Download Topic 16-Plant Structure and Reproduction

Chapter 31
Plant Structure,
Reproduction, and
Development
PowerPoint Lectures for
Biology: Concepts and Connections, Fifth Edition
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
A Gentle Giant
• Gymnosperms
– Are one of two groups of seed plants
–
Bear seeds in cones
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• Angiosperms, or flowering plants
–
Are the most familiar and diverse group
of plants
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TALKING ABOUT SCIENCE
31.1 Plant scientist Natasha Raikhel studies the
Arabidopsis plant as a model biological system
• Natasha Raikhel
– Is one of America’s most prominent plant
biologists
Figure 31.1A
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• Dr. Raikhel works with Arabidopsis
– A popular model organism for studying
biological systems
Figure 31.1B
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PLANT STRUCTURE AND FUNCTION
31.2 The two main groups of angiosperms are the
monocots and the dicots
• Monocots and dicots differ in
–
The number of seed leaves and in the
structure of roots, stems, leaves, and flowers
Seed leaves
Leaf veins
Stems
Flowers
Roots
MONOCOTS
One
cotyledon
Main veins usually parallel
Vascular bundles in
complex arrangement
Floral parts usually
in multiples of three
Fibrous
root system
Floral parts usually in
multiples of four or five
Taproot
usually present
DICOTS
Figure 31.2
Two
cotyledons
Main veins usually branched
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Vascular bundles
arranged in ring
31.3 A typical plant body consists of roots and
shoots
• A plant’s root system
– Anchors it in the soil
– Absorbs and transports minerals and water
and stores food
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• The shoot system of a plant
– Is made up of stems, leaves, and
adaptations for reproduction, flowers
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• The body of a dicot
Terminal bud
Blade
Leaf
Flower
Petiole
Axillary bud
Shoot
system
Stem
Node
Internode
Taproot
Root
system
Figure 31.3
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Root hair
Root
hairs
Epidermal cell
31.4 Many plants have modified roots, stems, and
leaves
• Some plants have unusually large taproots
–
That store food in the form of carbohydrates
Figure 31.4A
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• Many plants have modified stems
– That store food or function in asexual
reproduction
Strawberry
plant
Potato plant
Stolon (runner)
Ginger plant
Taproot
Rhizome
Rhizome
Tuber
Root
Figure 31.4B
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• Other types of plants have modified leaves
– That function in protection or climbing
Figure 31.4C
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31.5 Plant cells and tissues are diverse in structure and
function
• Most plant cells have three unique structures
–
Chloroplasts, the sites of photosynthesis
–
A central vacuole containing fluid
–
A cell wall that surrounds the plasma membrane
Nucleus
Chloroplast
Central
vacuole
Cell walls
Primary cell wall
Endoplasmic
reticulum
Secondary
cell wall
Middle
lamella
Mitochondrion
Golgi
apparatus
Cell walls of
adjoining cells
Ribosomes
Microtubules
Plasma
membrane
Plasmodesmata
Figure 31.5A
Plasma membrane
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Pit
• Plants have five major types of cells
– Parenchyma, which perform most of the
metabolic functions
– Collenchyma, which provide support
LM 270
Primary
cell wall
(thin)
Pit
Figure 31.5B
Starch-storing vesicles
LM 270
Primary
cell wall
(thick)
Figure 31.5C
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– Sclerenchyma, the main component of
wood
Secondary
cell wall
Pits
Sclereid
cells
Secondary
cell wall
Fiber
Figure 31.5D
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Primary
cell wall
Pits
Sclereid
LM 200
Primary
cell wall
LM 266
Fiber
cells
• Angiosperms have water-conducting cells
– Tracheids and vessel elements
Pits
Vessel element
Tracheids
Pits
Openings
in end wall
Colorized SEM 150
Figure 31.5E
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• Sieve-tube members
– Are food-conducting cells
Sieve plate
Companion
cell
Primary
cell wall
Cytoplasm
Figure 31.5F
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• Two kinds of vascular tissue are
– Xylem, which conveys water and minerals
– Phloem, which transports sugars
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31.6 Three tissue systems make up the plant body
Dicot leaf
• Each plant organ is
made up of three
tissue systems
Vein
Cuticle
Upper epidermis
Xylem
Phloem
Mesophyll
Guard
cells
Lower epidermis
–
The dermal,
vascular,
and ground
tissue
systems
Stoma
Sheath
Dicot stem
Monocot stem
Vascular
bundle
Vascular
bundle
Cortex
Pith
Epidermis
Epidermis
Xylem
Phloem
Vascular
cylinder
Epidermis
Key
Dermal tissue system
Ground tissue system
Cortex
Endodermis
Figure 31.6
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Dicot root
Vascular tissue system
• The dermal tissue system
– Covers and protects the plant
• The vascular tissue system
– Contains xylem and phloem and provides
long-distance transport and support
• The ground tissue system
– Consists of parenchyma cells and
supportive collenchyma and sclerenchyma
cells
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PLANT GROWTH
31.7 Primary growth lengthens roots and shoots
• Meristems, areas of unspecialized, dividing
cells
– Are where plant growth originates
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• Apical meristems
–
Are located in the tips of roots and in the
terminal and axillary buds of shoots
–
Initiate primary (lengthwise) growth by producing
new cells
Terminal bud
Axillary buds
Arrows =
direction
of growth
Root
tips
Figure 31.7A
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• Roots are covered with a root cap
–
That protects the cells of the apical meristem
Vascular cylinder
Root hair
Cortex
Epidermis
Zone of
maturation
Zone of
elongation
Cellulose
fibers
Zone of
cell division
Apical
meristem
region
Key
Dermal tissue system
