Download Bio22013Plantae (renee) File

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Botany is the study of plants. All plants are
said to have a common ancestor; it is thought
that plants have evolved from an ancient
group of green algae. Plants and green algae
share a common evolutionary ancestry
(phylogeny).
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I) photosynthesis
II) ability to absorb water and nutrients
III) ability to conserve water and reduce the
drying effect of air
IV) process of gas exchange
V) presence of supporting tissues
VI) ability to reproduce
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Plants can be classified according to the
presence or absence of vascular tissue.
Vascular tissue is the tissue that supplies
water and the products of photosynthesis
throughout a plant.
Plants lacking vascular tissue are called
bryophytes.
Plants which have vascular tissue are called
tracheophytes.
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Vascular tissue is made up of xylem and
phloem cells.
Xylem carries water and minerals to the
leaves of plants.
Phloem transports food synthesized in leaves
throughout the plant.
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Land plants have a cuticle and stomata (sing.
stoma) present.
A cuticle is a noncellular layer secreted by
epidermal cells which helps to protect cells
from drying out.
Stomata are pores in the epidermis of a plant,
particularly the leaves, which permit the
exchange of gases between the plant and the
air around it
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1. Nonvascular (Bryophytes)
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2. Vascular (Tracheophytes)
◦ Ex. mosses, liverworts, hornworts
A. Seedless (Spore-bearing plants)
◦ Ferns and fern allies; ex. whiskferns, club mosses,
horesetails, ferns
B. Seed (embryo + stored food + tough water proof
coat or seed coat)
◦ Gymnosperms (cone-bearing plants): ex.
conifers/evergreens.
◦ Angiosperms (flowering plants): classified into two
groups according to number of seed leaves or
cotyledons on the embryo within the seed —
monocots (one seed leaf) and dicots (two seed
leaves).
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The life cycle of plants alternates between
two generations – the diploid generation is
called the sporophyte and the haploid
generation is called the gametophyte.
This process is called alternation of
generations.
One generation or the other will be dominant
in a plant life cycle.
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Bryophytes are nonvascular land plants that
are small in size and grow close to the
ground.
Commonly found in moist, shaded areas.
Examples: mosses, liverworts and
hornworts.
For bryophytes, the dominant part of the
life cycle is the gametophyte generation.
(See Figure 6.7, p. 170).
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They lack specialized tissue that transports
water as in vascular plants. There is a problem
of dessication or drying out in these plants.
They lack true roots, stems and leaves and are
anchored to the ground by structures called
rhizoids. A rhizoid is a simple structure (other
than a true root) which doesn’t channel water
to other parts of the plant.
They require water for sexual reproduction.
Water is needed for fertilization to occur.
Sperm must swim through water in order to
reach the egg.
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Tracheophytes are “true” terrestrial plants.
Examples would be ferns, herbs, shrubs,
trees and flowering plants.
They are vascular plants and have vascular
tissue.
These are modern-day plants and the
sporophyte generation is predominant.
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Vascular
Seedless – reproduce using spores
Possess true roots, stems and leaves
Life cycle – sporophyte is the dominant
generation
Depend on water to move sperm
Examples: ferns, whisk ferns, horsetails
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Vascular
Seed-producing
Possess true roots, stems and leaves
Cone-bearing
Life cycle – sporophyte is the dominant
generation
Do not depend on water to move sperm
Wind/insects move sperm to egg
Examples: evergreens, conifers
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Vascular
Seed-producing
Possess true stems, leaves and roots
Flower-bearing
Life cycle – sporophyte is the dominant
generation
Do not depend on water to move sperm
Wind/insects move sperm to egg
Examples: deciduous trees, mongolias, peas,
roses
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The angiosperms are the flowering plants and are
the most diverse plant group. More than 75% of
all plants are angiosperms. This diversity is due to
a variety of factors, such as:
the assistance of animals and wind in pollination;
the presence of structures in plants specific to
attracting certain animal pollinators whom the
plants supply with food;
the way seeds are protected;
the function of fruits in seed dispersal, and
the presence of specialized tissues in plants to
help them survive heat, cold, and droughts.
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1. A sporangium produces haploid spores
that germinate to form a gametophyte called
a prothallus.
2. The prothallus produces antheridia (male
organs) and archegonia (female organs).
3. Sperm swim through a droplet of water to
an egg produced by the archegonium.
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4. The fertilized egg begins to grow into a
sporophyte.
5. The sporophyte matures and roots and
fronds develop out of the growing rhizome.
6. Sori develop on the pinnae. Spores are
formed in the sori by meiosis.