Question 1

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?

Accepted Answer

A)  basidiospores 
B)  spores of ectomycorrhizae 
C)  soredia 
D)  yeasts

Question 2

Use the following information to answer the question.
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.
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?

Accepted Answer

A)  by wind-blown spores 
B)  by flagella 
C)  by cilia 
D)  by hyphae

Question 3

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?

Accepted Answer

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.

Question 4

Some companies advertise and sell mycorrhizae to home gardeners and commercial farms, claiming that the presence of mycorrhizae improves plant growth and survival. If the company conducted experiments on plants with and without mycorrhizae, which of the following measurements would support their claim?

Accepted Answer

A)  smaller apple size in plants with mycorrhizae than in plants without mycorrhizae 
B)  increased production of corn ears in plants with mycorrhizae than in plants without mycorrhizae 
C)  increased need for fertilizer in plants with mycorrhizae than in plants without mycorrhizae 
D)  increased mortality in plants with mycorrhizae than in plants without mycorrhizae

Question 5

Fungi interact with many organisms in mutualistic ways. Which of the following involves a fungus that is mutualistic with another organism?

Accepted Answer

A)  a fungus and a protozoan that live together as a lichen 
B)  a fungus that is raised by ants on leaves that the ants collect from trees and shrubs 
C)  a fungus that lives inside plant roots and produces toxins that kill neighboring plants 
D)  a fungus that produces penicillin that is used by humans to kill infectious bacteria

Question 6

The Neurospora genome is quite compact, lacking many of the noncoding DNA sequences that occur in humans and many other eukaryotes. Which of the following are probable benefits of the compactness of the genome?

Accepted Answer

A)  The organism saves energy during cell division because fewer DNA bases must be duplicated. 
B)  It is more difficult for viruses to insert themselves into a compact genome. 
C)  There is less genetic variation that can lead to mutation. 
D)  The spores will be small and thus travel a greater distance.

Question 7

Use the following information to answer the question.
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. However, when adult amphibian skin harbors populations of the bacterium Janthinobacterium lividum (Jl), chytrid infection seems to be inhibited.
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?

Accepted Answer

A)  A toxin secreted by Jl cells kills Bd cells when both are present together on frog skin. 
B)  Jl cells infect and kill Bd cells when both are present together on frog skin. 
C)  Jl outcompetes Bd when both are present together on a frog's skin. 
D)  The presence of Jl on frog skin causes a skin reaction that prevents attachment by Bd cells.

Question 8

Use the following information to answer the question.
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

Which of the following conclusions can best be drawn from these results?

Accepted Answer

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.

Question 9

Use the following information to answer the question.
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.
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 of these statements make sense on the basis of this information?

Accepted Answer

A)  S. schenkii produces asexual spores within lymph nodes; it continues to have no known sexual stage. 
B)  S. schenkii produces asexual spores within lymph nodes; S. schenkii yeasts belonging to two different mating strains were introduced by the same thorn prick. 
C)  S. schenkii should be reclassified; S. schenkii yeasts belonging to two different mating strains were introduced by the same thorn prick. 
D)  The hyphae growing in lymphatic vessels probably belonged to a different fungal species; S. schenkii yeasts belonging to two different mating strains were introduced by the same thorn prick.

Question 10

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 ________.

Accepted Answer

A)  secondary endoparasitism 
B)  horizontal gene transfer 
C)  paraphyletic evolution 
D)  convergent evolution

Question 11

Which of the following cells or structures are associated with asexual reproduction in fungi?

Accepted Answer

A)  ascospores 
B)  basidiospores 
C)  zygosporangia 
D)  conidiophores

Question 12

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.

Examine the effect of AMF species on Sanguisorba officinalis. Which of the following conclusions can be correctly drawn from the data?

Accepted Answer

A)  Growth is best with AMF species D. 
B)  Growth is best with AMF species A. 
C)  Growth is best with a mixture of AMF species. 
D)  AMF presence had no effect on S. officinalis growth.

Question 13

Mycorrhizae are to the roots of vascular plants as endophytes are to the ________ of vascular plants.

Accepted Answer

A)  leaf mesophyll 
B)  stem apical meristems 
C)  root apical meristems 
D)  xylem

Question 14

Use the following information to answer the question.
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.
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?

Accepted Answer

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.

Question 15

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 ________.

Accepted Answer

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

Question 16

Early fungi probably formed mutualistic associations with early plants, providing nutrients to the plant and receiving energy-containing compounds. Evidence that plants' ability to form a mutualistic association with fungi is due to ancient genes includes which of the following occurrences?

Accepted Answer

A)  presence of genes in the earliest fungi that showed an ability to digest cellulose and lignin 
B)  presence of genes for chitin in the oldest flowering plants and oldest fungi 
C)  fossils that show hyphae wrapped around seeds 
D)  restoration of the ability to form mycorrhizae with fungi by a flowering plant after biologists transferred a gene from a liverwort to the flowering plant

Question 17

Arrange the following in order from largest to smallest, assuming that they all come from the same fungus.

Accepted Answer

A)  mycelium, gill, basidiocarp, basidium, basidiospore 
B)  gill, basidiocarp, mycelium, basidium, basidiospore 
C)  gill, basidiocarp, basidiospore, basidium, mycelium 
D)  mycelium, basidiocarp, gill, basidium, basidiospore

Question 18

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.

What is the most probable location of the oldest portion of this mycelium?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D

Question 19

The adaptive advantage associated with the filamentous nature of fungal mycelia is primarily related to ________.

Accepted Answer

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

Question 20

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 van der Heijden et al. (1998) graphs in the figure, which of the following is the best description of the data supporting the idea that a plant species did not form mycorrhizae with a fungus? Its biomass is greatest when ________.

Accepted Answer

A)  no AMF are present 
B)  AMF species A is present 
C)  AMF species B is present 
D)  AMF species C is present

Exam 31: Fungi