Deck 31: Fungi

Question 1

The fungus Saccharomyces cerevisiae is a model eukaryotic cell for genetic studies.Which of the following is an important attribute that makes this organism ideal for this purpose?

A)It is multicellular.
B)It is resistant to culturing.
C)It has an interesting and highly complex genome and morphology.
D)It divides rapidly under good conditions.
E)All of the above apply.

Answer 1

D

Question 2

Which fungal class is not matched with its most common habitat?

A)EMF → northern coniferous forests
B)EMF → warm climate forests
C)AMF → tropics
D)AMF → grasslands

Answer 2

B

Question 3

Looking at Figure 31.1,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 3

Inverse of figure values

Question 4

Why are mycorrhizal fungi superior to plants at acquiring mineral nutrition from the soil?

A)Hyphae are 100 to 1000 times smaller than plant roots.
B)Fungi secrete extracellular enzymes that can break down large molecules.
C)Fungi can transport compounds through their mycelium from areas of surplus to areas of need.
D)All of the above answers apply.

Question 5

Which of the following is an important role for fungi in the carbon cycle?

A)Fungi help release fixed carbon back to the environment for other plants and photosynthetic organisms to utilize.
B)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.
C)Fungi get involved in the fixation of carbon by undergoing photosynthesis.
D)All of the above are important roles for fungi.

Question 6

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 they are associated with.
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 label experiments show that plants pass crucial raw materials to the fungus for manufacturing sugars.

Question 7

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)none of the above

Question 8

Which of these fungal features supports the phylogenetic conclusion that fungi are more closely related to animals than plants?

A)The cell wall of fungi and insects are both made of chitin.
B)Chytrid spore flagella are similar to animal flagella.
C)Animals and fungi both store polysaccharides as glycogen.
D)All of the above apply.

Question 9

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 ATP production.
D)This enzyme releases heat energy from the breakdown of lignin that is used to kill off competing fungi.

Question 10

The fungi that we commonly know as mushrooms produce which of the following reproductive structures?

A)basidia
B)zygosporangium
C)chytrids
D)asci

Question 11

After looking at Figure 31.1 above,why do you think the spike in fungal abundance ended so "abruptly"? Why didn't fungal abundance remain high?

A)As the acidity of the environment increased,fungi were not able to survive.
B)The sudden increase in carbon from the plants' mass extinction was not sustained.
C)The plants recovered and outcompeted the fungi,thereby decreasing fungal numbers.

Question 12

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)Plants acquire more radioactive nitrogen when they are associated with fungi.
B)Radioactively labeled nitrogen shows up in fungi when they are symbiotic with plants.
C)When plants are associated with fungi,they can fix atmospheric nitrogen that has been tagged with a radioactive label.
D)Radioactively labeled sugars in plants eventually find their way to their symbiotic fungi.

Question 13

This group of fungi has the ability to penetrate its host's cell wall,thus increasing the efficiency with which materials are passed from fungus to host.

A)ectomycorrhizal fungi
B)arbuscular mycorrhizal fungi
C)all of the above

Question 14

There was a mass extinction of plants and animals at the end of the Permian period 250 million years ago.Which of the following would be a reasonable prediction for the fungal fossil record?

A)There should be a massive increase in mycorrhizal fossils during the extinction and few afterward.
B)There should be a massive increase in saprophytic fossils during the extinction,and then a massive decline shortly after the extinction was complete.
C)There should be a massive decrease in all fungal fossils just prior to the time that plant and animal species started to decline,and the number of these fossils should remain low throughout the extinction period.
D)There should be a slow increase in all fungal fossils during the time that plant and animal species declined,with their numbers staying relatively high afterward,since there was little competition from other species.

Question 15

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)Count all the plant species and multiply by six,as David Hawksworth did when determining the ratio of fungal to plant species in England.
B)Collect all the fruiting structures (mushrooms,morels,etc.)found aboveground.
C)Do direct sequencing on representative soil samples from across the forest.
D)Expose the trees to radiolabeled CO₂ and then collect the soil samples with the greatest radioactivity and do direct sequencing.

Question 16

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.

Question 17

Most coal was formed during the Carboniferous period.What is a reasonable hypothesis that explains this observation?

A)Plants from this period did not require fungal associations.
B)There were not many saprophytic fungi during this period.
C)There were not many mycorrhizal fungi during this period.
D)Coal was formed from an explosion of fungal species during this period.

Question 18

Fungi are most closely related to which of these groups?

A)plants
B)green algae
C)animals
D)red algae

Question 19

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.
Describe what you believe would be the best method of providing the appropriate fungi to the newly transplanted pines described in the previous question.Be sure to identify the source of the fungi and the stage of the life cycle during which you would transport them.Also explain how you would introduce the fungi to their new home.Explain why you believe your method would work,including relevant elements of fungal biology.

