Ch 31 - Exam 3
Leaf-cutter ants harvest plant leaves and bring them back to their nests. There, in the warm, moist environments of their underground nests, they grow fungi (Leucoagaricus) that they then eat. These ants also host bacteria on their exoskeleton. Another fungus, Escovopsis, kills Leucoagaricus when the ants are removed from the nest. Knowing that the bacteria on the ants are in the same phylogenetic group of other bacteria that produce antibiotics, which of the following research hypotheses is most likely correct? A) The bacteria on the exoskeleton produce chemicals that kill Leucoagaricus. B) The bacteria on the exoskeleton produce chemicals that kill Escovopsis. C) The bacteria on the exoskeleton provide nutrition to the ants. D) The bacteria on the exoskeleton cause disease in the ants.
? NOT A
28) Asexual reproduction in yeasts occurs by budding. Due to unequal cytokinesis, the "bud" cell receives less cytoplasm than the parent cell. Which of the following should be true of the smaller cell until it reaches the size of the larger cell? A) It should produce fewer fermentation products per unit time. B) It should be transcriptionally less active. C) It should have reduced motility. D) It should have a smaller nucleus.
A
3) 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) The lower volume prevents the cells from drying out too quickly, which can interfere with absorption. C) This high ratio creates more room inside the cells for additional organelles involved in absorption. D) This high ratio means that fungi have a thick, fleshy structure that allows the fungi to store more of the food it absorbs.
A
36) You observe the gametes of a fungal species under the microscope and realize that they resemble animal sperm. To which of the following group does the fungus belong? A) Chytrids B) Zygomycetes C) Basidiomycota D) Ascomycota
A
38) Arrange the following in order from largest to smallest. 1. ascospore 2. ascocarp 3. ascomycete 4. ascus A) 3 → 2 → 4 → 1 B) 3 → 4 → 1 → 2 C) 2 → 3 → 4 → 1 D) 2 → 4 → 1 → 3
A
48) A researcher took water in which a Jl population had been thriving, filtered the water to remove all bacterial cells, and then applied the water to the skins of adult amphibians to see if there would subsequently be a reduced infection rate by Bd when frog skins were inoculated with Bd. For which of the following hypotheses is the procedure described a potential test? A) the hypothesis that a toxin secreted by Jl cells kills Bd cells when both are present together on frog skin B) the hypothesis that Jl cells infect and kill Bd cells when both are present together on frog skin C) the hypothesis that Jl outcompetes Bd when both are present together on a frog's skin D) the hypothesis that the presence of Jl on frog skin causes a skin reaction that prevents attachment by Bd cells
A
5) Based on the idea that fungi have pores between their cell walls, which allow cytoplasm to move from one end of the mycelium to the other, which of the following hypotheses is the most plausible? A) If a single mycorrhizal fungus formed symbiotic associations with more than one tree, carbon could travel from one plant to another. B) Parasitic fungi steal nutrients from their hosts. C) Predatory fungi capture their prey by encircling them with hyphae, and the flowing of the cytoplasm through the pores helps the hyphae to move around the prey. D) Fungi function as part of the global carbon cycle not only by converting carbon from one form to another, but by physically moving it from one location to another.
