31.5 Fungi play key roles in nutrient cycling, ecological interactions, and human welfare

Question 1

60) 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 ʺCʺ?
A) septic tank
B) tree stump
C) deceased animal
D) fire pit
E) cement-capped well

Answer 1

B) tree stump

Question 2

61) Chemicals, secreted by soil fungi, that inhibit the growth of bacteria, are known as
A) antibodies.
B) aflatoxins.
C) hallucinogens.
D) antigens.
E) antibiotics.

Answer 2

E) antibiotics.

Question 3

62) Lichens are symbiotic associations of fungi and
A) mosses.
B) cyanobacteria.
C) green algae.
D) either A or B
E) either B or C

Answer 3

E) either B or C

Question 4

63) Lichens sometimes reproduce asexually using
A) coenocytic fungal hyphae located within photosynthetic cells.
B) the fruiting bodies of fungi.
C) flagellated, conjoined spores of both the fungus and alga.
D) specialized conidiophores.
E) small clusters of fungal hyphae surrounding photosynthetic cells.

Answer 4

E) small clusters of fungal hyphae surrounding photosynthetic cells.

Question 5

64) In both lichens and mycorrhizae, what does the fungal partner provide to its
photosynthetic partner?
A) carbohydrates
B) fixed nitrogen
C) antibiotics
D) water and minerals
E) protection from harmful UV

Answer 5

D) water and minerals

Question 6

65) The symbiotic associations involving roots and soil fungi are considered
A) parasitic.
B) mutualistic.
C) commensal.
D) harmful to the plant partner.
E) the beginning stages of the formation of soil.

Answer 6

B) mutualistic.

Question 7

66) If all mycorrhizae were somehow disrupted, then which of the following would be true?
A) There would be fewer infectious diseases.
B) We wouldnʹt have any antibiotics.
C) There would be no mushrooms for pizza.
D) Most vascular plants would be stunted in their growth.
E) Cheeses like blue cheese or Roquefort would not exist.

Answer 7

D) Most vascular plants would be stunted in their growth.

Question 8

67) 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.
E) Algal cells and fungal cells mix together without any apparent structure. cells are surrounded by fungal hyphae.
D) The fungi grow on rocks and trees and are covered by algae.
E) Algal cells and fungal cells mix together without any apparent structure.

Answer 8

C) Photosynthetic cells are surrounded by fungal hyphae.

Question 9

68) 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) fungi get all of the nutrition they need via the ʺleakinessʺ of photosynthetic partners.
E) soredia are asexual reproductive structures combining both the fungal and
photosynthetic partners.

Answer 9

B) lichens are not purely mutualistic relationships.

Question 10

69) How are the vascular plants that are involved in mycorrhizae and the photosynthetic cells
that are involved in lichens alike?
A) They provide organic nutrients to fungal partners.
B) They secrete acids that keep the fungal partner from growing too quickly.
C) They are in intimate associations with chytrids.
D) They are digested by fungal enzymes while still alive.
E) They contain endosymbiotic fungi.

Answer 10

A) They provide organic nutrients to fungal partners.

Question 11

70) 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) fungicide isnʹt also harmful to insect pests.
C) lichens growing on the vinesʹ branches are not harmed.
D) fungicide might also kill mycorrhizae.
E) sheeting is transparent so that photosynthesis can continue.

Answer 11

D) fungicide might also kill mycorrhizae.

Question 12

71) Which term below refers to symbiotic relationships that involve fungi living between the
cells in plant leaves?
A) pathogens
B) endosymbioses
C) endophytes
D) lichens
E) mycorrhizae

Answer 12

C) endophytes

Question 13

72) If Penicillium typically secretes penicillin without disturbing the lichen relationship in
which it is engaged, then what must have been true about its partner?
A) It should have lacked peptidoglycan in its cell wall.
B) It was probably a red alga.
C) It was probably a member of the domain Bacteria.
D) It was probably a heterotrophic prokaryote.
E) It was probably infected by bacteriophage.

