Download 9.1 Leaf Structure

9.1 Leaves
IB Assessment Statement

Draw and Label diagrams to show distribution
of tissues in the stem and leaf of a
dicotyledonous plant

Explain the relationship between the
distribution of tissues in the leaf and the
functions of these tissues.
9.1 Leaves
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Leaves are involved in photosynthesis
Leaves vary great in form but generally the
consist of a flattened portion called the blade
and a stalk called the petiole that attaches to
the blade to the stem.
9.1.1 Draw and label plan diagrams to show the
distribution of tissues in the stem and leaf of a
dicotyledonous plant
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Cuticle is a waxy
layer which reduces
water loss through the
upper epidermis.
Upper epidermis is a
flattened layer of cell
that forms the surface
of the leaf and makes
the cuticle.
9.1.1 Draw and label plan diagrams to show the
distribution of tissues in the stem and leaf of a
dicotyledonous plant

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Palisade Layer: This
is the main
photosynthetic region
of the leaf.
Vascular bundle:
contains the transport
system and vascular
meristem tissue (xxylem, p-phloem).
9.1.1 Draw and label plan diagrams to show the
distribution of tissues in the stem and leaf of a
dicotyledonous plant

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Spongy mesophyll:
contains spaces that
allows the movement
of gases and water
through the leaf
tissue..
Lower epidermis:
bottom surface layer
of tissues which
contains the guard
cells that form each
stoma.
9.1.3 Explain the relationship between the
distribution of tissues in the leaf and the functions
of these tissues.( 3)
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Leaf Tissues:
(a) Phloem transports the
products of photosynthesis
(sugars, amino acids).
(b) Xylem transports water
and minerals into the leaf
tissue from the stem and
roots.
c) Epidermis produces a
waxy cuticle for the
conservation of water.
9.1.3 Explain the relationship between the
distribution of tissues in the leaf and the functions
of these tissues.( 3)

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(d) Palisade layer which is
the main photosynthetic
region.
(e) Spongy layer creates
the spaces and surfaces
for the movement of water
and gases.
(f) Lower epidermis
contains the stomatal pores
which allow gas exchange
with the leaf.
9.1.3 Explain the relationship between the
distribution of tissues in the leaf and the functions
of these tissues.( 3)

The xylem and
phloem tissues
combine in the
vascular tissue to
provide support to
the leaf.
Stomata a pore on the lower side of a leave that
allows for gas exchange
Leaf Structure
9.1.1 Assessment Statement

9.1.1 Draw and label plan diagrams to show
the distribution of tissues in the stem and leaf
of a dicotyledonous plant. Either sunflower,
bean or another dicotyledonous plant with
similar tissue distribution should be used.

Note that plan diagrams show distribution of
tissues (for example, xylem, phloem) and do not
show individual cells. They are sometimes called
“low- power” diagrams.
9.1.1 Assessment Statement

9.1.3 Explain the relationship between the
distribution of tissues in the leaf and the
functions of these tissues.

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This should be restricted to dicotyledonous plants.
The functions should include: absorption of light,
gas exchange, support, water conservation, and
the transport of water and products of
photosynthesis.