Question 20

Why is it important that ectomycorrhizal fungi (EMF)have peptidase enzymes?

A)These enzymes are necessary to break through the tough lignin layers in plants.
B)These enzymes assist with the breakdown of cellulose.
C)These enzymes are needed to release nitrogen from dead plant material in colder environments.
D)These enzymes catalyze the formation of the compounds used during decomposition.

Question 21

Based on the idea that fungi have pores between their cell walls,allowing 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.

Question 22

If seedlings in the shade commonly do receive sugars from plants in the sunlight,which of the following areas should be investigated by future research? Explain why you think each area should (or should not)be investigated? Issues to consider: (1)Plausibility-can the research be performed with current technologies? (2)Is it an interesting question that will lead to valuable future knowledge? If so,describe why the information will be helpful.
A.The above-described exchanges were all among seedlings of the same age.Is the rate or degree of carbon transfer from one plant to another more affected by the degree of shading,or by the relative photosynthetic ability (size/age of the tree)?
B.Does the identity of the partners matter for rate or degree of carbon transfer? Is there a greater exchange among trees of the same species compared to trees of different species? Or do different fungal species have different capacities for transfer?
C.How far (linear distance in meters)can carbon be transferred in nature? Do exchanges occur only between adjacent plants,or can sugars be taken up by plants outside the immediate neighbors? Does distance affect the rate/degree of exchange in and of itself? (Can a heavily shaded tree that is farther away receive more carbon than a nearby tree in the sun?)
D.All of these areas should be investigated.

Question 23

Simard et al.(1997)further hypothesized that if reciprocal transfer did occur,it would be a source-sink relationship driven by photosynthetic rates.That is,if one seedling is in full sun and the other in deep shade,there will be a net movement of carbon from the seedling in full sun to the one in deep shade.If a shade was placed over the birch seedlings and the cedar,and the Douglas fir was left in full sun,what result could Simard and colleagues expect?

A)More ¹³C would be found in the birch than in the Douglas fir.
B)More ¹³C would be found in the Douglas fir than the birch.
C)The most ¹³C would be found in the cedar.
D)The most ¹⁴C would be found in the cedar.

Question 24

The researchers then wanted to know if plant biodiversity and productivity would increase in a natural system as a result of increasing AMF diversity beyond just four species. Consider Figure 31.6 below (Figure 2 from van der Heijden et al. 1998):

Figure 31.6
Plant biomass (growth)in Figure 31.6 increases as fungal diversity increases.True or false?

Question 25

Canadian and Swiss researchers (van der Heijden et al., 1998)interested in factors affecting biodiversity, grew a variety of grassland plants in combination with one of four arbuscular mycorrhizal (AMF)species, no AMF, or all four AMF species together; 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 were present. Use the graphs in Figure 31.5 to answer the questions that follow. Note that 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.

Figure 31.4

Figure 31.5
Why does total biomass (graph e,Figure 31.5)not vary with AMF diversity?

A)Plant growth is unaffected by fungal diversity.
B)Most of the plants in this system do not form mycorrhizal associations.
C)Bromus is the dominant plant species.
D)Lotus corniculatus is a rare species.

Question 26

There is much discussion in the media about protecting biodiversity, but does it 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, no AMF, or all four AMF species together; 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. Use the graphs in Figure 31.4 to answer the questions that follow. Note that 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.

Figure 31.4
Based on the van der Heijden et al.(1998)graphs in Figure 31.4,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?

A)Its biomass is greatest when no AMF are present.
B)Its biomass is greatest when AM fungus A is present.
C)Its biomass is greatest when AM fungus B is present.
D)Its biomass is greatest when AM fungus C is present.
E)Its biomass is greatest when all AMF are present.

Question 27

The researchers then wanted to know if plant biodiversity and productivity would increase in a natural system as a result of increasing AMF diversity beyond just four species. Consider Figure 31.6 below (Figure 2 from van der Heijden et al. 1998):

Figure 31.6
If the number of mycorrhizal fungal species increases to 20,the amount of P in the soil will likely decline to zero (Figure 31.6).True or false?

Question 28

There is much discussion in the media about protecting biodiversity, but does it 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, no AMF, or all four AMF species together; 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. Use the graphs in Figure 31.4 to answer the questions that follow. Note that 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.

Figure 31.4
Which of the following best explains the data given in graph (b)of Figure 31.4 about Lotus corniculatus?

A)This plant grows best when AMF taxa A or C are present.
B)Lotus corniculatus does not form mycorrhizal associations.
C)Mycorrhizal fungi parasitize the plant's roots when they are present,reducing its growth.
D)This plant forms multiple AMF associations,growing best with increased fungal diversity.

