. Which of the following is an example of such a relationship? Endophytes in leaves produce toxins that deter herbivores. Fungi help break down wood in the guts of termites. Fungi can help increase drought tolerance in plants Fungi help break down plant material in the guts of grazing mammals. All of the above.

lignin

Fungi in the phylum Basidiomycota are the most important decomposers of wood because of their ability to break down __________. opisthokonts jet fuel cellulose lignin mycorrhizae

absorption Fungi are heterotrophs that acquire their nutrients by absorbing small molecules from the surrounding medium.

Fungi obtain nutrients through _____. photosynthesis chemosynthesis absorption ingestion endocytosis

saclike structures

Fungi of the phylum Ascomycota are recognized on the basis of their production of _____ during sexual reproduction. lichens saclike structures a dikaryotic structure yeasts flagellated zoospores

haploid

Fungi produce _____ spores. dikaryotic heterokaryotic haploid diploid triploid

coenocytic

Fungi that consist of a continuous mass containing hundreds or thousands of nuclei are known as __________. coenocytic septic dikaryotic chytrids imperfect fungi

mycosis

General term for a fungal infection.

are specialized hyphae of both mutualistic and parasitic fungi

Haustoria _________. are the fruiting bodies of asexual fungi are specialized hyphae of mutualistic fungi form symbiotic relationships with lichens are specialized hyphae of parasitic fungi are specialized hyphae of both mutualistic and parasitic fungi

dikaryotic

Hyphae with two nuclei per cell are called __________. heterozygotic dikaryotic diploid multicellular prokaryotic

gastrulation

In animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo.

pheromone

In animals and fungi, a small molecule released into the environment that functions in communication between members of the same species. In animals, it acts much like a hormone in influencing physiology and behavior.

nuclei undergo mitosis without cytokinesis

In coenocytic hyphae, __________. nuclei undergo mitosis without cytokinesis a megakaryon forms nuclei undergo meiosis without cytokinesis nuclei undergo mitosis with cytokinesis nuclei undergo meiosis with cytokinesis

spore

In fungi, a haploid cell, produced either sexually or asexually, that produces a mycelium after germination.

These sexual processes generate genetic variation. The sexual processes of karyogamy and meiosis generate extensive genetic variation, a prerequisite for natural selection.

In fungi, haploid hyphae fuse to produce dikaryotic and then diploid nuclei, only to restore the haploid condition by meiosis before the growth of new hyphae. What is the significance of a transient diploid state in fungi? These sexual processes generate genetic variation. The diploid state is more advanced than the haploid state. All organisms must reproduce sexually at some point in their life cycle.

obtaining food

In fungi, the function of the mycelium is _____. obtaining food dispersal to distant habitats surviving a period of food shortage defense movement

karyogamy

In fungi, the fusion of haploid nuclei contributed by the two parents; occurs as one stage of sexual reproduction, preceded by plasmogamy.

plasmogamy

In fungi, the fusion of the cytoplasm of cells from two individuals; occurs as one stage of sexual reproduction, followed later by karyogamy.

soredium

In lichens, a small cluster of fungal hyphae with embedded algae.

zygosporangium

In zygomycete fungi, a sturdy multinucleate structure in which karyogamy and meiosis occur.

mold

Informal term for a fungus that grows as a filamentous fungus, producing haploid spores by mitosis and forming a visible mycelium.

nucleariid

It has been suggested that the fungal ancestor was a ___________. deuteromycete chytrid nucleariid glomeromycete opisthokont

diploid zygote

Karyogamy produces a _____. diploid zygote haploid zygote spores mycelium hypha

symbiotic associations of photosynthesizers and fungi

Lichens are _____. predatory fungi the sexual stage of deuteromycetes symbiotic associations of photosynthesizers and fungi used to produce blue cheese mutualistic associations of fungi and plant roots

they are important in the initial stages of soil formation

Lichens are important pioneers in areas that have been burned by fires or destroyed by lava flows because __________. they release chemicals that maintain the surfaces of the underlying substratum All of the listed responses are correct. they are important in the initial stages of soil formation they thrive on acid rain they take up excess nitrogen

and animals have a common ancestor

Molecular evidence suggests that fungi __________. were once photosynthetic evolved from a multicellular protist are a polyphyletic group and animals have a common ancestor evolved from plants

filaments called hyphae

Multicellular fungal bodies are composed of ___________. cells called yeasts filaments called hyphae vascular bundles called the stele haustoria filaments called mycelia

hypha

One of many connected filaments that collectively make up the mycelium of a fungus.

