Transcript plant

Chapter 16
Plants, Fungi, and the Move
onto Land
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
© 2010 Pearson Education, Inc.
Biology and Society:
Will the Blight End the Chestnut?
• American chestnut trees
– Once dominated forests of the eastern United States
– Were prized for their
–
Rapid growth
–
Huge size
–
Rot-resistant wood
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Figure 16.00
• Around 1900, an Asian fungus was accidentally introduced from
China into North America, and in just 25 years, blight caused by
the fungus killed virtually all adult American chestnut trees.
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• Fortunately, this type of harmful interaction between plant and
fungus is unusual.
• Many plants and fungi benefit from each other’s existence.
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COLONIZING LAND
• Plants are terrestrial organisms that include forms that have
returned to water, such as water lilies.
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Terrestrial Adaptations of Plants
Structural Adaptations
• A plant is
– A multicellular eukaryote
– A photoautotroph, making organic molecules by photosynthesis
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• In terrestrial habitats, the resources that a photosynthetic organism
needs are found in two very different places:
– Light and carbon dioxide are mainly available in the air
– Water and mineral nutrients are found mainly in the soil
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• The complex bodies of plants are specialized to take advantage of
these two environments by having
– Aerial leaf-bearing organs called shoots
– Subterranean organs called roots
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Reproductive
structures (such as
those in flowers)
contain spores
and gametes
Plant
Leaf performs
photosynthesis
Cuticle reduces water
loss; stomata regulate
gas exchange
Shoot supports plant
(and may perform
photosynthesis)
Alga
Surrounding
water supports
the alga
Whole alga
performs
photosynthesis;
absorbs water,
CO2, and
Roots anchor plant;
minerals from
absorb water and
the water
minerals from the
soil (aided by fungi)
Figure 16.1
• Most plants have mycorrhizae, symbiotic fungi associated with
their roots, in which the fungi
– Absorb water and essential minerals from the soil
– Provide these materials to the plant
– Are nourished by sugars produced by the plant
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Roots
Fungus
Root
surrounded
by fungus
Figure 16.2
• Leaves are the main photosynthetic organs of most plants, with
– Stomata for the exchange of carbon dioxide and oxygen with the
atmosphere
– Vascular tissue for transporting vital materials
– A waxy cuticle surface that helps the plant retain water
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Phloem
Xylem
Vascular
tissue
Oak leaf
Figure 16.3
• Vascular tissue in plants is also found in the
– Roots
– Shoots
• Two types of vascular tissue exist in plants:
– Xylem transports water and minerals from roots to leaves
– Phloem distributes sugars from leaves to the roots and other
nonphotosynthetic parts of the plant
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Reproductive Adaptations
• Plants produce their gametes in protective structures called
gametangia, which have a jacket of protective cells surrounding a
moist chamber where gametes can develop without dehydrating.
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• The zygote develops into an embryo while still contained within
the female parent in plants but not in algae.
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LM
Embryo
Maternal
tissue
Figure 16.4
The Origin of Plants from Green Algae
• The algal ancestors of plants
– Carpeted moist fringes of lakes or coastal salt marshes
– First evolved over 500 million years ago
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• Charophytes
– Are a modern-day lineage of green algae
– May resemble one of these early plant ancestors
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LM
LM
Figure 16.5
LM
Figure 16.5a
LM
Figure 16.5b
PLANT DIVERSITY
• The history of the plant kingdom is a story of adaptation to
diverse terrestrial habitats.
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Highlights of Plant Evolution
• The fossil record chronicles four major periods of plant evolution.
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Bryophytes
Origin of vascular tissue
(about 425 mya)
Gymnosperms
Angiosperms
600
500
400
300
200
100
Seed plants
Origin of flowers
(about 140 mya)
Vascular plants
Origin of seeds
(about 360 mya)
Seedless
vascular
plants
Ferns and other
seedless vascular
plants
Land plants
Origin of first terrestrial adaptations
(about 475 mya)
Ancestral
green algae
Nonvascular
plants
(bryophytes)
Charophytes (a group
of green algae)
0
Millions of years ago
Figure 16.6
• (1) About 475 million years ago plants originated from an algal
ancestor giving rise to bryophytes, nonvascular plants, including
mosses, liverworts, and hornworts that are nonvascular plants
without
– Lignified walls
– True roots
– True leaves
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• (2) About 425 million years ago ferns evolved
– With vascular tissue hardened with lignin
– But without seeds
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• (3) About 360 million years ago gymnosperms evolved with
seeds that consisted of an embryo packaged along with a store of
food within a protective covering but not enclosed in any
specialized chambers.
