Bio II Chapter 31: Fungi

Suppose a certain fungus is a mutualist that lives within an insect host, yet its ancestors were parasites that grew in and on the insect's body. What derived traits might you find in this mutualistic fungus?

. The ancestors of such a mutualist most likely secreted powerful enzymes to digest the body of their insect host. Since such enzymes would harm a living host, it is likely that the mutualist would not produce such enzymes or would restrict their secretion and use

Some of the approximately _______ chytrid species are _______, while other are parasites of protists, other fungi, plants, or animals. Other chytrids are important ______. For example, anaerobic chytrids that live in the digestive tracts of sheep and cattle help to break down plant matter, thereby contributing significantly to the animal's growth.

1,000; parasites; mutualists

Between ____% and ____% of the world's fruit harvest is lost annually due to fungi, and grain crops also suffer major losses each year.

10;50

How many known species of microsporidians are there?

1300

Fungi have diversified into ______ million species.

2-4

How many species of fungi reproduce asexually?

20,000

More than _____% of all ascomycete species live with green algae or cyanobacteria in beneficial symbiotic associations called ____. Some ascomycetes form mycorrhizae with plants. Many other live between _____ cells in leaves; some of these species release _____ compounds that help protect the plant from insects.

25; lichens; mesophyll; toxic

How many known species of cryptomycetes are there?

30

About ____% of the _____ known species of fungi make a living as parasites or pathogens, mostly of plants.

30; 145,000

Fossils show that lichens were on land _____ mya.

420

The oldest undisputed fossils of fungi are about

460 million years old

Plants colonized land about ______ mya.

470

How many known species of basidiomycetes are there?

50,000

Fungi are placed into ____ groups

7

How many known species of mucoromycetes are there?

750

______ vascular plants have mycorrhizae.

80%

About ______% of all plant species have mutualistic partnerships with arbuscular mycorrhizae.

85

How many species of ascomycetes are there?

90,000

The figure depicts the outline of a large fairy ring that has appeared overnight in an open meadow, as viewed from above. The fairy ring represents the furthest advance of this mycelium through the soil. Locations A-D are all 0.5 meters below the soil surface. Which location is nearest to basidiocarps?

A

heterokaryon

A fungal mycelium that contains two or more haploid nuclei per cell; the fused part of the mycelium

conidia

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

What characteristics of pathogenic fungi result in their being efficiently transmitted?

A hardy spore stage enables dispersal to host organisms through a variety of mechanisms; their ability to grow rapidly in a favorable new environment enables them to capitalize on the host's resources.

Opisthokonts

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

Mucoromycetes

A member of the fungal phylum Mucoromycota, characterized by the formation of a sturdy structure called a zygosporangium during sexual reproduction; includes a species of fast-growing molds responsible for causing foods such as bread, peaches, strawberries, and sweet potatoes to rot during storage (Rizopus stolonifer -black bread mold)

Mycorrhizae

A mutualistic association of plant roots and fungus; mycorrhizal fungi can improve delivery of phosphate ions and other minerals to plants because the vast mycelial networks of the fungi are more efficient than the plants' roots at acquiring these minerals from the soil. In exchange, the plants supply the fungi with organic nutrients such as carbohydrates.

basidium

A reproductive appendage that produces sexual spores on the gills of mushrooms (club fungi) (a cell in which karyogamy occurs, followed immediately by meiosis

asci

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.

What are some of the benefits that lichen algae can derive from their relationship with fungi?

A suitable environment for growth, retention of water and minerals, protection from intense sunlight, and protection from being eaten

Ectomycorrhizal fungi

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 mycorrhizal 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).

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

All of the above.

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

All of the listed responses are correct.

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

All of the listed responses are correct.

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

Arbuscules Arbuscules are the tiny tips of glomeromycete hyphae that invade plant roots and branch into treelike structures within root cells, forming arbuscular mycorrhizae.

How are fungi important as decomposers, mutualists, and pathogens?

As decomposers, fungi break down the bodies of dead organisms, thereby recycling elements between the living and nonliving environments. Without the activities of fungi and bacterial decomposers, essential nutrients would remain tied up in organic matter, and life as we know it would cease. As an example of their key role as mutualists, fungi form mycorrhizal associations with plants. These associations improve the growth and survival of plants, thereby indirectly affecting the many other species (humans included) that depend on plants. As pathogens, fungi harm other species. In some cases, fungal pathogens have caused their host populations to decline across broad geographic regions, as in the case of the American chestnut.

________ are some of the worst plant pathogens. ____________ was introduced in the late 1900s from Asia. It infects trees through cracks in the bark. ______ ______ was the most dominant tree in the eastern US. Nuts were major food source for animals. Reductions let oaks, maples, and hickories dominate today.

Ascomycetes; Chestnut blight; American Chesnut

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

Ascomycota

Plasmogamy is indicated by the letter _____.

B

Compare and contrast the nutritional mode of a fungus with your own nutritional mode.

Both a fungus and a human are heterotrophs. Many fungi digest their food externally by secreting enzymes into the food and then absorbing the small molecules that result from digestion. Other fungi absorb such small molecules directly from their environment. In contrast, humans (and most other animals) ingest relatively large pieces of food and digest the food within their bodies.

What do fungi and arthropods have in common? The haploid state is dominant in both groups. Both groups use chitin for support. Both groups are predominantly autotrophs that produce their own food. Both groups have cell walls.

Both groups use chitin for support.

The figure depicts the outline of a large fairy ring that has appeared overnight in an open meadow, as viewed from above. The fairy ring represents the furthest advance of this mycelium through the soil. Locations A-D are all 0.5 meters below the soil surface.What is the most probable location of the oldest portion of this mycelium?

C

The process indicated by the letter _____ produces a diploid structure.

C

Some mycoses are opportunistic, occurring only when a change in the body's microorganisms, chemical environment, or immune system allows fungi to grow unchecked. ________ _______, for example, is one of the normal inhabitants of most epithelia, such as the vaginal lining. Under certain circumstances, it can grow too rapidly and become pathogenic, leading to _______ ______.

Candida albicans; yeast infections

Review Figure 10.3 and Figure 10.5. If a plant has mycorrhizae, where might carbon that enters the plant's stomata as CO2 eventually be deposited: in the plant, in the fungus, or both? Explain.

