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Transcript of Chapter 31 and 33
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
PowerPoint Lectures forBiology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Chapter 31Chapter 31
Plant Structure, Reproduction, and Development (Sections 7 and 8)
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
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Angiosperms, or flowering plants
– Are the most familiar and diverse group of plants
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
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
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Dr. Raikhel works with Arabidopsis
– A popular model organism for studying biological systems
Figure 31.1B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
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
Figure 31.2
Fibrousroot system
MONOCOTS
Seed leaves Leaf veins Stems Flowers Roots
Onecotyledon Main veins usually parallel
Vascular bundles in complex arrangement
Floral parts usuallyin multiples of three
Twocotyledons Main veins usually branched
Vascular bundles arranged in ring
Floral parts usually inmultiples of four or five
Taprootusually present
DICOTS
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
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
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• The shoot system of a plant
– Is made up of stems, leaves, and adaptations for reproduction, flowers
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Terminal bud
Blade
PetioleAxillary bud
Stem
TaprootRoothairs
Epidermal cell
Root hairInternode
Node
Flower
Shootsystem
Rootsystem
Leaf
• The body of a dicot
Figure 31.3
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
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
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Strawberry plant
Potato plant
Stolon (runner)
Taproot
Rhizome
Tuber
Ginger plant
Rhizome
Root
• Many plants have modified stems
– That store food or function in asexual reproduction
Figure 31.4B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Other types of plants have modified leaves
– That function in protection or climbing
Figure 31.4C
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Figure 31.5A
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 membraneChloroplast Central
vacuoleCell walls
Primary cell wall
Middle lamella
Secondary cell wall
Plasmamembrane
Cell walls of adjoining cells
Plasmodesmata
PitPlasma membrane
MicrotubulesRibosomes
Golgiapparatus
Mitochondrion
Endoplasmicreticulum
Nucleus
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Plants have five major types of cells
– Parenchyma, which perform most of the metabolic functions
– Collenchyma, which provide supportPrimary cell wall (thin)
Pit
Starch-storing vesicles
LM 2
70
Figure 31.5B
Primary cell wall (thick)
LM 2
70
Figure 31.5C
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
– Sclerenchyma, the main component of wood
Figure 31.5D
Secondary cell wall
Pits
Fiber cells
Primary cell wall
Secondary cell wall
Primary cell wall Pits
Sclereid cells
Fiber Sclereid
LM
26
6
LM
20
0
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Pits
Openings in end wall
Vessel element Tracheids
Pits
Colorized SEM 150
• Angiosperms have water-conducting cells
– Tracheids and vessel elements
Figure 31.5E
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Figure 31.5F
• Sieve-tube members
– Are food-conducting cellsSieve plate
Companion cell
Primary cell wall
Cytoplasm
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Two kinds of vascular tissue are
– Xylem, which conveys water and minerals
– Phloem, which transports sugars
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
31.6 Three tissue systems make up the plant body
• Each plant organ is made up of threetissue systems
– The dermal,vascular, and ground tissue systems
Vein
Guard cells
Cuticle
Upper epidermis
Mesophyll
Lower epidermis
Stoma
Xylem
Phloem
Dicot leaf
Dicot stem
Sheath
Vascular bundle
Cortex
Pith
Epidermis
Monocot stemVascular bundle
Epidermis
Epidermis
Vascular cylinder
Xylem
Phloem
Cortex
Endodermis
Dicot root
Key
Dermal tissue system
Ground tissue system
Vascular tissue system
Figure 31.6
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• 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
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
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
Figure 31.7A
Terminal bud
Axillary buds
Root tips
Arrows = direction of growth
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Roots are covered with a root cap
– That protects the cells of the apical meristem
Figure 31.7B
Vascular cylinder
Root hair
Cortex
Epidermis
Zone of maturation
Zone of elongation
Zone of cell division
Root cap
Apical meristem region
Cellulose fibers
KeyDermal tissue system
Ground tissue system
Vascular tissue system
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Axillary bud meristems
– Are found near the apical meristems
Figure 31.7C
Apical meristem
Leaves
Axillary bud meristems
1 2
LM 1
03
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
31.8 Secondary growth increases the girth of woody plants
• Secondary growth arises from cell division
– In a cylindrical meristem called the vascular cambium
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• The vascular cambium thickens a stem
– By adding layers of secondary xylem, or wood, next to its inner surface
Year 1Early Spring
Year 1Late Summer
Year 2Late Summer
GrowthGrowth
Growth
Primary xylem
Vascular cambium
Primary phloem
Cor tex
EpidermisSecondary
xylem (wood)Cork
Corkcambium
Secondary phloem
Bark
Shed epidermis
Secondary xylem (2 years’ growth)
Key
Dermal tissue system
Ground tissue system
Vascular tissue system
Figure 31.8A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• 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
Figure 31.8B
Heartwood
Sapwood
Rings
Wood rays
Heartwood
Vascular cambium
Sapwood
Secondary phloem
Cork cambium
Cork
Bark
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
PowerPoint Lectures forBiology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Chapter 33Chapter 33
Control Systems in Plants
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
What Are the Health Benefits of Soy?
