+ chapter 18 evolution of plants and fungi. + plant characteristics: contain chlorophylls a and b...
TRANSCRIPT
+
Chapter 18Evolution of Plants and Fungi
+Plant Characteristics:
Contain chlorophylls a and b and various accessory pigments
Store excess carbohydrates as starch
Have cellulose in their cell wall
Meristem tissue Produces new cells / organs
Plasmodesmata Openings that allow for passage
Protection of zygote Pass nutrients and keep from drying out
Alternation of generations Sporophyte vs gametophyte
18-2
+Plants have an alternation of generations life cycle
2 multicellular individuals alternate, each producing the other Sporophyte represents the diploid generation (2n)
Produces spores by meiosis spore is a haploid reproductive cell that develops into a new
organism without needing to fuse with another reproductive cell spore undergoes mitosis to become a gametophyte
Gametophyte represents the haploid generation (n) Produces gametes In plants, eggs and sperm are produced by mitosis A sperm and egg fuse, forming a diploid zygote that undergoes
mitosis and becomes the sporophyte
18-3
+ 18-4
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zygote (2n)
sporophyte (2n)
spore (n)
gametophyte (n)
(n)(n)
gametes
Mito
sis
Mitosis
Mitosis
sporangium (2n)
diploid (2n)
haploid (n)MEIOSISFERTILIZATION
+ size of the gametophyte is progressively reduced as the sporophyte becomes more dominant
18-5
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Moss Fern Gymnosperm Angiosperm
roots
roots
roots
rhizoids
Gametophyte
(n)
Sporophyte
(2n)
seed seedspores spores
rhizoids
+Sporophyte anatomy
Cuticle Impermeable Barrier to water loss
Also to gas exchange
Stomata Openings to allow for gas exchange
18-6
+Embryophta – land plants
Nonvascular Bryophytes
Mosses Hornworts Liverworts
Vascular (tracheophytes) Seedless
Lycophytes Ferns
Seeds Gymnosperms Angiosperms (Flowering
plants )
18-7
+Bryophytes
Hornworts, liverworts, and mosses Prefer damp shaded areas Form a mat on ground Turn brown when dry but becomes green when watered again
First plants to colonize land
Successfully reproduce on land protect the embryo and produce wind-blown spores
No true roots, stems, or leaves – no vascular tissue Non-vascular plants
18-8
+Bryophytes
Bryophyte reproduction Gametophyte is the dominant generation Female gametophyte produces eggs in archegonia Male gametophyte produces flagellated sperm in antheridia Following fertilization, the zygote becomes a sporophyte
Sporophyte attached to, and derives its nourishment from, the photosynthetic gametophyte
18-9
+18-10
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(top): © Peter Lilja/Getty Images; (bottom): © Steven P. Lynch
zygote
spermegg
Archegonia
Antheridia
Spores
Sporangium
Gametophytes
buds
Mitosis
Mitosis
haploid (n)
diploid (2n)
1
2
5
6
Developing sporophyte: The sporophyte embryo is retained within the archegonium, where it develops, becoming a mature sporophyte.
developingsporophyte
Fertilization: Flagellated sperm produced in antheridia swim in external water to archegonia, each bearing a single egg.
The maturegametophytes:In mosses, thedominantgametophyte shootsbear either antheridiaor archegonia, wheregametes areproduced by mitosis.
Spore dispersal: Spores are released when they are most likely to be
dispersed by air currents.
The immature gametophyte: A spore germinates into the first stage of the male and the female gametophytes.
3
archegonium
antheridium
The sporophyte: The dependent sporophyte has a foot buried in female gametophyte tissue, a stalk, and an upper capsule (the sporangium), where meiosis occurs and windblown spores are produced.
