Transcript Unit 2 part 5 Plants

Bellringer
Why
is a
daisy
considered
an
autotroph?
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UNIT 2 PART 5: PLANT
STRUCTURE AND FUNCTION
 Plants,
like animals, are
made up of tissues that
form organs. Their
organs are roots, stems,
leaves, and
reproductive structures.
Plants do not have
organ systems.
ROOTS
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 Roots
hold the plant in the
soil and take in water and
minerals from the soil.
 Root hairs greatly increase
the surface area for water
absorption.
 There are usually as many
roots below the ground as
stems and branches
above the ground.
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STEMS
Stems
have many
functions:
 Contain
vascular tissue to
transport food and water.
 Hold the leaves in such a
way as to maximize their
exposure to the sun for
photosynthesis.
 Can be modified to store
food or water, or for
reproduction.
 Provide support.
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REPRODUCTIVE
STRUCTURES
 FLOWERS
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AND CONES
Female parts
Male parts
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Specialized
LEAVES
structures to capture light
for photosynthesis.
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INTERNAL STRUCTURE OF LEAVES
 Each
part of the leaf has an important job.
chloroplasts
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 Cuticle
– the outermost layer of both the
upper and lower surfaces of the leaf. It is clear
and waxy to prevent against water loss.
 Epidermis – a layer of cells one cell thick that
provides protection for the inner tissues. These
cells are clear to allow light to reach the
photosynthetic tissues.
 Mesophyll – between the epidermal layers. It
contains palisade cells that are tall, tightly
packed, and filled with chloroplasts for
photosynthesis. It also has spongy cells which
are irregularly shaped, have large air spaces
between them, and fewer chloroplasts.
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 Stomates
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– openings in the
surface of the leaf and stems
for gas exchange. The lower
surface of a leaf usually has
more. Water vapor also
passes out through these holes.
 Guard cells – two of these special cells
surround each stomate and regulate the
opening and closing of the stomate.
 Veins – contain the vascular tissue that is
continuous with that in the stem. Xylem
carries water and minerals upward. Phloem
carries dissolved food throughout the plant.
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TRANSPIRATION
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 Plants
must supply water to
all their tissues. It moves from
the roots up the stem to the
leaves by capillary action.
 Most of the water plants take
up is lost to the atmosphere
by evaporation.
 The evaporation of water
vapor from plant surfaces is
called transpiration.
 Most takes place through
stomates.
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The
rate of transpiration is regulated by
the size of the opening of the
stomates.
They are usually closed when there is
too little water available, temperature
is low, or there is little light.
Most plants open their stomates during
the day and close them at night.
This is controlled by
the guard cells.
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Bellringer
What
is transpiration?
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Bellringer
In
our last lab, why did some substances
diffuse through the membrane while
other substances did not?
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GUARD CELLS AND PLANT HOMEOSTASIS
 Guard
cells are kidney-shaped with thick
inner walls and thin outer walls.
 When they become full of water (turgid) the
unevenness of the walls causes them to bow
outward and the stomate opens.
 When they lose water they become less
turgid and the stomate closes.
 Guard cells gain
and lose water by
osmosis.
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What
Bellringer
gas do autotrophs give off?
What gas do they take in?