Transcript Evolution of Plants

Evolution of Plants
Ch 29-30
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Plants
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multicellular, photosynthetic
autotroph and eukaryotic
cell walls made of cellulose,
starch is storage
Land based
take up water via capillary
action from the ground
have alternation of
generation
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Evolution of Plants – p.602-603
Major adaptations for land survival
 1) Except for Bryophytes (moss), dominant
generation is the diploid sporophyte
generation, so?
 this
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masks mutations, greater survival
2) Cuticle = waxy covering, p.604, so?
 reduce
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water loss
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3) Vascular system → p.612
 reduced dependency on water (store it) so it can
be farther away from it, tissue specialization
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4) Evolution of pollen & seeds (from spores) ability to move in the air (vs. water), p.620
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5) In Anthophyta - gametophytes→ gametes
enclosed & protected in an ovary, p.626
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6) Conifers and Anthophyta have developed
adaptations to seasonal variations in availability of
water and light → ex. Deciduous trees
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Divisions– (division is after kingdom, before phylum)
0) Charophytes (green algae) - precursor of plants, how know?
 4 reasons, p.600
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rosette-shaped cellulose-synthesizing complexes
peroxisome enzymes
structure of flagellated sperm
formation of phragmoplast
1) Bryophytes - simplest plants, no true stems or leaves, can't
live far from water or grow tall
 Repro. in water, antheridia (male) and archegonia (female)
 gametophyte is dominant generation, p.607
 ex. moss, hornworts, liverworts, p.608
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2) Tracheophytes/Pteridophytes – seedless, vascular
 xylem (water up) and phloem (sugar), p.614
 roots, hairs
 sporophyte is dominant, makes spores, ex. ferns
3) Gymnosperms - "naked seed” or pollen replaced the spore,
better dispersal, *p.622-623
 cone bearing = conifers, includes cycads and ginkgo
 increased vascular tissue, ex. evergreens, spruce, pine
4) Angiosperms - flowering plants, p.630-631, life cycle p.629
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Flower
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petals, sepals attract pollinators
Stamen – male parts
Anther – produces pollen
or microspores
 Filament – holds the anther
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Pistil – female parts (carpel(s))
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Stigma – sticky, capture pollen
Style – long tube, connects stigma and ovary
Ovary – where fertilization occurs, ovules are here, eggs are
called megaspores, fruit here
ovary develops into a fruit, disperses seeds by insects,
birds and mammals – coevolution
 →plants use for medicines, wood and food
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Plant Structure and
Growth- structure and
function
Ch 35-39
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Angiosperm - flowering plants
2 classes:
 1) Monocots- 1 cotyledon (storage
seed), parallel veins, complex
vascular bundle, floral parts in
groups of 3's
 2) Dicots - 2 cotyledons, web-like
veins, vascular tissue in a circle,
taproots, floral parts in 4's or 5's
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Plant Tissues
Dermal – protective
cover (water loss and
disease)
 Ground – metabolic
functions
 Vascular – transports
materials between
root and shoots
systems
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Types of plant cells- p744
Protoplast – contents inside the cell wall
1) Parenchyma – unspecialized cells, most metabolic
functions
2) Collenchyma- most growing cells, elongate stems,
support
3) Sclerenchyma- don’t grow, very strong, some are
dead, strengthened by lignin (p.612)
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Types of plant cells (con’t)- p.745
Vascular system
4) Xylem - water & minerals up the plant,
made of tubes called tracheids and vessel
elements, dead at functional maturity
5) Phloem - food up and down to the plant,
made of sieve tubes, alive, but reduced
organelles to speed up transport
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Root system
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Roots = anchor, absorb, storage
taproot – 1 large root, strong and
large, ex. carrot
fibrous root – has extensions called
root hairs, increases SA
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Shoot system
= Stems and Leaves
 Stem – attachment of
leaves, similar structure
to roots
 Leaves – photosynthetic
organ
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Plant Growth = Germination
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seeds remain dormant until a cue (ex. water, light
or temp.)= photoperiod
1st growth occurs when water is absorbed, seed
coat cracks
Seeds – contain the embryo and storage material
the top of the embryo produces a shoot
Indeterminate Growth – grow throughout life, p.746
– complete entire life cycle in 1 year or less
 Biennial – need 2 growing seasons to complete life cycle
 Perennial – live many years
 Annual
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Primary Growth
growth occurs at the tips of roots and
shoots called apical meristem =
meristematic tissue
3 zones of growth
 zone of cell division - newly dividing
cells
 zone of elongation- new cell growth
 zone of differentiation - cells
differentiate