• Today, conifers, consisting mainly of cone-bearing trees such as
pines, are the most diverse and widespread gymnosperms.
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• (4) About 140 million years ago angiosperms evolved with
complex reproductive structures called flowers that bear seeds
within protective chambers called ovaries.
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• The great majority of living plants
– Are angiosperms
– Include fruit and vegetable crops, grains, grasses, and most trees
– Are represented by more than 250,000 species
Video: Flower Blooming (time lapse)
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PLANT DIVERSITY
Bryophytes
(nonvascular plants)
Ferns
(seedless vascular plants)
Gymnosperms
(naked-seed plants)
Angiosperms
(flowering plants)
Figure 16.7
Figure 16.7a
Figure 16.7b
Figure 16.7c
Figure 16.7d
Bryophytes
• Bryophytes, most commonly mosses
– Sprawl as low mats over acres of land
– Need water to reproduce because their sperm swim to reach eggs within
the female gametangium
– Have two key terrestrial adaptations:
–
A waxy cuticle that helps prevent dehydration
–
The retention of developing embryos within the mother plant’s
gametangium
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Figure 16.8
• Mosses have two distinct forms:
– The gametophyte, which produces gametes
– The sporophyte, which produces spores
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Spores
Spore capsule
Sporophyte
Gametophytes
Figure 16.9
• The life cycle of a moss exhibits an alternation of generations
shifting between the gametophyte and sporophyte forms.
• Mosses and other bryophytes are unique in having the
gametophyte as the larger, more obvious plant.
Blast Animation: Alternation of Generations
Animation: Moss Life Cycle
Blast Animation: Non-Flowering Plant Life Cycle
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Gametophyte
(n)
Gametes:
sperm
and eggs
(n)
Key
Haploid (n)
Diploid (2n)
Figure 16.10-1
Gametophyte
(n)
Gametes:
sperm
and eggs
(n)
FERTILIZATION
Zygote
(2n)
Key
Haploid (n)
Diploid (2n)
Figure 16.10-2
Gametophyte
(n)
Gametes:
sperm
and eggs
(n)
FERTILIZATION
Spore
capsule
Sporophyte
(2n)
Zygote
(2n)
Key
Haploid (n)
Diploid (2n)
Figure 16.10-3
Spores
(n)
Gametophyte
(n)
Gametes:
sperm
and eggs
(n)
FERTILIZATION
MEIOSIS
Spore
capsule
Sporophyte
(2n)
Zygote
(2n)
Key
Haploid (n)
Diploid (2n)
Figure 16.10-4
Spores
(n)
Gametophyte
(n)
Gametes:
sperm
and eggs
(n)
FERTILIZATION
MEIOSIS
Spore
capsule
Sporophyte
(2n)
Zygote
(2n)
Key
Haploid (n)
Diploid (2n)
Figure 16.10-5
Ferns
• Ferns are
– Seedless vascular plants
– By far the most diverse with more than 12,000 known species
• The sperm of ferns, like those of mosses
– Have flagella
– Must swim through a film of water to fertilize eggs
Animation: Fern Life Cycle
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Spore capsule
“Fiddlehead”
(young leaves
ready to unfurl)
Figure 16.11
Figure 16.11a
Figure 16.11b
Spore capsule
Figure 16.11c
“Fiddlehead”
(young leaves
ready to unfurl)
Figure 16.11d
• During the Carboniferous period, from about 360 to 300 million
years ago, ferns
– Were part of a great diversity of seedless plants
– Formed swampy forests over much of what is now Eurasia and North
America
• As they died, these forests formed coal.
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• Fossil fuels
– Include coal, oil, and natural gas
– Formed from the remains of long-dead organisms
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Figure 16.12
Gymnosperms
• At the end of the Carboniferous period, the climate turned drier
and colder, favoring the evolution of gymnosperms, which can
– Complete their life cycles on dry land
– Withstand long, harsh winters
• The descendants of early gymnosperms include the conifers, or
cone-bearing plants.
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Conifers
• Conifers
– Cover much of northern Eurasia and North America
– Are usually evergreens, which retain their leaves throughout the year
– Include the tallest, largest, and oldest organisms on Earth
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Figure 16.13
Terrestrial Adaptations of Seed Plants
• Conifers and most other gymnosperms have three additional
terrestrial adaptations:
– Further reduction of the gametophyte
– Pollen
– Seeds
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• Seed plants have a greater development of the diploid sporophyte
compared to the haploid gametophyte generation.
