Bell task
1. What are
plasmodesmata?
2. What is transpiration?
3. What is translocation?
Starter – answer the following
questions - sentences
1.
2.
3.
4.
5.
6.
7.
8.
Which tubes carry water in plants?
Which tubes carry sucrose in plants?
Draw a diagram of the arrangement of these
tubes in the stem of a plant. (p134)
Explain why they are arranged in this way.
Draw a diagram of the arrangement of these
tubes in the leaves of plants. (p134)
Explain why they are arranged in this way.
Draw a diagram of the arrangement of these
vessels in the root of the plant. (p131)
Give a reason for this arrangement.
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•
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Which tubes carry water in plants? Xylem
Which tubes carry sucrose in plants?
Phloem
Stem: Explain why they are arranged in this
way.
Reduce water loss through stem
Leaves:Explain why they are arranged in
this way.
Reduce water loss through leaf
Root:Give a reason for this arrangement.
Move water away from root hair to preserve
water potential gradient
Lesson objectives
Know the functions of xylem and
phloem tissues
Know the arrangement of Xylem and
Phloem vessels in the roots and leaves,
and the reasons for them
Be able to Identify the key parts of
xylem and phloem on diagrams
Understand how xylem vessels are
formed
Using Fg10.7 P133 and Fig 10.15
p140 answer the following
questions
1. Which type of vessel have
organelles?
2. Which organelles are missing from
the vessel?
3. Are a) xylem and b) phloem alive or
dead? Explain your answer
1. Which type of vessel have organelles?
Phloem
1. Which organelles are missing from the
vessel?
Nucleus; RER/ribosomes; vacuole
(tonoplast);
1. Are a) xylem and b) phloem alive or dead?
Explain your answer
a) Dead – nothing in them to maintain life
b) Alive – however cannot survive without
companion cells
Xylem formation – Quick study
A series of normal plant cells (end to end)
Lignin deposits in the cell walls
(impermeable and waterproof) continues
through time
Pits form where no lignin is laid due to
plasmodesmata
Due to lack of essential substances, contents
of the cell die
End sections of the cells break down,
causing a tube like structure to form
Normally a tube like this would collapse in on
itself, however the lignin gives support which
prevents this
Spend 5 minutes adding to
your notes on Xylem – page
133/4
It is obvious who is showing
commitment to their studies
Phloem – quick study
Living cells which are lined up end to end (called
sieve elements)
Small pores/gaps in the end parts of the cells which
allow substances to pass through (sieve plates)
Very small amount of cytoplasm arranged around
the edge of the cell
No nucleus or ribosomes (no protein synthesis)
Companion cells lined up alongside sieve elements
and are linked/connected to them. These cells
provide the things that the sieve element cannot
provide for themselves (many mitochondria and
ribosomes)
Spend 5 minutes adding to
your notes on Phloem – Page
140
Lesson objectives – have we met
them????????
Know the functions of xylem and
phloem tissues
Know the arrangement of Xylem and
Phloem vessels in the roots and leaves,
and the reasons for them
Be able to Identify the key parts of
xylem and phloem on diagrams
Understand how xylem vessels are
formed
Plenary – link the structure to
the description
Xylem
Living cells which have no nucleus or
ribosomes, whose cell walls develop
gaps/pores in their ends
Sieve tube
element
Closely associated with another cell,
death usually leads to death of
associated cell Dense cytoplasm with
the usual organelles.
Metabolically very active
Companion
cell
Elongated and lignified dead cells with
empty lumens. Formed by fusion of
many cells