29. Fungi

All fungi are a. symbiotic. b. heterotrophic. c. flagellated. d. decomposers.

The mycelial growth habit leads to a body with a high surface-area-to-volume ratio. Why is this important? a. Mycelia have a large surface area for absorption. b. The hyphae that make up mycelia are long, thin tubes. c. Most hyphae are broken up into compartments by walls called septa, although some exist as single, gigantic cells. d. Hyphae can infiltrate living or dead tissues.

Which statement about the daughter cells following mitosis and cytokinesis is correct? a. They are genetically different from each other and from the parent cell. b. They are genetically identical to each other and to the parent cell. c. They are genetically identical to each other but different from the parent cell. d. Only one of the two daughter cells is genetically identical to the parent cell.

Which of the following cells or structures are associated with asexual reproduction in fungi? a. ascospores b. basidiospores c. zygosporangia d. conidiophores

After S phase, what makes up a single chromosome? a. two daughter chromosomes b. a double-stranded DNA molecule c. two single-stranded DNA molecules d. two sister chromatids

The closest relatives of fungi are thought to be the a. animals. b. vascular plants. c. mosses. d. slime molds.

Progression through the cell cycle is regulated by oscillations in the concentration of which type of molecule? a. p53, Rb, and other tumor suppressors b. receptor tyrosine kinases c. cyclins d. cyclin-dependent kinases

The hyphae of arbuscular mycorrhizal fungi (AMF) form bushy structures after making contact with the plasma membrane of a root cell. What is the function of these structures? a. They anchor the fungus inside the root, so the association is more permanent. b. They increase the surface area available for the transfer of nutrients. c. They produce toxins that protect the plant cells against herbivores. d. They break down cellulose and lignin in the plant cell wall.

The most important adaptive advantage associated with the filamentous nature of fungal mycelia is a. the ability to form haustoria and parasitize other organisms. b. the potential to inhabit almost all terrestrial habitats. c. the increased chance of contact between mating types. d. an extensive surface area well suited for invasive growth and absorptive nutrition.

What does it mean to say that a hypha is dikaryotic? a. Two nuclei fuse during sexual reproduction to form a zygote. b. Two independent nuclei, derived from different individuals, are present in each cell. c. The nucleus is diploid or polyploid—not haploid. d. It is extremely highly branched, which increases its surface area and thus absorptive capacity.

Identify at least two events in the cell cycle that must be completed successfully for daughter cells to share an identical complement of chromosomes.

The Greek root ecto means 'outer.' Why are ectomycorrhizal fungi, or EMF, aptly named? a. Their hyphae form tree-like branching structures inside plant cell walls. b. They are mutualistic. c. Their hyphae form dense mats that envelop roots but do not penetrate the cell walls. d. They transfer nitrogen from outside their plant hosts to the interior.

Explain why fungi that degrade dead plant materials are important to the global carbon cycle. Do you accept the text's statement that, without these fungi, 'Terrestrial environments would be radically different than they are today, and probably much less productive'? Why or why not?

Evaluate each of the following defects. Which could lead to uncontrolled growth in cancer? Select True or False for each statement. T/F The overexpression of MPF activity. T/F A nonfunctional Rb protein. T/F The overexpression of G1 cyclin. T/F A nonfunctional E2F protein.

Lignin and cellulose provide rigidity to the cell walls of plants. But in most fungi, chitin performs this role. Why is it logical that most fungi don't have lignin or cellulose in their cell walls?

Lawns are sometimes fertilized with nitrate that can be washed into neighboring woodlots by rain. If the trees in that woodlot are associated with EMF, what effect might the excess nitrate have on the fungi and/or trees? a. Fungal growth may be stimulated, causing the trees to transport more nitrogen to the fungi. b. The fungi may secrete more peptidases to break down the nitrate. c. The trees may take up the nitrate directly into their roots and rely less on the fungi. d. The excess nitrate may stimulate the fungi to transport more sugar to the trees.

A particular cell type spends 4 hours in G1 phase, 2 hours in S phase, 2 hours in G2 phase, and 30 minutes in M phase. If a pulse–chase experiment were performed with radioactive thymidine on an asynchronous culture of such cells, what percentage of mitotic cells would be radiolabeled 9 hours after the pulse? a. 0 percent b. 50 percent c. 75 percent d. 100 percent

When a fruit fly embryo first begins to develop, a large cell is generated that contains over 8000 genetically identical nuclei. What is most likely responsible for this result?

Many mushrooms are extremely colorful. One hypothesis is that the colors serve as a warning to prevent animals from eating mushrooms, much like the bright yellow and black stripes on wasps help to deter potential predators. Design an experiment to test this hypothesis.