AY Honors/Fungi/Answer Key
1. Give the name of five classes of fungi and examples of each.
Chytridiomycota: The phylum Chytridiomycota, the chytrids, represents a group of primitive aquatic fungi. They are characterized by having gametes that are motile by means of flagella. Also some fungi reproduce sexual by Oospores this fungi are known as Oomycetes.
- Zygomycota
- The zygomycetes, in phylum Zygomycota, are characterized by the formation of sexual spores called zygospores. The zygospores are not contained within a specialized fruiting body or sac. Zygospores form when the haploid nuclei at the ends of two hyphae fuse together in a process of fertilization to form a diploid zygote. The zygote immediately undergoes meiosis to form haploid cells that develop into zygospores. The zygospores are unenclosed, or “naked,” between the parental hyphae. An example of a zygomycete is the common black bread mold, Rhizopus nigricans.
- Glomeromycota
- Members of the Glomeromycota are also known as the arbuscular mycorrhizal fungi. Only one species has been observed forming zygospores; all other species only reproduce asexually.
- Ascomycota
- The ascomycetes are members of the phylum Ascomycota. They are also called the “sac fungi” because their sexual spores (ascospores) are enclosed in tube-like sacs known as asci. The formation of ascospores is similar to that of zygospores, except that the ascospores formed by meiosis are enclosed in the asci. Neurospora crassa is an ascomycete mold that was important in studies of genetic linkage.
- Basidiomycota
- Basidiomycetes, also known as the “club fungi,” are classified in phylum Basidiomycota. Their sexual spores, or basidiospores, are formed on complex fruiting body structures called basidia. Basidiomycetes include some of the most complex fungi, including mushrooms and puffballs.
2. Identify fifteen common fungi of your locality. Draw or photograph them from live specimens.
3. Name three important fungi and tell what their value is.
Saccharomyces cerevisiae: This fungus is used in baker's yeast.
Aspergillus niger: This fungus is used to make citric acid commercially, and it also can be used to make gluconic acid. Both are important food additives.
Penicillium chrysogenum: This is the organism that makes penicillin, from which the majority of the large class of beta-lactam antibiotics are derived. Penicillin and its derivatives have saved countless lives since they were discovered and isolated, starting in the 1940s.
4. Tell the life history of one example of each of the following:
a. Rust
- The life histories of rusts often are mind-bogglingly complex, often with the fungus spending part of its life on one kind of plant, then another part on a completely different kind of plant. For example, near my trailer there's an Eastern Redcedar tree, Juniperus virginiana. All winter some brown, bumpy, woody, tumor-like items about the size of golfballs were visible growing on the branches. In early spring the bumps on the thing developed slender, sharp "horns" from which pollen-like dust emerged. You can see the item at the left, magnified about four times.
b. Mold
c. Mushroom
d. Yeast
5. Identify five fungus plant diseases.
Fusarium oxysporum
Adventist Youth Honors Answer Book/Nature/Fungi/Fusarium oxysporum
Pinkroot
Pinkroot, Phoma terrestris.
Downy mildew
Adventist Youth Honors Answer Book/Nature/Fungi/Downy mildew
Botrytis leaf blight
Botrytis leaf blight, Botrytis squamosa.
Neck rot
Neck rot, Botrytis allii.
Smut
Smut, Urocystis cepulae.
Smudge
Smudge, Colletotrichum circinans.
White rot
White rot, Sclerotium cepivorum.