• Soy protein
– Is one of the few plant proteins that contains all the essential amino acids
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Phytoestrogens, a class of plant hormones
– Are found in soy
CH3
OH
HO HO
O OH
OHO
Estrogen (Estradiol) Phytoestrogen (Genistein)
Chemical structures of a humanestrogen and a plant phytoestrogen
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Soy products contain isoflavones
– A type of phytoestrogen that may provide human health benefits
Soybeans
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
PLANT HORMONES
33.1 Experiments on how plants turn toward light led to the discovery of a plant hormone
• Plants exhibit phototropism
– The growth of shoots in response to light
Figure 33.1A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Microscopic observations of plants
– Indicate that a cellular mechanism underlies phototropism
Shaded side of shoot
Illuminated side of shoot
Light
Figure 33.1B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Showing That Light Is Detected by the Shoot Tip
• Charles Darwin showed that the tip of a grass seedling detects light
– And transmits a signal down to the growing region of a shoot
Light
Control Tipremoved
Tip covered byopaque cap
Tip coveredby trans-parent cap
Base coveredby opaqueshield
Tip separatedby gelatinblock
Tip separatedby mica
Darwin and Darwin (1880) Boysen-Jensen (1913)
Figure 33.1C
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Isolating the Chemical Signal
• The hormone auxin
– Was determined to affect phototropism
– Promotes faster cell elongation on the shaded site of the shoot
Agar
Shoot tip placed on agar block.Chemical (later called auxin)diffuses from shoot tipinto agar.
Other controls:Blocks with nochemical haveno effect.
Offset blocks withchemical stimulatecurved growth.Control
Block withchemicalstimulatesgrowth.
No light
Figure 33.1D
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33.2 Five major types of hormones regulate plant growth and development
• Even in small amounts, plant hormones
– Trigger signal transduction pathways
– Regulate plant growth and development
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• The major types of plant hormones
Table 33.2
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
33.3 Auxin stimulates the elongation of cells in young shoots
• Plants produce auxin (IAA)
– In the apical meristems at the tips of shoots
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• At different concentrations, auxin
– Stimulates or inhibits the elongation of shoots and roots
Figure 33.3A, B
Roots
Stems
0
0.9 g/L
10–8 10–6 10–4 10–2 1 102
Increasing auxin concentration (g/L)
Elo
ngat
ion
Inhi
bitio
n
Pro
mot
ion
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Auxin may act by weakening cell walls
– Allowing them to stretch when cells take up water
Plasmamembrane
Cellwall H+
1
2H+
3H2O
Vacuole
Cellelongation
Cellulose loosens; cell can elongate
Cellulosemolecule
Cross-linkingmolecule
Enzyme
Cellulosemolecule
Cell wall
Cytoplasm
H+ pump(protein)
Figure 33.3C
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Auxin promotes growth in stem diameter
– By stimulating the development of vascular tissues and cell division in vascular cambium
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
33.4 Cytokinins stimulated cell division
• Cytokinins
– Are produced by growing roots, embryos, and fruits
– Promote cell division
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Cytokinins from roots may balance the effects of auxin from apical meristems
– Causing lower buds to develop into branches
Figure 33.4
Terminal bud
No terminal bud
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
33.5 Gibberellins affect stem elongation and have numerous other effects
• Gibberellins
– Stimulate the elongation of stems
Figure 33.5A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Gibberellins
– Stimulate the development of fruit
– Function in embryos in some of the early events of seed germination
Figure 33.5B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
33.6 Abscisic acid inhibits many plant processes
• Abscisic acid (ABA)
– Inhibits the germination of seeds
• The ratio of ABA to gibberellins
– Often determines whether a seed will remain dormant or germinate
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• Seeds of many plants remain dormant
– Until their ABA is inactivated or washed away
Figure 33.6
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• ABA also acts as a “stress hormone”
– Causing stomata to close when a plant is dehydrated
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
33.7 Ethylene triggers fruit ripening and other aging processes
• As fruit cells age
– They give off ethylene, which triggers a variety of aging processes
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Fruit Ripening
• Ethylene
– Triggers fruit ripening
1
2
3
Figure 33.7A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
The Falling of Leaves
• A changing ratio of auxin to ethylene
– Is triggered by shorter days
– Probably causes autumn color changes and the loss of leaves from deciduous trees
Leafstalk
Stem(twig)
Abscissionlayer
Protectivelayer
Stem Leaf stalk
LM 2
0
Figure 33.7B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
CONNECTION
33.8 Plant hormones have many agricultural uses
• Farmers use auxin
– To delay or promote fruit drop
Figure 33.8
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Auxins and gibberellins
– Are used to produce seedless fruits
• A synthetic auxin called 2,4-D
– Is used to kill weeds
– Has safety questions associated with its use