1) The hydrolytic digestion of which of the following should produce monomers that are aminated (i.e., have an amine group attached) molecules of β-glucose?
A) insect exoskeleton
B) plant cell walls
C) fungal cell walls
D) Three of these responses are correct.
E) Two of these responses are correct.
Answer: E
2) 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) plants
B) protists
C) prokaryotes
D) animals
E) mutualistic fungi
Answer: C
3) When a mycelium infiltrates an unexploited source of
dead organic matter, what are most likely to appear within the food source soon
thereafter?
A) fungal haustoria
B) soredia
C) fungal enzymes
D) increased oxygen levels
E) larger bacterial populations
Answer: C
4) Which of the following is a characteristic of hyphate
fungi (fungi featuring hyphae)?
A) They acquire their nutrients by phagocytosis.
B) Their body plan is a unicellular sphere.
C) Their cell walls consist mainly of cellulose microfibrils.
D) They are adapted for rapid directional growth to new
food sources.
E) They reproduce asexually by a process known as
budding.
Answer: D
5) The functional significance of porous septa in certain
fungal hyphae is most similar to that represented by which pair of structures
in animal cells and plant cells, respectively?
A) desmosomestonoplasts
B) gap junctionsplasmodesmata
C) tight junctionsplastids
D) centriolesplastids
E) flagellacentral vacuoles
Answer: B
6) What do fungi and arthropods have in common?
A) Both groups are commonly coenocytic.
B) The haploid state is dominant in both groups.
C) Both groups are predominantly heterotrophs that ingest
their food.
D) The protective coats of both groups are made of
chitin.
E) Both groups have cell walls.
Answer: D
7) In septate fungi, what structures allow cytoplasmic
streaming to distribute needed nutrients, synthesized compounds, and organelles
throughout the hyphae?
A) multiple chitinous layers in cross-walls
B) pores in cross-walls
C) complex microtubular cytoskeletons
D) two nuclei
E) tight junctions that form in cross-walls between cells
Answer: B
8) What accounts most directly for the extremely fast
growth of a fungal mycelium?
A) rapid distribution of synthesized proteins by
cytoplasmic streaming
B) a long tubular body shape
C) the readily available nutrients from their ingestive
mode of nutrition
D) a dikaryotic condition that supplies greater amounts
of proteins and nutrients
Answer: A
9) The vegetative (nutritionally active) bodies of most
fungi are
A) composed of hyphae.
B) referred to as a mycelium.
C) usually underground.
D) Three of these responses are correct.
E) Two of these responses are correct.
Answer: D
10) Both fungus-farming ants and their fungi can
synthesize the same structural polysaccharide from the β-glucose. What is this
polysaccharide?
A) amylopectin
B) chitin
C) cellulose
D) lignin
E) glycogen
Answer: B
11) Consider two hyphae having equal dimensions: one from
a septate species and the other from a coenocytic species. Compared with the
septate species, the coenocytic species should have
A) fewer nuclei.
B) more pores.
C) less chitin.
D) less cytoplasm.
E) reduced cytoplasmic streaming.
Answer: C
12) Immediately after karyogamy occurs, which term
applies?
A) plasmogamy
B) heterokaryotic
C) dikaryotic
D) diploid
Answer: D
13) Which description does not apply equally well to both
sexual and asexual spores?
A) have haploid nuclei
B) represent the dispersal stage
C) are produced by meiosis
D) upon germination, will subsequently undergo S phase
and mitosis
Answer: C
14) Plasmogamy can directly result in which of the
following?
1. cells with a single haploid nucleus
2. heterokaryotic cells
3. dikaryotic cells
4. cells with two diploid nuclei
A) 1 or 2
B) 1 or 3
C) 2 or 3
D) 2 or 4
E) 3 or 4
Answer: C
15) After cytokinesis occurs in budding yeasts, the
daughter cell has a
A) smaller nucleus and more cytoplasm than the mother
cell.
B) smaller nucleus and less cytoplasm than the mother
cell.
C) larger nucleus and less cytoplasm than the mother
cell.
D) similar nucleus and less cytoplasm than the mother
cell.
Answer: D
16) In most fungi, karyogamy does not immediately follow
plasmogamy, which consequently
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.
E) is strong support for the claim that fungi are not
truly eukaryotic.
Answer: D
17) If all of their nuclei are equally active
transcriptionally, then the cells of both dikaryotic and heterokaryotic fungi,
in terms of the gene products they can make, are essentially
A) haploid.
B) diploid.
C) alloploid.
D) completely homozygous.
E) completely hemizygous.
Answer: B
18) Which process occurs in fungi and has the opposite
effect on a cell's chromosome number than does meiosis I?
A) mitosis
B) plasmogamy
C) crossing over
D) binary fission
E) karyogamy
Answer: E
19) Which of the following statements is true of
deuteromycetes?
A) They are the second of five fungal phyla to have
evolved.
B) They represent the phylum in which all the fungal
components of lichens are classified.
C) They are the group of fungi that have, at present, no
known sexual stage.
D) They are the group that includes molds, yeasts, and
lichens.
E) They include the imperfect fungi that lack hyphae.
Answer: C
20) Fossil fungi date back to the origin and early
evolution of plants. What combination of environmental and morphological change
is similar in the evolution of both fungi and plants?
A) presence of "coal forests" and change in
mode of nutrition
B) periods of drought and presence of filamentous body
shape
C) predominance in swamps and presence of cellulose in
cell walls
D) colonization of land and loss of flagellated cells
E) continental drift and mode of spore dispersal
Answer: D
21) Which of the following characteristics is shared by
both chytrids and other kinds of fungi?
A) presence of flagella
B) zoospores
C) autotrophic mode of nutrition
D) cell walls of cellulose
E) nucleotide sequences of several genes
Answer: E
22) The multicellular condition of animals and fungi
seems to have arisen
A) due to common ancestry.
B) by convergent evolution.
C) by inheritance of acquired traits.
D) by natural means, and is a homology.
E) by serial endosymbioses.
Answer: B
23) 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 should be true of the smaller cell
until it reaches the size of the larger cell?
A) It should produce fewer fermentation products per unit
time.
B) It should produce ribosomal RNA at a slower rate.
C) It should be transcriptionally less active.
D) It should have reduced motility.
E) It should have a smaller nucleus.
Answer: A
24) The microsporidian, Brachiola gambiae, parasitizes
the mosquito, Anopheles gambiae. Adult female mosquitoes must take blood meals
in order for their eggs to develop, and it is while they take blood that they
transmit malarial parasites to humans. Male mosquitoes drink flower nectar. If
humans are to safely and effectively use Brachiola gambiae as a biological control
to reduce human deaths from malaria, then how many of the following statements
should be true?