Carbon that enters the plant through stomata is fixed into sugar through photosynthesis. Some of these sugars are absorbed by the fungus that partners with the plant to form mycorrhizae; others are transported within the plant body and used in the plant. Thus, the carbon may be deposited in either the body of the plant or the body of the fungus.

What are some examples of fungi that attack food crops that are toxic to humans?

Claviceps purpurea, which grows on rye plants, forming purple structures call ergots. If infected rye is milled into flour, toxins from the ergots can cause ergotism, characterized by gangrene, nervous spasms, burning sensations, hallucinations, and temporary insanity.

What is the evidence that multicellularity evolved in animals and fungi independently from different single-celled ancestors?

DNA evidence indicates that animals are more closely related to a different group of protists (the choanoflagellates) than they are to either fungi or nucleariids.

Why are fungi classified as opisthokonts despite the fact that most fungi lack flagella?

DNA evidence indicates that fungi, animals, and their protistan relatives form a clade, the opisthokonts. Furthermore, chytrids and other fungi thought to be members of basal lineages have posterior flagella, as do most other opisthokonts. This suggests that other fungal lineages lost their flagella after diverging from ancestors that had flagella.

basidiocarps

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

Which microsporidian has the smallest genome of any eukaryote sequenced to date?

Encephalitozoon intestinalis; it has just 2.3 Mb of DNA

What feature of chytrids supports the hypothesis that they include members of basal fungal lineages?

Flagellated spores; molecular evidence also suggests that chytrids include species that belong to lineages that diverged from other fungi early in the history of the group.

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

Fungi are heterotrophic, and plants are autotrophic.

If fungi colonized land before plants, where might the fungi have lived? How would their food sources have differed from what they feed on today?

Fungi are heterotrophs. Prior to the colonization of land by plants, terrestrial fungi would have lived where other organisms (or their remains) were present and provided a source of food. Thus, if fungi colonized land before plants, they could have fed on prokaryotes or protists that lived on land or by the water's edge—but not on the plants or animals on which many fungi feed today.

Why is it important that a fungus maximize its surface area to volume ratio?

Fungi are not motile in a typical sense- they cannot run, swim, or fly in search of food or mates. However, as they grow, such fungi can move into new territory, swiftly extending the tips of their hyphae. The structure of the mycelium maximizes its surface-to-volume ratio, making feeding very efficient. The fungus concentrates its energy and resources on adding hyphal length and thus overall absorptive surface area, rather than on increasing hyphal girth.

Along with bacteria and protozoa, some chytrid fungi live in the digestive tracts of cattle and aid in the digestion of plant matter; thus, all three groups represent potential mutualists with cattle. In an experiment designed to test how much of a contribution to cell wall digestion was made by fungi in one part of the stomach (rumen), Lee et al. fed grain to cattle and then removed samples of the rumen contents. They took these samples to the laboratory and experimentally treated them with various chemicals to produce fractions that contained (A) only fungi, (B) only bacteria, (C) only protozoa, and (D) all of the potential mutualists. They then measured the percent of the cell wall that was degraded (see the figure). Which of the following conclusions can be drawn correctly from the data? Fungi contribute as much to cell wall degradation as all the potential mutualists together.Of all three potential mutualists, protozoa contribute the most to cell wall digestion.The cattle did not benefit from the presence of fungi; therefore, the fungi are not mutualistic with the cattle.Of all three potential mutualists, fungi contribute the least to cell wall digestion.

Fungi contribute as much to cell wall degradation as all the potential mutualists together.

Describe the ways fungi obtain nutrition, including how it differs from animals.

Fungi do not ingest their food like animals. A fungus absorbs nutrients from the environment outside of its body. Many fungi do this by secreting hydrolytic enzymes into their surroundings. These enzymes break down complex molecules to smaller organic compounds that the fungi can absorb into their cells and use. Other fungi use enzymes to penetrate the walls of cells, enabling the fungi to absorb nutrients from the cells. Collectively, the different enzymes found in various fungal species can digest compounds from a wide range of sources, living or dead.

Why are mycorrhizal fungi superior to plants at acquiring mineral nutrition from the soil? Hyphae have a smaller surface area-to-volume ratio than do the hairs on a plant root. Fungi secrete extracellular enzymes that can break down large molecules. Hyphae are 100 to 1,000 times larger than plant roots. Mycelia are able to grow in the direction of food.

Fungi secrete extracellular enzymes that can break down large molecules.

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

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

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

Glomeromycota

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

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.

plasmogamy

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

soredia

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

spore

In the life cycle of a plant or alga undergoing alternation of generations, a meiotically produced haploid cell that divides mitotically, generating a multicellular individual, the gametophyte, without fusing with another cell.

Molds

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

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 keeps transposons from accumulating in fungal cells. It allows for the formation of more hyphae. It allows for more genetic recombination.It allows for the formation of more conidia.

It allows for more genetic recombination. During the long dikaryotic stage in basidiomycetes and ascomycetes, many nuclear fusion events may occur, leading to multiple meiosis events producing many genetically different spores.

Describe the mutualistic relationship between leaf-cutter ants and leaves.

Leaf-cutter ants scour tropical forest in search of leaves, which they cannot digest on their own but carry back to their nests and feed to the fungi. As the fungi grow, their hyphae develop specialized swollen tips that are rich in proteins and carbohydrates. The ants feed primarily on these nutrient rich tips. Not only do the fungi break down plant leaves into substances the insects can digest, but they also detoxify plant defensive compounds that would otherwise kill or harm the ants. In some tropical forests, the fungi have helped these insects become the major consumers of leaves.

How might life on Earth differ from what we know today if no mutualistic relationships between fungi and other organisms had ever evolved?

Many different outcomes might have occurred. Organisms that currently form mutualisms with fungi might have gained the ability to perform the tasks currently done by their fungal partners, or they might have formed similar mutualisms with other organisms (such as bacteria). Alternatively, organisms that currently form mutualisms with fungi might be less effective at living in their present environments. For example, the colonization of land by plants might have been more difficult. And if plants did eventually colonize land without fungal mutualists, natural selection might have favored plants that formed more highly divided and extensive root systems (in part replacing mycorrhizae).

