23
1- 11-1E FUNGI
FtEvIEvy
Fungi are saprotrophic, multicellular eukaryotes. The
body of a fungus is composed of hyphae, collectively
called a mycelium. Hyphae produce nonmotile and often
windblown spores during both asexual and sexual
reproduction.
During sexual reproduction, hyphae tips fuse;
dikaryotic hyphae result before zygote formation and
zygotic meiosis occur. The zygospore fungi are nonseptate (hyphae do not have cross walls), and during sexual reproduction, they form a thick-walled zygospore.
The sac fungi are also called ascomycetes. The sac
fungi are septate (hyphae have cross walls), and during
sexual reproduction, dikaryotic hyphae end in saclike
cells (asci) within a fruiting body. Each ascus produces
eight spores. Fungi that used to be classified as imperfect fungi have recently been reclassified as sac fungi on
the basis of molecular data, even if researchers have still
not observed when and if they form asci. Yeasts are unicellular ascomycetes; most reproduce by budding.
The club fungi are also called basidiomycetes. The
club fungi are septate, and during sexual reproduction,
dikaryotic hyphae end in club-shaped structures called basidia that produce basidiospores.
Fungi form symbiotic relationships with algae in
lichens and with seed plants in mycorrhizae.
Study the text section by section as you answer the questions that follow.
• Fungi are saprotrophic decomposers that aid the cycling of inorganic nutrients in ecosystems.
• The body of a fungus is multicellular; it is composed of thin filaments called hyphae.
• As an adaptation to life on land, fungi produce nonmotile and often windblown spores during asexual and
sexual reproduction.
Indicate whether these statements about fungi are true (T) or false (F).
a.
usually multicellular
b.
usually unicellular
c.
composed of hyphae
d.
saprotrophic
e.
can be parasitic
f.
can be photosynthetic
cell
wall contains cellulose
g.
h.
cell wall contains chitin
•
i.
have flagella at some time in their life cycle
j.
do not have flagella at any time in their life cycle
k.
form spores only during asexual reproduction
1.
form spores during both asexual and sexual reproduction
2. Fungi are mostly a.
decomposers that assist in the recycling of nutrients in ecosystems.
The bodies of most fungi are made up of filaments called b.
a collection of which are
called a(n) C.
. If hyphae have cross walls, they are d.
if they do not
have cross walls, they are e
,
;
182
• Zygospore fungi have a dormant stage consisting of a thick-walled zygospore.
• In some sac fungi, sexual reproduction has long been known; in others (asexual ascomycetes), sexual
reproduction has not yet been observed, and asexual reproduction is the norm.
• During sexual reproduction of sac fungi, saclike cells (asci) produce spores. Sometimes asci are located in
fruiting bodies.
• During sexual reproduction of club fungi, club-shaped structures (basidia) produce spores. Basidia are
located in fruiting bodies.
Zygcospore Fungi (P. 400)
3. Label the diagram of the life cycle of black bread mold using the following alphabetized list of terms (some
are used more than once).
asexual reproduction
gametangia
meiosis
mycelium
sexual reproduction
sporangium (used twice)
spores (used twice)
zygospore
zygospore germination
zygote
-
a.
,
diploid (2n)
A, ‘
t
1
d
e.
f.
haploid (n)
\Ot1
;,i.;.....,:.
k
g.
-
..-- ,-
C't
mating type + mating type
\
.
1.0711/1J
c
\\,
\ ,
sporangiophore
- --..,
._
i.
..
-. _..
..: tO.rmination
_ :i 'df spores
.
iI
stolont /
i' r i r i -
- mating type
183
4. Answer these questions based on the life cycle of the black bread mold.
a.
b.
c.
d.
e.
Is the adult diploid or haploid?
In which cycle (asexual or sexual) are haploid spores produced?
Where are the spores produced?
What are the functions of the enlarged diploid zygote formed in sexual reproduction?
How are the spores dispersed from the sporangium?
Sc Fungi (pp. 402-404)
• During sexual reproduction of sac fungi, the fingerlike sac (ascus) produces spores. Asci are located in
fruiting bodies.
5. Place the appropriate letter next to each description.
F—free-living sac fungi P—parasitic sac fungi
a.
powdery mildew that grows on leaves
b.
red mold that grows on bread
c.
cup fungus that grows on the forest floor
d.
chestnut blight that grows on chestnut trees
e.
ergot that grows on rye plants
f.
unicellular yeasts
6. Match the steps of ascospore production with the following sequential drawings of asci.
1. Zygote (2n) has formed.
2. Two nuclei are fusing.
3. A mitotic division has resulted in ascospores.
4. Meiosis has occurred.
a.
