Chapter 31

Plasmogamy is indicated by the letter _____.

Plasmogamy is the fusion of hyphae

Arrange the following in order from largest to smallest, assuming that they all come from the same fungus.

mycelium, basidiocarp, gill, basidium, basidiospore

The following statements describe something about the body structures or functions of fungi.

-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. -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.

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

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

Cup fungi are in the phylum _____.

Ascomycota

Which of the following results would support Simard et al.'s (1997) hypothesis that fungi can move carbon from one plant to another? [Hypothesis: Sugars made by one plant during photosynthesis can travel through a mycorrhizal fungus and be incorporated into the tissues of another plant.]

Carbon-14 is found in the Douglas fir seedling's tissues and carbon-13 in the birch.

Sort the following fungi based on whether they are decomposers, mutualists, or parasites.

Decomposer: -fungi in asso. with a fallen log -fungi in asso. with a dead rabbit -coprophilous fungi Mutualist: -mycorrhizal fungi on pine tree roots -fungi in the family Lepiotaceae Parasite: -Trichophyton spp. -Cryphonectria parasitica -Cordyceps spp. -Septobasidium spp. and an individual scale insect infeted by fungal hyphae

In most fungi, fertilization is complete after the cells fuse together.

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.

Which of the following is a difference between plants and fungi?

Fungi are heterotrophic, and plants are autotrophic.

Fungi form mutualistic relationships with plants and animals. Which of the following is an example of such a relationship?

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

Why are mycorrhizal fungi superior to plants at acquiring mineral nutrition from the soil?

Fungi secrete extracellular enzymes that can break down large molecules.

Almost all of the members of this phylum form arbuscular mycorrhizae in a mutualistic partnership with plants.

Glomeromycota

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

Hyphae are produced by mitosis.

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

Karyogamy produces a diploid zygote.

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

Multicellularity probably arose independently in fungi and animals.

Which structure allows the growing mushroom to nourish itself?

Mycelium

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

Photosynthetic cells are surrounded by fungal hyphae

Which term describes the fusion of cytoplasm from two individuals?

Plasmogamy is the fusion of cytoplasm from different individuals.

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.

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

Most of the cells in a mushroom contain haploid nuclei.

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.

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.

a. mycelium b. pore c. septum d. septate hypha e. coenocytic hypha

Fungi obtain nutrients through _____.

absorption

Where does meiosis occur in a mushroom?

basidia

The multicellular condition of animals and fungi seems to have arisen _____.

by convergent evolution

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

Most fungi are _____.

decomposers; Fungi obtain nutrients from nonliving organic matter.

Karyogamy produces a _____.

diploid zygote

When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter?

fungal enzymes

Deuteromycetes

fungi lacking sexual reproduction; are the group of fungi that have, at present, no known sexual stage

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 and water

All fungi share which of the following characteristics?

heterotrophic

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

hyphae ... mycelium

What sexual processes in fungi generate genetic variation?

karyogamy and meiosis

If haustoria from the fungal partner were to appear within the photosynthetic partner of a lichen, and if the growth rate of the photosynthetic partner consequently slowed substantially, then this would support the claim that _____.

lichens are not purely mutualistic relationships

Basidia produce spores by a process known as _____.

meiosis

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

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

prokaryotes

In most fungi, karyogamy does not immediately follow plasmogamy, which consequently _____.

results in heterokaryotic or dikaryotic cells

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

rusts; Rusts include destructive plant parasites.

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

saclike structures

A billionaire buys a sterile volcanic island that recently emerged from the sea. To speed the arrival of conditions necessary for plant growth, the billionaire might be advised to aerially sow what over the island?

soredia

Fungi release digestive enzymes into their _____.

surroundings

Which of these contains two haploid nuclei?

the heterokaryotic stage of the fungal life cycle