Ch 32: Fungi

Question 1

Fungi

Answer 1

An abundant and diverse group of heterotrophic eukaryotic organisms, principally responsible for the decomposition of plant and animal tissues.

Question 2

Hyphae

Answer 2

In fungi, highly branched multicellular filaments that provide a large surface area for absorbing nutrients.

Question 3

Mycelium

Answer 3

A network of branching hyphae.

Question 4

Chitin

Answer 4

A modified polysaccharide containing nitrogen that makes up the cell walls of fungi and the hard exoskeletons of arthropods.

Question 5

Septa

Answer 5

In fungal hyphae, a wall that partially divides the cytoplasm into separate cells.

Question 6

Yeast

Answer 6

A single-celled fungus found in moist, nutrient-rich environments. Many yeasts can metabolize sugar by means of fermentation.

Question 7

Ectomycorrhizae

Answer 7

One of the two main types of mycorrhizae; ectomycorrhizae produce a thick sheath of fungal cells (hyphae) that surround the root tip, as well as hyphae that grow between, but do not penetrate, cells in the interior of the root.

Question 8

Endomycorrhizal

Answer 8

One of the two main types of mycorrhizae; endomycorrhizal hyphae penetrate into root cells, where they produce highly branched structures (arbuscules) that provide a large surface area for nutrient exchange.

Question 9

Endophyte

Answer 9

A fungus that lives within leaves and that may help the host plant by producing chemicals that deter pathogens and herbivores.

Question 10

Lichen

Answer 10

Stable associations between a fungus and a photosynthetic microorganism, usually a green alga but sometimes a cyanobacterium.

Question 11

Fruiting Body

Answer 11

A multicellular structure in some fungi that facilitates the dispersal of sexually produced spores.

Question 12

Plasmogamy

Answer 12

The cytoplasmic union of two cells.

Question 13

Karyogamy

Answer 13

The fusion of two nuclei following plasmogamy.

Question 14

Heterokaryotic

Answer 14

Describes a stage in the life cycle of some fungi, in which plasmogamy is not followed immediately by karyogamy and the cells have unfused haploid nuclei from both parents.

Question 15

Dikaryotic

Answer 15

Having two haploid nuclei, one from each parent, in each cell.

Question 16

Mating types

Answer 16

Genetically distinct forms of individuals of a fungus species that, by enabling fertilization only between different types, prevent self-fertilization and promote out-crossing.

Question 17

Parasexual

Answer 17

Describes asexual species that generate genetic diversity by the crossing over of DNA during mitosis.

Question 18

Chytrid

Answer 18

Primarily aquatic fungi that have simple, often unicellular bodies and that produce flagellated gametes and spores.

Question 19

Zygomycota

Answer 19

Fungi that produce hyphae undivided by septa and do not form multicellular fruiting bodies; they make up less than 1% of known fungal diversity.

Question 20

Glomeromycota

Answer 20

A monophyletic fungal group of apparently low diversity but tremendous ecological importance that occurs in association with plant roots.

Question 21

Dikarya

Answer 21

A fungal group that includes about 98% of all described fungal species and in which dikaryotic cells are formed.

Question 22

Ascomycetes

Answer 22

A monophyletic fungal subgroup of the Dikarya in which nuclear fusion and meiosis take place in an elongated saclike cell called an ascus; also called sac fungi.

Question 23

Basidiomycetes

Answer 23

A monophyletic fungal subgroup of the Dikarya, including smuts, rusts, and mushrooms, in which nuclear fusion and meiosis take place in a club-shaped cell called a basidium; also called club fungi.

Question 24

T/F: Fungi are the most important decomposers of wood in the ecosystem.

Answer 24

True

Question 25

To what group do aquatic fungi with flagellated spores belong?

Answer 25

chytrids

Question 26

How do endophytes differ from endomycorrhizal fungi?

Answer 26

Endophytes live within leaves, whereas endomycorrhizal fungi live within roots.

Question 27

In what ways are mycelia and fruiting bodies similar?

Answer 27

Both are composed of hyphae.

Question 28

T/F: Ascomycete yeasts evolved from multicellular ancestors.

Answer 28

True

Question 29

T/F: Lichens are symbiotic relationships between a fungus and a plant.

Answer 29

False

Question 30

In fungi, _____ cells are cells composed of the cytoplasm of two or more cells, but they retain distinct sets of chromosomes contained in separate nuclei.

Answer 30

heterokaryotic

Question 31

A scientist collects a spore from a new species of fungus and observes that this spore has a flagellum. What does the presence of a flagellum suggest about the lifestyle of this species?

Answer 31

The species is aquatic.

Question 32

Fungi are most closely related to:

Answer 32

arthropods, which are organisms that also produce chitin.

Question 33

What is the advantage of a fungal body being composed of numerous thin hyphae instead of one or two very thick hyphae?

Answer 33

A greater surface area is available for absorption of nutrients.

Question 34

What is the primary advantage of having multiple mating type alleles?

Answer 34

There is an increased probability that two fungi encountering each other will have compatible mating types.

Question 35

The stage of the fungal life cycle during which two or more genetically distinct nuclei are found in the same cell is referred to as the:

Answer 35

heterokaryotic stage.

Question 36

Crossing over during mitosis increases genetic diversity during:

Answer 36

parasexuality.

Question 37

When a fungus encounters a particularly rich food source, what is the expected result?

Answer 37

Hyphae branch and extend rapidly from their tips to form a mycelium.

Question 38

T/F: One of the greatest advantages of sexual reproduction is the generation of variability.

Answer 38

True

Question 39

_____ and _____ are structures formed in the fruiting bodies of dikaryotic (n + n) fungi that produce spores.

Answer 39

Basidia; asci

Question 40

Toadstools are mushrooms with a central stalk and a cap with gills. Which type of fungus are toadstools?

Answer 40

basidiomycetes

Question 41

How is karyogamy different from plasmogamy?

Answer 41

Karyogamy is the fusion of nuclei, whereas plasmogamy is the fusion of cytoplasm.

Question 42

Within the fungal body, nutrients are transported from the _____ to the _____ by the process of _____.

Answer 42

mycelium; fruiting body; bulk flow

Question 43

What is the primary reason that fungi are important in the carbon cycle?

Answer 43

Fungi are able to reach incredibly large sizes. Their high ratio of surface area to volume allows them to decompose large amounts of dead and decaying material, thereby returning carbon to the atmosphere.

Question 44

How are the spores of zygomycetes such as Rhizopus dispersed?

Answer 44

By the wind

Question 45

Fungi produce fruiting bodies to:

Answer 45

enhance spore dispersal

Question 46

In many groups of fungi, karyogamy and plasmogamy are separated in time and space. One potential advantage of this arrangement is that:

Answer 46

mating and spore production can occur in different environments.