Club Fungi
(Pp.
b.
c.
406-407)
• During sexual reproduction of club fungi, club-shaped structures (basidia) produce spores. Basidia are
located in fruiting bodies.
7. What do mushrooms, puffballs, bird's nest fungi, stinkhorn fungi, and shelf fungi have in common?
8. Name two well-known parasites of cereal crops.
184
9. Label the diagram of the life cycle of a mushroom by following these directions:
1. Label a, b, and c by using these terms: diploid, dikaryotic (n + n), monokaryotic
2. The monokaryotic phase °tithe life cycle involves basidiospores and the haploid mycelium. Label the
spores and haploid mycelium.
3. The dikaryotic phase begins with cytoplasmic fusion and ends with nuclear fusion. Label cytoplasmic fusion and nuclear fusion.
4. During the dikaryotic phase, a dikaryotic mycelium gives rise to a fruiting body called a basidiocarp. The
basidiocarp is also called a mushroom. Label the dikaryotic mycelium and the basidiocarp.
5. Many basidia (club-shaped structures) form on the gills of the basidiocarp. Label the blowup of one basidium.
6. The diploid phase begins with nuclear fusion and ends when the zygote undergoes meiosis. Label the zygote and meiosis.
Mature mushroom
„
cap
annulus
portion of gill
gills
'
f
stalk
button stage
of mushroom
,
•
g
$-
pi ing
of rveil j
8
.
i 7,
) dikaryotic mycelium
rill/
------ --
nuclei
development of basidiocarp
--- ,------
-------- k.
,
•
basidiospores basidium
oit
•
10. In the life cycle of a mushroom, the basidiocarp is a(n) a.
structures called b.
, where C.
is a dikaryotic d.
that exists for years.
which contains club-shaped
are produced. Beneath each mushroom
,
185
• Fungi are classified according to differences in their life cycle and the type of structure that produces spores.
11. Match the types of fungi with the following phyla:
1. phylum Zygomycota
2. phylum Ascomycota
3. phylum Basidiomycota
a.
club fungi
b.
zygospore fungi
c.
sac fungi
d.
mushrooms
e.
cup fungi
f.
bread mold
form fruiting bodies
g.
h.
yeast
i.
j.
molds
Candida
12. Give evidence that fungi are classified according to sexual reproduction.
a. Zygospore fungi take their name from
b. Ascomycetes take their name from
c. Basidiomycetes take their name from
• Lichens, which can live in extreme environmental conditions, are an association between a fungus and a
cyanobacterium or a green alga. The fungus may be somewhat parasitic on the alga.
• Mycorrhizae are a mutualistic association between a fungus and the roots of a plant, such that the fungus helps
the plant absorb minerals and the plant supplies the fungus with carbohydrates.
13. Label the following diagram of a lichen, using these terms:
algal cells
fungal hyphae
a.
b.
14. Match each description to the type of lichen, using these terms:
crustose fruticose foliose
a.
compact
b.
leaflike
c.
shrublike
1 5 . a.
(fungus roots), b '
relationships between a(n) c.
and d.
roots, help plants acquire e.
nutrients.
186
E. r VN/c) Ft Co c icsswc Ft Co
Review key terms by completing this crossWord puzzle, using the following alphabetized list of terms:
ascus
basidium
conidiospore
fruiting body
fungus
hypha
lichen
mycelium
mycorrhiza
sporangium
zygospore
Across
1 Fingerlike sac in which nuclear fusion, meiosis,
and ascospore formation occur during the sexual
reproduction of the sac fungi
4 Symbiotic relationship between fungal hyphae and
roots of vascular plants; the fungus allows the plant
to absorb more mineral ions and obtains carbohydrates from the plant
6 Clublike structure in which nuclear fusion and meiosis occur and basidiospores are produced during
the sexual reproduction of club fungi
8 Spore produced by sac and club fungi during asexual reproduction
9 Symbiotic relationship between certain fungi and
algae, long been thought to be mutualistic, in which
the fungi provide inorganic food and the algae provide organic food
10 Tangled mass of hyphal filaments composing the vegetative body of a fungus
11 Saprotrophic decomposer; the body is made up of
filaments called hyphae that form a mass called a
mycelium
Down
Capsule that produces sporangiophores
Filament of the vegetative body of a fungus
Thick-walled, resting cell formed during sexual reproduction of zygospore fungi
Spore-producing and spore-disseminating structure found in sac and club fungi (two words)
187