Basidia produce spores by a process known as _____. decomposition mitosis meiosis hyphae binary fission

Meiosis

nucleariids

Member of a group of unicellular, amoeboid protists that are more closely related to fungi than they are to other protists; feed on algae and bacteria

Ascomycetes

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

Basidiomycetes

Member of the fungal phylum Basidiomycota, commonly called club fungus. The name comes from the club-like shape of the basidium; includes mushrooms, puffballs, and shelf fungi; rusts and smuts

chytrid

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

Select the correct statement(s) about the origin of fungi. Select all that apply. Fungi are more closely related to plants than to animals .Fungi evolved after the first plants colonized land .Multicellularity probably arose independently in fungi and animals.

Multicellularity probably arose independently in fungi and animals.

__________ fungi also absorb nutrients from a host, but they reciprocate with actions that benefit the hosts.

Mutualistic; for example, mutualistic fungi that live within the digestive tracts of certain termite species use their enzymes that break down wood, as do mutualistic protists in other termites.

The following statements describe something about the body structures or functions of fungi. Identify those statements that are correct. 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. All fungi are heterotrophs; some species live as decomposers and others as symbionts. Some fungi can grow as either filamentous or single-celled forms. Nutrients can flow through the entire mycelium in fungi with coenocytic hyphae, but not in fungi with septate hyphae. Some fungi secrete digestive enzymes into the environment and then absorb the digested nutrients.

Mycelia are made up of small-diameter hyphae that form an interwoven mass, providing more surface area for nutrient absorption. All fungi are heterotrophs; some species live as decomposers and others as symbionts. 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.

Describe the importance of mycorrhizae, both today and in the colonization of land. What evidence supports the antiquity of mycorrhizal associations?

Mycorrhizae form extensive networks of hyphae through the soil, enabling nutrients to be absorbed more efficiently than a plant can do on its own; this is true today, and similar associations were probably very important for the earliest plants (which lacked roots). Evidence for the antiquity of mycorrhizal associations includes fossils showing arbuscular mycorrhizae in the early plant Aglaophyton and molecular results showing that genes required for the formation of mycorrhizae are present in liverworts and other basal plant lineages.

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 prey on nematodes in the soil. 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 assist plants in the absorption of essential nutrients. Mycorrhizal fungi are very important to the overall health of over 85% of the plants on the planet.

Biologists in the 1930s used _____ in research that led to the one gene-one enzyme hypothesis. This tiny fungus has about 3/4 as many genes as the fruit fly Drosophila, and about half as many as a human. Its genome is relatively compact, having few of the stretches of noncoding DNA that occupy so much space in the genomes of humans and other eukaryotes. In

Neurospora

Hyphae

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

septa

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

Ascomycetes vary greatly in morphology (see also Figure 31.10). How could you confirm that a fungus is an ascomycete?

One or both of the following would apply to each species: DNA analyses would reveal that it is a member of the ascomycete clade, or aspects of its sexual life cycle would indicate that it is an ascomycete (for example, it would produce asci and ascospores).

_________ fungi absorb nutrients from the cells of living hosts.

Parasitic; Some parasitic fungi are pathogenic, including many species that cause diseases in plants and other s that cause diseases in animals.

Which of the following best describes the physical relationship of the partners involved in lichens? Photosynthetic cells are surrounded by fungal hyphae. Fungi grow on rocks and trees and are covered by algae. Lichen cells are enclosed within fungal cells. Fungal cells are enclosed within algal cells.

Photosynthetic cells are surrounded by fungal hyphae

Did multicellularity originate independently in fungi and animals? Explain.

Phylogenetic analyses show that fungi and animals are more closely related to each other than either is to other multicellular eukaryotes (such as plants or multicellular algae). These analyses also show that fungi are more closely related to single-celled protists called nucleariids than they are to animals, whereas animals are more closely related to a different group of single-celled protists, the choanoflagellates, than they are to fungi. In combination, these results indicate that multicellularity evolved in fungi and animals independently, from different single-celled ancestors.

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

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

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

Plasmogamy, karyogamy, meiosis, germination

Give examples of how form fits function in mucoromycetes, ascomycetes, and basidiomycetes.

Possible answers include the following: In mucoromycetes, the sturdy, thick-walled zygosporangium can withstand harsh conditions and then undergo karyogamy and meiosis when the environment is favorable for reproduction. In one group of mucoromycetes, the glomeromycetes, the hyphae have a specialized morphology that enables the fungi to form arbuscular mycorrhizae with plant roots. In ascomycetes, the asexual spores (conidia) are often produced in chains or clusters at the tips of conidiophores, where they are easily dispersed by wind. The often cup-shaped ascocarps house the sexual spore-forming asci. In basidiomycetes, the basidiocarp supports and protects a large surface area of basidia, from which spores are dispersed.

It has been hypothesized that fungi and plants have a mutualistic relationship because plants make sugars available for the fungi's use. What is the best evidence in support of this hypothesis? Fungi survive better when they are associated with plants. Radioactively labeled sugars produced by plants eventually show up in the fungi with which they are associated. Radioactive labeling experiments show that plants pass crucial raw materials to the fungus for manufacturing sugars. Fungi associated with plants have the ability to undergo photosynthesis and produce their own sugars, while those not associated with plants do not produce their own sugars.

Radioactively labeled sugars produced by plants eventually show up in the fungi with which they are associated.

dikaryotic

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

What are the key benefits of Mycorrhizal Fungi?

Root system growth: Mycorrhizal fungi support faster plant establishment, the hyphae access water and nutrients beyond the root zone and deliver them to the plant's vascular network, they increase absorption area by as much as 50 times, the increase overall root biomass Nutrient efficiency: the hyphae absorb and actively deliver nutrients directly to the roots, the improve the utilization of soil nutrients including nitrogen, phosphorus, potassium, and micronutrients Water absorption: the hyphae absorb and transport soil moisture from beyond the root zone to the plant's roots, the symbiosis increases the plant's effective water utilization capability, improved tolerance to stress, greater resistance to drought

The yeast ______ _______ is the most important of all cultured fungi. It is available as many strains of baker's yeast and brewer's yeast.

