Chapter 31 terms and concepts

Question 1

Describe the major characteristics of fungi and locate them in the phylogenetic tree of supergroups

Answer 1

Chytrids (phylum chytridiomycota): found in freshwater and marine habitats (including hydrothermal vents). They are decomposers, parasites, and mutualists. Diverged the earliest in fungal evolution. Unique in that they have flagellated spores, called zoospores. Usually unicellular. If multicellular, they have coenocytic hyphae

Zygomycetes (Phylum zygomycota): Fast-growing molds, parasites, and commensal symbionts. They have coenocytic hyphae. They have asexual sporangia that produce haploid spores. They have zygosporangia produced in life-cycle, which is where they got their name - the site of karyogamy and then meiosis, diverged after chytrids

Glomeromycetes (Phylum glomeromycota) - although once considered zygomycetes, they now are considered in their own phylum. Nearly all species form arbuscular mycorrhizae (mutualistic relationships with plant species) diverged after zygomycetes

Ascomycetes (Phylum Ascomycota) : produce sexual spores in sac-like structures called asci, which are contained in fruiting bodies called ascocarps. They vary in size and complexity - unicellular yeast, to complex cup fungi and morels. They are pathogens to plants, decomposers, and symbionts. They also form symbiotic relationships with green algae or cyanobacteria - lichens

Basidiomycetes (phylum basidiomycota) : includes mushrooms, puffballs, and shelf fungi. Some form arbuscular mycorrhizae, but others are parasitic. Similar to ascomycetes, they also have a fruiting body called a basidiocarp - and many are decomposers of wood. Life cycle includes a long-live dikaryotic mycelium.

Question 2

Describe the two main types of hyphae and how they differ

Answer 2

Septate hypha and coenocytic hypha

Septate hypha are hyphae that are divided into cells called septa, with pores allowing cell-to-cell movement of organelles

Coenocytic hypha are hyphae that lack septa and are a continuous cytoplasmic mass with hundreds or thousands of nuclei

Question 3

Mycelium

Answer 3

Fungal hyphae that form an interwoven mass underground, similar to a root system

Question 4

Fungi phylogeny info

Answer 4

Fungi and animals are more closely related to each other than they are to plants or other eukaryotes

The ancestor of fungi was an aquatic, single-celled, flagellated protist

Question 5

What is the fungal body structure comprised of?

Answer 5

It is most commonly composed of multicellular filaments or unicellular (yeasts). Fungi make complicated underground networks of filaments and mycelium, while also have multicellular filaments above ground

Question 6

Give examples of how fungi interact with organisms

Answer 6

Some fungi are parasitic (more often to plants, but also with animals as well), some are commensal symbionts, while others are mutualistic symbionts. If they are mutualistic, it is usually with a plant species, where arbuscular mycorrhizae which allows them to exchange nutrients with the tree species.

Question 7

Discuss the consequences of having plasmogamy and karyogamy temporally separated

Answer 7

Plasmogamy: the union of the cytoplasms of two parent mycelia.

Karyogamy: the fusion of two parent nuclei

If these processes are temporarily separated, a dikaryotic mycelium (two nuclei) would be created, which can divide in tandem without fusing. This pairing can cause further genetic recombination, increasing genetic diversity

Question 8

What are lichens? What are the 3 kinds and their general appearance?

Answer 8

Lichens are a symbiotic association between a photosynthetic microorganism (either an algae or a cyanobacteria) and a fungus

Fruticose: shrub-like
Foliose: (leaf-like)
Crustose: (encrusting form)