Download Plants, Fungi, and the Move onto Land

CHAPTER 16
Plants, Fungi, and the Move
onto Land
Figures 16.1 – 16.5
PowerPoint® Lecture Slides for
Essential Biology, Second Edition & Essential Biology with Physiology
Neil Campbell, Jane Reece, and Eric Simon
Presentation prepared by Chris C. Romero
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Some giant sequoia trees weigh
more than a dozen space shuttles
• Flowering plants such as
corn, rice, and wheat
provide nearly all our
food.
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• A mushroom is
probably more closely
related to humans than
it is to any plant
• Every 2 seconds
humans destroy an area
of tropical rain forest
equal to the area of 3
football fields.
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1
BIOLOGY AND SOCIETY:
THE BALANCING ACT OF FOREST
CONSERVATION
• Coniferous forests are highly productive
– They provide lumber for building and wood pulp for
paper.
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• Our demand for wood and paper is so great that
clear-cut areas have become commonplace.
Figure 16.1
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• The loss of coniferous forests
– Threatens the trees and other organisms that live in
forests
– Can be minimized by conservation practices.
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COLONIZING LAND
• Plants
– Are terrestrial organisms
– Are multicellular eukaryotes that make organic
molecules by photosynthesis.
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Terrestrial Adaptations of Plants
Structural Adaptations
• Living on land poses different problems from living
in water
– Plants require structural specializations
– Roots and shoots.
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Plant
Leaf
performs photosynthesis
Cuticle
reduces water loss;
stomata allow 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
Roots
anchor plant;
absorb water
and minerals
from the soil
(aided by
fungi)
Figure 16.2
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3
• Most plants have mycorrhizae, symbiotic fungi
associated with their roots.
Figure 16.3
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• Leaves
– Are the main
photosynthetic organs of
most plants
– Have stomata for gas
exchange
– Contain vascular tissue
for transporting vital
materials.
Figure 16.4
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• Other types of vascular tissue are found in the roots
and shoots of plants.
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4
Reproductive Adaptations
• Plants produce their gametes in protective structures
called gametangia.
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• In plants, but not algae, the zygote develops into an
embryo while still contained within the female
parent.
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Ovary of
flower
Embryo
Maternal
tissue
Figure 16.5
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5
The Origin of Plants from Green Algae
• The move onto land and the spread of plants to
diverse terrestrial environments were incremental
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• Molecular comparisons and other evidence place a
group of green algae called charophyceans closest
to plants.
Figure 16.6
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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.
Angiosperms
Gymnosperms
(e.g., conifers)
Seedless vascular plants
(e.g., ferns)
Bryophytes (e.g., mosses)
Mesozoic
Paleozoic
Charophyceans (a group of green algae)
Cenozoic
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Diversification of
flowering plants
First seed plants
Early vascular plants
Origin of plants
Figure 16.7
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• The first period
– Was the origin of plants from their aquatic ancestors,
charophyceans
• The second period
– Was the diversification of vascular plants
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• The third period
– Began with the origin of the seed
• The fourth period
– Was the emergence of flowering plants, or
angiosperms.
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Bryophytes
• Mosses
– Are the most familiar bryophytes.
Figure 16.8
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• Mosses display two key terrestrial adaptations
– A waxy cuticle that helps prevent dehydration
– The retention of developing embryos within the
mother’s gametangium.
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• Mosses have two distinct versions of the plant
– The gametophyte,
which produces
gametes
– The sporophyte,
which produces
spores.
Figure 16.9
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• The life cycle of a moss exhibits an alternation of
generations.
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Spores
n
M
si
ito
Mi
to
s
sis
Gametes
(sperm and
eggs)
n
Gametophyte
n
Haploid
Fertilization
Meiosis
Diploid
Spore
capsule
Sporophyte
2n
ito
M
s
si
Zygote
2n
Figure 16.10
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Ferns
• Ferns
– Are seedless
vascular
plants.
Figure 16.11
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• During the Carboniferous period, about 290–360
million years ago, ferns formed swampy forests that
covered much of what is now Eurasia and North
America
– These forests formed what would become fossil fuels.
Figure 16.12
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Gymnosperms
• A drier, colder climate at the end of the
Carboniferous period favored the evolution of
gymnosperms, the first seed 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.
Figure 16.13
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Terrestrial Adaptations of Seed Plants
• Conifers and most other gymnosperms have three
terrestrial adaptations
– Further reduction of the gametophyte
– The evolution of pollen
– The advent of the seed.
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• The first adaptation is a greater development of the
diploid sporophyte compared to the haploid
gametophyte generation.
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Haploid (n)
Gametophyte (n)
Sporophyte (2n)
Gametophyte (n)
Sporophyte (2n)
(a) Sporophyte
dependent on
gametophyte (e.g.,
mosses)
Sporophyte (2n)
(b) Large sporophyte and
small, independent
gametophyte (e.g.,
ferns)
Diploid (2n)
Gametophyte (n)
(c) Reduced gametophyte
dependent on
sporophyte (seed
plants)
Figure 16.14
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• A pine tree of other
conifer is actually a
sporophyte with
tiny gametophytes
living in cones.