Saccharomyces cerevisiae

yeasts

Single-celled fungus. Yeasts reproduce asexually by binary fission or by the pinching of small buds off a parent cell. Many fungal species can grow both as yeasts and as a network of filaments; relatively few species grow only as yeasts.

Arbuscules

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

Suppose that the mutation of an ascomycete changed its life cycle so that plasmogamy, karyogamy, and meiosis occurred in quick succession. How might this affect the ascospores and ascocarps?

Such a change to the life cycle of an ascomycete would reduce the number and genetic diversity of ascospores that result from a mating event. Ascospore number would drop because a mating event would lead to the formation of only one ascus. Ascospore genetic diversity would also drop because in ascomycetes, one mating event leads to the formation of asci by many different dikaryotic cells. As a result, genetic recombination and meiosis occur independently many different times—which could not happen if only a single ascus was formed. It is also likely that if such an ascomycete formed an ascocarp, the shape of the ascocarp would differ considerably from that found in its close relatives.

This diagram shows the structure of a multicellular fungus, with an expanded view of two types of hyphae. Identify the structures and determine which hypha is septate and which is coenocytic. (Note that although this diagram shows the two types of hyphae, a fungus can have either one type or the other, but not both.)

The body of a multicellular fungus consists of a network of hyphae, which form an interwoven mass called a mycelium. Some hyphae, called septate hyphae, are divided into cells by crosswalls, or septa. Coenocytic hyphae do not have septa; these hyphae consist of a continuous cytoplasmic mass that contains many nuclei and organelles.

How does the morphology of multicellular fungi affect the efficiency of nutrient absorption?

The body of a multicellular fungus typically consists of thin filaments called hyphae. These filaments form an interwoven mass (mycelium) that penetrates the substrate on which the fungus grows and feeds. Because the individual filaments are thin, the surface-to-volume ratio of the mycelium is maximized, making nutrient absorption highly efficient.

Fungi produce many compounds that humans are able to use medically. How can you account for these compounds? The compounds probably provide a benefit to the fungi. Humans used artificial selection to develop fungi that produced specific compounds. The presence of the compounds in the fungi were accidentally produced and have no function. The compounds are produced as a result of sexual reproduction and recombination.

The compounds probably provide a benefit to the fungi.

__________ fungi absorb nutrients from living organisms. Parasitic Mutualistic Decomposer The first and second responses are both correct. All of the listed responses are correct.

The first and second responses are both correct. Both parasitic and mutualistic fungi depend on living organisms for their nutrients. Decomposer fungi, on the other hand, obtain nutrients from nonliving organic material

ascocarps

The fruiting body of a sac fungus (ascomycete)

Compare the genetic variation found in spores produced in the sexual and asexual portions of the life cycle. Why do these differences occur?

The haploid spores produced in the sexual portion of the life cycle develop from haploid nuclei that were produced by meiosis; because genetic recombination occurs during meiosis, these spores will differ genetically from one another. In contrast, the haploid spores produced in the asexual portion of the life cycle develop from nuclei that were produced by mitosis; as a result, these spores are genetically identical to one another.

Fungi have an extremely high surface-to-volume ratio. What is the advantage of this characteristic to an organism that gets most of its nutrition through absorption? This high ratio means that fungi have a thick, fleshy structure that allows the fungi to store more of the food it absorbs. This high ratio creates more room inside the cells for additional organelles involved in absorption. The lower volume prevents the cells from drying out too quickly, which can interfere with absorption. The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.

The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.

Use the diagram to determine the ploidy of a cell in the aboveground stalk of a mushroom.

The hypha is composed of cells that are haploid (n), as indicated by the teal-colored arrow behind it.

What is the ploidy of a cell in the specialized hypha shown in 2?

The hypha is composed of cells that are haploid (n), as indicated by the teal-colored arrow behind it.

Compare Figure 31.5 with Figure 13.6. In terms of haploidy versus diploidy, how do the life cycles of fungi and humans differ?

The majority of the fungal life cycle is spent in the haploid stage, whereas the majority of the human life cycle is spent in the diploid stage.

Could a fungal parasite have caused some of the many amphibian population declines and extinctions in recent decades? One study found that the number of yellow-legged frogs (Rana muscosa) plummeted after the chytrid Batrachochytrium dendrobatidis reached the Sixty Lake Basin area of California. Yellow-legged frogs can be killed by B. dendrobatidis infection. In the years leading up to the chytrid's 2004 arrival, there were more than 2,300 frogs in these lakes. By 2009, only 38 frogs remained; all the survivors were in two lakes (yellow) where researchers had applied a fungicide to reduce the chytrid's impact. Do the data indicate that the chytrid caused or is correlated to the drop in frog numbers? The data suggest that chytrid fungi are only correlated to frog population declines because in many lakes, the chytrid appeared only after frog populations had already declined. There is no evidence that chytrid fungi directly harm frogs, suggesting that the fungi are only correlated to frog population declines. The data suggest that the chytrid caused the decline because populations in areas without the chytrid are thriving, whereas populations exposed to the chytrid have gone extinct. The timing of the declines and the survival of frogs treated with fungicides suggest that the chytrid caused the decline in frog populations.

The timing of the declines and the survival of frogs treated with fungicides suggest that the chytrid caused the decline in frog populations.

Suppose that you sample the DNA of two mushrooms on opposite sides of your yard and find that they are identical. Propose two hypotheses that could reasonably account for this result.

The two mushrooms might be reproductive structures of the same mycelium (the same organism). Or they might be parts of two separate organisms that have arisen from a single parent organism through asexual reproduction (for example, from two genetically identical asexual spores) and thus carry the same genetic information.

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? All organisms must reproduce sexually at some point in their life cycle. The diploid state is more advanced than the haploid state. These sexual processes generate genetic variation.

These sexual processes generate genetic variation

Which of the following statements about decomposers is false? They play a key role in chemical recycling. They are autotrophs. They break down waste products, leaf litter, and the bodies of dead organisms. They include prokaryotic and eukaryotic species.

They are autotrophs

Deuteromycetes

Traditional classification for a fungus with no known sexual stage.

What are some of the benefits of fungi?

