7. Chapter 31: Fungi

Question 1

What is the main function of fungi?

Answer 1

decompose organic material

Question 2

What are the similarities and differences between plant and fungi?

Answer 2

Similar: eukaryotes and most are multicellular Differences: nutritional mode (heterotrophs by nutrient absorption), cell walls, growth, and reproduction

Question 3

What are exoenzymes?

Answer 3

Secreted by the fungus, digest food outside its body to simpler compounds

Question 4

How are fungi constructed?

Answer 4

tiny filaments that form an interwoven mat (Hyphae: tiny filaments that form the body of most fungi, Mycelium: a densely branched network of hyphae in a fungus)

Question 5

Do fungal hyphae have cell walls?

Answer 5

Yes, these are built mainly of chitin – a strong but flexible polysaccharides. (Chitin is also found in the exoskeleton of arthropod)

Question 6

What is the function of septa?

Answer 6

divides the multicellular fungi with hyphae into cells. (generally have large pores)

Question 7

What do fungi that lack septa consist of?

Answer 7

continuous cytoplasmic mass with hundreds of nuclei (can have repeated nuclear division without cytoplasmic division)

Question 8

What are haustoria?

Answer 8

some modified hyphae in parasitic fungi; nutrient-absorbing tips that penetrate the tissue of their host (some adapted to preying on animals)

Question 9

How do fungi reproduce?

Answer 9

By releasing spores

Question 10

How many fungi species are known? How many species estimated worldwide?

Answer 10

More than 100, 000 species of fungi are known; 1.5 million species worldwide.

Question 11

What are the four phyla of fungi?

Answer 11

Zygomycota, Ascomycota, Basidiomycota

Question 12

Answer 12

(We don’t use the term of male or female here, we only use positive or negative (they are not genetically identical) In heterokaryotic stage = zygosporangium Karyogamy => 2N nuclei)

1. Asexual reproduction
2. sexual reproduction
3. mycelium
4. spore-producing structures
5. spores
6. germination
7. plasmogamy (fusion of cytoplasm)
8. Heterokaryotic stage
9. karyogamy (fusion of nuclei)
10. zygote
11. meiosis

Question 13

What is the ploidy of the nuclei of fungal hyphae and spores of most species?

Answer 13

Haploid

Question 14

What is the process in which the cytoplasm of two genetically different hyphae fuse?

Answer 14

Plasmogamy (results in the formation of a heterokaryon)

Question 15

What is a heterokaryon?

Answer 15

a mycelium with two genetically distinct nuclei

Question 16

What is Karyogamy?

Answer 16

fusion of the haploid nuclei contributed by the two parents, occurs after the fusion of the cytoplasm

Question 17

The life cycle and biology of Rhizopus stolonifer, black bread mold, is typical of zygomycetes.

Answer 17

First a spore must reach the bread; they are almost everywhere. Hyphae spread out over food and digest nutrients. In the asexual phase, hundreds of haploid spores develop in sporangia. If environmental conditions deteriorate, they reproduce sexually. Plasmogamy (fusion of cytoplasm) of opposite mating types produces a resistant structure, the zygosporangium. In the zygosporangium, the multiple haploid nuclei undergo Karyogamy, the fusion of the haploid nuclei contributed by the two parents. These diploid nuclei undergo meiosis, producing haploid spores. Note: there is no multicellular diploid stage.

Question 18

What is phylum ascomycota also known as? Where do half of the species live?

Answer 18

sac fungi (range in size and complexity from unicellular yeasts to elaborate cup fungi and morels) About half the ascomycete species live with algae in mutualistic associations called lichens.

Question 19

What is the defining feature of ascomycota?

Answer 19

the formation of an ascus, a sac containing eight spores formed during sexual reproduction.

Question 20

Where is the name of the phylum Basidiomycota derived?

Answer 20

the basidium, a reproductive appendage that produces sexual spores. (The club like shape of the basidium is responsible for the common name, club fungus.)

Question 21

How many know species of fungi are in phylum Basidiomycota? List some examples.

Answer 21

Approximately 25,000 fungi, including mushrooms, shelf fungi, and puffballs

Question 22

What is a mold?

Answer 22

rapidly growing, asexually reproducing fungus. (the same fungus may reproduce sexually, producing zygosporangia, ascocarps, or basidiocarps)

Question 23

Why can’t some molds be classified as zygomycetes, ascomycetes, or basidiomycetes?

Answer 23

because they have no known sexual stages (imperfect fungi)

Question 24

What are yeast? How do they reproduce?

Answer 24

unicellular fungi that inhabit liquid or moist habitats, including plant sap and animal tissues. asexually by simple cell division or budding off a parent cell. (Some yeast reproduce sexually, forming asci or basidia, but others have no known sexual stage)

Question 25

What are lichens?

Answer 25

a mutualistic symbiosis of millions of photosynthetic microorganisms held in a mesh of fungal hyphae. (The fungal component is commonly an ascomycete. The photosynthetic partners are usually green algae)

Question 26

What are mycorrhizae?

Answer 26

mutualistic associations of plant roots and fungi. (Extensions increases the absorptive surface of the plant roots; Fungus accesses some minerals from the soil, and the plant provides organic nutrients; Almost all vascular plants have it; some plants that grow in nitrogen poor soil rely on their fungal symbionts to fix N2.)

Question 27

Draw the zygomycota life cycle.

Answer 27