The Xylem and Phloem (SQA National 5 Biology): Revision Note

The role of the xylem is to transport water and mineral ions from the roots to other parts of the plant

• Water enters the plant via the roots hairs and moves through the root and up the stem in the xylem vessels

Xylem are formed from dead cells, with walls that contain a material called lignin

• The dead cells result in a hollow tube

• Lignin reinforces the cells and prevents breakage

The role of the phloem is to transport sugars and amino acids up and down the plant, from where they are produced or stored, to where they are needed

• E.g. sugars and amino acids are produced in the leaves when plants photosynthesise, so they are transported from the leaves to other parts of the plant in the phloem

The phloem is formed from living cells that line up end-to-end; the end plates of these cells contain holes to allow the passage of sugars