Xylem & Phloem (Cambridge (CIE) IGCSE Biology): Revision Note

The xylem & phloem

What is the function of the xylem and phloem

• Plants contain two types of transport vessel:

  • Xylem vessels (pronounced: zi-lem) transport water and minerals (opens in a new tab) roots to the stem and leaves

  • Phloem vessels (pronounced: flow-em) transport food materials (mainly sucrose and amino acids) (opens in a new tab) made by the plant from photosynthesising leaves to non-photosynthesising regions in the roots and stem

• These vessels are arranged throughout the root, stem and leaves in groups called vascular bundles

Adaptations of xylem vessels: Extended

• Function: transport tissue for water and dissolved mineral ions

• Adaptations:

  • Cells joined end to end with no cross walls to form a long continuous tube

  • Cells are essentially dead, without cell contents, to allow free passage of water

  • Outer walls are thickened with a substance called lignin, strengthening the tubes, which helps support the plant