PLANT ORGANS

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PLANT ORGANS AND TISSUES
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The "Typical" Plant Body
The Shoot System -Above ground (usually)
-Elevates the plant above the soil -Many
functions including ? photosynthesis
? reproduction dispersal ? food and water
conduction -nb. The shoot system includes the
leaves and the reproductive organs The Root
System -Underground (usually) -Anchor the
plant in the soil -Absorb water and nutrients
-Conduct water and nutrients -Food Storage
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Plant cells are organized together to form
tissues Examples  xylem, phloem Tissues are
organized together to form organs (two or more
tissues performing specific functions) Examples
leaves, stamens Organs are organized together
to form organ systems Examples shoots, roots
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• Growth patterns
• ? ?
• DETERMINATE INDETERMIANTE

Organism has growth phases, then stops growing
Organism capable of growth throughout entire life
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MERISTEMS Areas of a plant where growth occurs
APICAL MERISTEMS ? located at the tips of
roots and shoots ? supply cells for the
plant to increase in length (upward in shoots,
downward in roots) ? growth in this
direction is known as primary growth
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MERISTEMS Areas of a plant where growth occurs
LATERAL MERISTEMS ?
located near the periphery of the plant, usually
in a cylinder ? supply cells for the
plant to increase in diameter ? growth
in this direction is known as secondary growth
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v.c. ?
v.c. ?
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PLANT VASCULAR TISSUES
PHLOEM
XYLEM
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XYLEM tubes conduct water and dissolved minerals
from the roots to all the other parts of the
plant.
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Xylem tube
Xylem tube
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PHLOEM tubes conduct the products of
photosynthesis - sugars and amino acids - from
the place where they are manufactured (e.g.,
leaves) to the places where they are consumed or
stored
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ROOTS
functions of roots?
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taproot
fibrous roots
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dicot root x-section
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STEMS
functions of stems?
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monocot stem x-section
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herbaceous dicot stem x-section
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trees are dicots
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What causes water to move upward in xylem tubes?
What causes solutions to move downward in phloem
tubes?
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TRANSPIRATION HYPOTHESIS
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Waters POLARITY is important to transpiration
water is COHESIVE and ADHESIVE because it is so
highly polar
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Water enters the xylem in the roots by osmosis. 
Once in the xylem the water molecules hydrogen
bond forming a continuous string of water
molecules up to the leaf. Water is
constantly lost by transpiration in the
leaf.  When one water molecule is
lost, another is pulled along.  
Transpiration pull is the main
cause of water movement in plants.
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Movement of dissolved sugars through phloem tubes
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LEAVES
LEAVES
functions of leaves?
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structure of a typical leaf
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internal structure of a dicot leaf
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monocot leaf x-section
? note parallel venation ?
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Leaves must be able to breathe (i.e., exchange
gasses w. their environment)
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a stoma
stomata on lower surface of leaf
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The stoma is the opening (arrow) formed between tw
o GUARD CELLS
?
G.C.
G.C.