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CEB Textbook Chapter 16, pages 316-327; 333-335
Mastering Biology; Chapter 16
TOPIC 21 PLANTS Learning outcomes: After studying this topic, you should be able to:
Name the main components of a plant and describe their
basic functions.
Describe the fundamental differences between the four
major groups of plants.
Give an example of a bryophyte, a fern, a gymnosperm
and an angiosperm.
Describe the main characteristics of ferns and explain how
they reproduce.
Outline the three main adaptations found in gymnosperms
that are not found in ferns.
Name the main parts of a flower and describe the
angiosperm life cycle.
Figure 16.UN01
Bacteria
Archaea
Eukarya
Protists
Plants
Fungi
Animals
COLONIZING LAND
A plant is
a multicellular
eukaryote and
a photoautotroph,
making organic
molecules by
photosynthesis.
Figure 16.1
Reproductive structures
contain spores and gametes
Leaf performs photosynthesis
Cuticle reduces water loss; stomata regulate
gas exchange
Shoot supports plant
Surrounding water supports the alga
Roots anchor plant; absorb water and minerals from the soil (aided by fungi)
Whole alga performs photo-
synthesis; absorbs water,
CO2, and minerals from the
water
Alga
Plant
Figure 16.UN07 Leaves are the main photosynthetic organs
Gametangia protect gametes from dehydration; female gametangia also protect developing embryos
Stomata regulate gas exchange between plant and atmosphere
Cuticle reduces water loss
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
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STRUCTURAL ADAPATATIONS
Leaves – main site of photosynthesis
Stomata – pores in leaf for gas exchange
Vascular Tissue – series of vessels throughout plant (xylem transports water, phloem transports sugar)
Cuticle – Waxy layer coating leaf
Figure 16.3
Phloem
Xylem
Oak leaf
Vascular tissue
ORIGIN OF PLANTS FROM GREEN ALGAE
The algal ancestors of plants
carpeted moist fringes of lakes or coastal salt
marshes and
first evolved over 500 million years ago.
LM
PLANT DIVERSITY
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, which are
also evident in the
diversity of modern
plants.
PLANT EVOLUTION – FOUR MAIN GROUPS Bryophytes (475 mya)
- includes mosses, liverworts,
hornworts
- Nonvascular (no vessels), no lignin,
no seeds, no true roots or leaves
Ferns (425 mya)
- Has vascular tissue (xylem) hardened
with lignin (similar to calcium), no
seeds
Gymnosperms (360 mya) –
Conifers
- First type of plant to have seeds
Angiosperms (140 mya) –
Flowering plants
- Has flowers which bear seeds within
Figure 16.6
Ancestral green algae
Origin of first terrestrial adaptations
Origin of vascular tissue
Origin of seeds
600 500 400 300 200 100 0
Origin of flowers
Millions of years ago
Angio- sperms
Gymno- sperms
Ferns
Bryophytes
Charophytes
Land
plan
ts Vascu
lar With
se
ed
s
See
d-
less
No
n-
vascular
1
2
3
4
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Figure 16.7
PLANT DIVERSITY
Bryophytes (nonvascular
plants)
Ferns (seedless
vascular plants)
Gymnosperms (naked-seed
plants)
Angiosperms (flowering
plants)
Figure 16.UN08
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 16.8
Peat Moss Bog in Scotland BRYOPHYTES Mosses – Need water to
reproduce because sperm have to swim to reach eggs within the female gametangium
Lack vascular tissue
Has two main forms
- Gametophyte (produces gametes)
- Sporophyte (produces spores)
- The moss will alternate between these two forms in its life cycle (alternation of generations)
Figure 16.9
Spore capsule
Sporophytes
Gametophytes
© 2013 Pearson Education, Inc.