septum

One of the cross-walls that divide a fungal hypha into cells. they generally have pores large enough to allow ribosomes, mitochondria, and even nuclei to flow from cell to cell.

haustoria

Parasitic fungi possess hyphae that are modified to penetrate and absorb nutrients from host tissue. Such modified hyphae are called _____. haustoria mycorrhizae basidiocarps asci septa

dikaryotic

Referring to a fungal mycelium with two haploid nuclei per cell, one from each parent.

yeast

Single-celled fungus. they reproduce asexually by binary fission or by the pinching of small buds off a parent cell.

Arbuscules

Specialized branching hyphae that are found in some mutualistic fungi and exchange nutrients with living plant cells.

glomeromycete

The __________ clade includes 160 species, with most producing arbuscular mycorrhizae. ascomycete zygomycete chytrid glomeromycete basidiomycete

conidia

The asexual spores produced by members of the phylum Ascomycota are called __________. asci mycorrhizae mushrooms lichens conidia

hyphae ... mycelium

The body of most fungi consists of threadlike _____, which form a network called a _____. hyphae ... chytrid sporangia ... dikaryon mycelia ... dikaryon hyphae ... mycelium mycelia ... hypha

chitin

The cell walls of fungal cells are composed of _____. cellulose peptidoglycan pectin chitin lignin

chytrid

The decline of amphibian populations is most probably due to a(n) ________ parasite. glomeromycete zygomycete basidiomycete chytrid ascomycete

mycelium

The densely branched network of hyphae in a fungus.

fungus Most fungi are haploid except for a very brief diploid stage that is seen only when a fungus reproduces sexually.

The diploid phase of the life cycle is shortest in which of the following? moss fungus angiosperm gymnosperm fern

All fungi are heterotrophs; some species live as decomposers and others as symbionts. Mycelia are made up of small-diameter hyphae that form an interwoven mass, providing more surface area for nutrient absorption. Some fungi can grow as either filamentous or single-celled forms. Some fungi secrete digestive enzymes into the environment and then absorb the digested nutrients. (All fungi are heterotrophs. Most obtain carbon compounds by decomposing organic matter, while others live in a symbiotic association with other organisms. The feeding structure of a multicellular fungus is the mycelium, which consists of numerous small-diameter filaments, or hyphae. Nutrients absorbed by the hyphae can flow throughout the mycelium in both coenocytic hyphae and septate hyphae.)

The following statements describe something about the body structures or functions of fungi. Identify those statements that are correct. Select all that apply. Cellulose gives rigidity and strength to the cell walls of fungi. Mycelia are made up of small-diameter hyphae that form an interwoven mass, providing more surface area for nutrient absorption. Nutrients can flow through the entire mycelium in fungi with coenocytic hyphae, but not in fungi with septate hyphae. Some fungi can grow as either filamentous or single-celled forms. Some fungi secrete digestive enzymes into the environment and then absorb the digested nutrients. All fungi are heterotrophs; some species live as decomposers and others as symbionts.

ascocarp

The fruiting body of a sac fungus (ascomycete).

