Chapter 31

For the past several decades, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis. Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. When adult amphibian skin harbors populations of the bacterium Janthinobacterium lividum, chytrid infection seems to be inhibited. Which of the following is the best experimental design to test whether this inhibition is actually due to the presence of J. lividum?

Take infected amphibians and assign them to two populations. Leave one population alone; inoculate the other with J. lividum. Measure the rate at which infection proceeds in both populations.

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?

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

Fungi interact with many organisms in mutualistic ways. Which of the following involves a fungus that is mutualistic with another organism?

a fungus that is raised by ants on leaves that the ants collect from trees and shrubs

Fungi obtain nutrients through _____.

absorption

The most important adaptive advantage associated with the filamentous nature of fungal mycelia is...

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

Which of the following statements describes an adaptive advantage associated with the filamentous nature of fungal mycelia?

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

The closest relatives of fungi are thought to be the...

animals

Where does meiosis occur in a mushroom?

basidia

Orchid seeds are tiny, with virtually no endosperm and with miniscule cotyledons. If orchid seeds are deposited in a dark, moist environment, then which of the following represents the most likely means by which fungi might assist in seed germination?

by providing the embryos with some of the organic nutrients the fungi have absorbed

You observe the gametes of a fungal species under the microscope and realize that they resemble animal sperm. To which of the following groups does the fungus belong?

chytrids

Fungi and plants evolved during the same time period. What combination of environmental and morphological change is similar in the evolution of both fungi and plants?

colonization of land and loss of flagellated cells

Which of the following cells or structures are associated with asexual reproduction in fungi?

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 the result of which of the following processes?

convergent evolution

Which of the following describes the evolution of multicellularity in fungi and animals?

convergent evolution

A fungal spore germinates, giving rise to a mycelium that grows outward into the soil surrounding the site where the spore originally landed. Which of the following accounts for the outward growth of the mycelium?

cytoplasmic streaming in hyphae

Most fungi are _____.

decomposers

Which of the following ecological roles is/are played by at least some fungi?

decomposition & predation

For the past several decades, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis. Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. Sexual reproduction has not been observed in B. dendrobatidis. If its morphology and genetics did not identify it as a chytridiomycete, then to which fungal group would B. dendrobatidis be assigned?

deuteromycetes

Karyogamy produces a _____.

diploid zygote

If you wanted to use fungi to improve the environment, which of the following research goals would make the most sense?

discover the lignin-digesting enzymes of fungi, and use them to digest plant tissues left over from food-crop residues to reduce landfill waste

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

false

Which feature seen in chytrids supports the hypothesis that they diverged early in fungal evolution?

flagellated spores

Which of the following observations would best support the hypothesis that the ability to form mycorrhizal associations arose very early in plant evolution?

formation of mycorrhizae by a flowering plant that expresses a gene from a liverwort

When a mycelium infiltrates a recently killed mouse carcass, which of the following is most likely to appear within the tissues of the mouse soon thereafter?

fungal enzymes

Which of the following statements correctly describes a difference between plants and fungi?

fungi are heterotrophic, but plants are autotrophic

Which of the following best explains how mycorrhizal fungi are more efficient than plants at acquiring mineral nutrition from the soil?

fungi secrete extracellular enzymes that can break down large molecules

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. Which of the following results might be a concern for the grape farmers who engage in this practice?

fungicide might also kill mycorrhizae

The diploid phase of the life cycle is shortest in which of the following?

fungus

Fungi produce _____ spores.

haploid

An important example of interaction between fungi and certain other organisms is mycorrhizae, in which the fungal partners _____.

help plants take up nutrients faster

Plasmogamy can directly result in which of the following types of cells?

heterokaryotic cells or dikaryotic cells

All fungi are...

heterotrophic

In the United States and Canada, bats have become infected by a fungus, Geomyces destructans. Many infected bats have a delicate, white filamentous mat on their muzzles, which is referred to as white-nose syndrome (WNS). The G. destructans mat most likely consists of which of the following structures?

hyphae

Which of the following events occurs first in the development of a spore into a mature mushroom?

hyphae are produced by mitosis

The body of most fungi consists of threadlike __________, which form a network called a __________.

hyphae, mycelium

Some companies advertise and sell mycorrhizae to home gardeners and commercial farms, claiming that the presence of mycorrhizae improves plant growth and survival. If the company conducted experiments on plants with and without mycorrhizae, which of the following results would support their claim?

increased production of corn ears in plants with mycorrhizae than in plants without mycorrhizae Submit

In most fungi, karyogamy does not immediately follow plasmogamy. Which conclusion is most consistent with this information?

it results in heterokaryotic or dikaryotic cells

What sexual processes in fungi generate genetic variation?

karygamy & meiosis

Mycorrhizae are often found associated with the roots of vascular plants. Where are fungal endophytes typically found in vascular plants?