Animation: Moss Life Cycle
Right click slide / select “Play”
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Figure 16.10-1
Gametes: sperm
and eggs (n) Gametophyte
(n)
Key Haploid (n)
Diploid (2n)
Figure 16.10-2
Gametes: sperm
and eggs (n)
Zygote (2n)
Gametophyte (n)
Key Haploid (n)
Diploid (2n)
FERTILIZATION
Figure 16.10-3
Spore capsule
Gametes: sperm
and eggs (n)
Zygote (2n)
Gametophyte (n)
Sporophyte (2n)
Key Haploid (n)
Diploid (2n)
FERTILIZATION
FERNS
Seedless
Vascular
12,000 known
species
The sperm of ferns,
like those of mosses,
have flagella and
must swim through a
film of water to
fertilize eggs.
© 2013 Pearson Education, Inc.
Blast Animation: Non-Flowering Plant Life Cycle
Select ”Play”
© 2013 Pearson Education, Inc.
Animation: Fern Life Cycle
Right click slide / select “Play”
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Figure 16.11
Spore capsule
“Fiddlehead” (young leaf
ready to unfurl)
Gametophyte
New sporophyte
Ferns (seedless vascular plants)
GYMNOSPERMS
Adapted to drier colder climates
Cone bearing plants like pine (conifers)
Cover most of northern Eurasia and North America
Usually evergreen
Includes the tallest, largest and oldest organisms on Earth!
Figure 16.13
GYMNOSPERMS - CONIFERS
Three additional adaptations of gymnosperms which allow them to live in a more diverse range of terrestrial habitats
Seeds
Pollen
Further reduction of the gametophyte
Figure 16.14
Key Haploid (n)
Gametophyte (n) Sporophyte
(2n)
Sporophyte (2n)
Gametophyte (n)
Gametophyte (n)
Sporophyte (2n)
Diploid (2n)
Figure 16.14a
Key
Haploid (n)
Diploid (2n)
Gametophyte (n) Sporophyte
(2n)
(a) Sporophyte dependent on gametophyte (e.g., mosses)
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Figure 16.14b
Key
Haploid (n)
Diploid (2n)
Gametophyte (n)
Sporophyte (2n)
(b) Large sporophyte and small, independent gametophyte (e.g., ferns)
Figure 16.14c
Key
Haploid (n)
Diploid (2n)
Gametophyte (n)
Sporophyte (2n)
(c) Reduced gametophyte dependent on sporophyte (seed plants)
– A pine tree or other conifer is actually a sporophyte with tiny gametophytes living in cones.
© 2013 Pearson Education, Inc.
Animation: Pine Life Cycle
Right click slide / select “Play”
Figure 16.15 Scale
Ovule-producing cones
Pollen-producing cones
Ponderosa pine
ADAPTATIONS OF SEED PLANTS
Pollen Grain – much reduced male gametophyte which houses sperm
Seed – Consisting of plant embryo, food supply and protective seed coat
Ovules - where seeds are developed
Seeds can lay dormant for long periods
Female cone, cross section
Figure 16.16-1
(a) Ovule
Haploid (n) Diploid (2n) Cross section
of scale Female cone, cross section
Integument
Spore
Spore case
Egg nucleus
Key
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Figure 16.16-2
(a) Ovule
Haploid (n) Diploid (2n)
(b) Fertilized ovule
Cross section of scale
Female cone, cross section
Integument
Spore
Spore case
Pollen tube
Spore case
Egg nucleus
Female gametophyte
Discharged sperm nucleus Pollen grain
Key
Figure 16.16-3
(a) Ovule
Haploid (n) Diploid (2n)
(b) Fertilized ovule
(c) Seed
Cross section of scale
Female cone, cross section
Integument
Spore
Spore case
Pollen tube
Spore case
Egg nucleus
Female gametophyte
Discharged sperm nucleus
Seed coat
Embryo
Food supply
Pollen grain
Key
ANGIOSPERMS – FLOWERING PLANTS
Angiosperms dominate the modern
landscape,
are represented by about 250,000 species, and
supply nearly all of our food and much of our fiber for textiles.
Their success is largely due to refinements in vascular
tissue that make water transport more efficient and
the evolution of the flower.