Question 29

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). Figure 31.2 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 (¹³CO₂ and ¹⁴CO₂, isotopes of carbon). As the seedlings photosynthesized, the radioactive carbon dioxide was converted into radioactively labeled sugars that could be tracked and measured by the researchers.

Figure 31.2
Refer to Figure 31.2.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)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.

Question 30

This symbiotic association grows on rocks,where it begins the process of soil formation,and it is a major food source for caribou.

A)arbuscular mycorrhizal fungi
B)ectomycorrhizal fungi
C)endophytes
D)lichens
E)chytrids

Question 31

Canadian and Swiss researchers (van der Heijden et al., 1998)interested in factors affecting biodiversity, grew a variety of grassland plants in combination with one of four arbuscular mycorrhizal (AMF)species, no AMF, or all four AMF species together; 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 were present. Use the graphs in Figure 31.5 to answer the questions that follow. Note that 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.

Figure 31.4

Figure 31.5
What is the major difference between Bromus erectus (graph f)and the other plant species (graphs a-d)included in the study?

A)Bromus grows best with a diversity of fungal partners.
B)Bromus is unaffected by AMF diversity.
C)Bromus does not form mycorrhizal associations.
D)Bromus produces very little biomass regardless of AMF.

Question 32

Figure 31.3
Referring to Figure 31.3 (Simard et al.,1997-third-year seedlings only),shown above,was there a net transfer of carbon from plants in sunlight to plants in shade?

A)yes
B)no

Question 33

There is much discussion in the media about protecting biodiversity, but does it 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, no AMF, or all four AMF species together; 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. Use the graphs in Figure 31.4 to answer the questions that follow. Note that 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.

Figure 31.4
Based on the graphs shown above,which of the following plant species is most likely not to form mycorrhizal associations?

A)Carax flacca (graph a)
B)Lotus corniculatus (graph b)
C)Sanguisorba officinalis (graph c)
D)Centaurium erythrea (graph d)

Question 34

Canadian and Swiss researchers (van der Heijden et al., 1998)interested in factors affecting biodiversity, grew a variety of grassland plants in combination with one of four arbuscular mycorrhizal (AMF)species, no AMF, or all four AMF species together; 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 were present. Use the graphs in Figure 31.5 to answer the questions that follow. Note that 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.

Figure 31.4

Figure 31.5
Based on graphs (e)and (f)in Figure 31.5,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.

Question 35

Why is it reasonable to hypothesize that lichens might predict air quality?

A)because of their absorptive life style (receive mineral nutrition from dust and substrate)
B)because of their flat morphology (high ratio of surface area to volume)
C)both of the above
D)neither of the above

Question 36

Canadian and Swiss researchers (van der Heijden et al., 1998)interested in factors affecting biodiversity, grew a variety of grassland plants in combination with one of four arbuscular mycorrhizal (AMF)species, no AMF, or all four AMF species together; 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 were present. Use the graphs in Figure 31.5 to answer the questions that follow. Note that 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.

Figure 31.4

Figure 31.5
Using grams of biomass as an indicator of abundance,which species is most likely the dominant species in this ecosystem (see Figure 31.5)?

A)Bromus erectus
B)Carax flacca
C)Sanguisorba officinalis
D)Centaurium erythrea

Question 37

The researchers then wanted to know if plant biodiversity and productivity would increase in a natural system as a result of increasing AMF diversity beyond just four species. Consider Figure 31.6 below (Figure 2 from van der Heijden et al. 1998):

Figure 31.6
The plants in graphs (b),(c),(e),and (f)have mycorrhizal associations.True or false?

Question 38

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). Figure 31.2 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 (¹³CO₂ and ¹⁴CO₂, isotopes of carbon). As the seedlings photosynthesized, the radioactive carbon dioxide was converted into radioactively labeled sugars that could be tracked and measured by the researchers.

Figure 31.2
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 forms arbuscular mycorrhizae

Question 39

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). Figure 31.2 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 (¹³CO₂ and ¹⁴CO₂, isotopes of carbon). As the seedlings photosynthesized, the radioactive carbon dioxide was converted into radioactively labeled sugars that could be tracked and measured by the researchers.

Figure 31.2
Referring to Simard et al.(1997),what is the result that would most strongly refute their hypothesis?

A)No movement;carbon-14 is found in the birch seedling's tissues and carbon-13 in the Douglas fir.
B)Reciprocal exchange;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.

Question 40

Microsporidians are considered parasitic because of the ability to penetrate their host cells using this structure.

A)mycelium
B)polar tube
C)sporangia
D)chitin