vascular bundles

• Where are the xylem and phloem tissue found?

  in vascular bundles
• Where are vascular bundles located ?

  their location is dependent on which organ they're in as different organs are under different stresses
• In the roots, where is the vascular bundle located?

  the vascular bundle is located in the centre and the centre core of this is xylem tissue and the phloem tissue is found on the outside(closest to the epidermis)

  this helps the roots withstand the pulling strains that occur as the plant transports water upwards and grows

  the xylem tissue is the strongest so is in the centre - X structure, phloem is in four seperate sections?
• Where are vascular bundles located in the stems?

  around the outside

  xylem tissue is found on the inside, closest to the centre of the stem, to help support the plant

  phloEM on the outside (stEMs - EM on the outside)
• Where are vascular bundles located in the leaves?

  the vascular bundles form the midrib and veins and therefore spread from the centre of the leaf in a parallel line. the xylem tissue is found on the upper side of the bundles (closest to the upper epidermis) leaF- rooF- xylem is located on top of the phloem

  this only applies to dicotyledonous plants
• What are similarities of the structure of the xylem and phloem?

  both made up of cells joined end to end

  xylem vessels and phloem sieve tube elements both lack nuclei

  both are complex tissues made up of more than one cell type
• What are differences between the structures of xylem and phloem?

  xylem contains lignin, phloem isn't lignified, only contains cellulose

  xylem has a wider lumen, phloem has a smaller lumen

  xylem is a continuous tube, phloem has sieve plates

  xylem has no companion cells, phloem has companion cells

  xylem has bordered pits, phloem doesn't have pits

  xylem has no cytoplasm, phloem has cytoplasm and (named) organelles

  xylem doesn't have sieve tube elements, phloem does
• what type of cell makes up the cambium?

  meristem
• what is the procedure of observing the positions of xylem vessels in the leaf stalks of celery?

  put the stalks in dye or food colouring

  then transversely cut a thin cross section

  add a stain e.g methylene blue and observe with microscope under low power
• what are similarities between the xylem and phloem?

  both are made up of cells joined end to end

  xylem vessels and phloem sieve tube elements both lack nuclei

  both are complex tissues made up of more than one cell type
• what are differences between the xylem and phloem?

  xylem has lignified walls, phloem only contains cellulose

  xylem has a wide lumen, phloem has a small lumen

  xylem has no end walls, phloem has sieve plates

  xlyem doesn't have companion cells, phloem does

  xylem has vessels, phloem doesn't

  xylem doesn't have sieve tube elements phloem does
• xylem features on a diagram?

  vessel wall

  vessel lumen

  bordered pit
• what is the structure and function of the vascular system in the stem?


  phloem on the outside

  xylem on the inside of the bundle to provide support and flexibility

  layer of meristem cells that produce new xylem and phloem tissue when needed
• how can you observe the position of xylem vessels in the leaf stalks of celery?


  put the leaf stalks in dye/food colouring

  then cut transversely / a cross-section

  then add a stain

  observe with microscope under a low power
• why don't allow air to enter system?

  ensures continuous cloumn of water