4
MEIOSISFERTILIZATION
Sporophyte
stalk
foot (n)
+Vascular Plants
Have vascular tissue Xylem transports water
Contain lignin to strengthen cell walls Phloem transports nutrients
First vascular plants were like Cooksonia Rhyniophyte that flourished during Silurian period No roots or leaves Example of seedless vascular plant
Like lycophytes and ferns
18-11
+Transport begins in both the leaves and the roots of plants
Xylem Carries water and minerals from the roots to the
leaves Contain 2 types of nonliving conductive cells
Tracheids allow water to pass between
Vessel elements perforation plates at each end form a completely hollow pipeline from roots
to leaves
22-12
+Transport begins in both the leaves and the roots of plants
Phloem Transports sugar to all parts of the plant Composed of several cell types
Sieve-tube members living conducting cells, contain cytoplasm but
have no nucleus Companion cells
provide proteins to sieve-tube members
Water is a large part of xylem sap and phloem sap
22-13
A plant΄s transport system
blue = phloem; pink =sugar; red = xylem; light blue = water
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O2
xylemphloemstoma
CO2
Phloem is transporting sugarfrom the leaf to the root.
H2O
watersugar
H2Osugar
+Lycophytes
Lycophytes or club mosses True stems, leaves, and roots Leaves are microphylls
Only 1 strand of vascular tissue Sporophyte is dominant, as it is in all vascular plants Today there are 3 groups
Ground pines (Lycopodium) Spike mosses (Selaginella) Quillworts (Isoetes)
18-15
+18-16
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sporophyll
sporangiastrobili
branches
aerial stem
rhizome
root
Leaf
Strobilusleaves(microphylls)
Root
stoma
vascular tissue
phloemxylem
+Ferns
seedless vascular plants
Have megaphyllsBroad leaves with
several strands of vascular tissue
Allow plants to collect more solar energy
18-17
+
Microphylls and megaphylls18-18
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a. Microphyll Megaphyll
b. Megaphyll evolution process
branchedvascular tissue
single strand ofvascular tissue
branchedstem system
megaphyllleaf
Tissue filled in the spacesbetween the side branches.
The side branches flattenedinto a single plane.
One branch began todominate the stem system.
+Ferns
Whisk ferns Psilotum and
Tmesipteris Epiphytes
Plants that live on/in trees
No leaves
18-19
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rhizome
sporangium
aerial stem
scale
root
(Left): © CABISCO/Phototake
+Ferns
Ferns 11,00 species Megaphylls called
fronds Leaves first appear as
fiddleheads 2 generations separate
and independent
18-20
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Cinnamon fern, Osmunda cinamomea
frond(undivided)
Hart’s tongue fernCampyloneurum scolopendrium
Maidenhair fern,Adiantum pedatum
spores onfertile frond
axis
leaflet
(cinnamon fern): © James Randklev/Getty Images; (hart's tongue): © Walter H. Hodge/Peter Arnold/Photolibrary; (maidenhair): © Jeff Foott/Getty Images
frond(divided)
+Fern life cycle 18-
21Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Sporophyte
fiddlehead roots
frond
Sporangium
sperm
Antheridium
egg
Archegonium
Gametophyte
Spores
zygote
leaflet
Sorus
sporangium
MEIOSIS
Dryopterus
Mitosis
Mitosis
haploid (n)
diploid (2n)
5
6
4
3
2
1 The sporophyte: The sporophyte is dominant in ferns.
Young sporophyte:The sporophyteembryo developsinside anarchegonium. As the distinctivefirst leaf appearsabove thegametophyte, and as the roots develop below it,the young sporophyte becomes visible.
young sporophyteon gametophyte
FERTILIZATION
The sporangia:In this fern, thesporangia arelocated within sori(sing., sorus) onthe underside of the leaflets.
The spores:Within asporangium,meiosis occursand spores areproduced. When asporangium opens,the spores arereleased.
germinatingspore
The gametophyte:A spore germinates into aheart-shaped gametophyte,which typically bears archegoniaat the notch and antheridia at thetip between the rhizoids.
Fertilization: Fertilization takes place when moisture is present, because the flagellated sperm must swim in a film of water from the antheridia to eggs within archegonia.
