Download iii. plant classification

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A CLOSER LOOK AT KINGDOM PLANTAE
I. INTRODUCTION (pp. 551-552)
Plants are placed into groups based on structural and functional similarities, but
all plants share the following characteristics:
A. Plants are _eukaryotic____, _multicellular____ organisms with _organs &
organ systems__
B. All plant cells have _cell walls___ composed of _cellulose_____.
C. Plants are _autotrophic____, which means they can use energy from the
_sun___ to make _glucose__ in _photosynthesis___. Photosynthesis
takes place in the _chloroplasts_____ of plant cells. The equation for
photosynthesis is _6CO2 + 6H2O → C6 H12 O6 + 6O2______________.
D. Plants are _non-motile_____; therefore, special adaptations are required for
_reproduction_______.
II. PLANT STRUCTURE & GROWTH
(pp. 579 - 597)
A. Plant Transport
Larger plants must have a way to transport _water_, _minerals____and
_food____. This is carried out by two types of _vessels____. Together the
vessels (cells working together) make up a _tissue______ in plants known as
_vascular_______ tissue. Plants are divided into two groups, based on
whether or not they have vascular tissue.
1. Xylem transports _water___ & _minerals____ from the _root___ to the
rest of the plant.
 Water evaporates from the plant through opening on the underside of the
leaves called stomata.
2. Phloem transports _”food” (glucose)___ from the _leaves_____ to the rest
of the plant.
 It carries sugars in two directions.
B. Plant Growth
1. Primary Growth – Lifelong growth occurs at the tips of the _stem____ and
the end of the _roots_ in tissue called the _meristem_______.
 Apical meristem is located at the tips of stems and roots (group of
undifferentiated cells that divide to produce increased length of stems and
roots)
2. Secondary Growth – Trees and some other plants have a second type of
meristem tissue; allows them to grow in width or girth.
 Cambium is the meristem tissue that allows plants to get wider.
C. Roots
Roots _anchor the plant ___, absorb _water____ and _minerals____ from
the soil, and transport these materials to the stem. Some plants also store
food in their roots. Each root has root hairs, tiny extensions of epidermal cells
that increase _surface area______ for _water absorption_____.
 Water is absorbed into the plant by the process of osmosis.
 There are two kinds of roots:
Taproots - a large, main, primary root. Example= carrot, dandelion
Fibrous - branching, secondary roots. Example = grasses
D. Stems
Stems typically have two main functions:
– Supporting leaves and flowers.
– Transporting water, minerals, and nutrients (food) (contain xylem &
phloem)
E. Leaves
• The blade is the actual leaf.
• It attached to the stem by a thin structure called a petiole.
• The vascular tissue enters the leaf through the petiole and forms the veins
of the leaf.
Leaves are the main organ for _photosynthesis_____. They have a large
surface area for maximum _light absorption_. The structures of a leaf include:
A. Cuticle - _Waxy_____ covering to prevent _water loss_____
B. Epidermis – Outermost layer of cells; prevents _injury, infection_____
C. Mesophyll - _Photosynthetic______ layer of leaf
1. Palisade layer – Upper portion of mesophyll with closely packed cells;
site of most _photosynthesis_____
2. Spongy layer – Underside of leaf; loosely-packed cells to allow for
exchange of _CO2 and O2_____
D. Vein - _xylem___ + _phloem___
E. Stomata – Opening in underside of leaf that allows _ CO2_(carbon
dioxide)_ to enter; _ O2_(oxygen)____ to exit.
F. Guard Cells – Control size of _stomata_____. Work to preserve balance
between allowing for gas exchange without losing too much _water__.
“Plant sweat” is known as _transpiration___.
III. PLANT CLASSIFICATION
Plants are divided into two basic groups based on whether they contain
_vascular____ tissue:
A. Bryophytes – No vascular tissue present (pp. 556-559)
Bryophytes, or _mosses____, are the only group of plants that lack vascular
tissue. This limits both the _size___and _location__ of this group of plants.
Mosses are _small____ and typically live in _moist___areas. In addition, a
moist climate is required because mosses have _”swimming”__sperm. The
sperm must swim to the _egg__ cell in order for _fertilization__to take place.
MOSS LIFE CYCLE
B. Ferns – Contain vascular tissue
(pp. 560 - 562)
No pollen, no seeds, no fruits
Although ferns contain vascular tissue, they are still found predominantly in
moist climates because the sperm must _swim__ to the egg cell.