A
60) Mycorrhizae are to the roots of vascular plants as endophytes are to vascular plants' _____. A) leaf mesophyll B) stem apical meristems C) root apical meristems D) xylem
A
Diploid nuclei of the ascomycete, Neurospora crassa, contain 14 chromosomes. A single diploid cell in an ascus will undergo one round of meiosis, followed in each of the daughter cells by one round of mitosis, producing a total of eight ascospores. 51) If a single, diploid G2 nucleus in an ascus contains 400 nanograms (ng) of DNA, then a single ascospore nucleus of this species should contain how much DNA (ng), carried on how many chromosomes? A) 100, carried on 7 chromosomes B) 100, carried on 14 chromosomes C) 200, carried on 7 chromosomes D) 200, carried on 14 chromosomes
A
In the United States and Canada, bats use one of two strategies to survive winter: They either migrate south, or they hibernate. Recently, those that hibernate seem to have come under attack by a fungus, Geomyces destructans (Gd), an attack that is occurring from Missouri to southern Canada. Many infected bats have a delicate, white filamentous mat on their muzzles, which is referred to as white-nose syndrome (WNS). The fungus invades the bat tissues, causes discomfort, and awakens the bat from its hibernation. The bat fidgets and wastes calories, using up its stored fat. The bat then behaves abnormally, leaving its cave during daytime in winter to search for food. Their food, primarily insects, is scarce during the winter, and the bats ultimately starve to death. Since 2007, it is estimated that up to one million bats have perished from WNS. 1) The Gd mat on the fur of the bats should be expected to consist of _____. A) hyphae B) haustoria C) yeasts D) basidia
A
Recent genetic studies of the structure of microsporidian genomes, as well as the sequences of their tubulin genes and the gene for RNA polymerase II, indicate that microsporidians are closely related to the fungi. Microsporidians lack flagella, centrioles, peroxisomes, and mitochondria (although they do have degenerate mitochondria, called mitosomes). They have the smallest genome of any eukaryote, and it is a genome that changes quickly. The genome is contained within two haploid nuclei. All microsporidians are obligate intracellular parasites. They use a unique organelle called a polar filament to gain access to the cells of their hosts. One species causes chronic diarrhea in AIDS patients. Another parasitizes Anopheles gambiae, the mosquito that transmits a fatal form of malaria to humans. 34) Given the eukaryotic structures they lack, it should be expected that microsporidians also lack _____. A) the "9 + 2 pattern" of microtubules B) centrosomes C) lysosomes D) nuclei
A
Use the information to answer the following question. The figure depicts the outline of a large fairy ring that has appeared overnight in an open meadow, as viewed from above. The fairy ring represents the furthest advance of this mycelium through the soil. Locations A-D are all 0.5 meters below the soil surface. A circle is shown with four points marked. Point A is on the circle's rim. Point B is halfway between rim and the circle's center. C is at the circle's center. D is just outside the circle. The four points would lie roughly on an invisible line. Which location is nearest to basidiocarps? A B C D
A
Use the following information to answer the question. Canadian and Swiss researchers wanted to know if the diversity of arbuscular mycorrhizal fungi (AMF) was important to the productivity of grasslands (M.G.A. van der Heijden, J. N. Klironomos, M. Ursic, P. Moutoglis, R. Streitwolf-Engel, T. Boler, A. Wiemken, and I. R. Sanders. 1998. Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability, and productivity. Nature 396:69-72). Specifically, they wanted to know if it mattered which specific AMF species were present, or just that some type of AMF was present. They grew various plants in combination with one of four AMF species (A, B, C, and D), no AMF species (O), or all four AMF species together (A + B + C + D); and they measured plant growth under each set of conditions. All plant species were grown in each plot, so they always competed with each other with the only difference being which AMF species were present. On the graphs, the x-axis labels indicate the number and identity of AMF species (bar 0 = no fungi; bars A - D = individual AMF species; bar A + B + C + D = all AMF species together). The y-axis indicates the amount (grams) of plant biomass for the species shown in italics above each graph. Graph e is the total biomass (grams) of all 11 plant species combined; graph f is the biomass of Bromus erectus plants only, separated from the total. FIG MISSING Based on graphs e and f, which is the most well-supported prediction for the effect on total plant biomass if AMF diversity were increased to eight species? A) No effect is predicted, because the dominant species is unaffected by AMF diversity. B) Total biomass for eight species would double in comparison to that for four species. C) Rare species would produce more biomass compared to the case when fewer AMF are present. D) No effect is predicted, because the dominant species is non-mycorrhizal.
A) No effect is predicted, because the dominant species is unaffected by AMF diversity.
Fungi have an extremely high surface-to-volume ratio. What is the advantage of this characteristic to an organism that gets most of its nutrition through absorption? A) The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane. B) The lower volume prevents the cells from drying out too quickly, which can interfere with absorption. C) This high ratio creates more room inside the cells for additional organelles involved in absorption. D) This high ratio means that fungi have a thick, fleshy structure that allows the fungi to store more of the food it absorbs.
A) The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.
