Please Do Now: 1) What is the main function of
leaves in plants?
2) What force generates turgor pressure within
the cell?
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Do Now
Leaf Anatomy notes
Set up growth cart
What generates turgor pressure?
 When osmosis is pulling
water into the cell, the
cell gets larger
 This will continue until
the cell begins pushing
on the rigid cell wall
 At this point the
osmotic pressure pulling
molecules into the cell is
resisted by the cell wall
pushing back on it
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Leaves main function is
to photosynthesize
Photosynthesis
requires the proper
balance of air, water,
and sunlight
Leaves are made up of
a bunch of different
kinds of cells
All of those cells have
a form that matches
their function as a part
of the whole leaf
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Top to Bottom
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Cuticle
Upper Epidermis
Palisade mesophyll
Spongy mesophyll (with veins running through it)
Lower epidermis
Cuticle
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The cuticle of the
leaf is a layer of
wax on the surface
The plant secretes
it to prevent water
loss
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The epidermis cells
are wide and flat
Form the barrier
between the inside
of the plant and the
outside (protection)
Also on the surface
of the leaf in
between the
epidermis are guard
cells and stomata
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Palisade Mesophyll
◦ Below the upper
epidermis
◦ Tightly packed vertically
oriented cells
◦ Tons of chloroplasts
(best conditions for
photosynthesis are
found here,
light/water/air)
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Spongy Mesophyll
◦ Located below the
palisdae mesophyll,
still inside the
epidermis layers
◦ Is spongy (lots of air
spaces)
◦ Fewer chloroplasts
Why are all those air
space there?
Why are all those air
space there?
The spongy mesophyll
has air spaces to allow
CO2 to get from the
stomata to the densely
packed palisade
mesophyll, where most
of photosynthesis
occurs
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The small branches
of the xylem and
phloem also run
through the leaf,
taking away sugars
and bringing water
an nutrients
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We need to get the plant growth cart set up,
because your plants need light
Many hands make light work
Things that need to be done:
◦ Empty the potting soil in the pots in the cart now
into that Styrofoam bucket (separate the tongue
depressors)
◦ Move your plants into the cart (space them out a
bit)
◦ Water the plants
◦ Stack the un used pots when they are emptied