We depend on their ecological services as decomposers and recyclers of organic matter; they are used to ripen cheeses; morels and truffles are prized for their complex flavors; yeasts are used to produce alcoholic beverages and bread; medical value (a compound extracted from ergots is used to reduce high blood pressure and to stop maternal bleeding after childbirth, some fungi produce antibiotics; basic research- yeast is used to study the molecular genetics of eukaryotes; genetically modified fungi can treat people with medical conditions;

What is a fungi "compatibility test"?

When the mycelia of two fungi are of different mating types, the pheromones from each partner bind to receptors on the other, and the hyphae extend toward the source of the pheromones. When the hyphae meet, they fuse.

Which feature below is unique to chytrids? f Cell walls made of chitin Zoospores (flagellated spores) Asci (spore-producing sacs) Soredia Conidia

Zoospores (flagellated spores) Chytrids are thought to be members of the earliest fungal lineage. Their zoospores are evidence that fungi evolved from flagellated protists.

One tradition group of fungi, _________, has been abandoned because it was paraphyletic, and its members have been reassigned to other groups.

Zygomycota

coenocytic fungi

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

cryptomycetes

a member of the fungal phylum Cryptomycota, unicellular fungi that have flagellated spores; cryptomycetes and their sister taxon (microsporidians) are a basal fungal lineage.

Microsporidians

a member of the fungal phylum Microsporidia, unicellular parasites of protists and animals; microsporidians and their sister taxon (cryptomycetes) are a basal fungal lineage

zoopagomycetes

a member of the fungal phylum Zoopagomycota, multicellular parasites or commensal symbionts of animals; sexual reproduction, where known, involves the formation of a sturdy structure called a zygosporangium

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

a saclike structure containing spores In Ascomycota, the fruiting bodies, or ascocarps, contain the sexual spores in saclike asci.

Fungi obtain nutrients through _____. absorption endocytosis photosynthesis chemosynthesis ingestion

absorption

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

an ascomycete The disease, chestnut blight, is caused by an introduced ascomycete.

The adaptive advantage associated with the filamentous nature of fungal mycelia is primarily related to _____. an extensive surface area well suited for invasive growth and absorptive nutrition the potential to inhabit almost all terrestrial habitats the increased probability of contact between different mating types the ability to form haustoria and parasitize other organisms

an extensive surface area well suited for invasive growth and absorptive nutrition

The most important adaptive advantage associated with the filamentous nature of fungal mycelia is the ability to form haustoria and parasitize other organisms. the potential to inhabit almost all terrestrial habitats. the increased chance of contact between mating types. an extensive surface area well suited for invasive growth and absorptive nutrition.

an extensive surface area well suited for invasive growth and absorptive nutrition.

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

and animals have a common ancestor There is evidence that both fungi and animals evolved from aquatic flagellated protists.

The closest relatives of fungi are thought to be the animals. vascular plants. mosses. slime molds.

animals

The ancestor of fungi was an ______

aquatic, single-celled flagellated protist

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 conidium; supply the rest of the fungus with chitin monomers dikaryon; store a food reserve ascocarp; scatter sexually produced spores

ascocarp; scatter sexually produced spores A mushroom is an example of a basidiocarp, the source of sexual spores in Basidiomycota. In Ascomycota, the fruiting bodies, or ascocarps, contain the sexual spores in saclike asci.

During their sexual stage, most ascomycetes develop fruiting bodies, called ______, which range in size from microscopic to macroscopic. The _______ contain the spore-forming asci.

ascocarps; ascocarps

In lichen, ______ reproduction as a symbiotic unit is common. This can occur either by ________ of the parental lichen or by the formation of ________, small clusters of hyphae with embedded algae.

asexual; fragmentation; soredia

Two of the most common mycoses (fungal infections) in humans are _____. ergots and rusts Saccharomyces cerevisiae and Penicillium athlete's foot and Candida (yeast) infections rusts and smuts chytrids and coccidiodomycosis

athlete's foot and Candida (yeast) infections

The white mushrooms you find in the supermarket are examples of

basidiocarps

The multicellular condition of animals and fungi seems to have arisen _____. by convergent evolution by serial endosymbioses due to common ancestry by inheritance of acquired traits

by convergent evolution

How does a fungi "compatibility test" contribute to genetic variation?

by preventing hyphae from fusing with other hyphae from the same mycelium or another genetically identical mycelium

In most lichens, the alga or cyanobacterium provides _________ ________. A cyanobacterium also fixes _______ and provides other organic ______ compounds. The fungus provides its photosynthetic partner with a suitable environment for growth. The physical arrangement of hyphae allows for ______ exchange, protects the photosynthetic partner, and retains water and minerals. The fungus also secretes _____, which aid in the uptake of minerals.

carbon compounds; nitrogen; nitrogen; gas; acids

Fungi are __________ organisms.

chemoheterotrophic; Like animals, fungi are chemoheterotrophs. They must get both their energy and carbon skeletons by absorbing pre-digested nutrients from the environment.

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

chitin The chitin found in fungal cell walls is identical to the chitin found in the exoskeleton of arthropods.

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

coenocytic The coenocytic condition results from the repeated division of nuclei without cytoplasmic division.

In Mucoromycetes reproduction, the hyphae are _______, with septa found only where reproductive cells are formed. In the _____ phase, bulbous black sporangia develop at the tips of upright hyphae. Within each sporangium, hundreds of genetically identical ______ spores develop and are dispersed through the air. Spores that happen to land on moist food germinate, growing into new ______.

coenocytic; asexual; mycelia

Fossil fungi date back to the origin and early evolution of plants. What combination of environmental and morphological change is similar in the evolution of both fungi and plants? predominance in swamps and presence of cellulose in cell walls periods of drought and presence of filamentous body shape colonization of land and loss of flagellated cells presence of "coal forests" and change in mode of nutrition

colonization of land and loss of flagellated cells

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

conidia

Ascomycetes reproduce asexually by producing enormous numbers of asexual spores called _____. Unlike the asexual spores of most mucoromycetes, in most ascomycetes, conidia are not formed inside _______. Rather, they are produced externally at the tips of specialized hyphae called ________, often in clusters or long chains, from which they may be dispersed by the wind.

