Edexcel IGCSE Biology: Double Science 复习笔记 2.8.2 Transport Systems in Flowering Plants

• The roots, stem and leaves form a plant organ system for the transport of substances around the plant
• Plants also possess two specialist transport vessels called the xylem and phloem
• The xylem and phloem are arranged throughout the root, stem and leaves in groups called vascular bundles

Structure and function of the xylem

• Xylem vessels transport water and minerals (pronounced: zi-lem) from the roots to the stem and leaves
• The xylem has some key structural features
  • It is composed of dead cells which form hollow tubes
  • Xylem cells are strengthened by lignin and so are adapted for the transport of water in the transpiration stream

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