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Gametophyte
(n)
Sporophyte
(2n)
Sporophyte
(2n)
Sporophyte
(2n)
Gametophyte
(n)
Gametophyte
(n)
(a) Sporophyte dependent
on gametophyte (e.g.,
mosses)
(b) Large sporophyte and small,
Independent gametophyte (e.g.,
ferns)
(c) Reduced gametophyte
dependent on sporophyte
(seed plants)
Key
Haploid (n)
Diploid (2n)
Figure 16.14
• A pine tree or other conifer is actually a sporophyte with tiny
gametophytes living in cones.
Animation: Pine Life Cycle
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Scale
Ovule-producing
cones; the scales
contain female
gametophytes
Pollen-producing
cones; they
produce male
gametophytes
Ponderosa pine
Figure 16.15
Ponderosa pine
Figure 16.15a
Scale
Ovule-producing cones; the scales
contain female gametophytes
Figure 16.15b
Pollen-producing cones; they produce
male gametophytes
Figure 16.15c
• A second adaptation of seed plants to dry land was the evolution
of pollen.
• A pollen grain
– Is actually the much-reduced male gametophyte
– Houses cells that will develop into sperm
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• The third terrestrial adaptation was the development of the seed,
consisting of
– A plant embryo
– A food supply packaged together within a protective coat
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• Seeds
– Develop from structures called ovules, located on the scales of female
cones in conifers
– Can remain dormant for long periods before they germinate, as the
embryo emerges through the seed coat as a seedling
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Female cone,
cross section
Integument
Spore
Haploid (n)
Diploid (2n)
Cross section
of scale
Spore case
(a) Ovule
Egg nucleus
Figure 16.16-1
Female cone,
cross section
Integument
Spore
Spore case
Haploid (n)
Diploid (2n)
Cross section
of scale
Spore case
(a) Ovule
Egg nucleus
Female
gametophyte
(b) Fertilized ovule
Pollen tube
Pollen grain
(male
gametophyte)
Discharged
sperm nucleus
Figure 16.16-2
Female cone,
cross section
Integument
Spore
Spore case
Haploid (n)
Diploid (2n)
Cross section
of scale
Spore case
(a) Ovule
Egg nucleus
Female
gametophyte
(b) Fertilized ovule
Pollen tube
Pollen grain
(male
gametophyte)
Food supply
(derived from
female
gametophyte
tissue)
Discharged
sperm nucleus
Seed coat
(derived from
integument)
(c) Seed
Embryo
(new
sporophyte)
Figure 16.16-3
Figure 16.16a
Angiosperms
• Angiosperms
– Dominate the modern landscape
– Are represented by about 250,000 species
– Supply nearly all of our food and much of our fiber for textiles
• Their success is largely due to
– A more efficient water transport
– The evolution of the flower
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Flowers, Fruits, and the Angiosperm Life Cycle
• Flowers help to attract pollinators who transfer pollen from the
sperm-bearing organs of one flower to the egg-bearing organs of
another.
Video: Bee Pollinating
Video: Bat Pollinating Agave Plant
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• A flower is actually a short stem with four whorls of modified
leaves:
– Sepals
– Petals
– Stamens
– Carpels
Blast Animation: Flower Structure
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Petal
Stamen
Anther
Stigma
Style
Filament
Ovary
Ovule
Sepal
Carpel
Figure 16.17
• Flowers come in many forms.
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Pansy
Bleeding heart
California poppy
Water lily
Figure 16.18
Pansy
Figure 16.18a
Bleeding heart
Figure 16.18b
California
poppy
Figure 16.18c
Water lily
Figure 16.18d
• Flowers are an essential element of the angiosperm life cycle.