Ground tissue system
Figure 31.7B
Vascular tissue system
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Root
cap
• Axillary bud meristems
– Are found near the
apical meristems
Axillary bud
meristems
1
Figure 31.7C
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2
LM 103
Leaves
Apical
meristem
31.8 Secondary growth increases the girth of
woody plants
• Secondary growth arises from cell division
– In a cylindrical meristem called the vascular
cambium
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• The vascular cambium thickens a stem
–
By adding layers of secondary xylem, or
wood, next to its inner surface
Year 1
Early Spring
Year 2
Late Summer
Year 1
Late Summer
Key
Dermal tissue system
Ground tissue system
Vascular tissue system
Shed
epidermis
Primary
xylem
Epidermis
Vascular
cambium
Cork
Secondary
xylem (wood)
Cor tex
Primary
phloem
Figure 31.8A
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Cork
cambium
Secondary
phloem
Bark
Secondary xylem
(2 years’ growth)
• The heartwood and sapwood
–
Consist of different layers of xylem
• Outside the vascular cambium, the bark consists mainly of
–
Secondary phloem, cork cambium, and protective cork
cells
Sapwood
Rings
Wood
rays
Heartwood
Sapwood
Vascular cambium
Secondary phloem
Heartwood
Bark
Cork cambium
Cork
Figure 31.8B
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REPRODUCTION OF FLOWERING PLANTS
31.9 Overview: The sexual life cycle of a flowering plant
• The angiosperm flower consists of
–
Sepals, petals, stamens, and carpals
Stigma
Carpel
Anther
Style
Stamen
Filament
Ovary
Petal
Ovule
Figure 31.9A
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Sepal
• Pollen grains develop in anthers
– At the tip of stamens
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• The tip of the carpel, the stigma
– Receives pollen grains
• The ovary, at the base of the carpel
– Houses the egg-producing structure, the ovule
Ovary, containing
ovule
Embryo
Fruit, (mature ovary),
containing seed
Seed
Mature plant with
flowers, where
fertilization occurs
Seedling
Germinating seed
Figure 31.9B
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31.10 The development of pollen and ovules
culminates in fertilization
• In the diploid sporophyte of an angiosperm
– Haploid spores are formed within ovules
and anthers
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• The spores in the anthers
– Give rise to male gametophytes, pollen
grains, which produce sperm
• A spore in an ovule
– Produces the embryo sac, the female
gametophyte, which contains an egg cell
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• Pollination
– Is the arrival of pollen grains onto a
stigma
• A pollen tube grows into the ovule
– And sperm pass through it and fertilize
both the egg and a second cell in a
process called double fertilization
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• Gametophyte development and fertilization in
an angiosperm
Development of male
gametophyte
(pollen grain)
Development of female
gametophyte
(embryo sac)
Anther
Ovule
Cell within
anther
Meiosis
Ovary
Meiosis
Surviving
cell (haploid
spore)
Four haploid
spores
Pollen germinates
Single spore
Mitosis
Wall forms
Mitosis
(of each spore)
Pollination
Two cells
Pollen grain
released from
anther
Embryo
sac
Egg cell
Two sperm in
pollen tube
Pollen
tube
enters
embryo sac
Figure 31.10
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Double
fer tilization
occurs
Two sperm
discharged
Triploid (3n)
endosperm
nucleus
Diploid (2n)
zygote
(egg plus sperm)
31.11 The ovule develops into a seed
• After fertilization, the ovule becomes a seed
–
And the fertilized
egg within it divides
and becomes
an embryo
Triploid cell
Ovule
Shed
epider
mis
Cotyledons
Zygote
Endosperm
Seed coat
Two cells
C
Second Shoot
or
ary
Cork
xylem
cambik
(wood)
um
Second
ary
phloem
Embryo
Root
Figure 31. 11A
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Seed
• The other fertilized cell
– Develops into the endosperm, which
stores food for the embryo
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• The internal structures of dicot and monocot seeds
– Differ in a variety of ways
Embryonic
leaves
Embryonic
shoot
Embryonic
root
Seed coat
Cotyledons
Common bean (dicot)
Fruit tissue
Cotyledon
Seed coat
Embryonic
leaf
Sheath
Figure 31.11B
Corn (monocot)
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Endosperm
Embryonic
Shoot
Embryonic
root
31.12 The ovary develops into a fruit
• Angiosperms form fruits
– Which help protect and disperse the seeds
1
3
2
Figure 31.12A
Upper part
of carpel
Ovule
Seed
Ovar y
wall
Sepal
Figure 31.12B
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Pod
(opened)
• Angiosperm fruits
– May differ in size and development
Figure 31.12C
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31.13 Seed germination continues the life cycle
• A seed starts to germinate
– When it takes up water and starts to
expand
• The embryo resumes growth
– And absorbs nutrients from the
endosperm
• An embryonic root emerges
– And a shoot pushes upward and expands
its leaves
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• In dicot germination, the root emerges first
– Followed by the shoot, which is covered
by a protective hook
Embryonic
shoot
Foliage leaves
Embryonic
root
Figure 31.13A
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Cotyledons
• In monocot germination
– A protective sheath surrounding the
shoot breaks the soil
Foliage
leaves
Protective sheath
enclosing shoot
Figure 31.13B
Embryonic
root
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Cotyledon
31.14 Asexual reproduction produces plant clones
• Asexual reproduction can be achieved via
– Bulbs, sprouts, or runners
Figure 31.14A
Figure 31.14B
Figure 31.14C
Figure 31.14D
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CONNECTION
1.15 Asexual reproduction is a mainstay of
modern agriculture
• Propagating plants asexually from cuttings or
bits of tissue
– Can increase productivity but can also
reduce genetic diversity
Figure 31.15
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