Mycorrhizae are to the roots of vascular plants as endophytes are to the ________ of vascular plants. A) leaf mesophyll B) stem apical meristems C) root apical meristems D) xylem
A) leaf mesophyll
13) 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) mutualistic C) commensal D) predatory
B
23) Deuteromycetes _____. A) represent the phylum in which all the fungal components of lichens are classified B) are the group of fungi that have, at present, no known sexual stage C) are the group that includes molds, yeasts, and lichens D) include the imperfect fungi that lack hyphae
B
25) Plasmogamy can directly result in which of the following? 1. cells with a single haploid nucleus 2. heterokaryotic cells 3. dikaryotic cells 4. cells with two diploid nuclei A) 1 or 3 B) 2 or 3 C) 2 or 4 D) 3 or 4
B
29) The microsporidian Brachiola gambiae parasitizes the mosquito Anopheles gambiae. Adult female mosquitoes must take blood meals for their eggs to develop, and it is while they take blood that they transmit malarial parasites to humans. Male mosquitoes drink flower nectar. If humans are to safely and effectively use Brachiola gambiae as a biological control to reduce human deaths from malaria, then how many of the following statements should be true? 1. Brachiola should kill the mosquitoes before the malarial parasite they carry reaches maturity. 2. The microsporidian should not be harmful to other insects. 3. Microsporidians should infect mosquito larvae, rather than mosquito adults. 4. The subsequent decline in anopheline mosquitoes should not significantly disrupt human food resources or other food webs. 5. Brachiola must be harmful to male mosquitoes, but not to female mosquitoes. A) 2 and 5 B) 1, 2, and 4 C) 2, 3, 5 D) 3 and 4
B
32) The multicellular condition of animals and fungi seems to have arisen _____. A) due to common ancestry B) by convergent evolution C) by inheritance of acquired traits D) by serial endosymbioses
B
35) 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) Fungi survive better when they are associated with plants. B) Radioactively labeled sugars produced by plants eventually show up in the fungi with which they are associated. C) 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. D) Radioactive labeling experiments show that plants pass crucial raw materials to the fungus for manufacturing sugars.
B
49) 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 is always the first group of fungi to begin any kind of plant decomposition. B) This fungal group can break down the tough lignin, which cannot be harnessed for energy, to get to the more useful cellulose. C) This is the only group of fungi that can use lignin for adenosine triphosphate (ATP) production. D) This enzyme releases heat energy from the breakdown of lignin that is used to kill off competing fungi.
B
54) If haustoria from the fungal partner were to appear within the photosynthetic partner of a lichen, and if the growth rate of the photosynthetic partner consequently slowed substantially, then this would support the claim that _____. A) algae and cyanobacteria are autotrophic B) lichens are not purely mutualistic relationships C) algae require maximal contact with the fungal partner in order to grow at optimal rates D) soredia are asexual reproductive structures combining both the fungal and photosynthetic partners
B
8) When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter? A) fungal haustoria B) fungal enzymes C) increased oxygen levels D) larger bacterial populations
B
9) The functional significance of porous septa in certain fungal hyphae is most similar to that represented by which pair of structures in animal cells and plant cells, respectively? A) desmosomes — tonoplasts B) gap junctions — plasmodesmata C) tight junctions — plastids D) centrioles — plastids
B
For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection. 46) Apart from direct amphibian-to-amphibian contact, what is the most likely means by which the zoospores spread from one free-living amphibian to another? A) by wind-blown spores B) by flagella C) by cilia D) by hyphae
B
For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection. 50) If Bd cannot grow properly at temperatures above 28°C (82°F), then, assuming the amphibians can survive, in which time or place should the chytrid infection proceed most rapidly? 1. cooler months 2. warmer months 3. lower altitudes 4. higher altitudes A) 1 or 3 B) 1 or 4 C) 2 or 3 D) 2 or 4
B
Rose-picker's disease is caused by the yeast Sporothrix schenkii (S. schenkii). The yeast grows on the exteriors of rose-bush thorns. If a human gets pricked by such a thorn, the yeasts can be introduced under the skin. The yeasts then assume a hyphal morphology and grow along the interiors of lymphatic vessels until they reach a lymph node. This often results in the accumulation of pus in the lymph node, which subsequently ulcerates through the skin surface and then drains. 53) Humans have immune systems in which lymph nodes are important, because many phagocytes and lymphocytes reside there. Given that a successful infection by S. schenkii damages lymph nodes themselves, which of the following is most probable? A) The hyphae secrete antibiotics, which increases the ability of the infected human to tolerate the fungus. B) Their conversion from yeast to hyphal morphology allows such fast growth that the body's defenses are at least temporarily overwhelmed. C) Defensive cells of humans cannot detect foreign cells that are covered with cell walls composed of cellulose. D) Given that most fungal pathogens attack plants, human defenses are simply not adapted to seek out and destroy fungi.