chytrids and the zygomycetes

The fungal groups that are paraphyletic—that is, a group of taxa that consists of a common ancestor and some, but not all, of its descendants—are the __________. glomeromycetes and the ascomycetes ascomycetes and the basidiomycetes zygomycetes and the glomeromycetes chytrids and the zygomycetes chytrids and the glomeromycetes

ascocarp ... scatter sexually produced spores

The mushroom in a basidiomycete life cycle serves the same function as the _____ in the ascomycete life cycle, which is to _____. zygosporangium ... produce sexual spores plasmodium ... form gametes dikaryon ... store a food reserve ascocarp ... scatter sexually produced spores conidium ... supply the rest of the fungus with chitin monomers

lichen

The mutualistic association between a fungus and a photosynthetic alga or cyanobacterium.

develops a rough, thick-walled coating that can resist harsh conditions for months

The zygosporangium _________. is the asexual fruiting body of bread mold always contains monokaryotic nuclei develops a rough, thick-walled coating that can resist harsh conditions for months produces spores by mitosis is always a diploid structure

mycelia

There is a fungus in Oregon that covers 890,965 hectares! The bulk of this fungus is most likely _____. mycelia haustoria pathogenic sporangia reproductive structures

deuteromycete

Traditional classification for a fungus with no known sexual stage.

False In most fungi, fertilization is a two-step process consisting of the fusion of cells and then the fusion of nuclei in the fused cells.

True or false? In most fungi, fertilization is complete after the cells fuse together. True False

True A mushroom consists mainly of hyphae that are heterokaryotic, which means they have two distinct haploid nuclei per cell; these nuclei may fuse in specialized cells called basidia and become diploid in preparation for meiosis and spore production.

True or false? Most of the cells in a mushroom contain haploid nuclei. True False

athlete's foot and yeast infections

Two of the most common mycoses (fungal infections) in humans are __________. indoor molds and Aspergillus ergots and rusts rusts and white rot fungi Saccharomyces cerevisiae and Penicillium athlete's foot and yeast infections

It allows for more genetic recombination.

What is the importance of the extended dikaryotic stage in the life cycles of basidiomycetes and ascomycetes? It increases the surface area for the production of basidiospores. It allows for more genetic recombination. It allows for the formation of more conidia. It keeps transposons from accumulating in fungal cells. It allows for the formation of more hyphae.

Arbuscules

What is the major feature of glomeromycetes? Arbuscules Soredia Mycorrhizae The containment of millions of photosynthetic microorganisms in their hyphae Ascocarps

Fungi use these chemical signals to determine whether a potential sexual partner is of a suitable mating type.

What role do pheromones play in fungal sexual reproduction? Pheromones initiate the production of spores in molds. Pheromones initiate zygotes to form during karyogamy. After plasmogamy, pheromones cause the haploid nuclei from each parent to exchange genes. Pheromones allow the hyphae of two distinct mycelia to follow each other as they grow. Fungi use these chemical signals to determine whether a potential sexual partner is of a suitable mating type.

karyogamy and meiosis During karyogamy, the haploid nuclei fuse, and meiosis produces genetic variation in several ways.

What sexual processes in fungi generate genetic variation? budding and meiosis karyogamy and meiosis plasmogamy and meiosis diploidy and the heterokaryotic condition haustoria and karyogamy

in a mushroom, when the nuclei of a dikaryotic cell fuse

Where and when does fertilization occur in the mushroom life cycle? underground, when the hyphae of different mating types fuse on the surface of the ground, when a basidiospore germinates underground, as a mycelium begins to spread in a mushroom, when eggs and sperm meet in a mushroom, when the nuclei of a dikaryotic cell fuse

Basidia Basidia are specialized cells in the gills of a mushroom in which haploid nuclei fuse in preparation for meiosis.

Where does meiosis occur in a mushroom? Hyphae Basidia Mycelium Spores

Plasmogamy, karyogamy, meiosis, germination

Which choice below generally represents the correct order of events in fungal sexual reproduction? Germination, meiosis, karyogamy, plasmogamy Karyogamy, meiosis, plasmogamy, germination Meiosis, plasmogamy, karyogamy, germination Plasmogamy, meiosis, germination, karyogamy Plasmogamy, karyogamy, meiosis, germination

zoospores (flagellated spores)

Which feature below is unique to chytrids? zoospores (flagellated spores) soredia asci (spore-producing sacs) cell walls made of chitin conidia (asexual spores)

Hyphae are produced by mitosis. The spore undergoes mitosis to produce hyphae, which then form a filamentous network called a mycelium.

