Download Gametophyte

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
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Bacteria
Archaea
Protists
Eukarya
Plants
Fungi
Animals
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Figure 16.UN01
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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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
Xylem transports
water and minerals
from roots to
leaves
Phloem
Xylem
Oak leaf
Vascular
tissue
Phloem distributes
sugars from leaves to
the roots and other
nonphotosynthetic
parts of the plant
Figure 16.3
The fossil record chronicles four major periods of
plant evolution.
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
The history of the plant kingdom is a story of adaptation
to diverse terrestrial habitats.
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.
The great majority of living plants are angiosperms:
They include fruit and vegetable crops, grains,
grasses, and most trees
They are represented by more than 250,000 species
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PLANT DIVERSITY
Bryophytes
(nonvascular plants)
Ferns
(seedless vascular plants)
Gymnosperms
(naked-seed plants)
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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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.
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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 16.10-5
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
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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• 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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Figure 16.12
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
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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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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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.
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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
• 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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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.
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Petal
Stamen
Anther
Stigma
Style
Filament
Ovary
Ovule
Sepal
Carpel
Figure 16.17
Flowers come in many forms
Pansy
Bleeding heart
California poppy
Water lily
Figure 16.18
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
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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• 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
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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
Fungal Nutrition
• Fungi
– Are chemoheterotrophs
– Acquire their nutrients by absorption
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Reproductive
structure
Spore-producing
structures
Hyphae
Mycelium
Mycelium
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
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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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• 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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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