1. Brachiola should kill the mosquitoes before the
malarial parasite they carry reaches maturity.
2. The microsporidian should not be harmful to other
insects.
3. Microsporidians should infect mosquito larvae, rather
than mosquito adults.
4. The subsequent decline in anopheline mosquitoes should
not significantly disrupt human food resources or other food webs.
5. Brachiola must be harmful to male mosquitoes, but not
to female mosquitoes.
A) one statement only
B) two statements
C) three statements
D) four statements
E) all five statements
Answer: C
25) Many infected animals are induced by the parasitic
microsporidians to develop huge cells, known as xenomas, which are full of
spores. Given their large size, what should be true of the xenomas?
A) The parasite must endow the xenoma with some way to
overcome its unfavorable surface area-to-volume ratio.
B) The xenoma must obtain mitochondria to survive.
C) The xenoma must gain a cell wall; otherwise, it will
lyse.
D) The xenoma acts as a prison, of sorts, to keep the
spores from escaping and infecting other organisms.
Answer: A
26) What are the sporangia of the bread mold Rhizopus?
A) asexual structures that produce haploid spores
B) asexual structures that produce diploid spores
C) sexual structures that produce haploid spores
D) sexual structures that produce diploid spores
Answer: A
27) Which of these paired fungal structures are
structurally and functionally most alike?
A) conidia and basidiocarps
B) sporangia and hyphae
C) soredia and gills
D) haustoria and arbuscules
E) zoospores and mycelia
Answer: D
28) You are given an organism to identify. It has a
fruiting body that contains many structures with eight haploid spores lined up
in a row. What kind of a fungus is this?
A) zygomycete
B) ascomycete
C) deuteromycete
D) chytrid
E) basidiomycete
Answer: B
29) Which of the following has the least affiliation with
all of the others?
A) Glomeromycota
B) mycorrhizae
C) lichens
D) arbuscules
E) mutualistic fungi
Answer: C
30) Arrange the following from largest to smallest:
1. ascospore
2. ascocarp
3. ascomycete
4. ascus
A) 3 → 4 → 2 → 1
B) 3 → 2 → 4 → 1
C) 3 → 4 → 1 → 2
D) 2 → 3 → 4 → 1
E) 2 → 4 → 1 → 3
Answer: B
31) Arrange the following from largest to smallest,
assuming that they all come from the same fungus.
1. basidiocarp
2. basidium
3. basidiospore
4. mycelium
5. gill
A) 4 → 5 → 1→ 2 → 3
B) 5 → 1 → 4 → 2 → 3
C) 5 → 1 → 4 → 3 → 2
D) 5 → 1 → 3 → 2 → 4
E) 4 → 1 → 5 → 2 → 3
Answer: E
32) Among sac fungi, which of these correctly
distinguishes ascospores from conidia?
A) Ascospores are diploid, whereas conidia are haploid.
B) Ascospores are produced only by meiosis, whereas
conidia are produced only by mitosis.
C) Ascospores have undergone genetic recombination during
their production, whereas conidia have not.
D) Ascospores are larger, whereas conidia are smaller.
E) Ascospores will germinate into haploid hyphae, whereas
conidia will germinate into diploid hyphae.
Answer: C
33) A fungal spore germinates, giving rise to a mycelium
that grows outward into the soil surrounding the site where the spore
originally landed. Which of the following accounts for the fungal movement, as
described here?
A) karyogamy
B) mycelial flagella
C) alternation of generations
D) breezes distributing spores
E) cytoplasmic streaming in hyphae
Answer: E
34) In what structures do both Penicillium and
Aspergillus produce asexual spores?
A) asci
B) zygosporangia
C) rhizoids
D) gametangia
E) conidiophores
Answer: E
35) 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: E
36) Lichens are symbiotic associations of fungi and
A) mosses.
B) cyanobacteria.
C) green algae.
D) Three of these responses are correct.
E) Two of these responses are correct.
Answer: E
37) 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: D
38) 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.
Answer: C
39) 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
"leakiness" of photosynthetic partners.
E) soredia are asexual reproductive structures combining
both the fungal and photosynthetic partners.
Answer: B
40) 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) lichens growing on the vines' branches are not harmed.
C) fungicide might also kill mycorrhizae.
D) sheeting is transparent so that photosynthesis can
continue.
Answer: C
41) Which of the following terms 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: C
42) 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: A
43) 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 ascomycetes.
B) They do not form heterokaryons.
C) Their spores are probably produced by mitosis.
D) Three of these responses are correct.
E) Two of these responses are correct.
Answer: C
44) 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: A
45) 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) basidiospores
B) spores of ectomycorrhizae
C) soredia
D) yeasts
E) leaves (as food for fungus-farming ants)
Answer: C
46) Mycorrhizae are to the roots of vascular plants as
endophytes are to vascular plants'
A) leaf mesophyll.
B) stem apical meristems.
C) root apical meristems
D) xylem.
E) waxy cuticle.
Answer: A
47) Which of the following conditions is caused by a
fungus that is accidentally consumed along with rye flour?
A) ergotism
B) athlete's foot
C) ringworm
D) candidiasis (Candida yeast infection)
E) coccidioidomycosis
Answer: A
48) 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 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: C
49) See Fig
Which tree depicts the microsporidians as a sister
group of the ascomycetes?
A) I
B) II
C) III
D) IV
Answer: A
50) Which tree depicts the closest relationship between
zygomycetes and chytrids?
A) I
B) II
C) III
D) IV
Answer: C
51) Which tree depicts the microsporidians as a sister
group of the fungi, rather than as a fungus?
A) I
B) II
C) III
D) IV
Answer: D
52. The following 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 AD are all 0.5 meters below the soil
surface. Responses may be used once, more than once, or not at all.
What is the most probable location of the oldest
portion of this mycelium?
A) A
B) B
C) C
D) D
Answer: C
53. The following 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 AD are all 0.5 meters below the soil
surface. Responses may be used once, more than once, or not at all.
Which location is nearest to basidiocarps?
A) A
B) B
C) C
D) D
Answer: A
54. The following 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 AD are all 0.5 meters below the soil
surface. Responses may be used once, more than once, or not at all.
At which location is the mycelium currently absorbing
the most nutrients per unit surface area, per unit time?
A) A
B) B
C) C
D) D
Answer: A
55. The following 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 AD are all 0.5 meters below the soil
surface. Responses may be used once, more than once, or not at all.
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?
