Chapter 29

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Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Figure 29.1 1) After looking at Figure 29.1 above, why do you think the spike in fungal abundance ended so "abruptly"? Why didn't fungal abundance remain high? A) The sudden increase in carbon from the plants' mass extinction was not sustained. B) The plants recovered and outcompeted the fungi, thereby decreasing fungal numbers. C) As the acidity of the environment increased, fungi were not able to survive. Answer: A SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 2) Looking at Figure 29.1, draw a new graph that plots the percentage of plant species in the fossil pollen and spore record, and write a figure legend comparing it to the original figure. Answer: Inverse of figure values 1

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 3) You are a forester charged with increasing productivity in a South American forest newly planted with pines from Oregon. You believe that the southern forest lacks the fungal diversity needed by the North American pines, and that this lack of fungi is affecting the pines' productivity, but you have no evidence to support your ideas. To count how many fungal species were present in the Oregon forest, which methodology would you choose, and why? A) Do direct sequencing on representative soil samples from across the forest. B) Collect all the fruiting structures (mushrooms, morels, etc.) found aboveground. C) Expose the trees to radiolabelled CO 2 and then collect the soil samples with the greatest radioactivity and do direct sequencing. D) Count all the plant species and multiply by six, as David Hawksworth did when determining the ratio of fungal to plant species in England. Answer: A 4) When pathogenic fungi are found growing on the roots of grapevines, grape farmers sometimes respond by covering the ground around their vines with plastic sheeting and pumping a gaseous fungicide into the soil. The most important concern of grape farmers who engage in this practice should be that the A) sheeting is transparent so that photosynthesis can continue. B) lichens growing on the vines' branches are not harmed. C) the plastic sheeting decreases evaporation of water from the soil. D) fungicide might also kill mycorrhizae. E) fungicide might also kill the native yeasts residing on the surfaces of the grapes. Answer: D 5) Most coal was formed during the Carboniferous period. What is a reasonable hypothesis that explains this observation? A) Coal was formed from an explosion of fungal species during this period. B) Plants from this period did not require fungal associations. C) There were not many saprophytic fungi during this period. D) There were not many mycorrhizal fungi during this period. Answer: C 6) Why is it more difficult to treat fungal infections than bacterial infections in humans? A) Fungi are able to mutate more quickly than bacteria, so they quickly develop resistance to antifungal drugs. B) Fungal cells are larger than bacteria. Thus, the drugs used must be able to diffuse more quickly. C) Fungi are larger organisms than bacteria and thus require stronger drugs to stop an infection. D) Fungal and animal cells and proteins are similar. Thus, drugs that disrupt fungal cell or protein function may also disrupt human cell or protein function. E) Most fungi are multicellular and thus the drugs required to treat a fungal infection must be able to kill several types of cells; bacteria, on the other hand, are unicellular and thus simpler to kill. Answer: D 2

7) Which of the following is an important role for fungi in the carbon cycle? A) One of fungi's main roles is to provide already fixed carbon to plants that the plants then use for the production of cellular tissues. B) Fungi get involved in the fixation of carbon by undergoing photosynthesis. C) Fungi help release fixed carbon back to the environment for other plants and photosynthetic organisms to utilize. D) All of the above are important roles for fungi. Answer: C 8) The vegetative (nutritionally active) bodies of most fungi are I. composed of hyphae. II. referred to as a mycelium. III. usually underground. A) II and III B) I, II, and III C) only II D) I and II E) I and III Answer: B 9) Fungi have an extremely high surface - area - to - volume ratio. What is the advantage of this to an organism that gets most of its nutrition through absorption? A) The larger surface area allows for more material to be transported through the cell membrane. B) This high ratio means that fungi have a thick, fleshy structure that allows the fungi to store more of the food it absorbs. C) This high ratio creates more room inside the cells for additional organelles involved in absorption. D) The lower volume prevents the cells from drying out too quickly, which can interfere with absorption. Answer: A 10) Fungi are most closely related to which of these groups? A) red algae B) plants C) green algae D) animals Answer: D 11) It has been hypothesized that fungi and plants have a mutualistic relationship because fungi provide critical nitrogen for the plants' use. How do we know this happens? A) When plants are associated with fungi, they can fix atmospheric nitrogen that has been tagged with a radioactive label. B) Plants acquire more radioactive nitrogen when they are associated with fungi. C) Radioactively labeled sugars in plants eventually find their way to their symbiotic fungi. D) Radioactively labeled nitrogen shows up in fungi when they are symbiotic with plants. Answer: B 12) It has been hypothesized that fungi and plants have a mutualistic relationship because plants make sugars available for the fungi's use. What is the best evidence in support of this hypothesis? A) Radioactive label experiments show that plants pass crucial raw materials to the fungus for manufacturing sugars. B) Fungi associated with plants have the ability to undergo photosynthesis and produce their own sugars, while those not associated with plants do not produce their own sugars. C) Radioactively labeled sugars produced by plants eventually show up in the fungi they are associated with. D) Fungi survive better when they are associated with plants. Answer: C 13) The fungi that we commonly know as mushrooms produce which of the following reproductive structures? A) asci B) chytrids C) zygosporangium D) basidia Answer: D 3