conidia; sporangia; conidiophores

Which of the following cells or structures are associated with asexual reproduction in fungi? ascospores basidiospores zygosporangia conidiophores

conidiophores

Chitin is a long-chain polymer derived from glucose. It strengthens cell walls of fungi and the outer covering (exoskeleton) of arthropods (including crabs, shrimps, and insects). The presence of chitin in these groups is likely due to ________. convergent evolution paraphyletic evolution horizontal gene transfer secondary endoparasitism

convergent evolution

Fungi that are _______ break down and absorb nutrients from nonliving organic material, such as fallen longs, animal corpses, and the wastes of organisms.

decomposers

Many ascomycetes are important ______, particularly of plant material.

decomposers

Most fungi are _____. photoautotrophs decomposers herbivores carnivores chemoautotrophs

decomposers

Mycelium

densely branched network of the hyphae of a fungus

Mycologists have traditionally lumped all fungi lacking sexual reproduction into a group called ________

deuteromycetes

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

dikaryotic In many fungi, after plasmogamy, the nuclei from each parent pair up but do not fuse, forming a dikaryon (a cell with two 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 diploid nuclei dikaryotic cells with diploid nuclei monokaryotic cells with a haploid nucleus more than one of the cell types listed

dikaryotic cells with haploid nuclei Environmental cues, such as rain and temperature changes, induce the dikaryotic mycelium (containing two haploid nuclei) to form compact masses that develop into basidiocarps, or mushrooms.

In most fungi, the haploid nuclei contributed by each parent do not fuse right away. Instead, parts of the fused mycelium contain coexisting, genetically different nuclei. Such a mycelium is said to be a _________. In some species, the haploid nuclei pair off two to a cell, one from each parent. Such a mycelium is _______.

dikaryotic; as a dikaryotic mycelium grows, the two nuclei in each cell divide in tandem without fusing. Because these cells retain two separate haploid nuclei, they differ from diploid cells, which have pairs of homologous chromosomes within a single nucleus.

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

diploid zygote

Unlike animals, fungi do not _________. Instead, a fungus absorbs nutrients from the environment outside of its body.

eat ingest their food.

zoospores

flagellated spores in chytrids

Some fungi that attack ____ ______ produce compounds that are toxic to ______.

food crops; humans

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

fossils Fossils from the late Silurian indicate that mycorrhizae existed in conjunction with some of the earliest vascular plants.

Zygosporangia are resistant to _______ and ______ and are metabolically _______. When conditions improve, the nuclei of the zygosporangium undergo _____, the zygosporangium germinates into a sporangium, and the sporangium releases genetically diverse _______ spores that may colonize a new substrate. Some mucoromycetes can actually ______ and then shoot their sporangia toward ______ ______.

freezing; drying; inactive; haploid; aim; bright light

When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter? larger bacterial populations fungal haustoria fungal enzymes increased oxygen levels

fungal enzymes

DNA sequence data indicate that these three groups of eukaryotes, the _______, ________, and _________, form a _________ group, or clade.

fungi, animals, and protistan relatives; monophyletic

Almost any carbon-containing substrate- even jet fuel and house paint- can be consumed by at least some _______. Fungi and Bacteria are primarily responsible for keeping ecosystems stocked with the _____ ______ essential for plant growth. Without these decomposers, carbon, nitrogen, and other elements would remain tied up in organic matter. If that were to happen, plants and animals that eat them could not exist because elements taken from the soil would not be returned.

fungi; inorganic nutrients

When pathogenic fungi are found growing on the roots of grape vines, grape farmers sometimes respond by covering the ground around their vines with plastic sheeting and pumping a gaseous fungicide into the soil. The most important concern of grape farmers who engage in this practice should be that the _____. fungicide might also kill the native yeasts residing on the surfaces of the grapes lichens growing on the vines' branches are not harmed fungicide might also kill mycorrhizae sheeting is transparent so that photosynthesis can continue

fungicide might also kill mycorrhizae

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

fungus

The ______ usually gives a lichen its overall shape and structure, and tissues formed by hyphae account for most of the lichen's mass. The cells of the alga or cyanobacterium generally occupy an ______ _____ below the lichen surface.

fungus; inner layer

mycosis

general term for a fungal infection

For a mycorrhizal fungus and its plant partner to establish a symbiotic relationship, certain _____ must be expressed by the fungus, and others by the plant. Researchers focused on three plant _____ called ________., whose expression is required for the formation of mycorrhizae in flowering plants. They found that these genes were present in all major plant lineages, including basal lineages such as liverworts. Furthermore, after they transferred a liverwort ______ _______ to a flowering plant mutant that could not form mycorrhizae, the mutant recovered its ability to form mycorrhizae. These results suggest that _______ _______ ______ were present in early plants, and that the function of these ______ has been conserved for hundreds of millions of years as plants continued to adapt to life on land.

genes; genes; sym genes; sym gene; mycorrhizal sym genes; genes

As in ascomycetes, the basidiomycetes have a long-lived dikaryotic mycelium. This extended dikaryotic stage provides many opportunities for ___________, multiplying the results of a single mating.

genetic recombination events

Mucoromycota includes the _______, clade of fungi that form abuscular mycorrhizae. The tips of the hyphae that push into plant root cells branch into tiny treelike arbuscles.

glomeromycetes

Researchers have described life on land before the arrival of plants as a "_______ ______" that consisted of cyanobacteria, algae, and a variety of small, heterotrophic species, including fungi. With their capacity for _____ ______, fungi would have been well suited for feeding on other early terrestrial organisms.

green slime; extracellular digestion

Fungi produce _____ spores. dikaryotic heterokaryotic haploid diploid triploid

haploid

The nuclei of fungal hyphae and the spores of most fungi are _____, although many species have transient _________ stages that form during sexual life cycles.

haploid, diploid

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

haustoria Haustoria are the modified hyphae of parasitic fungi.