A) A
B) B
C) C
D) D
Answer: D
56. The following 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 AD are all 0.5 meters below the soil
surface. Responses may be used once, more than once, or not at all.
Assume that all four locations are 0.5 m above the
surface. On a breezy day with prevailing winds blowing from left to right,
where should one expect to find the highest concentration of free basidiospores
in an air sample?
A) A
B) B
C) C
D) D
Answer: D
57. The following 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 AD are all 0.5 meters below the soil
surface. Responses may be used once, more than once, or not at all.
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?
A) skin mycoses
B) coccidiomycosis (lung infection)
C) systemic (bloodborne) Candida infection
D) Sporothrix infection of lymphatic vessels
E) Tinea tonsurans infection limited to interior of hair
shafts
Answer: A
58. The following 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 AD are all 0.5 meters below the soil
surface. Responses may be used once, more than once, or not at all.
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"?
A) septic tank
B) tree stump
C) deceased animal
D) fire pit
E) cement-capped well
Answer: B
59. 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) 100, carried on 7 chromosomes
B) 100, carried on 14 chromosomes
C) 200, carried on 7 chromosomes
D) 200, carried on 14 chromosomes
E) 400, carried on 14 chromosomes
Answer: A
60. 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.
What is the ploidy of a single mature ascospore?
A) monoploid
B) diploid
C) triploid
D) tetraploid
E) polyploid
Answer: A
61. 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.
Each of the eight ascospores present at the end of
mitosis has the same chromosome number and DNA content (ng) as each of the four
cells at the end of meiosis. What must have occurred in each spore between the
round of meiosis and the round of mitosis?
A) double fertilization
B) crossing over
C) nondisjunction
D) autopolyploidy
E) S phase
Answer: E
62. Unicellular yeasts can be represented as spheres, whereas
filamentous hyphae more closely resemble cylinders. As these two geometric
figures increase in size, their surface area-to-volume ratios change. The
following tables demonstrate how this ratio changes, first for spheres, and
second for cylinders. For the cylinder, girth (i.e., radius, r) will remain
constant, whereas length, L, will increase. Note the formulas below the
respective tables.
As a direct result of increasing surface area in both
yeasts and filamentous hyphae, which cell structures/materials must also
increase?
1. amount of chitin
2. number of nuclei
3. amount of plasma membrane
4. number of mitochondria
5. amount of peptidoglycan
A) 1 only
B) 1 and 3
C) 2 and 3
D) 2 and 4
E) 1, 3, and 5
Answer: B
63. Unicellular yeasts can be represented as spheres, whereas
filamentous hyphae more closely resemble cylinders. As these two geometric
figures increase in size, their surface area-to-volume ratios change. The
following tables demonstrate how this ratio changes, first for spheres, and
second for cylinders. For the cylinder, girth (i.e., radius, r) will remain
constant, whereas length, L, will increase. Note the formulas below the
respective tables.
Which statement is a correct interpretation of the
data in the previous tables?
A) As a sphere gets bigger, its surface area and volume
increase at about the same pace.
B) As a cylinder gets bigger, its surface area increases
at a greater pace than does its volume.
C) As a cylinder gets bigger, its volume increases at
about the same pace at which the volume of a sphere increases.
D) As spheres and cylinders get bigger, the surface area
of a cylinder increases at a faster pace than does the surface area of a
sphere.
Answer: B
64) Both axes of the graph are linear.
Thus, the shape of
the line plotted on this graph most accurately depicts the
A) volume of a sphere as the radius, r, increases.
B) surface area of a sphere as the radius, r, increases.
C) volume of a cylinder as length, L, increases.
D) surface area of a cylinder as length, L, increases.
Answer: C
65) Surface area represents the area available for
exchange with the environment, whereas volume represents the cytoplasm which
requires nutrients and from which waste products (usually toxic) must be
removed.
Which of the following should provide the most favorable conditions
for effective exchange?
A) a smaller unicellular yeast
B) a larger unicellular yeast
C) a shorter filamentous hypha
D) a longer filamentous hypha
Answer: D
66) Some fungi can exist either as unicellular yeasts or
as filamentous hyphae.
Which of these forms would be most favorable in an
environment where nutrients are limited?
A) a smaller unicellular yeast
B) a larger unicellular yeast
C) a shorter filamentous hypha
D) a longer filamentous hypha
Answer: D
67. Recent genetic studies of the structure of microsporidian
genomes, as well as the sequences of their tubulin genes and the gene for RNA
polymerase II, indicate that microsporidians are closely related to the fungi.
Microsporidians lack flagella, centrioles, peroxisomes, and mitochondria
(although they do have degenerate mitochondria, called mitosomes). They have
the smallest genome of any eukaryote, and it is a genome that changes quickly.
The genome is contained within two haploid nuclei. All microsporidians are
obligate intracellular parasites. They use a unique organelle called a polar
filament to gain access to the cells of their hosts. One species causes chronic
diarrhea in AIDS patients. Another parasitizes Anopheles gambiae, the mosquito
that transmits a fatal form of malaria to humans.
Given the eukaryotic structures they lack, it should
be expected that microsporidians also lack
A) the "9 + 2 pattern" of microtubules.
B) chitin.
C) lysosomes.
D) nuclei.
E) centrosomes.
Answer: A
68. Recent genetic studies of the structure of microsporidian
genomes, as well as the sequences of their tubulin genes and the gene for RNA
polymerase II, indicate that microsporidians are closely related to the fungi.
Microsporidians lack flagella, centrioles, peroxisomes, and mitochondria
(although they do have degenerate mitochondria, called mitosomes). They have
the smallest genome of any eukaryote, and it is a genome that changes quickly.
The genome is contained within two haploid nuclei. All microsporidians are
obligate intracellular parasites. They use a unique organelle called a polar
filament to gain access to the cells of their hosts. One species causes chronic
diarrhea in AIDS patients. Another parasitizes Anopheles gambiae, the mosquito
that transmits a fatal form of malaria to humans.
The lifestyle of microsporidians is most similar to
that of
A) scavengers.
B) viruses.
C) free-living yeasts.
D) ectoparasites.
Answer: B
69. Recent genetic studies of the structure of microsporidian
genomes, as well as the sequences of their tubulin genes and the gene for RNA
polymerase II, indicate that microsporidians are closely related to the fungi.
Microsporidians lack flagella, centrioles, peroxisomes, and mitochondria
(although they do have degenerate mitochondria, called mitosomes). They have
the smallest genome of any eukaryote, and it is a genome that changes quickly.
