Transcript Unit 4 Powerpoint

Unit 4- Plants
M. Lauria
Background on Plants
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The Plant
kingdom
includes more
than 270,000
species
Believed to have
evolved from
green algae
(chlorophyta).
http://homepage.smc.edu/gallogly_ethan/travel
_photos/misc/sean_mom_giant_redwood_tree.J
PG
Adaptations to Land
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In order to prevent water loss on dry
land, plants have a cuticle (waxy
covering).
Some have roots, stems and leaves to
help obtain, transport, and use water
and nutrients efficiently.
Use spores and seeds to protect
reproductive cells.
Adaptations to Land (cont.)
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Some plants have vascular tissues
called xylem and phloem to help
transport water and nutrients
throughout the different parts of the
plant.
Some have stomates to prevent water
loss and control gas exchange with
the atmosphere.
Stomates
www.emc.maric
opa.edu/.../
BIOBK/BioBook
PS.html
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Stomates are small openings along the surface
of a leaf that control gas exchange.
They close when the plant is beginning to lose
to much water.
They open when the plant needs CO2
Cross- Section of a Leaf
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/leafst
ru.gif
Xylem
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Conducts water
Xylem cell is called a tracheid, its cell
walls are impermeable to water
Vessel elements are xylem cells found in
angiosperms
When these cells die, their cytoplasm
disintegrates and they are able to conduct
water.
Phloem
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Conducts a variety of plant nutrients and
products
Phloem cells are called sieve tube
elements, are positioned end to end and
have holes that connect their interiors.
Companion cells are located next to sieve
tubes and help to control them.
Cross Section of a Stem: Xylem and Phloem
cd.ed.gov.hk/.../ Root/Ranuculus%2011.jpg
Classifying Plants
From Modern Biology: Holt, Rinehart, and
Winston
Non-vascular Plants
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Lack vascular tissue and do not
form true roots, stems or leaves.
Are seedless, and need water to
reproduce sexually.
Have an alternation of
generations- sporophyte and
gametophyte.
Seedless Vascular Plants
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http://www.ct-botanicalsociety.org/ferns/fernpics/phegopterishexa_frond.jpg
Vascular plants
can grow larger
and live longer.
Why?
Include: Ferns,
whisk ferns, club
mosses,
horsetails.
Alternation of Generations in a Fern
staff.jccc.net/.../ celldivision/images/fern.gif
Vascular Seed Plants
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Plants with seeds have a greater
chance at reproductive success
than seedless plants. Why?
Two main groups of seed-bearing
plants: gymnosperms (“naked”
seed) and angiosperms (seed
protected in fruits).
Gymnosperms
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http://www.pfc.forestry.ca/diseases/CTD/Group/Rust/lrg_
images/fig30b.gif
Have specialized
male and female
reproductive
structures called
scales.
Larger structure
is called a cone.
Gymnosperms
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Conifers
(evergreens)
include pines,
spruce, fir, cedars,
redwoods.
Leaves are needleshaped.
Do not necessarily
shed needles in the
fall.
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Pollen from a
pollen cone
fertilizes egg
within a seed
cone.
Seed within a
seed cone is
considered
“naked.”
Angiosperms
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Flowering plants
are most
widespread of all
plants? Why?
Reproduce using
pollination of
flowers
Seeds are
contained within a
protective fruit.
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Some flowers
have both male
parts (stamenpollen
producing) and
female parts
(ovary- egg
producing)
Flower Parts
www.ncsu.edu/project/
agronauts/images/flower.gif
Alternation of Generations In Vascular Seed Plants
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http://www.stevedibler.com/photos/N
ature-Scenery/Dogwood_tree.jpg
Sporophyte is
the dominant
form, and the
gametophyte
grows within the
flowers or cones
of the
sporophyte.