(Top right): © Matt Meadows/Peter Arnold/Photolibrary
Sori
+Seed Plants
Evolution of the seed was the next significant innovation in the evolution of plants
Gymnosperms and angiosperms are seed plants
Seed contains a sporophyte generation, along with stored food, within a
protective seed coat
Ability of seeds to survive harsh conditions until the environment is again favorable for growth largely accounts for the dominance of seed plants today
18-22
+Gymnosperms
Seeds are naked
Diversity of Gymnosperms Four groups of living gymnosperms: cycads, ginkgoes, gnetophytes,
and conifers All have ovules and develop seeds that are exposed on the surface
of cone scales or analogous structures
Conifers Consist of about 575 species of trees
Many are evergreens such as pines, spruces, firs, cedars and hemlocks
Economic Value of Conifers Wood of conifers is used extensively in construction
18-23
+ Pine life cycle18-24
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Pollen sac
Seedstored food
seed coat
zygote
seed wing
Sporophyte
pollen cone scale
Seed cones
seed cone scale
Pollen cones
sperm
pollen tube
egg
Mature female gametophyte
Pollen grain
Pollination
Megaspores
Microspores
pollen grain
Megaspores:Megaspore mother cellin ovule undergoesmeiosis to producemegaspores.Onemegaspore willbecome theegg-producing
The pollen grain:The pollen grain has two wings and is carried by thewind to the seed cone during pollination
Mature male gametophyte
200 µm
MEIOSIS MEIOSIS
Ovule
Ovule
Mitosis
Mitosis
Mitosis
haploid (n)
diploid (2n)
3
4
5
1
2
FERTILIZATION
The sporophyteembryo:Afterfertilization, theovule matures andbecomes the seedcomposed of theembryo, reservefood, and a seedcoat. Finally, in thefall of the secondseason, the seedcone, bynow woody andhard, opens torelease wingedseeds. Whena seed germinates,the sporophyte
sporophyteembryo
Fertilization:Once a pollen grainreaches a seed cone,it becomes a maturemale gametophyte.A pollen tube digestsits way slowlytoward a femalegametophyte anddischargesnonflagellated sperm. The fertilizedegg isa zygote.
ovulewall
megasporemother cell
microsporemother cell
The pollen cones:Typically, the pollencones are quite smalland develop near thetips of lowerbranches.
The seed cones: The seed cones arelarger than the pollencones and are locatednear the tips of higherbranches.
Microspores:Microspore mothercells undergo meiosisto producemicrospores. Eachmicrospore becomes apollen grain.
(Bottom right): © Phototake
+Angiosperms
Seeds are covered
Angiosperms are flowering plants Evolved some 200 MYA Innovations are flower and fruit 240,000 known species Ovules always enclosed within sporophyte tissue
Angiosperm Diversity Monocotyledones (or monocots) – One cotyledon Eudicotyledones (or eudicots) – Two cotyledons Cotyledons – seed leaves with nutrients that nourish the
embryo
18-25
+
Shoot system – stem, branches, leaves, and flowers (organs of sexual reproduction)
Root system – main root and its branches
21-26
stem
internode
petiole
axillary bud
terminal bud
node
Shoot systemRoot system
node
leaf blade
root tip
vascular tissues(xylem and phloem)
lateralbranchrootroothairs
primaryroot
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+Flowering plants typically have roots, stems, and leaves
Roots 3 main functions
1. Anchor plant in soil2. Absorb water and minerals from soil3. Produce hormones Some also store food
Root hairs increase surface-to-volume ratio
Tap roots vs. fibrous roots
21-27
+21-28Taproot system (left) versus fibrous root system (right)
(taproot): © Jonathan Buckley/Getty Images;; (fibrous root): © The McGraw-hill companies Inc./Evelyn Jo Johnson, photographer