The genome is contained within two haploid nuclei. All microsporidians are
obligate intracellular parasites. They use a unique organelle called a polar
filament to gain access to the cells of their hosts. One species causes chronic
diarrhea in AIDS patients. Another parasitizes Anopheles gambiae, the mosquito
that transmits a fatal form of malaria to humans.
Which of the following microsporidian features are
shared with many other fungi?
1. chitinous cell wall
2. two haploid nuclei per cell
3. polar filament
4. chemoheterotrophy
A) 1 and 2
B) 1 and 3
C) 1 and 4
D) 1, 2, and 4
E) 2, 3, and 4
Answer: D
70. 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?
A) by wind-blown spores
B) by flagella
C) by cilia
D) by pseudopods
E) by hyphae
Answer: B
71. 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.
The chytrid sporangia reside within the amphibian
epidermal cells. Consequently, which term(s) apply to Bd?
1. ectosymbionts
2. parasites
3. commensals
4. pathogens
5. endosymbionts
A) 1 and 2
B) 1 and 3
C) 2 and 4
D) 2, 3, and 5
E) 2, 4, and 5
Answer: E
72. 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.
Which of the following are protists, the organisms
thought to share the closest ancestor with the chytrids?
A) nucleariids
B) choanoflagellates
C) zygomycetes
D) algae
E) diplomonads
Answer: A
73. 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.
Sexual reproduction has not been observed in Bd. A Bd
sporangium initially contains a single, haploid cell. Which of the following
processes must be involved in generating the multiple zoospores eventually
produced by each sporangium?
1. S phase
2. cytokinesis
3. mitosis
4. meiosis
A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 1, 2, and 3
E) 1, 2, and 4
Answer: D
74. 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.
Sexual reproduction has not been observed in Bd. If
its morphology and genetics did not identify it as a chytridiomycete, then to
which fungal group would Bd be assigned?
A) ascomycetes
B) zygomycetes
C) glomeromycetes
D) basidiomycetes
E) deuteromycetes
Answer: E
75. 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.
If infection primarily involves the outermost layers
of adult amphibian skin, and if the chytrids use the skin as their sole source
of nutrition, then which term best applies to the chytrids?
A) anaerobic chemoautotroph
B) aerobic chemoautotroph
C) anaerobic chemoheterotroph
D) aerobic chemoheterotroph
Answer: D
76. 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.
If Bd cannot grow properly at temperatures above 28°C
(82°F), then, assuming the amphibians can survive, in which time or place
should the chytrid infection proceed most rapidly?
1. cooler months
2. warmer months
3. lower altitudes
4. higher altitudes
A) 1 or 3
B) 1 or 4
C) 2 or 3
D) 2 or 4
Answer: B
77. 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.
What makes it risky to rely on the presence of chitin
in adult amphibian skin as the sole positive test for the presence of chytrids?
A) Other mycoses may be in progress in the same amphibian
simultaneously.
B) The amphibian may harbor arthropod ectoparasites
simultaneously.
C) Bacterial infections may be simultaneously underway in
the amphibian.
D) Three of the responses above are correct.
E) Two of the responses above are correct.
Answer: E
78. 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.
The fact that infection by Bd causes lethargy in many
infected amphibians can have what effect on efforts to accurately census the
numbers of dead or dying amphibians at a particular time, in a particular
habitat?
A) It can cause underestimation, due to infected
amphibians preferring to seek out refuges relative to uninfected amphibians.
B) It can cause underestimation, due to increased
predation on, and removal of, infected amphibians relative to uninfected
amphibians.
C) It can cause overestimation, because infected frogs
should be more readily observable to human census-takers than should uninfected
amphibians.
D) All three of the above statements are plausible.
E) Two of the above statements are plausible.
Answer: E
79. 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 for
conclusively determining whether this inhibition is real?
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.
Answer: C
80. 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.
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?
A) the hypothesis that a toxin secreted by Jl cells kills
Bd cells when both are present together on frog skin
B) the hypothesis that Jl cells infect and kill Bd cells
when both are present together on frog skin
C) the hypothesis that Jl outcompetes Bd when both are
present together on a frog's skin
D) the hypothesis that the presence of Jl on frog skin
causes a skin reaction that prevents attachment by Bd cells
Answer: A
81. Rose-picker's 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 then drains.
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: B
82. Rose-picker's 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 then drains.
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: D
83. Rose-picker's 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 then drains.
Humans have immune systems in which lymph nodes are
important, because many phagocytes and lymphocytes reside there. Given that a
successful infection by S. schenkii damages lymph nodes themselves, which of
the following 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 body's 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: B
84) All fungi share which of the following
characteristics?
A) symbiotic
B) heterotrophic
C) flagellated
D) pathogenic
E) act as decomposers
Answer: B
85) 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: C
86) 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: D
87) The photosynthetic symbiont of a lichen is often
A) a moss.
B) a green alga.
C) a brown alga.
D) an ascomycete.
E) a small vascular plant.
Answer: B
88) 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: A
89) 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: E
THEORY
REVIEW
DETAIL
THEORY
Jamur merupakan kelompok organisme eukariotik yang
membentuk dunia jamur atau regnum fungi.
Ciri-ciri umum jamur antara lain:
- Tidak memiliki klorofil.
- Berkembang biak dengan membentuk spora.
- Tubuh berupa benang-benang halus yang disebut hifa.
- Tubuh belum dapat dibedakan antara akar, batang, dan daun.
- Jamur yang bersel satu dikelompokkan pada prokariotik dan yang bersel banyak bertipe eukariotik.
Struktur tubuh jamur tergantung pada jenisnya.
- Jamur yang mempunyai satu sel, misalnya khamir.Soliter , bisa juga membentuk koloni (tunas tunas).
- Ada pula jamur yang multiseluler membentuk tubuh buah besar yang ukurannya mencapai satu meter, contohnya jamur kayu.
- Tubuh jamur tersusun dari komponen dasar yang disebut hifa.
- Hifa membentuk jaringan yang disebut miselium.
- Miselium menyusun jalinan-jalinan semu menjadi tubuh buah.Hifa adalah struktur menyerupai benang yang tersusun dari dinding berbentuk pipa.
- Dinding ini menyelubungi membran plasma dan sitoplasma hifa. Sitoplasmanya mengandung organel eukariotik.
Berdasarkan hifa serta cara berkembangbiak, jamur
dikelompokkan menjadi :
- Subdivisi Oomycota
- Subdivisi Zygomycota
- Subdivisi Ascomycota
- Subdivisi Basidiomycota
- Subdivisi Deuteromycota
Ciri-ciri Oomycota yaitu :
- Hifa tidak bersekat, berkembangbiak secara seksual melalui pembentukan zoospora hasil peleburan gamet jantan dan gamet betina.
