Question 1

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.

At which location should one find the lowest concentration of fungal enzymes, assuming that the enzymes do not diffuse far from their source and that no other fungi are present in this habitat?

Accepted Answer

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

Question 2

In most fungi, karyogamy does not immediately follow plasmogamy, which consequently ________.

Accepted Answer

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

Question 3

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.
% mortality of five host species from five Heterobasidion isolates
$$\begin{array} { | l | l | l | l | l | l | } 
\hline & \text { Isolate } & \text { Isolate } & \text { Isolate } & \text { Isolate } & \text { Isolate } \
\hline \text { Host } & 63 & 117 & 195 & 126 & 118 \
\hline \text { Slash Pine } & 50 & 69 & 94 & 100 & 94 \
\hline \text { Shortleaf Pine } & 75 & 56 & 94 & 94 & 100 \
\hline \text { Red Cedar } & 38 & 32 & 19 & 50 & 25 \
\hline \text { Yellow-Poplar } 0 & 0 & 0 & 6 & 6 & 6 \
\hline \text { Sycamore } & 0 & 0 & 0 & 0 & 6 \
\hline
\end{array}$$
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 4

You observe the gametes of a fungal species under the microscope and realize that they resemble animal sperm. To which of the following groups does the fungus belong?

Accepted Answer

A)  chytrids 
B)  zygomycetes 
C)  Basidiomycota 
D)  Ascomycota

Question 5

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?

Accepted Answer

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 the fungi have absorbed 
D)  by strengthening the seed coat that surrounds each seed

Question 6

What do fungi and arthropods have in common?

Accepted Answer

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.

Question 7

Use the following information to answer the 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.

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?

Accepted Answer

A)  skin mycoses 
B)  coccidiomycosis (lung infection) 
C)  systemic (bloodborne) Candida infection 
D)  infection of lymphatic vessels

Question 8

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.

If the fungus that produced the fairy ring can also produce arbuscules, then which of the following is most likely to be buried at location "C"?

Accepted Answer

A)  tree stump 
B)  deceased animal 
C)  fire pit 
D)  cement-capped well

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 feature seen in chytrids supports the hypothesis that they diverged earliest in fungal evolution?

Accepted Answer

A)  the absence of chitin within the cell wall 
B)  coenocytic hyphae 
C)  flagellated spores 
D)  parasitic lifestyle

Question 12

Deuteromycetes ________.

Accepted Answer

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

Question 13

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 statements should be an accurate characterization of the smaller cell until it reaches the size of the larger cell?

Accepted Answer

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.

Question 14

The closest relatives of fungi are thought to be the

Accepted Answer

A)  animals. 
B)  vascular plants. 
C)  mosses. 
D)  slime molds.

Question 15

Which of the following characteristics would be most helpful in distinguishing among different species of fungi?

Accepted Answer

A)  morphology 
B)  hyphae structure 
C)  DNA sequence 
D)  life cycle

Question 16

Which of the following best describes the physical relationship of the partners involved in lichens?

Accepted Answer

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)  Fungi grow on rocks and trees and are covered by algae.

Question 17

If you wanted to use fungi to improve the environment, which of the following research goals would make the most sense?

Accepted Answer

A)  Discover the lignin-digesting enzymes of fungi, and use them to digest plant tissues left over from food-crop residues and produce a biofuel. 
B)  Discover the enzymes that the fungal partner in lichens uses to break down rock so that large rock expanses can be turned into agricultural lands. 
C)  Discover the enzymes that fungi use to break down plant matter and use them to increase decomposition rates in order to slow global warming. 
D)  Develop a strain of fungus that produces enzymes that absorb oxygen and will help slow global warming.

Question 18

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

Question 19

Use the following information to answer the question.
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.

Figure A

Accepted Answer

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.

Question 20

The most important adaptive advantage associated with the filamentous nature of fungal mycelia is

Accepted Answer

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.

Exam 31: Fungi