Download Ch 29 - MsBabbey

Chapter 29
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500 mya plants and fungi
moved from the land to
the water
All plants evolved from an
aquatic green algae
In Kingdom Plantae, there
are 4 main subdivisions:
Bryophytes, Seedless
Vascular Plants (ch 29),
Gymnosperms, and
Angiosperms (ch 30)
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Plants and algae share 4 key traits due to
their evolutionary origins:
Rose-shaped complexes for cellulose
synthesis
Peroxisome enzymes (minimize glucose loss)
Structure of flagellated sperm
Formation of a phragmoplast (helps form the
cell plate during mitosis)
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Plants (and not algae) have 5 traits that
allowed them to move onto land:
Apical Meristems
Alternation of Generations
Walled spores produced in sporangia
Multicellular Gametangia
Multicellular, Dependent Embryos
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An apical meristem is a localized region of
cell division at the tips of roots and shoots.
Mitosis occurs rapidly here, so plants can
optimize water and mineral collection from
the soil and the atmosphere.
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The life cycle of land plants alternates
between a diploid multicellular organism
(sporophyte) and a haploid multicellular
organism (gametophyte).
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Plant spores are haploid
reproductive cells
Through mitosis, they can
develop into
gametophytes
The diploid sporophyte
has multicellular organs
called sporangia that
produce plant spores
Spores are formed from
sporocytes (inside
sporangia) that go
through meiosis
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Gametes are made in organs called
gametangia
Female gametangia are called archegonia
Male gametangia are called antheridia
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Zygotes undergo mitosis to become
multicellular embryos called embryophytes,
which stay inside the female parent’s tissues
The embryo has special cells called placental
transfer cells that enhance the transfer of
nutrients from parent to embryo
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Vascular tissue is made up of cells that
transport water and nutrients throughout a
plant.
Vascular plants either are seedless (mosses,
horsetails, and ferns) or have seeds
(gymnosperms like pine trees, angiosperms
like flowers)
Non-vascular plants include liverworts,
hornworts, and mosses
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Bryophytes are
non-vascular,
seedless plants
Liverworts
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Hornworts
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Mosses
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Phylum Hepatophyta
Gametophytes are shaped like livers
Common in Northern Hemisphere tropical
and subtropical regions
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Phylum Anthocerophyta
Sporophytes are shaped like blades of grass
5 cm high
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Phylum Bryophyta
Gametophytes look like carpets
Sporophytes are elongated and visible to the
naked eye
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Gametophytes (the haploid stage) are larger
and longer lived than sporophytes (the
diploid stage)
Germinating moss spores produce a
protonema, a mass of green, branched, onecell thick filaments.
They absorb water and form buds that
produce gametes called gametophores.
The protonema and the gametophore make
up the moss gametophyte.
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Gametophytes are anchored by delicate
rhizoids (long tubular single celled filaments).
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Bryophytes sporophytes are green and
photosynthetic, but remain attached to their
parental gametophytes which give them sugar,
amino acids, minerals and water.
Sporophytes are simple and small, made up of a
foot (absorbs nutrients), a seta (long stalk), and a
sporangium (on top of the stalk, makes spores).
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Ferns are vascular plants WITHOUT seeds
They have swimming sperm and need moist
environments
Ferns have a life cycle with a dominant
sporophyte
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Xylem are tubes that conduct water and
minerals in a plant
Xylem is made up of tracheids, tube shaped
cells that carry water
Their cell walls are strengthened by ligin
Phloem are tubes that conduct sugar in a
plant
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Roots are organs that anchor vascular plants
and enable them to absorb water and
nutrients from the soil
Leaves are organs that increase the surface
area of vascular plants, capturing more solar
energy for photosynthesis
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Sporophylls are leaves that bear sporangia
(which make spores)
A group of sporangia are called a sorus (sori),
and are shaped like cones called strobili.
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Seedless vascular plants, like ferns,
lychophytes, and horsetails, formed the first
forests
These removed CO2 from the atmosphere
and increased levels of oxygen, causing
global cooling and glacier formation.
These forests, after millions of years of
decay, heat, and pressure, became coal
(which now causes global warming).