- Berkembangbiak secara aseksual dengan membentuk spora berflagel yang disebut zoospora.
- Contoh subdivisi Oomycota yaitu pythium dan saprolegnia.
Ciri-ciri Zygomycota yaitu :
- Hifa tidak bersekat, berkembangbiak secara seksual melalui pembentukan zigospora sebagai hasil peleburan hifa (+) dan hifa (-).
- Berkembangbiak secara aseksual menggunakan spora dalam spongarium.
- Contohnya adalah Rhizopus Oligosporus dan Rhizopus Stolonifer
Ciri-ciri Ascomycota yaitu :
- Hifa bersekat, berkembangbiak secara seksual dengan membentuk spora yang dihasilkan dalam suatu kantung (askus) yang disebut askospora.
- Berkembangbiak secara aseksual dengan membentuk konidiospora, yaitu spora yang dihasilkan secara berantai pada ujung suatu hifa.
- Contohnya yaitu Aspergillus sp., Penicillium sp., Saccharomyces cerevisiae
Ciri-ciri Basidiomycota yaitu :
- Hifa bersekat, berkembangbiak secara seksual dengan membentuk basidiospora , yaitu sporayang dihasilkan pada basidium.
- Berkembangbiak secara aseksual dengan membentuk konidiospora, yaitu spora yang dihasilkan secara berantai pada ujung suatu hifa.
- Contohnya yaitu jamur kuping (Auricularia polytricha), jamur merang (Volvariellavolvaceae)
Ciri-ciri Deutereomycota yaitu :
- Hifa bersekat, berkembangbiak secara aseksual dengan membentuk konidiospora.
- Perkembangbiakan seksual belum diketahui. Contohnya adalah Helminthosporium oryzae dan Sclerotium rolfsi.
- Semua jenis jamur bersifat heterotrof. Namun, berbeda dengan organisme lainnya.
- Jamur tidak memangsa dan mencernakan makanan.
- Untuk memperoleh makanan, jamur menyerap zat organik dari lingkungan melalui hifa dan miseliumnya,kemudian menyimpannya dalam bentuk glikogen.
- Oleh karena jamur merupakan konsumen maka jamur bergantung pada substrat yang menyediakan karbohidrat,protein, vitamin, dan senyawa kimia lainnya. Semua zat itu diperoleh dari lingkungannya.
- Sebagai makhluk heterotrof, jamur dapat bersifat parasit obligat,parasit fakultatif, atau saprofit
REVIEW
1.
Jamur memiliki struktur tubuh yaitu sebagai
berikut :
a. Tubuh
jamur disusun oleh hifa
b. Memiliki
nukleus
c. Memiliki
septa
d. Memiliki
dinding sel yang mengandung zat kitin
e. Memiliki
lisosom penghasil enzim
2.
Hifa vegetatif pada jamur berfungsi untuk …
a. alat
reproduksi
b. alat
reproduksi dan mencari makan
c. mendukung
alat – alat reproduksi
d. menampung
air yang diperlukan
e. melekatkan
diri pada substrat
3.
Pada jamur Rhizopus sp peleburan gametangia akan
membentuk … dan kromosom bersifat …
a. zigospora,
haploid
b. zigospora,
diploid
c. zoospora,
haploid
d. zoospora,
diploid
e. konidiospora,
haploid
Jawaban : A
Pembahasan :
Perkembangbiakan seksual pada Rhizopus sp dimulai dengan
saling bersentuhan kedua ujung hifa yang merupakan cabang dari dua hifa yang
berlainan. Kedua ujung hifa itu akan membesar yang disebut progametangium yang
akan menjadi gametangium setelah terbentuk dinding penyekat antara kedua ujung
hifa dengan cabang hifa induknya masing-masing. Tahap berikutnya, kedua
gametangium tersebut melebur menjadi zigospora sehingga cairan dari
masing-masing gamet-angium yang mengandung banyak inti sel haploid (n) itu pun
akan bercampur yang diikuti dengan peleburan inti-inti diploid (2n) kemudian
dinding zigospora akan menebal.
4.
Saccaromyces cereviceae berperan dalam pembuatan
tape melalui proses fermentasi anaerob. Hasil proses fermentasi tersebut adalah
…
a. alkohol,
karbondioksida, energi
b. alkohol,
oksigen, energi
c. glukosa,
karbondioksida, energi
d. glukosa,
oksigen, energi
e. glukosa,
sellulosa, alkohol
Jawaban : A
Pembahasan :
Reaksi dalam fermentasi berbeda-beda tergantung pada
jenis gula yang digunakan dan produk yang dihasilkan. Secara singkat, glukosa
(C6H12O6) yang merupakan gula paling sederhana , melalui fermentasi akan
menghasilkan etanol (2C2H5OH). Reaksi fermentasi ini dilakukan oleh ragi, dan
digunakan pada produksi makanan. Hasil proses fermentasi dalam pembuatan tape
yaitu sebagai berikut :
Gula (glukosa, fruktosa, atau sukrosa) → Alkohol (etanol)
+ Karbon dioksida + Energi
Hasil fermentasinya berupa Alkohol, Karbondioksida dan
Energi.
5.
Penicillium merupakan jamur yang biasa tumbuh
pada tempat yang mengandung …
a. vitamin
b. lemak
c. protein
d. karbohidrat
e. gula
Jawaban : D
Pembahasan :
Penicillium merupakan salah satu genus dari divisi
ascomycota, Penicillium ini dimanfaatkan dalam pembuatan bahan makanan seperti
pembuatan roti, keju, oncom. Penicillium ini biasa hidup pada tempat yang
banyak mengandung Karbohidrat.(Riandari:2009)
6.
Jenis Deuteromycota yang menyebabkan kurap pada
kulit adalah …
a. Aspergillus
b. Neurospora
c. Monilia
d. Microsporium
e. Epidermophyton
Jawaban : E
Pembahasan :
Epidermophyton merupakan salah contoh dari jenis jamur
deuterimycota, jamur ini menyebabkan penyakit pada kulit yaitu penyakit
kurap.(Riandari:2009)
7.
Jamur di bawah ini menguntungkan, kecuali …
a. Aspergillus
wentii
b. Aspergillus
fumigatus
c. Penicillium
chrysogenum
d. Penicillium
notatum
e. Penicillium
camemberti
Jawaban : B
Pembahasan :
Peranan Jamur Divisi Ascomycota:
a) Aspergillus oryzae – Pembuatan tape
b) Aspergillus wentii – Pembuatan kecap
c) Aspergillus flavus – Penyebab kanker hati
d) Aspergillus fumigattus - Parasit pada paru – paru
burung
e) Penicillium notatim – Menghasilkan zat antibiotik
8.
