Bell task

1
Bell task

• What are plasmodesmata?
• What is transpiration?
• What is translocation?

2
Starter answer the following questions -
sentences

• 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.

3

• 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
• LeavesExplain why they are arranged in this way.
• Reduce water loss through leaf
• RootGive a reason for this arrangement.
• Move water away from root hair to preserve water
  potential gradient

4
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

5
Using Fg10.7 P133 and Fig 10.15 p140 answer the
following questions

• Which type of vessel have organelles?
• Which organelles are missing from the vessel?
• Are a) xylem and b) phloem alive or dead? Explain
  your answer

6

• Which type of vessel have organelles?
• Phloem
• Which organelles are missing from the vessel?
• Nucleus RER/ribosomes vacuole (tonoplast)
• Are a) xylem and b) phloem alive or dead? Explain
  your answer
• Dead nothing in them to maintain life
• Alive however cannot survive without companion
  cells

7
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

8
Spend 5 minutes adding to your notes on Xylem
page 133/4
It is obvious who is showing commitment to their
studies
9
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)

10
Spend 5 minutes adding to your notes on Phloem
Page 140
11
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

12
Plenary link the structure to the description
Living cells which have no nucleus or ribosomes,
whose cell walls develop gaps/pores in their ends
Xylem
Closely associated with another cell, death
usually leads to death of associated cell Dense
cytoplasm with the usual organelles. Metabolically
very active
Sieve tube element
Elongated and lignified dead cells with empty
lumens. Formed by fusion of many cells
Companion cell