14) Which of these fungal features supports the phylogenetic conclusion that fungi are more closely related to animals than plants? A) Animals and fungi both store polysaccharides as glycogen. B) The cell wall of fungi and insects are both made of chitin. C) Chytrid spore flagella are similar to animal flagella. D) All of the above apply. Answer: D 15) Why are mycorrhizal fungi superior to plants at acquiring mineral nutrition from the soil? A) Fungi secrete extracellular enzymes that can break down large molecules. B) Fungi can transport compounds through their mycelium from areas of surplus to areas of need. C) Hyphae are 100 to 1000 times smaller than plant roots. D) All of the above answers apply. Answer: D 16) Basidiomycetes are the only fungal group capable of synthesizing lignin peroxidase. What advantage does this group of fungi have over other fungi because of this capability? A) This fungal group can break down the tough lignin, which cannot be harnessed for energy, to get to the more useful cellulose. B) This is the only group of fungi that can use lignin for ATP production. C) This enzyme releases heat energy from the breakdown of lignin that is used to kill off competing fungi. D) This is always the first group of fungi to begin any kind of plant decomposition. Answer: A 17) Why is it important that ectomycorrhizal fungi (EMF) have peptidase enzymes? A) These enzymes catalyze the formation of the compounds used during decomposition. B) These enzymes are necessary to break through the tough lignin layers in plants. C) These enzymes are needed to release nitrogen from dead plant material in colder environments. D) These enzymes assist with the breakdown of cellulose. Answer: C 4

18) Which of the trees provided depicts the microsporidians as a sister group of the fungi, rather than as a fungus? A) I B) II C) III D) IV Answer: D 19) Predict what you would see if you were looking at a new species of zygomycetes. A) a zygote enclosed in a tough outer coat B) flagellated spores C) an ability to form an association with plant roots D) susceptibility to fungicide E) multicellularity Answer: A 5

20) Some fungal species can kill herbivores while feeding off of sugars from its plant host. What type of relationship does this fungus have with its host? A) parasitic B) commensal C) mutualistic D) none of the above Answer: C Use the following information when answering the corresponding question(s). Suzanne Simard and colleagues knew that the same mycorrhizal fungal species could colonize multiple types of trees. They w if the same fungal individual would colonize different trees, forming an underground network that potentially could transpor and nutrients from one tree to another (S. Simard et al. 1997. Net transfer of carbon between mycorrhizal tree species in the fie Nature 388:579 - 82). Figure 29.2 illustrates the team's experimental setup. Pots containing seedlings of three different tree species were set up and grown under natural conditions for three years; two of the three species formed ectomycorrhizae (Douglas fir, birch) and the other (cedar) formed arbuscular mycorrhizae. For the experiment, the researchers placed airtight bags over the Douglas fir and birch seedlings; into each bag, they injected either carbon dioxide made from carbon - 13 or carbon - 14 ( 13 CO 2 and 14 CO 2 , isotopes of carbon). As the seedlings photosynthesized, the radioactive carbon dioxide was converted into radioactively labelled sugars that could be tracked and measured by the researchers. Figure 29.2 21) Refer to Figure 29.2. Which of the following results would support Simard et al.'s (1997) hypothesis that fungi can move carbon from one plant to another? Hypothesis: Sugars made by one plant during photosynthesis can travel through a mycorrhizal fungus and be incorporated into the tissues of another plant. A) Either carbon - 13 or carbon - 14 is found in the cedar seedling's tissues. B) Carbon - 14 is found in the birch seedling's tissues and carbon - 13 in the Douglas fir. C) Either carbon - 13 or carbon - 14 is found in the fungal tissues. D) Carbon - 14 is found in the Douglas fir seedling's tissues and carbon - 13 in the birch. Answer: D 6

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