Xylem & Phloem Diagram IGCSE Biology 0610

Xylem and Phloem Diagram: Vascular Tissue Structure

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.

Key diagram

Xylem vessels are hollow, dead tubes with lignified walls that transport water and mineral ions upward. Phloem sieve tubes are living cells with sieve plates that transport dissolved sugars in both directions.

Xylem and phloem diagrams test whether students can link structural features to transport functions. Questions commonly ask for labelled cross-sections of a stem or for a comparison of the two tissue types.

Drawing xylem vessels

Draw xylem vessels as wide, hollow tubes with thick walls. The walls should be drawn with a distinct pattern to show lignin thickening: draw spiral or ring patterns on the walls. Xylem vessels are dead and hollow (no cytoplasm or end walls), forming a continuous tube from root to leaf.

Label the lignified wall, the hollow lumen and note that there are no end walls between vessel elements. The lignin provides strength and waterproofing.

Drawing phloem sieve tubes

Draw phloem as narrower tubes with thin walls. At intervals along the tube, draw perforated cross-walls called sieve plates. Adjacent to each sieve tube element, draw a smaller cell with a visible nucleus: this is the companion cell. Sieve tube elements are living but have no nucleus; they rely on companion cells for metabolic support.

Transport functions

Xylem carries water and dissolved mineral ions from the roots to the leaves. The flow is one-directional: upward only: driven by transpiration pull. Phloem carries dissolved sugars (mainly sucrose) and amino acids from sources (leaves) to sinks (growing points, storage organs, roots). Phloem transport is called translocation and can move substances in both directions.

Cross-section of a stem

In a cross-section of a dicotyledonous stem, xylem and phloem are found together in vascular bundles. Xylem is on the inside (towards the centre) and phloem is on the outside. Between them may be a layer of cambium cells. Drawing the xylem closer to the centre and phloem closer to the outer edge is essential for earning the mark.

Label checklist

Check these labels are present and correctly positioned before finishing your drawing.

✓ Xylem vessel
✓ Lignified wall
✓ Hollow lumen (no end walls)
✓ Phloem sieve tube
✓ Sieve plate
✓ Companion cell
✓ Vascular bundle

Try a diagram question (4 marks)

Compare the structure of xylem vessels and phloem sieve tubes. [4]

Show the answer and marking guidance

Xylem vessels are dead; phloem sieve tubes are living.
Xylem vessels have lignified walls; phloem has thin cellulose walls.
Xylem vessels have no end walls; phloem has sieve plates.
Xylem vessels are hollow with no cell contents; phloem sieve tubes have cytoplasm but no nucleus.

Original Cambridge-style practice written for this site.

Common diagram mistakes

Check these against your own drawing before moving on.

Saying phloem is dead: phloem sieve tube elements are living cells.
Forgetting sieve plates when drawing phloem.
Drawing xylem and phloem the same width: xylem vessels are wider.
Stating phloem only transports downward: it moves in both directions.
Omitting companion cells from the phloem diagram.