Ch 31

Cup fungi are in the phylum _____.

Ascomycota

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.

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

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

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

Glomeromycota Nearly all glomeromycetes form arbuscular mycorrhizae.

Fungi produce _____ spores.

Haploid

Which term describes the fusion of cytoplasm from two individuals?

Plasmogamy Plasmogamy is the fusion of cytoplasm from different individuals.

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

What sexual processes in fungi generate genetic variation?

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

Which of these contains two haploid nuclei?

the heterokaryotic stage of the fungal life cycle The heterokaryotic stage is produced by plasmogamy

Fungi obtain nutrients through _____.

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

Describe some body structures and functions of fungi

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. Some fungi secrete digestive enzymes into the environment and then absorb the digested nutrients. Some fungi can grow as either filamentous or single-celled forms.

Plasmogamy is indicated by the letter _____.

B Plasmogamy is the fusion of hyphae

Where does meiosis occur in a mushroom?

Basidia Basidia are 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

Karyogamy produces a _____.

Diploid zygote Karyogamy is the fusion of nuclei

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

Fungi are heterotrophic, and plants are autotrophic. Fungi are heterotrophic and absorb their nutrients, and plants are photosynthetic.

Which of the following events occurs first 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 a mycelium.

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

Hyphae form a network called a mycelium.

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

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

Which structure allows the growing mushroom to nourish itself?

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

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

Sac-like structures The production of saclike structures during sexual reproduction is characteristic of the phylum Ascomycota.

How is the structure of a multicellular fungus organized?

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.

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.

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

all of the above Fungi enter into these and many other mutualistic relationships with other organisms

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.