Blast Animation: Pollination and Fertilization
Blast Animation: Flowering Plant Life Cycle
Animation: Fruit Development
Animation: Plant Fertilization
Video: Flowering Plant Life Cycle (time lapse)
Animation: Seed Development
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Mature
sporophyte
plant with
flowers
Key
Haploid (n)
Diploid (2n)
Figure 16.19-1
Germinated pollen grain
(male gametophyte) on
stigma of carpel
Anther at tip of stamen
Mature
sporophyte
plant with
flowers
Pollen tube growing
down style of carpel
Ovary (base of carpel)
Ovule
Embryo sac
(female
gametophyte)
Egg
Two
sperm
nuclei
Key
Haploid (n)
Diploid (2n)
Figure 16.19-2
Germinated pollen grain
(male gametophyte) on
stigma of carpel
Anther at tip of stamen
Mature
sporophyte
plant with
flowers
Pollen tube growing
down style of carpel
Ovary (base of carpel)
Ovule
FERTILIZATION
Endosperm
Embryo sac
(female
gametophyte)
Egg
Zygote
Two
sperm
nuclei
Key
Haploid (n)
Diploid (2n)
Figure 16.19-3
Germinated pollen grain
(male gametophyte) on
stigma of carpel
Anther at tip of stamen
Mature
sporophyte
plant with
flowers
Pollen tube growing
down style of carpel
Ovary (base of carpel)
Ovule
FERTILIZATION
Endosperm
Embryo sac
(female
gametophyte)
Egg
Zygote
Two
sperm
nuclei
Embryo
(sporophyte)
Key
Haploid (n)
Diploid (2n)
Figure 16.19-4
Germinated pollen grain
(male gametophyte) on
stigma of carpel
Anther at tip of stamen
Pollen tube growing
down style of carpel
Mature
sporophyte
plant with
flowers
Ovary (base of carpel)
Ovule
FERTILIZATION
Endosperm
Embryo sac
(female
gametophyte)
Egg
Zygote
Two
sperm
nuclei
Embryo
(sporophyte)
Seed
Key
Seed (develops
from ovule)
Fruit (develops
from ovary)
Haploid (n)
Diploid (2n)
Figure 16.19-5
Germinated pollen grain
(male gametophyte) on
stigma of carpel
Anther at tip of stamen
Pollen tube growing
down style of carpel
Mature
sporophyte
plant with
flowers
Ovary (base of carpel)
Ovule
FERTILIZATION
Endosperm
Embryo sac
(female
gametophyte)
Egg
Zygote
Two
sperm
nuclei
Sporophyte
seedling
Embryo
(sporophyte)
Seed
Germinating
seed
Key
Seed (develops
from ovule)
Fruit (develops
from ovary)
Haploid (n)
Diploid (2n)
Figure 16.19-6
• Although both have seeds
– Angiosperms enclose the seed within an ovary
– Gymnosperms have naked seeds
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• Fruit
– Is a ripened ovary
– Helps protect the seed
– Increases seed dispersal
– Is a major food source for animals
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Wind
dispersal
Animal
transportation
Animal
ingestion
Figure 16.20
Wind
dispersal
Figure 16.20a
Animal transportation
Figure 16.20b
Animal ingestion
Figure 16.20c
Angiosperms and Agriculture
• Gymnosperms supply most of our lumber and paper.
• Angiosperms
– Provide nearly all our food
– Supply fiber, medications, perfumes, and decoration
• Agriculture is a unique kind of evolutionary relationship between
plants and animals.
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Plant Diversity as a Nonrenewable Resource
• The exploding human population is
– Extinguishing plant species at an unprecedented rate
– Destroying fifty million acres, an area the size of the state of Washington,
every year!
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Figure 16.21
• Humans depend on plants for thousands of products including
– Food
– Building materials
– Medicines
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Table 16.1
• Preserving plant diversity is important to many ecosystems and
humans.
• Scientists are now rallying to
– Slow the loss of plant diversity
– Encourage management practices that use forests as resources without
damaging them
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FUNGI
• Fungi
– Recycle vital chemical elements back to the environment in forms other
organisms can assimilate
– Form mycorrhizae, fungus-root associations that help plants absorb from
the soil
–
Minerals
–
Water
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• Fungi are
– Eukaryotes
– Typically multicellular
– More closely related to animals than plants, arising from a common
ancestor about 1.5 billion years ago
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• Fungi
– Come in many shapes and sizes
– Represent more than 100,000 species
Video: Water Mold Oogonium
Video: Water Mold Zoospores
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Colorized SEM
Bud
Budding yeast
Orange fungi
Roundworm
Body of fungus
Colorized SEM
Mold
Colorized SEM
A “fairy ring”
Predatory fungus
Figure 16.22
Orange fungi
Figure 16.22a
A “fairy ring”
Figure 16.22b
Bud
Budding yeast
Colorized SEM
Figure 16.22c
Mold
Figure 16.22d
Colorized SEM
Mold
Figure 16.22e
Roundworm
Predatory fungus
Body of fungus
Colorized SEM
Figure 16.22f
Characteristics of Fungi
• Fungi have unique
– Structures
– Forms of nutrition
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Fungal Nutrition
• Fungi
– Are chemoheterotrophs
– Acquire their nutrients by absorption
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• A fungus
– Digests food outside its body
– Secretes powerful digestive enzymes to break down the food
– Absorbs the simpler food compounds
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Fungal Structure
• The bodies of most fungi are constructed of threadlike filaments
called hyphae.
• Hyphae are minute threads of cytoplasm surrounded by a
– Plasma membrane
– Cell wall mainly composed of chitin
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• Hyphae branch repeatedly, forming an interwoven network called
a mycelium (plural, mycelia), the feeding structure of the fungus.
