7 Survey of Microorganisms: Fungi - MicroCore Review Center

Which group of fungi does arbuscular mycorrhizae belong to?

• Chytridiomycota

• Basidiomycota

• Zygomycota

• Glomeromycota

• Ascomycota

Answer explanation

The Glomeromycota is a monophyletic group of soil-borne fungi that are among the most important microorganisms on Earth, not only because they form intimate mycorrhizal associations with nearly 80% of land plants but also because they are believed to have been crucial in the initial colonization of the terrestrial realm by plants. Image from: Jacott CN, Murray JD, Ridout CJ. Trade-Offs in Arbuscular Mycorrhizal Symbiosis: Disease Resistance, Growth Responses and Perspectives for Crop Breeding. Agronomy. 2017; 7(4):75. https://doi.org/10.3390/agronomy7040075

Which fungal group are obligate parasites who have undergone significant genome reduction, losing many features that would allow them to live outside of a host cell?

• Glomeromycota

• Chytridiomycota

• Microsporidia

• Basidiomycota

• Ascomycota

Answer explanation

Colorized transmission electron micrograph of thin sections of cells of the microsporidium Encephalitozoon intestinalis (arrows) growing in human intestinal cells. The microsporidium Encephalitozoon, for example, lacks not only mitochondria and hydrogenosomes but also a Golgi complex (another key eukaryotic cell structure). Moreover, Encephalitozoon contains a very small genome of only 2.9 Mbp and contains only about 2000 genes (this is 1.5 Mbp and 2600 genes smaller than that of the bacterium Escherichia coli), thereby lacking genes for major metabolic pathways. Image from: Madigan, M. T., Martinko, J. M., Bender, K. S., Buckley, D. H., Sattley, W.M. & Stahl, D. A. (2018). Brock biology of microorganisms (Fifteenth edition.). Boston: Pearson.

Which fungal group do the common bread mold belong to?

• Chytridiomycota

• Ascomycota

• Zygomycota

• Basidiomycota

• Glomeromycota

Answer explanation

The common black bread mold Rhizopus nigricans is a widespread zygomycete. This organism undergoes a complex life cycle that includes both asexual and sexual reproduction. Image from: Madigan, M. T., Martinko, J. M., Bender, K. S., Buckley, D. H., Sattley, W.M. & Stahl, D. A. (2018). Brock biology of microorganisms (Fifteenth edition.). Boston: Pearson.

Which of the following is not a characteristic of fungi?

• All are eukaryotic

• Many reproduce both sexually and asexually

• All fungal cell walls consist of chitin, a polymer of N-acetylglucosamine, instead of peptidoglycan in bacteria

• Some are filamentous, while some are unicellular

• All are chemoorganotrophic

Answer explanation

Chitin and chitosan are not components of cell wall in all fungal species. The fungal classes of Basidiomycetes, Ascomycetes, Zygomycetes, and Deuteromycetes are known to contain chitin and chitosan in their cell walls.

What do you call a hyphae without any crosswalls?

• Mycelium

• Septate

• Thallus

• Haustoria

• Coenocytic

Answer explanation

Coenocytic hyphae are aseptate, which means they do not contain septa or a long cell that is not divided into compartments. This type of hyphae is found in Zygomycota (bread molds). Image from: http://www.medical-labs.net/fungi-hyphae-1522/

What do you call the outgrowth of somatic hypha in parasitic fungi?

• Aeriel hyphae

• Vegetative hyphae

• Haustoria

• Rhizoids

• Stolon

Answer explanation

Haustoria penetrate the host plant's cell wall and siphon nutrients from the space between the cell wall and plasma membrane but do not penetrate the plant's cell membrane itself. Image from: http://biologywriteup.blogspot.com/2012/03/haustorium.html

What do you call the reproductive structures of lichens?

• Cyst

• Mycobiont

• Phycobiont

• Stolon

• Soredia

Answer explanation

Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria or green algae. Fungal hyphae make up the basic body structure of lichen. The soredia are released through openings in the upper cortex of the lichen structure. After their release, the soredia disperse to establish the lichen in a new location. Image from: https://www.macmillanhighered.com/BrainHoney/Resource/

6716/digital_first_content/trunk/test/hillis2e/asset/img_ch22/c22_fig09.html

Which of the following is not true regarding the reproduction of fungi?

• Asexual reproduction results in the production of numerous individuals

•  

  Sexual cycle is usually repeated several times during the season, whereas asexual stage of many fungi is produced only once a year

• Examples of asexual mode of reproduction are budding and fragmentation

• The three phases of sexual reproduction in order are, plasmogamy, karyogamy, and meiosis

Answer explanation

Asexual cycle is usually repeated several times during the season, whereas sexual stage of many fungi is produced only once a year, so it is the more favored mode of reproduction. The most common mode of asexual reproduction is through the formation of asexual spores, which are produced by one parent only (through mitosis) and are genetically identical to that parent. Spores allow fungi to expand their distribution and colonize new environments. Image from: Gherbawy, Y., C. Kesselboth, H. Elhariry and K. Hoffmann, 2010. Molecular barcoding of

microscopic fungi with emphasis on the mucoralean genera Mucor and Rhizopus. Mol. Iden. Fung., 33: 213‒250

What do you call the fusion of 2 hyphal tips?

• Spermatization

• Somatogamy

• Planogametic copulation

• Meiosis

Answer explanation

Spermatia are produced in spiral receptacles called spermagonia. Insects, wind or water to the female gametangium carries them, which is usually a special receptive hypha (or trichogyne) to which they become attached. A pore develops at the point of contact and the contents of spermatium pass into the particular respective hyphae. This results in plasmogamy and initiation of the dikaryotic stage of the cell. Image from: http://eagri.org/eagri50/PATH171/lec03.pdf

Which fungal infection involve the dermis, subcutaneous tissues, muscle and fascia?

• Systemic mycoses

• Superficial mycoses

• Cutaneous mycoses

• Subcutaneous mycoses

• Opportunistic mycoses

Answer explanation

Subcutaneous mycoses causes infections that are chronic and can be initiated by piercing trauma to the skin which allows the fungi to enter.