B
Rose-picker's disease is caused by the yeast Sporothrix schenkii (S. schenkii). The yeast grows on the exteriors of rose-bush thorns. If a human gets pricked by such a thorn, the yeasts can be introduced under the skin. The yeasts then assume a hyphal morphology and grow along the interiors of lymphatic vessels until they reach a lymph node. This often results in the accumulation of pus in the lymph node, which subsequently ulcerates through the skin surface and then drains. 57) The answer to which of these questions would be of most assistance to one who is attempting to assign the genus Sporothrix to the correct fungal phylum? A) Do these yeasts perform fermentation while growing on the rose-bush thorns, or do they wait until inside a human host? B) Does S. schenkii rely on animal infection to complete some part of its life cycle, or is the infection merely opportunistic? C) Are the hyphae in lymphatic vessels septate, or are they coenocytic? D) Is S. schenkii best described as a decomposer, parasite, pathogen, or mutualist of humans?
B
Suzanne Simard and colleagues knew that the same mycorrhizal fungal species could colonize multiple types of trees. They wondered if the same fungal individual would colonize different trees, forming an underground network that potentially could transport carbon and nutrients from one tree to another (S. Simard et al. 1997. Net transfer of carbon between mycorrhizal tree species in the field. Nature 388:579-82). Pots containing seedlings of three different tree species were set up and grown under natural conditions for three years (Fig. A). Two of the three species (Douglas fir, birch) could form ectomycorrhizal connections with the same fungal species, but the third species (cedar) could not form an ectomycorrhizal connection with the fungal species. In some of the pots, the researchers placed airtight bags over the Douglas fir and birch seedlings and injected carbon dioxide made from carbon-13 into the bags with the Douglas fir and carbon dioxide made from carbon-14 into the bags with the birch. (13C and 14C are different isotopes of carbon that can be detected and measured by researchers.) As the seedlings photosynthesized, the carbon dioxide was converted into sugars that could be tracked and measured by the researchers. The researchers measured whether the sugars in each plant contained only the carbon isotope that was in the air of their plastic bag or also the carbon isotope from the air around the other plant. 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) Carbon-14 is found in the birch seedling's tissues and carbon-13 in the Douglas fir. B) Carbon-14 is found in the Douglas fir seedling's tissues and carbon-13 in the birch. C) Either carbon-13 or carbon-14 is found in the fungal tissues. D) Either carbon-13 or carbon-14 is found in the cedar seedling's tissues.
B) Carbon-14 is found in the Douglas fir seedling's tissues and carbon-13 in the birch.
Some fungal species live in plants and can kill herbivores that feed on the plant. What type of relationship does this fungus have with its host? A) parasitic B) mutualistic C) commensal D) predatory
B) mutualistic
11) When pathogenic fungi are found growing on the roots of grape vines, 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) fungicide might also kill the native yeasts residing on the surfaces of the grapes B) lichens growing on the vines' branches are not harmed C) fungicide might also kill mycorrhizae D) sheeting is transparent so that photosynthesis can continue
C
2) What do fungi and arthropods have in common? A) The haploid state is dominant in both groups. B) Both groups are predominantly autotrophs that produce their own food. C) Both groups use chitin for support. D) Both groups have cell walls.
C
22) At which stage of a basidiomycete's life cycle would reproduction be halted if an enzyme that prevented the fusion of hyphae was introduced? A) fertilization B) karyogamy C) plasmogamy D) germination
C
33) Which feature seen in chytrids supports the hypothesis that they diverged earliest in fungal evolution? A) the absence of chitin within the cell wall B) coenocytic hyphae C) flagellated spores D) parasitic lifestyle
C
37) Which of the following has the LEAST affiliation with all of the others? A) Glomeromycota B) mycorrhizae C) lichens D) arbuscules
C
47) When adult amphibian skin harbors populations of the bacterium, Janthinobacterium lividum (Jl), chytrid infection seems to be inhibited. Which of the following represents the best experimental design to test whether this inhibition is real? A) Inoculate uninfected amphibians with Jl, and determine whether the amphibians continue to remain uninfected by chytrids. B) Inoculate infected amphibians with Jl, and determine whether the amphibians recover from infection by chytrids. C) Take infected amphibians and assign them to two populations. Leave one population alone; inoculate the other with Jl. Measure the rate at which infection proceeds in both populations. D) Take infected amphibians and assign them to two populations. Inoculate one population with a high dose of Jl; inoculate the other with a low dose of Jl. Measure the survival frequency in both populations.