Animation: Fungal Reproduction and Nutrition
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Reproductive
structure
Spore-producing
structures
Hyphae
Mycelium
Mycelium
Figure 16.23
Reproductive
structure
Spore-producing
structures
Hyphae
Mycelium
Figure 16.23a
Mycelium
Figure 16.23b
Fungal Reproduction
• Mushrooms
– Arise from an underground mycelium
– Mainly function in reproduction
• Fungi reproduce by releasing billions and trillions of spores that
are produced either sexually or asexually.
Video: Allomyces Zoospore Release
Video: Phlyctochytrium Zoospore Release
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The Ecological Impact of Fungi
• Fungi have
– An enormous ecological impact
– Many interactions with humans
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Fungi as Decomposers
• Fungi and bacteria
– Are the principal decomposers of ecosystems
– Keep ecosystems stocked with the inorganic nutrients necessary for plant
growth
• Without decomposers, carbon, nitrogen, and other elements
would accumulate in nonliving organic matter.
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• Molds can destroy
– Fruit
– Grains
– Wood
– Human-made material
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Parasitic Fungi
• Parasitic fungi absorb nutrients from the cells or body fluids of
living hosts.
• Of the 100,000 known species of fungi, about 30% make their
living as parasites, including
– Dutch elm disease
– Deadly ergot, which infests grain
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(a) American elm trees killed by Dutch
elm disease fungus
Figure 16.24a
(b) Ergots
Figure 16.24b
• About 50 species of fungi are known to be parasitic in humans
and other animals, causing
– Lung and vaginal yeast infections
– Athlete’s foot
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The Process of Science:
Did a Fungus Lead to the Salem Witch Hunt?
• Observation: In 1692, eight young girls were accused of being
witches and had symptoms consistent with ergot poisoning.
• Question: Did an ergot outbreak cause the witch hunt?
• Hypothesis: The girls’ symptoms were the result of ergot poisoning.
• Prediction: The historical facts would be consistent with this
hypothesis.
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Figure 16.25
• Results:
– Agricultural records from 1691, before the symptoms appeared, indicated
a particularly warm and wet year, in which ergot thrives.
– Records from the following year, when accusations of witchcraft died
down, indicate a dry year consistent with an ergot die-off.
– This correlation is consistent with the hypothesis but not conclusive.
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Commercial Uses of Fungi
• Fungi are commercially important. Humans eat them and use
them to
– Produce medicines such as penicillin
– Decompose wastes
– Produce bread, beer, wine, and cheeses
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Truffles
(the fungal kind, not the chocolates)
Blue cheese
Chanterelle
mushrooms
Figure 16.26
Truffles
(the fungal kind,
not the chocolates)
Figure 16.26a
Blue cheese
Figure 16.26b
Chanterelle
mushrooms
Figure 16.26c
Penicillium
Zone of inhibited growth
Staphylococcus
Figure 16.27
Evolution Connection:
Mutually Beneficial Symbiosis
• Symbiosis is the term used to describe ecological relationships
between organisms of different species that are in direct contact.
• Mutually beneficial symbiotic relationships benefit both species.
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• Examples of mutually beneficial symbiotic relationships
involving fungi include
– Mycorrhizae, the association of fungi and plant roots
– Lichens, the association of fungi and algae
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Colorized SEM
Algal cell
Fungal
hyphae
Figure 16.28
Figure 16.28a
Colorized SEM
Algal cell
Fungal hyphae
Figure 16.28b
Bacteria
Archaea
Protists
Eukarya
Plants
Fungi
Animals
Figure 16.UN01
Bryophytes
Ferns
Gymnosperms
Angiosperms
Figure 16.UN02
Bryophytes
Ferns
Gymnosperms
Angiosperms
Figure 16.UN03
Bryophytes
Ferns
Gymnosperms
Angiosperms
Figure 16.UN04
Bryophytes
Ferns
Gymnosperms
Angiosperms
Figure 16.UN05
Bacteria
Archaea
Protists
Eukarya
Plants
Fungi
Animals
Figure 16.UN06
Leaves
Gametangia
Stomata
Cuticle
Lignin
Shoot
Vascular tissues
Roots
Figure 16.UN07
Origin of
gametangia
(protect
gametes
and embryos)
Origin of
vascular
tissue
(conducts water
and nutrients)
Origin of seeds
(protect
embryos from
dessication and
other hazards)
Origin of flowers
(bear ovules
within protective
chambers called
ovaries)
Figure 16.UN08
Reproductive
structure
Hyphae
Mycelium
Figure 16.UN09