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Taproot Fibroous root system
+Flowering plants are either monocots or eudicots
Monocots have one cotyledon Root vascular tissue rings pith Vascular bundles scattered in stem Leaf veins are parallel Flower parts in multiples of three
Eudicots have two cotyledons Root phloem between arms of xylem Vascular bundles in a distinct ring Leaf veins form a net pattern Flower parts in multiples of four or five
21-29
+21-30Monocots and eudicots differ structurally in several ways
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Mo
no
cots
Eu
dic
ots
Two cotyledons in seedRoot phloem between
arms of xylemVascular bundlesin a distinct ring
Leaf veins forma net pattern
Flower parts in fours orfives and their multiples
axillary bud
pith
xylem
phloem
One cotyledon in seed
xylem
Seed Root Stem Leaf Flower
endosperm phloempith
Root xylem andphloem in a ring
Vascular bundlesscattered in stem
axillary bud
Flower parts in threesand multiples of three
Leaf veins forma parallel pattern
+Fruits and Seeds
Advantage of fruit Fruits of flowers aid in dispersal of seeds Eaten by animals
Then transport seeds
Advantage of seeds Dry environment 129 years!! Endosperm of seed provide nourishment
Helps new plant until photosynthesis begins
18-31
+ Generalized flower18-32
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petals (corolla) sepals (calyx)
stamens
anther
filament
receptacle
stigma
ovary
ovule
style
pollentube
carpel
Flowering plant life cycle
18-33
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ovary
stigma
style
Megaspores
sperm
pollen tube
Microspores
(mature male gametophyte)Pollen grain
Embryo sac
(mature female gametophyte)
Pollination
polar nuclei
ovule wall
egg
Seed
endosperm (3n)
sporophyte embryo
seed coat
SporophyteAnther
egg
polar nuclei
Stamen Carpel
stigmastyleovaryovule
filamentanther
MEIOSIS MEIOSIS
sperm
ovule
The mature male gametophyte:A p[ollen grain that lands on the carpel of the same typeof plant germinates and produces a pollen tube,which delivers two nonflagellated sperm to the femalegametophyte. A fully germinated pollen grain is themature male gametophyte.
Mitosis
Mitosis
Mitosis
Ovule
diploid (2n)
haploid (n)
Carpel
Double Fertilization
receptacle
3
4
5
6
1
2
The stamen:An anther at the top of eachstamen has four pollen sacs.
The carpel:The ovary at the base of acarpel contains one or moreovules. The contents of anovule change during theflowering plant life cycle.
pollensac
microsporemother cell megaspore
mother cell
degeneratingmegaspores
Microspores:Microspore mother cells undergo meiosis to producemicrospores. Each microspore becomes a pollen grain.
Megaspores:Megaspore mother cell inside ovule undergoes meiosis toproduce megaspores. One megaspore will become theegg-producing female gametophyte.
pollentube
FERTILIZATION
The mature female gametophyte:The ovule now contains the mature femalegametophyte (embryo sac), which typically consists of eight haploid nuclei embedded in a mass of cytoplasm. The cytoplasm differentiates into cells, one of which is an egg and another of which contains two polar nuclei.
Double fertilization: On reaching the ovule, thepollen tube discharges thesperm. One of the two spermmigrates to and fertilizes theegg, forming a zygote; theother unites with the twopolar nuclei, producing a 3n(triploid) endosperm nucleus.The endosperm nucleusdivides to form endosperm,food for the developing plant.
The seed:The ovule now develops intothe seed, which contains anembryo and food enclosedby a protective seed coat.The wall of the ovary andsometimes adjacent partsdevelop into a fruit thatsurrounds the seed(s).