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

help plants take up nutrients and water

Plasmogamy can directly result in which of the following? heterokaryotic cells or dikaryotic cells heterokaryotic cells or cells with two diploid nuclei cells with a single haploid nucleus or dikaryotic cells dikaryotic cells or cells with two diploid nuclei

heterokaryotic cells or dikaryotic cells

All fungi are symbiotic. heterotrophic. flagellated. decomposers.

heterotrophic

Like animals, fungi are _________. They cannot make their own food as plants and algae can.

heterotrophs

The microsporidian Nosema ceranae is a parasite of ________ and may contribute to ________ ________ Disorder, a devastating outbreak that has led to the loss of honeybee colonies throughout the world.

honeybees; Colony Collapse

Use the following information to answer the question. In the United States and Canada, bats use one of two strategies to survive winter. They either migrate south, or they hibernate. Recently, those that hibernate seem to have come under attack by a fungus, Geomyces destructans (Gd), an attack that is occurring from Missouri to New England, Canada, and even the state of Washington. Many infected bats have a delicate, white filamentous mat on their muzzles, which is referred to as white-nose syndrome (WNS). The fungus invades the bat tissues, causes discomfort, and awakens the bat from its hibernation. The bat fidgets and wastes calories, using up its stored fat. The bat then behaves abnormally, leaving its cave during daytime in winter to search for food. Their food, primarily insects, is scarce during the winter, and the bats ultimately starve to death. Since 2006, it is estimated that over six million bats have perished from WNS.The Gd mat on the fur of the bats should be expected to consist of ________. haustoria hyphae basidia yeasts

hyphae

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

hyphae ... mycelium

karyogamy

in fungi, the fusion of haploid nuclei contributed by two parents; produces diploid cells; occurs as one stage of sexual reproduction, preceded by plasmogamy; may take hours, days, or centuries; the only diploid stage in most fungi; zygotes form

zygosporangium

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

As a fungus absorbs nutrients from its environment, the concentrations of those nutrients in its cells ________, causes water to move into the cell by _______.

increases; osmosis; The movement of water into fungal cells creates pressure that could cause their cells to burst if they were not surrounded by a chitin-strengthened, rigid cell wall.

In zoopagomycetes, what does the zygosporangium do?

it houses and protects the zygote

In the basidiomycete life cycle, during ______, the two nuclei in each basidium fuse, producing a diploid nucleus. This nucleus undergoes _______, yielding four haploid nuclei, each of which ultimately develops into a basidiospore.

karyogamy; meiosis

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

lignin

How does the extended dikaryotic stage of ascomycetes provide additional opportunities for genetic recombination?

many dikaryotic cells can develop into asci. The haploid nuclei in the asci fuse, and their genomes then recombine during meiosis, resulting in a multitude of genetically different offspring from one mating event

Why does classifying fungi based on their type of sexual structure pose a problem?

many yeasts and filamentous fungi have no known sexual stage in their life cycle.

Where can cryptomycetes be found?

marine and freshwater communities, soil and aquatic habitats; aerobic and anaerobic environments, and geographical locations around the globe

Where do ascomycetes live?

marine, freshwater, and terrestrial habitats

After karyogamy, __________ then restores the haploid condition, ultimately leading to the formation of genetically diverse spores. This is a key step in sexual reproduction, so spores produced in this way are sometimes referred to as "___________" spores.

meiosis; sexual

Recent studies indicate that the _________, an enigmatic group of unicellular parasites, should be classified as fungi and may belong to a basal fungal lineage (one that diverged from other fungi early in the history of the group.)

microsporidians

Microsporidians have a highly reduced ______ and small _________, with only _______ genes in some species. They also lack ______ spores. Instead, they produce unique spores that infect cells via a _______-like organelle.

mitochondria; genome; 2,000; flagellated; harpoon

Yeasts often inhabit _________, including plant sap and animal tissues, where there is a ready supply of soluble nutrients, such as sugars and amino acids.

moist environments

Many fungi reproduce asexually by growing as filamentous fungi that produce spores by mitosis; these are informally referred to as ______, if they form visible _______

molds

As a result of data from molecular systematics, systematists now recognize that fungi and animals are ___________

more closely related to each other than either group is to plants or to most other eukaryotes

The most common fungal body structures are _______ and _________.

multicellular filaments and yeasts; Many fungal species can grow as both filaments and yeasts, but even more grow only as filaments; relatively few species grow only as single-celled yeasts.

While a zygosporangium represents the zygote stage in the life cycle, it is not a zygote in the usual sense. Rather a zygosporangium is a ________ structure- first ______ with many haploid nuclei from the two parents, then with many diploid nuclei after _______.

multinucleate; heterokaryotic; karyogamy

Some fungal species live in plants and can kill herbivores that feed on the plant. What type of relationship does this fungus have with its host? predatory parasitic commensal mutualistic

mutualistic

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

mycelia Fungal mycelia can be huge, although they usually escape our notice because they are subterranean.

Mycorrhizal fungi engage in mutualistic symbiosis with plants. Fossil evidence shows that these associations have been in existence since some of the first land plants. What benefit is derived by each partner from the other?

mycorrhizal fungi can improve delivery of phosphate ions and other minerals to plants because the vast mycelial networks of the fungi are more efficient than the plants' roots at acquiring these minerals from the soil. In exchange, the plants supply the fungi with organic nutrients such as carbohydrates.

The general term for an infection in an animal by a fungal parasite is ______

mycosis

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

obtaining food The hyphae form an interwoven mat called a mycelium, the feeding network of a fungus.

Where do lichens grow?

on the surfaces of rocks, rotting logs, trees, and roofs in various forms.

Why does the heterokaryotic condition of some fungi offer some of the advantages of diploidy?

one haploid genome may compensate for harmful mutations in the other

In asexual reproduction, one parent passes copies of all of its genes to its offspring after crossing over occurs. one parent passes copies of all of its genes to its offspring without the fusion of gametes. each parent passes copies of all of its genes to its offspring, causing the offspring to differ genetically from each other. each offspring has some cells derived by mitosis in the parent and other cells derived by meiosis in the parent.

one parent passes copies of all of its genes to its offspring without the fusion of gametes.

What is chytrid?

parasites that cause a skin infection in amphibians; They have been implicated in the recent decline or extinction of 500 species of frogs and other amphibians.

