Biology | Answers to Review Questions

Author Dr. George B. Johnson, Washington University
Author Dr. Peter H. Raven, Missouri Botanical Gardens & Washington University
Contributor Dr. Susan Singer, Carleton College
Contributor Dr. Jonathan Losos, Washington University

Answers to Review Questions

Chapter 36 (p. 732)

1. Hyphae are slender filaments. Incomplete septa permit the movement of reproductive materials between cells.

2. The fungal wall is composed of polysaccharide and chitin, which is an advantage because it renders the wall more resistant to degradation bacteria.

3. The fungal nuclei that are diploid are those of the zygote. All the rest are haploid. Heterokaryotic and dikaryotic hyphae contain two genetically distinct types of nuclei; homokaryotic and monokaryotic hyphae contain nuclei that are all genetically similar.

4. The three reproductive structures are sporangia, which form spores; gametangia, in which gametes form; and conidia, mostly multinucleate asexual spores not produced in sporangia.

5. Most fungi produce spores, often in prodigious amounts. These spores are typically "flung" some distance by the fungus or picked up and dispersed by the wind.

6. These asexual spores are called conidia and are multinucleate. They are carried by conidiophores, and the nonreproductive hyphae of this division are incompletely septate.

7. The yeasts belong mostly to the Ascomycota; they differ from other fungi because they are unicellular. It is more likely that this characteristic is degenerate—derived from multicellular ancestors.

8. The Fungi Imperfecti are those fungi in which sexual reproduction has not been observed; the best represented by this group is the Ascomycota. Individuals in the phylum Deuteromycota are classified by examination of hyphal structure and similarities in asexual reproduction.

9. Lichens are symbiotic associations between a fungus and a green alga and/or cyanobacterium. The best represented of this group is the Ascomycota.

10. Mycorrhizae live in association with plant roots. Endomycorrhizae hyphae penetrate the outer cells of the root; ectomycorrhizae surround but do not penetrate the roots.