Keuntungan yang diperoleh oleh tumbuhan pinus
dengan adanya mikoriza pada akarnya adalah mendapatkan …
a. bahan
– bahan anorganik
b. air
dan bahan anorganik
c. karbondioksida
d. enzim
pencerna makanan
e. toksin
pengusir hama
Jawaban : B
Pembahasan :
Tumbuhan pinus memiliki mikoriza pada akarnya yang
memiliki fungsi yaitu untuk meningkatkan kinerja pengangkutan air dari akar
menuju ke daun sehingga lebih mudah menyerap air serta mikoriza ini memudahkan
untuk mendapatkan bahan – bahan anorganikDETAIL
Pada musim hujan atau ketika keadaan udara lembab
kita sering menjumpai di sekitar kita organisme seperti tumbuhan kecil yang
biasanya berbentuk payung yang memiliki warna hitam, putih kelabu atau warna
lainnya, organisme ini disebut fungi atau jamur. Para ilmuan memperkirakan
terdapat sekitar 100 ribu spesies fungi yang tersebar di seluruh dunia.
1. Ciri-ciri Jamur
Fungi merupakan organisme eukariotik dengan dinding
sel yang mengandung kitin. Fungi tidak memiliki klorofil sehingga bersifatheterotrof.
Sebagian besar fungi bersifat multiseluler (bersel banyak)
yang berukuran mulai dari yang berukuran mikroskopik sampai yang berukuran
makroskopik. Fungi uniseluler memiliki berbagai bentuk seperti payung, bola,
dan kancing sedangkan fungi multiseluler berupa talus yang tersusun atas hifa,
hifa ada yang memiliki sekat dan ada yang tidak bersekat yang disebut hifa
soenositik. Hifa memiliki struktur yang bercabang-cabang ini membentuk miselium.
Miselium terbagi menjadi dua yaitu miselium vegetatif yang berfungsi untuk
menyerap makanan dan miselium generatif yaitu miselium yang biasanya
berdefrensiasi membentuk alat reproduksi yang dapat menghasilkan spora.
Fungi menyerap zat organik dari lingkungannya
melalui hifa dan miseliumnya, sebelum diserap zat organik diurai terlebih
dahulu dengan bantuan enzim yang dikeluarkan oleh jamur, pencernaan ini disebut
pencernaan ekstraseluler. Cara fungi memperoleh makanan dapat bersifat parasit,
saprofit, dan mutual.
- Parasit yaitu cara fungi memperoleh makanan berupa
zat organik dari inangnya, hal ini dapat merugikan organisme
inangnya karena dapat menyebabkan penyakit.
- Saprofit, yaitu mendapatkan makanan dari sisa-sisa
organisme yang telah mati seperti daun, ranting dan serasah.
- Mutual/simbiosis, yaitu saling menguntungkan dengan
organisme lainnya.
Fungi memiliki habitat yang bersifat kosmopolit
(mudah hidup di berbagai tempat) seperti di tempat lembab, hidup pada organisme
lain, di sisa organisme mati seperti bangkai dan tempat-tempat lain. Fungi juga
dapat hidup di tempat-tempat ekstrim seperti di lingkungan yang berasam,
lingkungan dengan konsentrasi gula tinggi, dan tempat dengan pH rendah. Fungi
dapat pula dijumpai di gurun, di laut (hidup bersimbiosis dengan organisme
laut), gunung bersalju, kutub dan sebagainya.
Reproduksi pada fungi berlangsung secara seksual
dan aseksual. Secara seksual melalui kontak gametangium yang
mengakibatkan terjadinya singami (penyatuan sel dari dua
individu). Singami terjadi dalam dua tahap yaitu plasmogami (penyatuan
plasma sel) dan tahap kariogami (penyatuan inti sel) yang
menghasilkan hifa dikarion(hifa berinti dua) yang haploid (n) dan
setelah itu mengalami penyatuan inti yang membentuk monokarion yang diploid
(2n), lalu membelah secara meiosis membentuk spora seksual yang haploid (n)
berupa zigospora, askospora, dan basidiospora.
Reproduksi secara aseksual terjadi dengan
pembentukan kuncup dan fragmentasi (pemutusan benang hifa) ini
terjadi pada fungi uniseluler sedangkan pada fungi multiseluler dengan carapembentukan
spora.
2. Klasifikasi Jamur
Berdasarkan struktur hifa serta struktrur penghasil
sporanya, fungi dibagi menjadi empat divisi yaitu Zygomycotina, Ascomycotina,
Basidiomycotina, dan Deuteromycotina.
a. Zygomycotina
Zygomycotina memiliki habitat di
tempat-tempat lembab. Fungi jenis ini hidup sebagai saprofit atau sebagai
parasit serta mempunyai rhizoid yang digunakan untuk melekat
pada substrat. Zygomycotina memiliki hifa yang bercabang-cabang dan tidak
bersekat (soenositik) dengan dinding sel yang tersusun atas zat kitin.
Ada tiga tipe hifa yaitu:
- Stolon, yaitu hifa yang menghubungkan dua kumpulan sporangium.
- Rhizoid, yaitu hifa yang menembus substrat untukmenyerap
makanan.
- Sporangiofor, yaitu hifa pendukung sporangium.
Reproduksi pada zygomycotina yaitu secara seksual
dan aseksual. Secara seksual yaitu menggunakan spora vegetatif dan dengan
fragmentasi. Pada pembentukan spora vegetatif beberapa hifa akan tumbuh ke atas
dengan ujung yang menggembung dan membentuk sporangium, yang merupakan struktur
penghasil spora vegetatif, sporangium yang telah masak kemudian pecah dan
tersebar ke tempat yang cocok dan akan tumbuh menjadi miselium baru.
Reproduksi aseksual pada zygomycotina yaitu dengan
pembentukan zigospora. Dimana awalnya hifa jantan (+) dan hifa
betina (-) yang masing-masing mengandung banyak inti haploid saling berdekatan
membentuk gametangium (cabang hifa), setelah itu dinding gametangium kemudian
pecah dan terjadi penyatuan plasma sel (plasmogami) yang diikuti dengan
kariogami, yaitu bertemunya inti haploid jantan dan betina sehingga terjadi
peleburan yang membentuk zigot.