Answer 13

A) It should have lacked peptidoglycan in its cell wall.

Question 14

73) Sexual reproduction has never been observed among the fungi that produce the blue-green
marbling of blue cheeses. What is true of these fungi and others that do not have a sexual
stage?
A) They are currently classified among the deuteromycetes.
B) They do not form heterokaryons.
C) Their spores are produced by mitosis.
D) Only A and B are correct.
E) A, B, and C are correct.

Answer 14

E) A, B, and C are correct.

Question 15

74) Both fungus-derived antibiotics and hallucinogens used by humans probably evolved in
fungi as a means to
A) reduce competition for nutrients.
B) help humanity survive.
C) promote their ingestion of foodstuffs.
D) eliminate other fungi.
E) discourage animal predators.

Answer 15

A) reduce competition for nutrients.

Question 16

75) 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) basiodiospores
B) spores of ectomycorrhizae
C) soredia
D) yeasts
E) leaves (as food for fungus-farming ants)

Answer 16

C) soredia

Question 17

76) Mycorrhizae are to the roots of vascular plants as endophytes are to vascular plantsʹ
A) leaf mesophyll.
B) stem apical meristems.
C) root apical merisems
D) xylem.
E) waxy cuticle.

Answer 17

A) leaf mesophyll.

Question 18

77) Which of the following conditions is caused by a fungus that is accidentally consumed
along with rye flour?
A) ergotism
B) athleteʹs foot
C) ringworm
D) candidiasis (Candida yeast infection)
E) coccidioidomycosis

Answer 18

A) ergotism

Question 19

78) 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 these 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

Answer 19

C) by providing the embryos with some of the organic nutrients they have absorbed

Question 20

Rose-pickerʹs disease is caused by the yeast, Sporothrix 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 drains.
79) 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?
E) Being a yeast, does S. schenkii perform the process of budding?

Answer 20

B) Does S. schenkii rely on animal infection to complete some part of its life cycle, or is the infection merely opportunistic?

Question 21

80) Say 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 that 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 3
D) 2 and 5
E) 4 and 5

Answer 21

D) 2 and 5

Question 22

81) Humans have immune systems in which lymph nodes are important, because many
phagocytes and lymphocytes reside therein. Given that a successful infection by S. schenkii
damages lymph nodes themselves, which of these 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 bodyʹs 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.
E) Given that most fungal pathogens of humans infect only the skin, human defenses are not adapted to seek out and destroy systemic fungal infections.

Answer 22

B) Their conversion from yeast to hyphal morphology allows such fast growth that the bodyʹs defenses are at least temporarily overwhelmed.

Question 23

1) All fungi share which of the following characteristics?
A) symbiotic
B) heterotrophic
C) flagellated
D) pathogenic
E) act as decomposers

Answer 23

B) heterotrophic

Question 24

2) 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) formation of resistant zygosporangia
E) parasitic lifestyle

Answer 24

C) flagellated spores

Question 25

3) Which of the following cells or structures are associated with asexual reproduction in fungi?
A) ascospores
B) basidiospores
C) zygosporangia
D) conidiophores
E) ascocarps

Answer 25

D) conidiophores

Question 26

4) 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) avoiding sexual reproduction until the environment changes.
C) the potential to inhabit almost all terrestrial habitats.
D) the increased probability of contact between different mating types.
E) an extensive surface area well suited for invasive growth and absorptive nutrition.

Answer 26

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

Question 27

5) The photosynthetic symbiont of a lichen is often a(n)
A) moss.
B) green alga.
C) brown alga.
D) ascomycete.
E) small vascular plant.

Answer 27

B) green alga.

Question 28

6) Among the organisms listed here, which are thought to be the closest relatives of fungi?
A) animals
B) vascular plants
C) mosses
D) brown algae
E) slime molds

Answer 28

A) animals