SORI
FERN LIFE CYCLE
Seeds
Not all plants produce seeds, but those that do have a tremendous reproductive
advantage. A seed consists of an _embryo____ surrounded by a tough
protective coat.
Survival Advantages of Seeds
a. Protection
b. Nourishment - _Starch_ is stored in the seed for developing _embryo_
c. Dispersal – Easily spread by _wind, animals, water__; reduces
competition for _nutrients___
d. Dormancy – Seeds remain dormant or _inactive_____ until conditions
are _favorable_____.
Leaves
Cotyledon
Seed Coat
Hypocotyl
Radicle
Seed Germination
The first visible evidence that a seed is germinating is the emergence of the
embryo's _root__(radicle)__, followed by the growth of an embryonic shoot
(hypocotyl) that develops into the plant's _stem_____.
C. Gymnosperms – Have pollen and seeds, no fruit
The word, “gymnosperm” means _”naked seed”___ because the seed is
not protected by a _fruit______. A unique characteristic of gymnosperms is
the presence of _cones____. The largest and most common phyla is
_Conifera (conifers)__ which includes _pines, spruce, cedar__.
Conifers have characteristic leaves called _needles___, which are
modified to _prevent water loss__ and _minimize ice build-up___. In
addition, gymnosperms (and angiosperms) have “flying sperm” or _pollen_,
so they are no longer tied to _water____ for reproduction.
Cypress
White Pine
Fir
Spruce
Redwood
Sago Palm
(Cycad Phyla)
3. Angiosperms – Have pollen, seeds, and fruit
IV. ANGIOSPERMS - TRACHEOPHYTES WITH SEEDS & FRUIT (pp. 569 - 572)
Angiosperms are the most complex and adaptable of all plant groups. They are
also the most successful due to two important modifications:
A. Fruit - A fruit is a mature _ovary___ that contains one or more seeds. It
provides the embryo with greater _protection_than found in gymnosperm
seeds. The fruit also increases seed dispersal because fruits are eaten by
_animals____, seeds pass through _digestive tract___and are
_eliminated____. Some fruits are not intended to be _edible_____.
B. Flower - The flower is the reproductive system of the angiosperm. It
enhances _pollination__, which occurs as a first step to fertilization.
1. The male reproductive organ is the _stamen____, which consists of
the _anther___ and _filament_______. _Pollen_____, is produced by
the anther and contains the _sperm cells______.
2. The female reproductive organ is the _pistil____, which consists of the
sticky top called the stigma, a neck called the style and a base called
the ovary. The ovary contains the female gametes - egg or ovules.
During pollination, pollen is transferred from the anther to the stigma.
When a pollen grain lands on a stigma, it sends out a pollen tube that
grows through the style to the ovary. Ovule fertilized by sperm.
Fertilization of the _egg___ cell occurs in the _ovary____.
3. The petals are usually colorful to attract pollinators.
4. The sepals are protective green leaves at the base of a flower. They
protect the bud before the flower blooms.
C. Types of Angiosperms – Angiosperms are further classified into two groups
based on the characteristics shown below.
Monocots include plants such as _grasses, corn, lilies__. Monocot seeds
have one cotyledon (seed leaf). These are seeds that cannot be split in half,
like a piece of corn. Dicots are more abundant and include plants such as
_roses, oak trees, etc_____. Dicots have two cotyledons. These seeds can
be split in half like peanuts and beans
.
V. PLANT RESPONSES
A hormone is a chemical substance that is produced in one part of an organism
and affects another part of the same individual. Plant hormones are chemical
substances that control a plant’s patterns of growth and development, and
the plants responses to environmental conditions.
A. Tropism- response of a plant to an environmental stimulus
1. Phototropism - is the tendency of a plant to grow toward a source of
light_. This process uses a hormone known as auxin. Auxin is produced
in the apical meristem and is transported downward into the rest of the
plant. Auxin production increases in the shaded part of the stem and it
stimulates __ cell elongation __. This causes the dark side of the stem to
elongate, resulting in the stem to bend away from the shade and toward
the light _.
2. Gravitropism - plant’s response to _ gravity _. This assures that roots
grow down and stems grow up. Auxin is also the hormone responsible for
gravitropism.
3. Thigmotropism - plant’s response to _ touch _. This allows a plant to
grow on a surface that can support it. Whenever the stem touches the
support, the cells on the opposite side of the stem grow longer, causing the
stem to coil around or grasp a hold of the support.
Importance
of plants?
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Food
Fiber
Fuel
Construction
Transport
Medicine