Transcript 23.1_Specialized_Tissues_in_Plants

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Review What are the three main tissue systems of
plants
Compare and Contrast How do the three main
functions of a plant’s tissue differ
Form and Function How might the presence of
meristems explain the ability of plants to
regenerate from cuttings
Infer With your prior knowledge of the circulatory
system, write a paragraph comparing and
contrasting the structure and function of the
vascular system of a plant to the human
circulatory system
CH 23 PLANT STRUCTURE AND FUNCTION
23.1 Specialized Tissues in Plants
Seed Plant Structure
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Three principal organs
of seed plants are roots,
stems, and leaves.
Roots
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Anchor plant in ground
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Help prevent erosion
Absorb water and
nutrients and transport
to rest of plant
Store food
Hold plant upright.
Stems
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Support system for the
plant body
Transport system that
carries nutrients
Defensive system to
protect against
predators and disease
Produces leaves and
flowers.
Leaves
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Main photosynthetic
organs
Regulates water by
controlling air exchange.
Plant Tissue Systems
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Three main tissue systems:
 Dermal
 Vascular
 Ground.
Dermal Tissue
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Protective outer covering of a plant
Epidermis
 Single
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layer of cells that makes up the dermal tissue
May have tiny hair like projections on leaves and
roots.
Vascular Tissue
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Supports the plant body
Transports water and
nutrients
 Xylem
 Phloem
 Consist
of long, slender cells
that connect almost like
sections of pipe.
Xylem
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Tracheids
 Xylem
cells
 Leave cell walls made of
lignin when they die
 Openings allow water
movement from cell to
cell.
Xylem
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Vessel elements
 Wider
than tracheids
and are arranged end
 After cell dies, cell walls
allow water to move
freely.
Phloem
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Alive at maturity
Transports sugar throughout plant
Sieve tube elements
Arranged end to end with ends having
many small holes
 Lose nuclei and organelles as they
mature
 Kept alive by companion cells.
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Phloem
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Companion cells
 Supports
sieve tube element.
Ground Tissue
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Produces and stores sugars
Contributes to physical support of plant
Neither dermal nor vascular
Three types of ground tissue:
 Parenchyma
 Collenchyma
 Sclerenchyma.
Parenchyma
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Main type of ground tissue
Have thin cell walls
Contain many chloroplasts in leaves.
Collenchyma
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Strong, flexible cell walls that help support plant
organs
Middle cell wall thickness.
Sclerenchyma
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Extremely thick, rigid cell walls
Makes ground tissue such as seed coats tough and
strong.
Meristems
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Regions of unspecialized cells in which mitosis
produces new cells
Found in tips of stems and roots.
Apical Meristems
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Meristem at tip of a stem
or root
Cells divide rapidly
Increases plants length.
Floral Meristems
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Produces flowers specialized cells
Develop from apical meristem.