Pada proses selanjutnya zigot membentuk kotak spora
(zigosporangium) dan sporanya disebut zigospora. Zigospora kemudian akan tumbuh
menjadi hifa selama masa dormansi. Zigospora kemudian mengalami penebalan
dinding sel untuk bertahan pada kondisi kering selama berbulan-bulan, dan jika
kondisi lingkungan memungkinkan zigospora akan tumbuh dan membentuk sporangium
yang ketika masak dindingnya akan robek sehingga spora dapat tersebar.
Terdapat berbagai contoh organisme zygomycotina dan
memiliki peranan dalam kehidupan, diantaranya adalah:
- Rhizopus stolonifer, merupakan fungi yang tumbuh pada roti basi.
- Rhizopus oligosporus dan Rhizopus oryzae adalah fungi yang membantu pembuatan tempe.
- Rhizopus nigricans, menghasilkan asam fumarat pada tomat.
- Murcor mucedo, hidup sebagai saprofit pada tumbuhan dan hewan, seperti pada kotoran hewan an roti busuk.
- Murcor javanicus, berperan dalam pembuatan tapai.
- Mucor hiemalis, berperan dalam fermentasi susu kedelai.
- Pilobus, hidup pada kotoran hewan yang telah terdekomposisi.
- Beauveria bassiana, sebagai parasit pada wereng.
- Metarrshisium anisopliae, berperan dalam pengendalian kumbang kolorado.
b. Ascomycotina
Struktur tubuh sebagian organisme
ascomycotina adalah multiseluler (bersel banyak) yang membentuk badan buah,
contohnya adalah Nectria. Sedangkan sebagian lagi bersifat
uniseluler (bersel satu) seperti saccharomyces. Ascomycotina hidup
sebagai saprofit, parasit, dan juga bersimbiosis. Struktur hifanya bersekat
melintang atau bercabang dan memiliki inti banyak, sedangkan dinding selnya
mengandung zat kitin.
Ascomycotina menghasikan spora dalam askus (askospora)
yang biasanya berjumlah delapan, kumpulan-kumpulan askus membentuk suatu
struktur yang disebut askokarp. Beberapa bentuk askokarp antara
lain :
1) Askus tanpa askokarp, yaitu kelompok fungi yang tidak
membentuk askokarp, sel fungi tunggalnya berfungsi sebagai askus, contoh
Saccharomycces dan candida.
2) Askus dengan askokarp berbentuk bola, contoh penicilium.
3) Askus dengan askokarp berbentuk botol berleher dan memiliki
ostiolum yaitu lubang untuk melepas askus dan askospora (peritesium). Contoh :
Neurospora crassa.
4) Askus dengan askokarp berbentuk mangkuk/cawan (apotesium)
contoh : Ascobolus.
Reproduksi aseksual pada ascomycotina uniseluler
adalah dengan membentuk tunas (blastophora) yang diawali
dengan dinding yang menonjol keluar dan membentuk tunas kecil. Nukleus dalam
sel induk membelah dan salah satu bergerak ke dalam sel tunas yang akan
memisahkan diri dari sel induk dan membentuk individu baru. Tapi kadang-kadang
tunas akan tetap melekat dan membentuk rantai sel yang disebut hifa
semu (pseudohifa).
Reproduksi aseksual pada Ascomycotina multiseluler
terjadi dengan fragmentasi miselium dan pembentukan konidia.
Konidia adalah spora aseksual yang terbentuk pada ujung konidiofor.
Reproduksi seksual pada ascomycotina uniseluler
adalah dengan cara konjugasi yang menghasilkan zigot yang
tumbuh menjadi askus, selanjutnya askus mengalami pembelahan meiosis sehingga
dihasilkan empat sel askospora. Sedangkan reproduksi seksual pada ascomycotina
multiseluler yaitu pertama kali askospora tumbuh menjadi benang hifa, hifa
kemudian membentuk miselium yang ujungnya berubah fungsi menjadi askogonium dan
anteridium yang saling berpasangan, selanjutnya terjadi pembelahan mitosis
membentuk hifa (2n) yang ketika dewasa membentuk askus. Inti askus kemudian
membelah lagi sehingga membentuk askospora. Askospora ini yang
kemudian akan tersebar dan jatuh di suatu tempat dan akan tumbuh menjadi
individu baru.
Ascomycotina memiliki peranan yang beragam dalam
kehidupan manusia baik itu menguntungkan maupun merugikan,
Beberapa
jenis ascomycotina dan peranannya diantaranya adalah :
- Saccharomyces cerevisiae untuk pembuatan tape, bir, wine, dan roti.
- Saccharomyces ovale untuk pembuatan tape
- Penicillium notatum, penghasil antibiotik pinisilin
- Penicillium islandium merusak beras
- Aspergillus flavus menghasilkan alfatoksin
- Trichoderma resei menghasilkan enzim selulase (enzim pengurai selulosa)
- Aspergillus wentii untuk pembuatan kecap
- Ascobolus scatigenus, saprofit pada kotoran sapi
- Claviseps purpurea menghasilkan bahan obat-obatan.
- Neurospora crassa dimanfaatkan dalam pembuatan oncom merah dari ampas tahu.
- Fusarium adalah parasit pada tebu, padi, tomat, dan kentang
- Nectria cinabarina adalah parasit pada kayu manis
Selain itu masih banyak lagi organisme fungi
ascomycotina yang terdapat di alam dan memiliki peranan yang beragam.
c. Basidiomycotina
Basidiomycotina kebanyakan bersifat saprofit pada
sisa-sisa makhluk hidup dan ada yang bersifat parasit pada tumbuhan dan
manusia. Hifa basidiomycotina bersekat melintang, hifa vegetatifnya mempunyai
satu inti (n) dan hifa generatif mempunyai dua inti (2n).
Badan buah basidiomycotina disebut basidiokarp yang
menjadi tempat pembentukan basidium. Basidiokarp memiliki berbagai
bentuk seperti payung, kuping, atau setengah lingkaran. Struktur tubuhnya
kebanyakan multiseluler dan berukuran makroskopis, pada umumnya tubuh buahnya
memiliki bagian-bagian antara lain stipe (tangkai tubuh buah), pileus (tudung),
volva, dan lamella (bilah).
Pada basidiomycotina terdapat 3 macam miselium
yaitu miselium primer (miselium berinti satu hasil pertumbuhan basidiospora),
miselium sekunder (miselium yang sel-selnya berinti dua), dan miselium tertier.