Suppose two species live in close contact with each other. One species benefits by eating the tissues of the other, and the other is harmed (by having its tissues consumed). The ecological interaction between these species is an example of mutualism and parasitism. symbiosis and mutualism. symbiosis and commensalism. parasitism and symbiosis.

parasitism and symbiosis.

The first antibiotic discovered was ______ made by the ascomycete mold ______.

penicillin; Penicillium

In fungi, sexual reproduction often begins when hyphae from two mycelia release signaling molecules called _________.

pheromones

Lichens are important pioneers on cleared rock and soil surfaces, such as volcanic flows and burned forests. They break down the surface by ______ penetrating and _______ attacking it, and they trap ________ _______. Nitrogen-fixing lichen also add organic nitrogen to some ecosystems.

physically; chemically; windblown soil

Zoopagomycetes form filamentous hyphae and reproduce asexually by ______ _______ ______.

producing nonflagellated spores

Most fungi propagate themselves by

producing vast numbers of spores, either sexually or asexually (puffballs, the reproductive structures of certain fungal species, may release trillions of spores)

Many of the cryptomycetes identified to date are parasites of ________ and _______.

protists and fungi

In most fungi, karyogamy does not immediately follow plasmogamy, which consequently _____. results in heterokaryotic or dikaryotic cells means that sexual reproduction can occur in specialized structures allows fungi to reproduce asexually most of the time results in multiple diploid nuclei per cell

results in heterokaryotic or dikaryotic cells

What are examples of human skin mycoses?

ringworm; athelete's foot

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

rusts

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

saclike structures

The symbioses are so complete that lichens are given _____ _____.

scientific names

Conidia may also be involved in ______ reproduction, fusing with _____ from a mycelium of a different mating type. Fusion of two different mating types is followed by _______, resulting in the formation of _________ cells, each with two haploid nuclei representing the two parents. The cells at the tips of the dikaryotic hyphae develop into many _____. Within each ascus,_________ combines the two parental genomes, and then meiosis forms four genetically different nuclei. This is usually followed by a _______ division, forming eight ascospores. The ascospores develop in and are eventually discharged from the ascocarp.

sexual; hyphae; plasmogamy; dikaryotic; asci; karyogamy; mitotic

If environmental conditions deteriorate, like if the mold consumes all its food, mucoromycetes may reproduce _______.

sexually

Periodically, in response to environmental stimuli, the mycelium in basidiomycetes reproduces ______ by producing elaborate fruiting bodies called ________.

sexually; basidiocarps

After cytokinesis occurs in budding yeasts, the daughter cell has a _____. similar nucleus and less cytoplasm than the mother cell larger nucleus and less cytoplasm than the mother cell smaller nucleus and less cytoplasm than the mother cell similar nucleus and more cytoplasm than the mother cell

similar nucleus and less cytoplasm than the mother cell

What are systemic mycoses?

spread through the body and cause very serious illnesses; caused by inhaled spores; coccidiodomycosis is a systemic mycosis that produces tuberculosis-like symptoms in the lungs

Fungi release digestive enzymes into their _____. surroundings gastrovascular cavity stomach hyphae mycelia

surroundings

lichen

symbiotic association between a fungus and a photosynthetic organism

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

symbiotic associations of photosynthesizers and fungi

All plant species studied to date appear to harbor _____ ______, fungi that live inside leaves or other plant parts without causing harm. Most fungal endophytes identified to date at _______ but some are _______.

symbiotic endophytes; ascomycetes; mucoromycetes;

Once on land, some fungi formed ______ associations with early _______. The early Aglaophyton contain evidence of ________ relationships. This includes fossils of _____ that have been penetrated with ______ cells and formed structures that resemble the ______ formed today. The earliest plants lacked ______, limiting their ability to extract nutrients from the soill. It is likely that soil nutrients were transferred to early plants via the extensive _____ formed by their symbiotic fungal partners.

symbiotic; plants; mycorrhizal; hyphae; plant; arbuscles; roots; mycelia

Where are chytrids found?

terrestrial, freshwater, and marine habitats

Which basal lineages of fungi have flagella? Moreover, most of the protists that share a close common ancestor with _____ and ______ have flagella.

the cryptomycetes and the chytrids; animals; fungi

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

the heterokaryotic stage of the fungal life cycle zygote

How do fungal endophytes benefit certain grasses and other non woody plants?

the may toxins that deter herbivores or by increasing host plant tolerance of heat, drought, or heavy metals

What does the "opistho" of opisthokonts refer to?

the posterior location of the flagellum

What is the defining feature of ascomycetes?

the production of spores in saclike asci.

Fungal species are assigned to particular phyla based on _____. the type of sexual structure they form their mode of nutrition whether they produce sexually or asexually whether they are mutualistic or parasitic their type of motility

the type of sexual structure they form Whenever a sexual stage of a so-called deuteromycete is discovered, the species is classified in a particular phylum, depending on the type of sexual structures it forms.

The photosynthetic partner of lichens are ______ or _______ ______ ______ or _________. The fungal component is most often an _________, but some glomeromycete and basidiomycete lichens are known.

unicellular or filamentous green algae or cyanobacteria; ascomycete

Cryptomycetes are _______ and have _________ spores. Like microsporidians, they can also synthesize a _____ _____ cell wall, a key structural feature of the fungi.

unicellular; flagellated; chitin-rich

Microsporidians are _______ parasites of _________ and ________

unicellular; protists and animals

What suggests that the ancestor of fungi was unicellular?

within the opisthokont clade, fungi are more closely related to several groups of single-celled protists than they are to animals

Basidiomycetes are important decomposers of ______ and other plant material. Of all the fungi, certain basidiomycetes are the best at decomposing the complex polymer ____, an abundant component of wood.

wood; lignin

Ascomycetes vary in size and complexity from unicellular _______ to elaborate _____ fungi and ______.

yeasts; cup; morels

Besides molds, other fungi reproduce asexually by growing as single-celled _______. Instead of producing spores, asexual reproduction in ____ occurs by ordinary cell ________, or by the pinching of small "_____ _____" off a parent cell.

yeasts; yeasts; division; bud cells

Nearly all chytrids have flagellated spores, called

zoospores

In Mucoromycetes, plasmogamy produces a sturdy structure called a ______ in which karyogamy and then meiosis occur.

zygosporangium