Chapter 31 Questions

Question 1

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 New England, Canada, and even the state of Washington. 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 2006, it is estimated that over six million bats have perished from WNS.
The Gd mat on the fur of the bats should be expected to consist of ___.
a. hyphae
b. yeasts
c. haustoria
d. basidia

Answer 1

a. hyphae

Question 2

What do fungi and arthropods have in common?

a. Both groups are predominantly autotrophs that produce their own food.
b. The haploid state is dominant in both groups.
c. Both groups have cell walls.
d. Both groups use chitin for support.

Answer 2

d. Both groups use chitin for support.

Question 3

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. This high ratio creates more room inside the cells for additional organelles involved in absorption.
b. This high ratio means that fungi have a thick, fleshy structure that allows the fungi to store more of the food it absorbs.
c. The lower volume prevents the cells from drying out too quickly, which can interfere with absorption.
d. The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.

Answer 3

d. The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.

Question 4

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. grasses
b. prokaryotes
c. protists
d. flowering plants

Answer 4

b. prokaryotes

Question 5

When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter?

a. larger bacterial populations
b. fungal enzymes
c. fungal haustoria
d. increased oxygen levels

Answer 5

b. fungal enzymes

Question 6

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?

a. increased mortality in plants with mycorrhizae than in plants without mycorrhizae
b. smaller apple size 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 production of corn ears in plants with mycorrhizae than in plants without mycorrhizae

Answer 6

d. increased production of corn ears in plants with mycorrhizae than in plants without mycorrhizae

Question 7

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. predatory
b. commensal
c. parasitic
d. mutualistic

Answer 7

d. mutualistic

Question 8

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. germination
b. fertilization
c. plasmogamy
d. karyogamy

Answer 8

c. plasmogamy

Question 9

After cytokinesis occurs in budding yeasts, the daughter cell has a ___.

a. similar nucleus and more cytoplasm than the mother cell
b. larger nucleus and less cytoplasm than the mother cell
c. smaller nucleus and less cytoplasm than the mother cell
d. similar nucleus and less cytoplasm than the mother cell

Answer 9

d. similar nucleus and less cytoplasm than the mother cell

Question 10

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

a. results in heterokaryotic or dikaryotic cells
b. means that sexual reproduction can occur in specialized structures
c. allows fungi to reproduce asexually most of the time
d. results in multiple diploid nuclei per cell

Answer 10

a. results in heterokaryotic or dikaryotic cells

Question 11

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

a. Mycelia are able to grow in the direction of food.
b. Hyphae have a smaller surface-area-to-volume ratio than do the hairs on a plant root.
c. Hyphae are 100 to 1,000 times larger than plant roots.
d. Fungi secrete extracellular enzymes that can break down large molecules.

Answer 11

d. Fungi secrete extracellular enzymes that can break down large molecules.

Question 12

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. horizontal gene transfer
b. convergent evolution
c. paraphyletic evolution
d. secondary endoparasitism

Answer 12

b. convergent evolution

Question 13

Arrange the following in order from largest to smallest.

a. ascocarp, ascus, ascospore, ascomycete
b. ascocarp, ascomycete, ascus, ascospore
c. ascomycete, ascocarp, ascus, ascospore
d. ascomycete, ascus, ascospore, ascocarp

Answer 13

c. ascomycete, ascocarp, ascus, ascospore

Question 14

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. 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. 200 ng on 7 chromosomes
b. 200 ng on 14 chromosomes
c. 100 ng on 7 chromosomes
d. 100 ng on 14 chromosomes

Answer 14

c. 100 ng on 7 chromosomes

Question 15

Fungi produce many compounds that humans are able to use medically. How can you account for these compounds?

a. Humans used artificial selection to develop fungi that produced specific compounds.
b. The compounds are produced as a result of sexual reproduction and recombination.
c. The compounds probably provide a benefit to the fungi.
d. The presence of the compounds in the fungi were accidentally produced and have no function.

Answer 15

c. The compounds probably provide a benefit to the fungi.

Question 16

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 providing the seeds with water and minerals
b. by strengthening the seed coat that surrounds each seed
c. by transferring some chloroplasts to the embryo in each seed
d. by providing the embryos with some of the organic nutrients the fungi have absorbed

Answer 16

d. by providing the embryos with some of the organic nutrients the fungi have absorbed

Question 17

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.
Figure.
What is the most probable location of the oldest portion of this mycelium?
a. A
b. B
c. C
d. D

Answer 17

c. C

Question 18

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?
a. Inoculate infected amphibians with Jl and determine whether the amphibians recover from infection by chytrids.
b. Inoculate uninfected amphibians with Jl, and determine whether the amphibians continue to remain uninfected 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.

Answer 18

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.

Question 19

Along with bacteria and protozoa, some chytrid fungi live in the digestive tracts of cattle and aid in the digestion of plant matter thus, all three groups represent potential mutualists with cattle. In an experiment designed to test how much of a contribution to cell wall digestion was made by fungi in one part of the stomach (rumen), Lee et al. fed grain to cattle and then removed samples of the rumen contents. They took these samples to the laboratory and experimentally treated them with various chemicals to produce fractions that contained (A) only fungi, (B) only bacteria, (C) only protozoa, and (D) all of the potential mutualists. They then measured the percent of the cell wall that was degraded.
Figure.
Which of the following conclusions can be drawn correctly from the data?
a. Of all three potential mutualists, fungi contribute the least to cell wall digestion.
b. Of all three potential mutualists, protozoa contribute the most to cell wall digestion.
c. Fungi contribute as much to cell wall degradation as all the potential mutualists together.
d. The cattle did not benefit from the presence of fungi; therefore, the fungi are not mutualistic with the cattle.

Answer 19

c. Fungi contribute as much to cell wall degradation as all the potential mutualists together.