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Secondary Growth
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Also lateral meristems = cylinders of dividing cells that
increase the girth (width) of stems and roots
Vascular cambium – adds vascular tissue called
secondary xylem (wood) and secondary phloem
Cork cambium – replaces the epidermis with thicker,
tougher layer
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Leaves
photosynthetic organ
 made of blade (end),
and petiole (connects the stem)
1) epidermis
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Cuticle- waxy layer, holds in water
2) palisade mesophyll- many parenchyma cells and
chloroplasts, photosynthesis
3) spongy mesophyll - space for CO2 and O2
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contains vein = xylem and phloem
4) Lower epidermis- bottom layer
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Stomata- opening for gas exchange
Guard cells – surround stoma, control their opening
Modifications – see page 742, protection, water storage
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Transport of water &
sugar
Ch 36
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Water
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absorbed in roots and
passes up the xylem
also moves through
the cell wall or
plasmodesmata
Short distance flow,
p.773 – regulated by
Casparian strip
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3 mechanisms
1) Osmosis
 moves into roots, then into xylem
 high mineral gradient inside
= root (turgor) pressure
 chemiosmosis, proton pumps
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2) Capillary action – movement by adhesion
 Adhesion – water "sticks" to sides of the tubes
3) Transpiration-Cohesion-Tension theory – most
water moves this way, water potential
 transpiration (bulk flow)– evaporation of water
from the leaves, lower [water] in the leaves, so
water goes up, works by negative pressure, p.774
 cohesion – attraction of water molecules
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Control of the
Stomata
regulates amount of CO2 , O2 and H2O
 aids in control of photosynthesis
 the guard cells control opening of stomata
 light, CO2 depletion in leaves, high temps,
and circadian rhythms regulate opening
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Sugar, p.779
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Translocation = movement of
sugar through the phloem
source/sink – sugar moves from
the source of sugar (leaf) to the
place where it is used = sink
pressure flow – high solute at
source→ lowers water potential
→water into sieve tubes→
causes lower pressure at sink
→the pressure difference moves
sugar through
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Nutrition
Ch 37
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soil, water, nitrogen, minerals
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Rhizobacteria, p.793
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Mycorrhizae, p.767
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Life cycle of plants
Ch 38
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Alternation of generation
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Gametophyte – haploid(n) generation, produces
haploid gametes by mitosis
gametes then combine to form a diploid plant
protected within the sporophyte plant
Sporophyte – diploid(2n) part, makes haploid
spores by meiosis
→In bryophytes gametopyte is dominant
→In others, sporophyte is dominant
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Cycle p.802
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1) spores (n) develop from the sporophyte plant
2) spores form gametophyte (n) part of plant
3) gametophyte forms gametes(n)
4) gametes combine (fertilization) to form zygote (2n)
mitosis, develop into mature sporophyte (2n), back to 1
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Double
Fertilization
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Plant controls
Ch 39
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Plant Hormones
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Auxin – made at apical meristem or embryo, elongation of
stem, root growth, fruit growth
Gibberellins – made at meristems, growth in young parts,
flowering, leaf growth, excess can cause bolting, germination
Cytokinins – stimulate cell division and differentiation, growth
of lateral buds, slows leaf aging
Ethylene gas– ripening of fruit, stimulates flower growth
Abscisic acid – inhibits growth, closes stomata, aids
dormancy
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Plant stimuli =
tropisms
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1) gravitrophism – response
to gravity, p.841
2) thigmotrophism –
response to touch, p.842
3) phototropism –response
to light, auxin is made
→plant grows, stem bends
toward light because auxin
collects on shady side
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Photoperiodism
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response to a change in the photoperiod or length of
daylight
this is circadian rhythm of a plant (internal clock)
controlled and reset by proteins called phytochromes
night light is responsible for resetting the internal
clock
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3 types of plants based on light – p839
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1) long day plants – (short night) flower in the spring
when night is shorter than a critical night period
2) short day plants – (long night) flower in late
summer, early fall, when night exceeds a critical
dark period
3) day neutral – plants don’t respond to daylight
changes, flowering triggered by temp. or water
amount
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