leaf mesophyll

A billionaire buys a sterile volcanic island that recently emerged from the sea. Seeding the island with which of the following would most likely accelerate the development of conditions that would support plant growth?

lichens

Basidia produce spores by a process known as _____.

meiosis

Select the correct statement(s) about the origin of fungi.

multicellularity probably arose independently in fungi & animals

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?

mutualistic

Which structure allows the growing mushroom to nourish itself?

mycelium

Which structure is not directly involved in the reproduction of at least one major group of fungi?

mycelium

Which answer arranges the following structures in order from largest to smallest, assuming that they all come from the same fungus?

mycelium, basidiocarp, gill, basidium, basidiospore

Which of the following best describes the physical relationship of the partners involved in lichens?

photosynthetic cells are surrounded by fungal hyphae

Almost all of the members of which phylum form arbuscular mycorrhizae in a mutualistic partnership with plants?

phylum Mucoromycota

Which statement(s) correctly describe(s) the interactions between plants and fungi?

plants depend on fungi as mutualistic symbionts & are harmed by fungal pathogens

At which stage of a basidiomycete's life cycle would reproduction be halted if an enzyme that prevented the fusion of hyphae was introduced?

plasmogamy

Which term describes the fusion of cytoplasm from two individuals?

plasmogamy

If all fungi in an environment were to suddenly die, then which group of organisms is most likely to benefit, due to the fact that its fungal competitors have been removed?

prokaryotes

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?

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

From the human perspective, which of the following kinds of fungi would be considered the least useful or beneficial?

rusts

Fungi of the phylum Ascomycota are recognized on the basis of their production of __________ during sexual reproduction.

saclike structures

Which of the following statements correctly describes the daughter cells that result from cytokinesis in budding yeasts?

similar nucleus and less cytoplasm than the mother cell

In which of the following human mycoses should one expect to find a growth pattern most similar to that of the mycelium that produces a fairy ring?

skin mycoses

Fungi release digestive enzymes into their _____.

surroundings

Fungi produce many compounds that humans use medicinally. Which of the following statements best describes the evolution of these compounds in fungi?

the compounds probably provide a benefit to the fungi

- Rose-picker's disease is caused by the yeast Sporothrix schenkii that if introduced into the human body can assume a hyphal morphology and grow along the interiors of lymphatic vessels until they reach a lymph node. - Lymph nodes are important for the immune system because many white blood cells (phagocytes and lymphocytes) reside there. Given that a successful infection by S. schenkii damages lymph nodes themselves, which of the following is most probable?

the fungal conversion from yeast to hyphal morphology allows such fast growth that the body's defenses are at least temporarily overwhelmed

Which of these contains two haploid nuclei?

the heterokaryotic stage of the fungal life cycle

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

Which of the following statements correctly describes deuteromycetes?

they are the group of fungi that have, at present, no known sexual stage

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

true

Truffles are the fruiting bodies of certain fungi whose mycelium grows below ground. The truffle is also underground and can be detected by many mammals, which eat the truffle and expel the spores with their feces. Which of the following statements is likely accurate with respect to this interaction?

truffles produce an odor that mammals can detect and find attractive

Cup fungi are in the phylum _____.

Ascomycota

Why might you expect to find many genes for membrane transporters in a mycorrhizal fungus such as L. bicolor?

Mycorrhizal fungi exchange nutrients with the roots of their plant hosts and would be expected to use membrane transporters in this exchange

Which of the following characteristics would be most helpful in distinguishing among different species of fungi?

DNA sequence

Some nematode worms consume plant juices from the roots of plants and are economically important agricultural pests. Some fungi are usually decomposers of plant material, but some trap and kill nematodes at times. Arthrobotrys traps and kills nematodes, especially when they lack nitrogen sources. These two facts suggest that farmers could find Arthrobotrys an important tool in combating nematode infestations. Which of the following research questions would make a good starting point for developing such a defense against nematode pests?

Does nitrogen fertilization of crops affect the likelihood that Arthrobotrys will trap and kill nematodes? Submit

Fungi form mutualistic relationships with plants and animals; which of the following statements is an example of such a relationship?

- fungi can help increase drought tolerance in plants - endophytes in leaves produce toxins that deter herbivores - fungi help break down plant material in the guts of grazing mammals - fungi help break down wood in the guts of termites

Select the correct statement(s) about fungal life cycles.

- fungi reproduce sexually but do not have male or female genders - in some fungi, plasmogamy precedes karyogamy by decades

Diploid nuclei of the ascomycete Neurospora crassa contain 14 chromosomes. A single diploid cell in an ascus will undergo one round of meiosis, followed in each of the daughter cells by one round of mitosis, producing a total of eight ascospores. How many chromosomes would a single ascospore nucleus of this species contain?

7 chromosomes