C
55) A billionaire buys a sterile volcanic island that recently emerged from the sea. To speed the arrival of conditions necessary for plant growth, the billionaire might be advised to aerially sow what over the island? A) basidiospores B) spores of ectomycorrhizae C) soredia D) yeasts
C
56) Orchid seeds are tiny, with virtually no endosperm and with miniscule cotyledons. If such seeds are deposited in a dark, moist environment, then which of the following represents the most likely means by which fungi might assist in seed germination, given what the seeds lack? A) by transferring some chloroplasts to the embryo in each seed B) by providing the seeds with water and minerals C) by providing the embryos with some of the organic nutrients they have absorbed D) by strengthening the seed coat that surrounds each seed
C
58) Suppose that S. schenkii had initially been classified as a deuteromycete. Asci were later discovered in the pus that oozed from an ulcerated lymph node, and the spores therein germinated, giving rise to S. schenkii yeasts. Which two of these are conclusions make sense on the basis of this information? 1. S. schenkii produces asexual spores within lymph nodes. 2. S. schenkii should be reclassified. 3. S. schenkii continues to have no known sexual stage. 4. The hyphae growing in lymphatic vessels probably belonged to a different fungal species. 5. S. schenkii yeasts belonging to two different mating strains were introduced by the same thorn prick. A) 1 and 3 B) 1 and 5 C) 2 and 5 D) 4 and 5
C
59) Which of the following best describes the physical relationship of the partners involved in lichens? A) Fungal cells are enclosed within algal cells. B) Lichen cells are enclosed within fungal cells. C) Photosynthetic cells are surrounded by fungal hyphae. D) The fungi grow on rocks and trees and are covered by algae.
C
7) If all fungi in an environment that perform decomposition were to suddenly die, then which group of organisms should benefit most, due to the fact that their fungal competitors have been removed? A) flowering plants B) protists C) prokaryotes D) grasses
C
Use the information to answer the following question. The figure depicts the outline of a large fairy ring that has appeared overnight in an open meadow, as viewed from above. The fairy ring represents the furthest advance of this mycelium through the soil. Locations A-D are all 0.5 meters below the soil surface. A circle is shown with four points marked. Point A is on the circle's rim. Point B is halfway between rim and the circle's center. C is at the circle's center. D is just outside the circle. The four points would lie roughly on an invisible line. What is the most probable location of the oldest portion of this mycelium? A (on left edge of ring) B (between b and c) C (center of the ring) D (outside of ring to the right)
C (center of the ring)
10) A fungal spore germinates, giving rise to a mycelium that grows outward into the soil surrounding the site where the spore originally landed. Which of the following accounts for the fungal movement, as described here? A) karyogamy B) mycelial flagella C) breezes distributing spores D) cytoplasmic streaming in hyphae
D
12) The adaptive advantage associated with the filamentous nature of fungal mycelia is primarily related to _____. A) the ability to form haustoria and parasitize other organisms B) the potential to inhabit almost all terrestrial habitats C) the increased probability of contact between different mating types D) an extensive surface area well suited for invasive growth and absorptive nutrition
D
26) After cytokinesis occurs in budding yeasts, the daughter cell has a _____. A) similar nucleus and more cytoplasm than the mother cell B) smaller nucleus and less cytoplasm than the mother cell C) larger nucleus and less cytoplasm than the mother cell D) similar nucleus and less cytoplasm than the mother cell
D
27) In most fungi, karyogamy does not immediately follow plasmogamy, which consequently _____. A) means that sexual reproduction can occur in specialized structures B) results in multiple diploid nuclei per cell C) allows fungi to reproduce asexually most of the time D) results in heterokaryotic or dikaryotic cells
D
30) Why are mycorrhizal fungi superior to plants at acquiring mineral nutrition from the soil? A) Hyphae are one hundred to one thousand times larger than plant roots. B) Hyphae have a smaller surface-area-to-volume ratio than do the hairs on a plant root. C) Mycelia are able to grow in the direction of food. D) Fungi secrete extracellular enzymes that can break down large molecules.
