Download A Closer Look at

A Closer Look at
Kingdom Plantae
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Introduction (pp. 551-552)
Plants are placed into groups based on structural and functional similarities, but all plants
share the following characteristics:
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Plants are eukaryotic, multicellular organisms with organs & organ systems
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 CO2+H2O C6H12O6
D. Plants are non-motile; therefore, special adaptations are required for reproduction
II Plant Structure & Growth (pp. 579-597)
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Plant Transport
Larger plants must have a way to transport water, food and minerals. This is carried out
by two type 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 always moves 1 direction-from the roots->stem->leaves
*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 all directions
*Sugar can be carried from where it is made (Usually the leaves)
to where it is stored (usually stems and roots.)
B. Plant Growth
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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 (groups 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;
allow them to grow in width or girth.
*Cambium is the meristem tissue that allows plants to get wider.
C. 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
1. Taproots- a large, main , primary root. Example = carrot
2. Fibrous- branching, secondary roots. Example = grass
D. Stems
Stems have 2 main functions
1. Supporting leaves and flowers.
2. Transporting water via xylem and food via phloem
 Some plant stems have the additional job of photosynthesis
E. Leaves
 The actual leaf is the organ. It is 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:
 Cuticle-Waxy covering to prevent water loss
 Epidermis-Outermost layer of cells; prevents injury, infection
 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
 Vein-xylem & phloem
 Stomata-Opening in underside of leaf that allow 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:
 Bryophytes (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.
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Tracheophytes (pp. 560-562)
Tracheophytes are vascular plant which allows them to grow larger and almost
anywhere. The tracheophytes are further subdivided based on the presence or absence
of pollen, seeds, and fruit:
 Pterophytes-No pollen, no seeds, no fruits
Pterophytes are commonly called ferns. Although ferns contain vascular tissue, they are
still foundpredominantly in moist climates because the sperm must swim to the egg
cell.
Tracheophytes with Seeds
All other tracheophytes produce seeds. Seeds provide a tremendous reproductive
advantage. A seed consists of an embryo surrounded by a tough protective coat.
 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
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Seed Germination
The first visible evidence that a seed is germinating is the emergence of the embryo’s root
followed by the growth of an embryonic shoot that develops into the plant’s stem.
Types of Seed Plants
1. 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 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.
2. 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 and nutrients than found in gymnosperm seeds. The fruit also
increases seed dispersal because fruits are eaten by animals, seeds pass through the
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, the neck called the style, and the base called the ovary. The ovary contains the
female gametes ovules or eggs. 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. Once the sperm reached the egg cell, fertilization
take place.
3. The petals are usually colorful to attract pollinators.
4. The sepals are protective green modified leaves at the base of a flower. They protect
the bud before the flower blooms.
C. Types of Angiosperms
1. Angiosperms are further classified into two groups based on characteristics.
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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
2. Angiosperms may also be classified according to the length of their life cycle.
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Annual- flowering plant that completes a life cycle within one growing season.
Biennial- flowering plant that completes its life cycle in two growing seasons.
Perennial- flowering plant that live more than 2 years.
V. PLANT HORMONES AND RESPONSE
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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.
Hormones
1.Auxins-Produced in the apical meristem; transported throughout the rest of the plant.
Works by “stretching” cells to elongate shoot, stem, and/or root.
2.Cytokinins-Produced in growing roots and in developing fruits/seeds. Cytokinins
stimulate cell division,growth of lateral buds, and dormant seeds to sprout. Cytokinins
often produce effects opposite to those of auxin.
3. Gibberellins- produce dramatic increases in size, by stimulating growth and
increasing size.
4. Ethylene-auxin controlled hormone that stimulates the ripening of fruit.
5. Abscisic Acid-prevents growth. Used to maintain seed dormancy and tolerate
drought.
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Tropism- response of a plant to an environmental stimulus.
1. Phototropism - is the tendency of a plant to grow toward a source of light. Auxin
production increases in the shaded part of the stem; causes the dark side of the stem to
elongatestem to bend toward the light.
2. Gravitropism - response to gravity due to action of auxin. This assures that roots
grow down and stems grow up.
3. Thigmotropism-Response to touch. May be used for venus fly trap, to capture insects,
or allow a plant to grow on a surface for support. Tendril