Figure 16.15
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• A second adaptation of seed plants to dry land was
the evolution of pollen
• A pollen grain
– Is actually the much-reduced male gametophyte
– Fertilizes the female gametophyte.
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• The third terrestrial adaptation was the development
of the seed
• A seed consists of a plant embryo packaged along
with a food supply within a protective coat.
Seed coat
(derived from
integuments)
Female
gametophyte
Integuments
Spore case
Food supply
(derived from
female
gametophyte
tissue)
Spore
Haploid (n)
Pollen tube
Egg
nucleus
Pollen grain
(male gametophyte)
Discharged
sperm
nucleus
Embryo
(new sporophyte)
Diploid (2n)
(a) Ovule
(b) Fertilized ovule
(c) Seed
Figure 16.16
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Angiosperms
• Angiosperms
– Supply nearly all our food and much of our fiber for
textiles
• More efficient water transport and the evolution of
the flower help account for the success of the
angiosperms.
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Flowers, Fruits, and the Angiosperm Life Cycle
• The dominant stage of the angiosperms is a
sporophyte with gametophytes in its flowers.
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Petal
Stamen
Carpel
Stigma
Anther
Filament
Style
Ovary
Ovule
Sepal
Figure 16.17
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• The life cycle of an angiosperm.
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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)
Endosperm
Egg
Zygote
Sperm
nuclei
Sporophyte
seedling
Embryo
(sporophyte)
Seed
Germinating
seed
Seed
(develops
from ovule)
Figure 16.18
Fruit
(develops
from ovary)
Haploid (n)
Diploid (2n)
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• The seed being enclosed within an ovary
distinguishes angiosperms from gymnosperms.
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• A fruit
– Is a ripened ovary
– Helps protect the
seed and increase
seed dispersal
– Is a major food
source for animals.
Figure 16.19
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Angiosperms and Agriculture
• Angiosperms
– 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.
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• Humans depend on plants for thousands of products
including food, building materials, and medicines.
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Table 16.1
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• Preserving plant diversity is important to many
ecosystems as well as humans.
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FUNGI
• Fungi are extremely important to ecosystems
because they decompose and recycle organic
materials.
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• Fungi
– Are eukaryotes, and most are multicellular
– Are more closely related to animals than plants.
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• A gallery of diverse fungi
Figure 16.20
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Characteristics of Fungi
• In this section, the structure and function of fungi
are described.
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Fungal Nutrition
• Fungi are heterotrophs
– They digest their food externally and acquire the
nutrients by absorption.
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Fungal Structure
• The bodies of most fungi are constructed of
structures called hyphae.
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• The hyphae
– Form an interwoven mat called a mycelium
– Are separated into cells by cross-walls made mainly
of chitin.
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Reproductive
structure
Sporeproducing
structures
Hyphae
Mycelium
Figure 16.21
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Fungal Reproduction
• Fungi reproduce by releasing spores that are
produced either sexually or asexually.
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The Ecological Impact of Fungi
• Fungi
– Have an enormous ecological impact.
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Fungi as Decomposers
• Fungi and bacteria
– Are the principal decomposers of ecosystems
– Keep ecosystems stocked with nutrients necessary
for plant growth.
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• Molds
– Can destroy fruit, wood, and human-made materials.
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Parasitic Fungi
• Of the 100,000
known species of
fungi, about 30%
make their living as
parasites.
Figure 16.22
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• About 50 species of fungi are known to be parasitic
in humans and other animals.
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Commercial Uses of Fungi
• Fungi are
commercially
important
– As food and in
baking
– In beer and
wine
production.
Figure 16.23
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• Some fungi produce antibiotics.
Figure 16.24
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EVOLUTION CONNECTION:
MUTUAL SYMBIOSIS
• Interdependence between species, or symbiosis, is
an evolutionary product
– Mutualism is symbiosis that benefits both species.
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• Lichens
– Are symbiotic
associations between
fungi and algae.
Figure 16.25
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SUMMARY OF KEY CONCEPTS
Leaves are main photosynthetic organs
• Terrestrial
Adaptations
of Plants.
Gametangia protect gametes from
dehydration; female gametangia protect
developing embryos
Cuticle reduces water loss
Stomata allow gas exchange between
plant and atmosphere
Lignin hardens cell walls
Shoot supports plant; may perform
photosynthesis
Vascular tissues transport water,
minerals, and sugars; provide support
Roots anchor plant; mycorrhizae
(root/fungus associations) help absorb
water and minerals from the soil)
Visual Summary 16.1
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• Highlights of Plant Evolution.
Origin of
gametangia
(protect
gametes and
embryos)
Diversification
of seedless
vascular plants
(vascular tissue
conducts water
and nutrients)
Origin of seeds
(protect embryos
from desiccation
and other
hazards)
Origin of flowers
(bear ovules
within protective
chambers called
ovaries)
Visual Summary 16.2
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23