D
31) Fossil fungi date back to the origin and early evolution of plants. What combination of environmental and morphological change is similar in the evolution of both fungi and plants? A) presence of "coal forests" and change in mode of nutrition B) periods of drought and presence of filamentous body shape C) predominance in swamps and presence of cellulose in cell walls D) colonization of land and loss of flagellated cells
D
39) Arrange the following in order from largest to smallest, assuming that they all come from the same fungus. 1. basidiocarp 2. basidium 3. basidiospore 4. mycelium 5. gill A) 4 →? 5 → 1→ 2 → 3 B) 5 → 1 → 4 → 2 → 3 C) 5 → 1 → 3 → 2 → 4 D) 4 → 1 → 5 → 2 → 3
D
For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection. 24) Sexual reproduction has not been observed in Bd. If its morphology and genetics did not identify it as a chytridiomycete, then to which fungal group would Bd be assigned? A) zygomycetes B) glomeromycetes C) basidiomycetes D) deuteromycetes
D
Use the information to answer the following question. The figure depicts the outline of a large fairy ring that has appeared overnight in an open meadow, as viewed from above. The fairy ring represents the furthest advance of this mycelium through the soil. Locations A-D are all 0.5 meters below the soil surface. A circle is shown with four points marked. Point A is on the circle's rim. Point B is halfway between rim and the circle's center. C is at the circle's center. D is just outside the circle. The four points would lie roughly on an invisible line. Assume that all four locations are 0.5 meters above the surface. On a breezy day with prevailing winds blowing from left to right, where should one expect to find the highest concentration of free basidiospores in an air sample? A B C D
D
Heterobasidion is a basidiomycete that contributes to mortality of trees. Kuhlman isolated 23 strains of Heterobasidion and applied them to 16 seedlings of 10 different tree species. Partial results of this experiment are shown in the table. (From Kuhlman, E. G. 1970. Seedling inoculations with Fomes annosus show variation in virulence and in host susceptibility. Phytopathology 60:1743-1746. https://www.apsnet.org/publications/phytopathology/backissues/Documents/1970Articles/Phyto60n12_1743.PDF) % mortality of five host species from five Heterobasidion isolates: Host: 63, 117, 195, 126, 118 Slash Pine: 50, 69, 94, 100, 94 Shortleaf Pine: 75, 56, 94, 94, 100 Red Cedar: 38, 32, 19, 50, 25 Yellow-Poplar: 0, 0, 6, 6, 6 Sycamore: 0, 0, 0, 0, 6 Which of the following conclusions can best be drawn from these results? A) All tree species are susceptible to Heterobasidion. B) Heterobasidion strains are equally lethal to all tree species. C) Heterobasidion reduces mortality of some species. D) Tree species vary in their susceptibility to Heterobasidion.
D) Tree species vary in their susceptibility to Heterobasidion.
Suzanne Simard and colleagues knew that the same mycorrhizal fungal species could colonize multiple types of trees. They wondered if the same fungal individual would colonize different trees, forming an underground network that potentially could transport carbon and nutrients from one tree to another (S. Simard et al. 1997. Net transfer of carbon between mycorrhizal tree species in the field. Nature 388:579-82). Pots containing seedlings of three different tree species were set up and grown under natural conditions for three years (Fig. A). Two of the three species (Douglas fir, birch) could form ectomycorrhizal connections with the same fungal species, but the third species (cedar) could not form an ectomycorrhizal connection with the fungal species. In some of the pots, the researchers placed airtight bags over the Douglas fir and birch seedlings and injected carbon dioxide made from carbon-13 into the bags with the Douglas fir and carbon dioxide made from carbon-14 into the bags with the birch. (13C and 14C are different isotopes of carbon that can be detected and measured by researchers.) As the seedlings photosynthesized, the carbon dioxide was converted into sugars that could be tracked and measured by the researchers. The researchers measured whether the sugars in each plant contained only the carbon isotope that was in the air of their plastic bag or also the carbon isotope from the air around the other plant. Referring to Simard et al. (1997), which design element is the control in this experiment and why? A) the bags over the seedlings to contain the different types of carbon dioxide B) the fact that all the seedlings are different species C) the cedar seedling, because it is not bagged D) the cedar seedling, because it does not form ectomycorrhizal connections with the tested fungus
D) the cedar seedling, because it does not form ectomycorrhizal connections with the tested fungus
