IGCSE Biology glossary
Phloem
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A plant transport tissue that carries dissolved sugars (mainly sucrose) and amino acids from sources (such as leaves where they are made) to sinks (such as roots, fruits and growing tips where they are used or stored). This transport is called translocation.
What to include in an exam answer
Phloem transports in BOTH directions (up and down). Phloem contains living cells (sieve tube elements and companion cells). Contrast with xylem: phloem cells are alive, xylem cells are dead.
Example in context
Compare the structure of xylem and phloem (2 marks): Xylem vessels are made of dead cells with lignified walls and no end walls. Phloem sieve tubes are made of living cells with perforated end plates (sieve plates) and companion cells.
Related syllabus topic
Transport in plants