Homework 10: Ch. 31 Fungi

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

- In some fungi, plasmogamy precedes kayogamy by decades - Fungi reproduce sexually but do not have male or female genders

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

- Multicellularity probably arose independently and fungi and animals.

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

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

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

- Predation - Decomposition

Part B - Fungal morphology and physiologyThe following statements describe something about the body structures or functions of fungi. Identify those statements that are correct. Select all that apply.

- 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.

Cup fungi are in the phylum _____.

Ascomycota; Cup fungi are a type of sac fungus.

Plasmogamy is indicated by the letter _____.

B Plasmogamy is the fusion of hyphae

Where does meiosis occur in a mushroom?

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

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

C. Karyogamy produces a diploid zygote

Part C - Ecological interactions of fungi Most fungi are decomposers; they recycle the nutrients from nonliving organic matter. Other fungi are specialized to live in symbiotic relationships with other organisms. Some fungi live as parasites and others as mutualists. Most plants, in fact, could not survive and grow without their fungal partner. This table lists some examples of different fungal strategies for obtaining nutrients. Sort the following fungi based on whether they are decomposers, mutualists, or parasites.Drag each item to the appropriate bin.

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 infected by fungal hyphae

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

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

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

Hyphae; mycelium

Part A - Structure of multicellular fungi 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.) Drag the labels to their appropriate locations on the diagram of the fungus and hyphae below.

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

Fungi obtain nutrients through _____.

absorption

The closest relatives of fungi are thought to be the

animals

Most fungi are ________

decomposers; fungi obtain nutrients from nonliving organic matter

Karyogamy produces a _____.

diploid zygote. Karyogamy is the fusion of nuclei

True or false? 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.

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; Mycorrhizae are mutualistic associations with the roots of plants, which enhance the absorption of nutrients

What sexual processes in fungi generate genetic variation?

karyogamy and meiosis

Basidia produce spores by a process known as _____.

meiosis

which structure allows the growing mushroom to nourish itself?

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

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

mycelium: network of filaments that form the body of a fungus

Which term describes the fusion of cytoplasm from two individuals?

plasmogamy; the fusion of cytoplasm from different individuals

Fungi release digestive enzymes into their _____.

surroundings, and then absorb the digested nutrients.

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

True or false? 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.