Reproduksi basidiomycotina adalah secara aseksual
dan seksual. Secara aseksual yaitu dengan membentuk spora vegetatif berupakonidia atau
dengan fragmentasi, sedangkan secara seksual dengan membentuk basidiospora yang
prosesnya diawali dari hifa (+) dan hifa (-) saling mendekat dan terjadi
plasmogami (peleburan dinding sel) sehingga terbentuk hifa dengan dua inti
haploid berpasangan (dikariotik), hifa ini kemudian berkembang menjadi miselium
sekunder, ujung miselium dikariotik berkembang menjadi basidium. Dua inti haploid
dalam basidium kemudian bersatu menjadi 2n (kariogami). Selain itu terbentuk
beberapa tonjolan pada ujung basidium (sterigma). Setelah itu inti 2n membelah
secara meiosis menghasilkan 4 inti haploid dan bergerak menuju sterigma dan
membentuk basidiospora yang akan tumbuh menjadi hifa bersekat (n).
Beberapa contoh Basidiomycota yang penting adalah sebagai berikut.
1. Volvariella volvacea dan Agaricus bisporus, jamur yang dibudidayakan untuk dimasak sebagai bahan makanan.
 |
| Volvariella volvacea |
 |
| Agaricus bisporus |
2. Auricularia polytrica (jamur kuping), jamur ini enak dimakan, hidup pada batang tumbuhan yang telah mati.
 |
| Auricularia polytrica |
B. Beberapa contoh Basidiomycota yang merugikan adalah sebagai berikut.
1. Puccinia graminis, jamur ini hidup parasit pada rumput.
 |
| Pucinia graminis |
2. Ustilago maydis, jamur ini parasit pada tanaman jagung,menyerang sukam daun , tongkol, jumbai dan tangkai.
 |
| Ustilago maydis |
3. Ganoderma applanatum, jamur ini menyebabkan kerusakan pada kayu.
 |
| Ganoderma applanatum |
4. Ganoderma pseudoferreum, jamur ini penyebab busuk akar pada tanaman coklat, kopi, teh, karet dan tanamanperkebunan lain.
 |
| Ganoderma pseudoferreum |
d. Deuteromycotina
Deuteromycotina jarang membentuk tubuh buah dan
memiliki ukuran mikroskopis, hifanya bersekat dan dinding selnya terdiri dari
zat kitin. Deuteromycotina kebanyakan hidup sebagai saprofit dan parasit.
Reproduksi seksual Deuteromycotina belum diketahui
sehingga tidak dapat dikelompokan dalam klasifikasi yang lain seperti
Ascomycotina atau Basidiomycotina. Oleh karena itu, fungi jenis ini juga
disebut sebagai fungi imperfecti (fungi tidak sempurna). Reproduksi aseksual
jamur jenis ini dengan cara membentuk konidia, blastophora (membentuk tunas),
dan Arthrospora (membentuk spora dengan menggunakan hifa)
Deuteromycotina memiliki banyak peranan dalam
kehidupan manusia, walaupun kebanyakan bersifat merugikan.
Beberapa jenis
deuteromycotina dan peranannya antara lain:
- Tinea versicolor penyebab panu pada manusia
- Trichophyton menyebabkan penyakit kulit pada manusia
- Epidermophyton penyebab penyakit kurap
- Helminthosprium oryzae sebagai parasit pada padi.
- Sclerotium rolfsii sebagai parasit pada bawang merah.
3. Simbiosis Fungi
Fungi dapat bersimbiosis dengan organisme lain
seperti tumbuhan tingkat tinggi. Simbosis fungi dengan organisme lain adalah
dengan mikoriza, selain itu, terdapat pula simbiosis lichenesatau
dikenal juga dengan lumut kerak.
a. Mikoriza
Mikoriza adalah fungi yang bersimbiosis dengan akar
tumbuhan. Biasanya simbiosis ini bersifat saling menguntungkan,
yaitu fungi memperoleh zat organik dan tumbuhan memperoleh air dan unsur hara.
Beberapa fungi jenis Zygomycotina, Ascomycotina, dan Basidiomycotina dapat
bersimbiosis dengan akar tumbuhan, contohnya seperti pada tumbuhan pinus.
Mikoriza dibedakan menjadi dua yaitu:
1) Ektomikoriza, hifa fungi hanya hidup pada jaringan
epidermis akar tumbuhan,misalnya mikoriza yang hidup di akar pinus.
2) Endomikoriza, hifa pada fungi mampu menembus masuk
sampai ke jaringan korteks akar, seperti mikoriza yang hidup pada akar tanaman
anggrek.
b. Lichenes
Lichenes juga disebut dengan lumut
kerak. Lichenes merupakan simbiosis mutualisme antara fungi dengan algae. Ada
beberapa organisme fotosintetik yang terlibat seperti Cyanobacteria atau Algae
hijau uniseluler, dimana struktur tubuh Lichenes berbentuk talus dengan bagian
luar berupa miselium dan bagian dalam tersusun atas hifa. Di antara miselium
dan hifa jamur terdapat sel-sel Algae. Adapun pembagiannya yaitu:
1) Bagian dari Algae disebut phicobiont yaitu dari divisi
Cyanophyta dan Chlorophyta.
2) Bagian Fungi disebut mycobiont yaitu dari divisi Ascomycotina
dan Basidiomycotina.
Dalam simbiosis ini kedua organisme ini memperoleh
keuntungan, fungi memperoleh bahan organik dari Algae dan sebaliknya Algae
memperoleh air dan mineral dari fungi, sedangkan hifa fungi berperan
mempertahankan kelembapan lingkungan. Lichenes memiliki habitat yang beragam
seperti melekat di bebatuan, melekat di batang pohon, atau terdapat
juga di tempat-tempat lembap yang lain.
Reproduksi seksual pada lichenes terjadi sesui dengan
divisi fungi dan alga.Jika askospora atau basidiospora bertemu dengan Algae,
akan terbentuk Lichenes baru. Sedangkan pada reproduksi aseksualnya dengan cara
fragmentasi. Setelah terjadi fragmentasi, terbentuklah soredia yang
merupakan sel alga yang diselubungi oleh hifa atau miselium jamur. Soredia
kemudian membentuk tepung soredia. Tepung soredia inilah yang akan
membentuk lichenes baru.
Ada tiga macam Lichenes berdasarkan bentuk
talusnya.
1) Krustose (seperti kerak) yang tumbuh melekat pada
substrat.
2) Foliosa (seperti daun) yang tumbuh rapat pada
substrat bahkan di dalam permukaannya.
3) Fruktikosa (seperti rumpun) yang berbentuk rumpun
tegak.
Terdapat berbagai contoh lichenes dan peranannya
bagi manusia seperti Cladonia rengiferina sebagai makanan
hewan, dan Cetraria islandica yang digunakan sebagai bahan
obat-obatan.