The sporophyte embryo:The embryo within a seedis the immature sporophyte.When a seed germinates,growth and differentiationproduce the maturesporophyte of a floweringplant.
fruit(mature ovary)seed(mature ovule)
+Adaptations of plants help them acquire nutrients
Root Nodules Some plants, such as legumes, soybeans, and alfalfa, have roots
colonized by Rhizobium bacteria Rhizobium can reduce atmospheric nitrogen (N2) to NH4
+ for incorporation into organic compounds
Mycorrhizae Involves fungi and almost any type of plant root Fungus increases the surface area available for mineral and water
uptake and breaks down organic matter in soil
22-34
+Mycorrhizae result in better growth 22-
35
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Mycorrhizae present
Mycorrhizae not present
mycorrhizae
(plants, top): © Runk/Schoenberger/Grant Heilman Photography; (mycorrhizae, circle): © Dana Richter/Visuals Unlimited
+
Parasitic plants, such as dodders, broomrapes, and pinedrops, send out rootlike projections called haustoria that tap into the xylem and phloem of the host stem
22-36
© Kevin Schafer/Corbis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
dodder(brown)
+
Carnivorous plants, such as the Venus flytrap and the sundew, digest insects as a source of nitrogen
By-pass need for nitrates from soil which may be lacking
22-37
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bulbs releasedigestive enzymes
stickyhairs
narrowleafform
Sundew leafenfolds prey
(sundew leaf, prey): © Dr. Jeremy Burgess/Photo Researchers, Inc .
+
Fungi
+ Fungi
– Yeasts and molds• Single-celled, microscopic
– Mushrooms• Multicellular, macroscopic
– Cell nucleus and other cellular structures
– Absorb nutrients from their environment
– Saprobes – Widely distributed in water and soil
+Fungi
Thermal dimorphism grow as molds at 30°C Grow as yeasts at 37°C
18-40
Fungal Organization - Mold
Fungal Cell StructureHyphae
MyceliumConidia / sporesSexual and asexual
reproductionCell wallsCell walls contain chitin Energy reserve is glycogen Nonmotile
Produce wind-blown sporesGrow toward food source
Fungal Organization
Yeasts Soft, uniform texture and
appearance
Unicellular (bicellular) False hyphae Beta-glycan cell wall
structure
+Fungi have mutualistic relationships with algae and plants
In a mutualistic relationship, two different species live together and help each other out Mycorrhizal fungi form mutualistic relationships (mycorrhizae) with
the roots of most plants Helps plants grow more successfully in dry or poor soils
particularly those deficient in inorganic nutrients
Lichen – a mutualistic association between a particular fungus and a cyanobacteria or green algae Fungal partner is efficient at acquiring nutrients and moisture Organic acids given off by fungal partner can be used by
photosynthetic partner
18-43
+Land fungi occur in three main groups
Zygospores
Ascospores
Basidiospores
18-44
+
Zygospore Fungi Mainly saprotrophs,
but some are parasites
18-45
Black bread mold, Rhizopus stolonifer
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zygospore
sporangium
mycelium
+
MEIOSIS2nn
34
Sexualreproduction
Asexualreproduction
1
2
(top left): © Runk/Schoenberger/Grant Heilman Photography
FERTILIZATION
–germinatingspores
5
1
+
Sac Fungi Nearly 75% of all
described fungal species
Name from ascus Yeast – unicellular
forms mainly in Ascomycota
No more Deuteromycota – use molecular data
18-46
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(cup fungi): © Felix Labhardt/Getty RF; (morel): © Robert Marien/Corbis RF
meiosis
Ascocarp of the cup fungus Sarcoscypha
Cup fungi
Morel
ascocarp
ascocarp
ascospores
male organ
female organ
nuclearfusion zygote
(2n)matureascus
dikaryotichyphae
+ mating type (n)spore
– mating type (n)spore
+
Club Fungi Name comes from the
reproductive structure, the basidium
The basidia are located within a basidiocarp
When you eat a mushroom, you are eating a basidiocarp
18-47
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basidiocarp
fusion meiosis
Sexual reproduction
spores
nuclei inbasidium
gill ofmushroom
+-
+Land Fungi Have Economic and Medical Importance
Economic Importance Help produce medicines and many foods
Mold Penicillium was original source of penicillin Excellent low-calorie meat substitute containing lots of
vitamins Fungal pathogens are a major concern for farmers
Medical Importance Certain mushrooms are poisonous Mycoses are diseases caused by fungi
Candida albicans Ringworm Aspergillus
18-48