FLOWER – ATTRACTS POLLINATORS Sepal – outer layer
Petal – attracts pollinators
Stamen – Male
reproductive structure
consisting of filament and
anther (makes pollen)
Carpel – Female
reproductive structure
consisting of stigma, style,
ovary (contains eggs) and
ovules (develop into eggs)
Figure 16.17 Petal
Carpel Stamen
Sepal Ovule
Anther
Filament
Stigma
Style
Ovary
Figure 16.18
Pansy Bleeding heart California poppy
Water lily
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© 2013 Pearson Education, Inc.
Blast Animation: Flowering Plant Life Cycle
Select “Play”
Figure 16.19a-1
Key
Haploid (n)
Diploid (2n)
Mature sporophyte plant with flowers
1
Figure 16.19a-2
Key
Haploid (n)
Diploid (2n)
Two sperm nuclei
Egg
Embryo sac (female gametophyte)
Ovule
Ovary
Pollen tube growing down style of carpel
Anther at tip of stamen
Germinated pollen grain (male gametophyte) on stigma of carpel
Mature sporophyte plant with flowers
1
2
3
Figure 16.19a-3
Key
Haploid (n)
Diploid (2n)
Two sperm nuclei
Egg
Zygote
Endosperm
Embryo sac (female gametophyte)
Ovule
Ovary
FERTILIZATION
Pollen tube growing down style of carpel
Anther at tip of stamen
Germinated pollen grain (male gametophyte) on stigma of carpel
Mature sporophyte plant with flowers
1
2
3
4
Figure 16.19
Mature sporophyte plant with flowers
Key Haploid (n)
Diploid (2n)
Sporophyte seedling
Germinating seed
Seed (develops from ovule)
Seed
Fruit (develops from ovary)
Embryo (sporophyte)
Two sperm nuclei
Egg Zygote
Endosperm Embryo sac (female gametophyte)
FERTILIZATION Ovule
Ovary (base of carpel)
Pollen tube growing down style of carpel
Anther at tip of stamen
Germinated pollen grain (male gametophyte) on stigma of carpel
1
2
3
4
6
5
© 2013 Pearson Education, Inc.
Animation: Plant Fertilization
Right click slide / select “Play”
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FLOWERS, FRUIT AND THE ANGIOSPERM
Although both have seeds
- Angiosperm seeds are protected by an ovary
- Gymnosperm seeds are naked
Fruit
- Is a ripened ovary
- Helps protect seed
- Increases seed dispersal
- Major source of food for all animals
Figure 16.19b-1
Key
Haploid (n)
Diploid (2n)
5
Embryo (sporophyte)
Figure 16.19b-2
Key
Haploid (n)
Diploid (2n)
6
5
Seed
Embryo (sporophyte)
Fruit (develops from ovary)
Seed (develops from ovule)
Figure 16.19b-3
Key
Haploid (n)
Diploid (2n)
6
5
Seed
Sporophyte seedling
Germinating seed
Embryo (sporophyte)
Fruit (develops from ovary)
Seed (develops from ovule)
© 2013 Pearson Education, Inc.
Animation: Fruit Development
Right click slide / select “Play”
Figure 16.20
Wind dispersal
Animal transportation
Animal ingestion
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ANGIOSPERMS AND AGRICULTURE Gymnosperms supply
most of our lumber and
paper.
Angiosperms
provide nearly all our food
and
supply fiber, medications,
perfumes, and decoration.
The exploding human population is extinguishing plant species
at an unprecedented rate and
destroying 50 million acres, an area the size of the state of Washington, every year!
Figure 16.21
Table 16.1
Homework • Unit Assessment Topic 21
• Mastering Biology Plant Assignment
• Fill in Key Terms table and Main adaptations of
Gymnosperms in Study Notes
• Learn parts of the Flower from handout and
draw your own sketch
Videos Crash Course Plant Reproduction
http://www.youtube.com/watch?v=ExaQ8shhkw8
Lesson Plants
http://www.youtube.com/watch?v=X4L3r_XJW0I
DOCUMENTARIES ON PLANTS
Intelligence of Plants
http://www.youtube.com/watch?v=NeX6ST7rexs
Secret World of Plants
http://www.youtube.com/watch?v=8QSWP56J8DA
Private Life of Plants Clips
http://www.youtube.com/watch?v=igkjcuw_n_U&list=PLCC07E66503F99BB5