Which of the following events occurs first in the development of a spore into a mature mushroom? Haploid nuclei fuse to form a diploid nucleus. Hyphae are produced by mitosis. A heterokaryotic mycelium forms. The mycelium forms.

Fungi are heterotrophic, and plants are autotrophic.

Which of the following is a difference between plants and fungi? Fungi have cell walls. Plants produce spores. Plants have diploid and haploid phases, and fungi have only haploid stages. Fungi are strictly asexual, and plants undergo sexual reproduction. Fungi are heterotrophic, and plants are autotrophic.

All of the listed responses are correct.

Which of the following statements about fungi is/are true? The dominant stage of the life cycle is usually haploid. Many species obtain their nutrients from decaying organic matter. The haploid nuclei of dikaryotic hyphal cells fuse to form a diploid zygote. Spores germinate and then mitotically divide to form a mycelium. All of the listed responses are correct.

the heterokaryotic stage of the fungal life cycle

Which of these contains two haploid nuclei? the heterokaryotic stage of the fungal life cycle zygote spore-producing structures mycelium hypha

All of the listed responses are correct.

Which statement below about zygosporangia is/are true? They are produced through plasmogamy. They are multinucleate formations. They are resistant to freezing and drying. They are metabolically inactive. All of the listed responses are correct.

Plants are harmed by fungal pathogens. Plants depend on fungi as mutualistic symbionts.

Which statement(s) correctly describe(s) the interactions between plants and fungi? Select all that apply. Plants are harmed by fungal pathogens. Plants depend on fungi as mutualistic symbionts. Plants compete with fungi for access to soil nutrients.

Mycelium The mycelium is a mass of filaments with a high surface-area-to-volume ratio, which allows for efficient nutrient absorption.

Which structure allows the growing mushroom to nourish itself? Spore Basidia Mycelium Gills

Mycelium A mycelium is a network of filaments that forms the body of a fungus.

Which structure is not directly involved in the reproduction of at least one major group of fungi? Basidium Mycelium Motile spores Asci

Plasmogamy Plasmogamy is the fusion of cytoplasm from different individuals.

Which term describes the fusion of cytoplasm from two individuals? Karyogamy Heterokaryotic Plasmogamy Spore

dikaryotic cells with haploid nuclei

While hiking through a forest, you discover a fungus growing on the remains of a decaying tree trunk. You hypothesize that it is a basidiomycete fungus because it resembles a mushroom in shape and size. If your logic is correct, microscopic analysis of the tissue found in the stalk of this fungus will reveal the presence of __________. dikaryotic cells with haploid nuclei monokaryotic cells with a haploid nucleus monokaryotic cells with diploid nuclei More than one of the cell types listed is correct. dikaryotic cells with diploid nuclei

Mycorrhizal fungi assist plants in the absorption of essential nutrients.

You can buy mycorrhizal fungus to add to soil when you plant trees and other plants. Why would you want to do this? Mycorrhizal fungi assist plants in the absorption of essential nutrients. Mycorrhizal fungi prevent transposons from accumulating in plant cells. Mycorrhizal fungi live in plant leaves and produce toxins that discourage herbivores. Mycorrhizal fungi produce carbohydrates needed by plants. Mycorrhizal fungi prey on nematodes in the soil.

Both parasitic and mutualistic

_________ fungi absorb nutrients from living organisms. Decomposer Parasitic All of the listed responses are correct. Both parasitic and mutualistic Mutualistic

Molecular clock analysis

____________ shows that the ancestors of animals and fungi diverged into separate lineages 1-1.5 billion years ago. Whole genome sequencing Molecular clock analysis Comparative gene expression Proteomics Microarray analysis