Chapter 31: Fungi

Question 1

What is fungi’s mode of nutrition?

Answer 1

Absorptive heterotroph

Question 2

What is the most common fungal body structure?

Answer 2

multicellular filaments and single cells (yeast)

Question 3

Define hyphae

Answer 3

many connected filaments that collectively make up the mycelium of a fungus

Question 4

Define mycelium

Answer 4

a mass of hyphae

Question 5

What do fungal cell walls contain?

Answer 5

Chitin (a strong but flexible nitrogen-containing polysaccharide)

Question 6

Define septa

Answer 6

the cross-walls that the cells of hyphae are divided into

Question 7

Define coenocytic fungi

Answer 7

Fungi are organisms that consist of a continuous cytoplasmic mass having hundred or thousands of nuclei. The coenocytic condition results from the repeated division of nuclei without cytokinesis.

Question 8

What are the two forms of hyphae?

Answer 8

Septate hypha and coenocytic hypha

Question 9

What is a septate hypha?

Answer 9

Hypha with multiple septums containing pores within the cytoplasm and nuclei

Question 10

What is a coenocytic hypha?

Answer 10

Hypha with only cytoplasm and nuclei

Question 11

What does the mycelium do?

Answer 11

infiltrates the material on which the fungus feeds. The structure maximizes its surface-to-volume ratio

Question 12

Define ectomycorrhizal fungi

Answer 12

a symbiotic fungus that forms sheaths of hyphae over the surface of plant roots and also grows into extracellular spaces of the root cortex

Question 13

Define arbuscular mycorrhizal fungi

Answer 13

A symbiotic fungus whose hyphae grow through the cell wall of plant roots and extend into the root cell (enclosed in tubes formed by invagination - pushing inward - of the root cell plasma membrane)

Question 14

Define mycorrhizae

Answer 14

a fungus which grows in association with the roots of a plant in a symbiotic or mildly pathogenic relationship

Question 15

Define pheromones

Answer 15

chemical substances that are created and emitted by organisms as odorants

Question 16

When does sexual reproduction begin in fungi?

Answer 16

When hyphae from two mycelia release sexual signaling molecules called pheromones

Question 17

What happens when the mycelia are of different mating types?

Answer 17

The pheromones from each partner bind to receptors on the other, and hyphae extend toward the source of the pheromones, where they fuse.

Question 18

Define plasmogamy

Answer 18

the union of the cytoplasm’s of two parent mycelia

Question 19

Define heterokaryon

Answer 19

a multinucleate cell that contains genetically different nuclei

Question 20

Define dikaryotic

Answer 20

characterized by the presence of two nuclei in each cell

Question 21

Define karyogamy

Answer 21

the haploid nuclei contributed by the two parents fuse, producing diploid cells
- zygotes and other transient structures form during this stage