Use the following information to answer the question. There is much discussion in the media about protecting biodiversity. But does biodiversity really matter? Canadian and Swiss researchers wanted to know if the diversity of arbuscular mycorrhizal fungi (AMF) was important to the productivity of grasslands (M.G.A. van der Heijden, J. N. Klironomos, M. Ursic, P. Moutoglis, R. Streitwolf-Engel, T. Boler, A. Wiemken, and I. R. Sanders. 1998. Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability, and productivity. Nature 396:69-72). Specifically, they wanted to know if it mattered which specific AMF species were present, or just that some type of AMF was present. They grew various plants in combination with one of four AMF species (A, B, C, and D), no AMF species (O), or all four AMF species together (A + B + C + D); and they measured plant growth under each set of conditions. All plant species were grown in each plot, so they always competed with each other, with the only difference being which AMF species were present. On the graphs, the x-axis labels indicate the number and identity of AMF species (bar 0 = no fungi; bars A - D = individual AMF species; bar A + B + C + D = all AMF species together). The y-axis indicates the amount (grams) of plant biomass for the species shown in italics above each graph. Based on the graphs in the figure, which of the following plant species is most likely not to form mycorrhizal associations? a- Carex flacca (graph a) b- Lotus corniculatus (graph b) c- Sanguisorba officinalis (graph c) d- Centaurium erythrea (graph d)
a- Carex flacca (graph a)
Some nematode worms suck plant juices from the roots of plants and are economically important agricultural pests. Some fungi are usually decomposers of plant material, but some trap and kill nematodes at times. Arthrobotrys traps and kills nematodes, especially when they lack nitrogen sources. These two facts suggest that farmers could find Arthrobotrys an important tool in combating nematode infestations. Which of the following research questions would make a good starting point for developing such a defense against plant-sucking nematodes? a- Does nitrogen fertilization of crops affect the likelihood that Arthrobotrys will trap and kill nematodes? b- Do nitrogen-fixing bacteria provide nitrogen to the fungi? c- What is the evolutionarily oldest method of trapping nematodes? d- What mechanisms do nematodes have that could allow them to escape from Arthrobotrys?
a- Does nitrogen fertilization of crops affect the likelihood that Arthrobotrys will trap and kill nematodes?
The closest relatives of fungi are thought to be the a- animals. b- vascular plants. c- mosses. d- slime molds.
a- animals.
The figure depicts the outline of a large fairy ring that has appeared overnight in an open meadow, as viewed from above. The fairy ring represents the furthest advance of this mycelium through the soil. In which of the following human mycoses should one expect to find a growth pattern most similar to that of the mycelium that produced the fairy ring? a- skin mycoses b- coccidiomycosis (lung infection) c- systemic (bloodborne) Candida infection d- infection of lymphatic vessels
a- skin mycoses
Biologists sometimes divide living organisms into two groups: autotrophs and heterotrophs. These two groups differ in ________. a- their sources of carbon b- their electron acceptors c- their mode of inheritance d- the way that they generate ATP
a- their sources of carbon
The ascomycete Brachiola gambiae parasitizes the mosquito Anopheles gambiae. Adult female mosquitoes must take blood meals for their eggs to develop, and it is while they take blood that they transmit malarial parasites to humans. Male mosquitoes drink flower nectar. If humans are to safely and effectively use Brachiola gambiae as a biological control to reduce human deaths from malaria, then which of the following statements should be correct? a- The ascomycete should not be harmful to other insects and must be harmful to male mosquitoes, but not to female mosquitoes. b- The ascomycete should kill the mosquitoes before the malarial parasite they carry reaches maturity and should not be harmful to other insects. c- The ascomycete should not be harmful to other insects and should infect mosquito larvae, rather than mosquito adults. d- The ascomycete should infect mosquito larvae, rather than mosquito adults, and the subsequent decline in anopheline mosquitoes should not significantly disrupt human food resources.
b- The ascomycete should kill the mosquitoes before the malarial parasite they carry reaches maturity and should not be harmful to other insects.
All fungi are a- symbiotic. b- heterotrophic. c- flagellated. d- decomposers.
b- heterotrophic.
Which of the following cells or structures are associated with asexual reproduction in fungi? a- ascospores b- basidiospores c- zygosporangia d- conidiophores
d- conidiophores
Chitin is a long-chain polymer derived from glucose. It strengthens cell walls of fungi and the outer covering (exoskeleton) of arthropods (including crabs, shrimps, and insects). The presence of chitin in these groups is likely due to ________. a- secondary endoparasitism b- horizontal gene transfer c- paraphyletic evolution d- convergent evolution
d- convergent evolution