Question 20

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

a. Discover the enzymes that fungi use to break down plant matter and use them to increase decomposition rates in order to slow global warming.
b. Discover the lignin-digesting enzymes of fungi, and use them to digest plant tissues left over from food-crop residues and produce a biofuel.
c. Develop a strain of fungus that produces enzymes that absorb oxygen and will help slow global warming.
d. 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.

Answer 20

b. Discover the lignin-digesting enzymes of fungi, and use them to digest plant tissues left over from food-crop residues and produce a biofuel.

Question 21

You are presented with several single-celled organisms, including one thought to belong to the kingdom Fungi. What unique feature helps you identify the fungus?

a. presence of mitochondria
b. absence of chloroplasts
c. presence of nuclei
d. presence of cell walls made of chitin

Answer 21

d. presence of cell walls made of chitin

Question 22

You are given a fungus to identify. It has a fruiting body that contains many structures with eight haploid spores lined up in a row. What kind of fungus is this?

a. zygomycete
b. chytrid
c. deuteromycete
d. ascomycete

Answer 22

d. ascomycete

Question 23

Many fungi produce antibiotics, such as penicillin, to stop bacterial growth. What is the evolutionary advantage of secreting antibacterial chemicals?

a. defense: preventing bacteria from infecting the fungus
b. defense: preventing bacteria from killing fungal spores
c. symbiosis: attracting helpful bacteria
d. competition: destroying bacteria that compete for their food
e. predation: eventually consuming the bacteria

Answer 23

d. competition: destroying bacteria that compete for their food

Question 24

Which phylum includes aquatic, flagellated fungi?

a. Ascomycota
b. Basidiomycota
c. Chytridiomycota
d. Zygomycota

Answer 24

c. Chytridiomycota

Question 25

Which statement about mycorrhizae is false?

a. They are important in natural systems and agriculture.
b. Almost all vascular plants have them.
c. Foresters inoculate pine seedlings with them to promote growth.
d. They colonize soils by dispersing spores that form new mycelia.
e. They are in a commensalistic relationship with plants.

Answer 25

e. They are in a commensalistic relationship with plants.

Question 26

All are lineages of fungi except _____.

a. chytrids
b. zygomycetes
c. glomeromycetes
d. ascomycetes
e. conidia

Answer 26

e. conidia

Question 27

What are lichens?

a. mutually beneficial relationships between fungi and plant roots
b. symbiotic associations between photosynthetic organisms and fungi
c. a type of plant pathogen
d. a type of marine eukaryote
e. single-celled, flagellated protist ancestors of fungi

Answer 27

b. symbiotic associations between photosynthetic organisms and fungi

Question 28

Why might you expect to find many genes for membrane transporters in a mycorrhizal fungus?

a. Mycorrhizal fungi exchange nutrients with the roots of their plant hosts and would be expected to use membrane transporters in this exchange.
b. The numerous chemical reactions that involve mycorrhizal fungi and their plant hosts are catalyzed by membrane transport proteins that function as enzymes.
c. Complex chemical communication occurs between mycorrhizal fungi and their plant hosts, and membrane transporters are crucial in this process.
d. Special junctions form between the cells of plant roots and mycorrhizal fungi, and membrane transporters are an important structural part of these junctions.

Answer 28

a. Mycorrhizal fungi exchange nutrients with the roots of their plant hosts and would be expected to use membrane transporters in this exchange.

Question 29

If you wanted to design a drug that would inhibit normal fungi feeding, the drug could reduce _____.

a. fungal cell surface area
b. fungal cell reproduction rate
c. fungal cell nuclear DNA content
d. fungal cell number

Answer 29

a. fungal cell surface area

Question 30

On a class tour of a brewery, you are told that making beer involves a single-celled fungus. Your friend says, “Can’t be; must be bacteria.” How do you respond?

a. “Yeah.”
b. “Must be a mutant.”
c. “Must be a chytridiomycete.”
d. “Must be a yeast.”

Answer 30

d. “Must be a yeast.”

Question 31

If you were setting up a lab exercise for which you needed to arrange specimens such that those most closely related were nearest each other, what would you place near the fungi?

a. plants
b. animals
c. bacteria
d. protists

Answer 31

b. animals

Question 32

What is most important for fungal spore production?

a. septa
b. hyphae
c. fruiting body
d. chitin
e. flagella

Answer 32

c. fruiting body

Question 33

Which has the longest dikaryotic mycelium?

a. a glomeromycete
b. a basidiomycete
c. a yeast
d. a chytridiomycete
e. a lichen

Answer 33

b. a basidiomycete

Question 34

All fungi are

a. symbiotic.
b. heterotrophic.
c. flagellated.
d. decomposers.

Answer 34

b. heterotrophic.

Question 35

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

a. ascospores
b. basidiospores
c. zygosporangia
d. conidiophores

Answer 35

d. conidiophores

Question 36

The closest relatives of fungi are thought to be the

a. animals.
b. vascular plants.
c. mosses.
d. slime molds.

Answer 36

a. animals.

Question 37

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

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.

Answer 37

d. an extensive surface area well suited for invasive growth and absorptive nutrition.

Question 38

Basidia produce spores by a process known as _____.

a. decomposition
b. mitosis
c. meiosis
d. hyphae
e. binary fission

Answer 38

c. meiosis

Question 39

What sexual processes in fungi generate genetic variation?

a. haustoria and karyogamy
b. budding and meiosis
c. diploidy and the heterokaryotic condition
d. plasmogamy and meiosis
e. karyogamy and meiosis

Answer 39

e. karyogamy and meiosis

Question 40

Karyogamy produces a _____.

a. diploid zygote
b. haploid zygote
c. spores
d. mycelium
e. hypha

Answer 40

a. diploid zygote