Transcript Chapter 16 Plants, Fungi, and the Move onto Land

Chapter 16
Plants, Fungi, and the Move onto Land
Laura Coronado Bio 10
Chapter 16
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
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.
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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Chapter 16
Bacteria
Archaea
Protists
Eukarya
Plants
Fungi
Animals
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Figure 16.UN01
Terrestrial Adaptations of Plants
Structural Adaptations
– Plants are terrestrial organisms that include forms that
have returned to water, such as water lilies.
– A plant is
• A multicellular eukaryote
• A photoautotroph, making organic molecules by
photosynthesis
– 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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Terrestrial Adaptations of Plants
Structural Adaptations
– 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
– 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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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
minerals from
the water
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Roots anchor plant;
absorb water and
minerals from the
soil (aided by fungi)
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Figure 16.1
Roots
Fungus
Root
surrounded
by fungus
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Figure 16.2
Plant Structures
– 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
– 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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Leaves
Gametangia
Stomata
Cuticle
Lignin
Shoot
Vascular tissues
Roots
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Figure 16.UN07
Phloem
Xylem
Oak leaf
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Vascular
tissue
Figure 16.3
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.
– 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
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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
– Charophytes
• Are a modern-day lineage of green algae
• May resemble one of these early plant ancestors
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LM
LM
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Chapter 16
Figure 16.5
PLANT DIVERSITY & EVOLUTION
– The history of the plant kingdom is a story of
adaptation to diverse terrestrial habitats.
– The fossil record chronicles four major periods of
plant evolution.
– (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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Origin of seeds
(about 360 mya)
Gymnosperms
600
500
400
300
200
100
Angiosperms
0
Millions of years ago
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Figure 16.6
Seed plants
Origin of flowers
(about 140 mya)
Land plants
Ferns and other
seedless vascular
plants
Origin of vascular tissue
(about 425 mya)
Vascular plants
Bryophytes
Seedless
vascular
plants
Origin of first terrestrial adaptations
(about 475 mya)
Ancestral
green algae
Nonvascular
plants
(bryophytes)
Charophytes (a group
of green algae)
Bryophytes
Ferns
Gymnosperms
Angiosperms
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Figure 16.UN02
PLANT EVOLUTION
– (2) About 425 million years ago ferns evolved
• With vascular tissue hardened with lignin
• But without seeds
– (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.
– (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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Plant Diversity
– 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
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PLANT DIVERSITY
Bryophytes
(nonvascular plants)
Ferns
(seedless vascular plants)
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Gymnosperms
(naked-seed plants)
Chapter 16
Angiosperms
(flowering plants)
Figure 16.7
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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Chapter 16
Laura Coronado Bio 10
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Figure 16.8
Spores
Spore capsule
Sporophyte
Gametophytes
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Figure 16.9
Mosses
– Mosses have two distinct forms:
• The gametophyte, which produces gametes
• The sporophyte, which produces spores
– 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.
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Spores
(n)
Gametes:
sperm
and eggs
(n)
Gametophyte
(n)
FERTILIZATION
MEIOSIS
Spore
capsule
Zygote
(2n)
Sporophyte
(2n)
Key
Haploid (n)
Diploid (2n)
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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
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Spore capsule
“Fiddlehead”
(young leaves
ready to unfurl)
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Figure 16.11
Carboniferous Period
– 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.
– Fossil fuels
• Include coal, oil, and natural gas
• Formed from the remains of long-dead organisms
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Chapter 16
Laura Coronado Bio 10
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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
– 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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Terrestrial Adaptations of Seed Plants
– Conifers and most other gymnosperms have three
additional terrestrial adaptations:
• Further reduction of the gametophyte
• Pollen
• Seeds
– Seed plants have a greater development of the
diploid sporophyte compared to the haploid
gametophyte generation.
– A pine tree or other conifer is actually a sporophyte
with tiny gametophytes living in cones.
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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)
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Figure 16.14
Scale
Ovule-producing
cones; the scales
contain female
gametophytes
Pollen-producing
cones; they
produce male
gametophytes
Ponderosa pine
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Figure 16.15
Terrestrial Adaptations of Seed Plants
– 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
– 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
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)
Laura Coronado Bio 10
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Figure 16.16-3
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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Chapter 16
Flowers, Fruits, & 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.
– A flower is actually a short stem with four whorls of
modified leaves:
•
•
•
•
Sepals
Petals
Stamens
Carpels
– Flowers are an essential element of the angiosperm
life cycle & come in many forms
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Petal
Stamen
Stigma
Anther
Style
Filament
Ovary
Ovule
Sepal
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Figure 16.17
Carpel
Pansy
Bleeding heart
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California poppy
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Water lily
Figure 16.18
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
Embryo sac
(female
gametophyte)
Egg
Endosperm
Zygote
Two
sperm
nuclei
Sporophyte
seedling
Embryo
(sporophyte)
Seed
Germinating
seed
Key
Seed (develops
from ovule)
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Fruit (develops
from ovary)
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Haploid (n)
Diploid (2n)
Figure 16.19-6
Seed Types
– Although both have seeds
• Angiosperms enclose the seed within an ovary
• Gymnosperms have naked seeds
– 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
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Figure 16.20
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!
– Humans depend on plants for thousands of products
including
• Food
• Building materials
• Medicines
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Chapter 16
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Figure 16.21
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Table 16.1
Plant Preservation
– 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
• Eukaryotes
• Typically multicellular
• More closely related to animals than plants, arising from a
common ancestor about 1.5 billion years ago
• Come in many shapes and sizes
• Represent more than 100,000 species
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Colorized SEM
Bud
Budding yeast
A “fairy ring”
Orange fungi
Colorized SEM
Mold
Body of fungus
Colorized SEM
Roundworm
Predatory fungus
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Figure 16.22
Roundworm
Predatory fungus
Body of fungus
Colorized SEM
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Figure 16.22f
Characteristics of Fungi
– Fungi have unique
• Structures
• Forms of nutrition is chemoheterotrophs
• Acquire their nutrients by absorption
– 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
– Hyphae branch repeatedly, forming an interwoven
network called a mycelium (plural, mycelia), the
feeding structure of the fungus.
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Reproductive
structure
Spore-producing
structures
Hyphae
Mycelium
Mycelium
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Figure 16.23
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.
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The Ecological Impact of Fungi
– Fungi have
• An enormous ecological impact
• Many interactions with humans
– 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.
– 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
– 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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Chapter 16
Parasitic Fungi
(a) American elm trees killed by Dutch
elm disease fungus
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(b) Ergots
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Figure 16.24a
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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Chapter 16
Laura Coronado Bio 10
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Figure 16.25
The Process of Science:
Did a Fungus Lead to the Salem Witch Hunt?
– 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
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Figure 16.26
Penicillium
Zone of inhibited growth
Staphylococcus
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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.
– 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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Chapter 16
Colorized SEM
Algal cell
Fungal
hyphae
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Figure 16.28